NC State Extension Publications

Pickling and slicing cucumbers are major crops in North Carolina with 27,000 to 36,000 total acres planted yearly. North Carolina cucumber acreage is concentrated in the central coastal plain, with substantial fresh-market production also located south of Asheville (Figure 1). Both pickling and slicing cucumbers have been included in this bulletin because many production practices are similar for both types. When necessary, distinctions are made between the cucumber types.

Figure 1. Shaded counties indicate the primary areas of cucumber production.

# Pickling Cucumbers

"Pickling" refers to cucumbers that are primarily used for processing or pickling. Pickling cucumbers have thin skins, are short and blocky, and usually have a color gradient from dark green at the stem end to light green at the blossom end. In addition, a pickling cucumber fruit has a whiter or lighter green belly (where fruit and soil are in contact) (Plate 1) than does a slicing cucumber (Plate 2).

In North Carolina, pickling cucumber acreage has fluctuated during the past 10 years with approximately 22,000 to 28,000 acres planted. In 1994, North Carolina led the nation in harvested pickling cucumber acreage (25,000 acres) and accounted for about 22% of US production acreage (USDA 1995). Other states leading in pickling cucumber production (based on harvested acreage) are Michigan (21%), Texas (12%), South Carolina (7%), Wisconsin (5%), California (4%), and Ohio (3%) (USDA 1995).

Pickling cucumber production has changed in the last 15 years. In eastern North Carolina, pickling cucumbers are a popular crop on tobacco farms, which usually have a labor surplus during June, the month with the most concentrated cucumber harvest. Traditionally, pickling cucumbers were grown on small acreages (less than 10 acres) with no irrigation and few inputs other than labor. Many tobacco farmers are now growing large acreages to diversify their farming operations and increase revenues. With the uncertain future of tobacco, these farmers have intensified their production practices for vegetables such as cucumbers to increase yield and profits. Most successful cucumber growers carefully follow recommended production procedures that result in substantial dollar returns (see Marketing section for more information).

Plate 1. Pickling cucumbers.

Plate 2. Slicing cucumbers.

# Slicing Cucumbers

"Slicing" refers to cucumbers sold fresh for immediate consumption usually as a salad item. Characterized by thick, uniform, dark green skins, slicing cucumbers are longer than pickling types, and their thicker skins are more resistant to damage during handling and shipping (Plate 2).

In North Carolina, slicing cucumber acreage has ranged from 5,000 to 8,000 acres during the past 10 years, depending on season and market conditions. In 1996, harvested slicing cucumber acreage (6,000 acres) in North Carolina accounted for approximately 10% of the US production acreage (Food Institute and Research Center 1996). More recently, a larger percentage of growers are producing and selling pickling cucumbers for fresh-market sales. There is a demand by certain markets for the fresh thin-skinned cucumbers which are often placed in cello packages. Most fresh-market cucumber acreage in the United States is concentrated in the South, as well as in California and Michigan (USDA 1995).

# General Cultivar (Variety) Considerations for Pickling and Slicing Cucumbers

Proper cultivar choice is important for successful cucumber production and marketing. Characteristics important in choosing a cultivar are market acceptance, yield, fruit quality, adaptability to environment/growing region, and disease resistance.

Market acceptance. Growers should select cultivars that meet the criteria set by specific end users.

Yield. For maximum profit, yield is an important consideration regardless of cucumber type. Yields and profits can be much greater and consistent over seasons with proper use and management of soils, fertilization, irrigation, bees, fertigation (fertilizer applied with water through the drip tube), plastic mulch, and pest management.

Fruit quality. Fruit quality (color, shape, diameter, and length) must meet market standards. All cucumber cultivars have black or white spines on the fruit surface. Black-spined cultivars turn orange or yellow, often prematurely, under the high temperatures found in North Carolina. Because of this, the most popular cultivars have white spines. Fruit must be straight and uniform. Culls include curved, pointed, and constricted fruits (Figure 2).

Adaptability. A cultivar must grow well and yield high-quality fruit under the varied environmental conditions of a production area. Many pickling and slicing cucumber cultivars and experimental lines have been extensively tested in eastern North Carolina. Testing in western North Carolina has been limited. Yield and quality results for a given planting may vary considerably because each growing season is different. Lists of the best-adapted pickling and slicing cultivars have been developed based on replicated tests and field observations (Tables 1 and 2, below). Try new cultivars on a limited basis to be sure they meet quality, yield, and market expectations.

Disease. Disease resistance is an important consideration. Normally, disease incidence increases as the season progresses. Thus, growers may need to choose a cultivar with high disease resistance at the expense of some yield or quality. Cucumber diseases occurring frequently in North Carolina are mosaic viruses, gummy stem blight, anthracnose, angular leaf spot, target spot, root-knot, belly rot, and damping-off (see the Disease Management section for more detail).

Figure 2. Curved (crook) and pointed (nub) fruit.

# Pickling Cultivars

Market acceptance. Pickling cucumber cultivars vary widely in fruit size and color as well as other characters. Because certain pickling cucumber cultivars are used for packing a specific product, processors designate the cultivars grown by buying seed and providing it to their growers for a fee.

Yield. Average yield for pickling cucumbers in North Carolina is 200 to 250 bushels per acre. Yields of 500 to 600 bushels per acre are readily obtainable with good production practices and favorable growing conditions.

Fruit quality. Grades are determined by diameter. Processors need dependable cultivars that produce a blocky rather than tapered fruit and a consistent length-to-diameter ratio. For pickling cucumbers, length requirements are met by growing cultivars with a given length-to-diameter ratio (see cultivar recommendations, Table 1). Culls include curved (crooks), and pointed (nubs) fruits (Figure 2).

Disease. Disease resistance is quite similar among recommended pickling cucumber cultivars (Table 1).

Table 1. Recommended pickling cucumber cultivars for North Carolina.
Cultivar Fruit L/Da Colorb Yield Potentialc Commentsd
Atlantic long medium medium machine only, MR
Calypso medium medium medium hand, MR, NC standard cultivare
Cross Country medium-long dark high hand/machine, tolerates excessive rain, MR
Discover long medium high machine, S
Excel long medium medium machine (performed well under DE growing conditions), HR
Fancipak medium medium medium hand, MR
Flurry medium-long medium medium hand/machine, MR
Jackson medium dark medium hand, very short-vined, S
Lafayette long medium medium machine, HR
Napoleon medium-long very dark high easier hand harvest, short-vined, lower seedling vigor, S
Navigator short-medium dark medium hand, high-quality fruit for processing, MR
Quest medium medium medium hand, MR
Regal long medium high machine, MR
Royal long medium medium machine, HR
Shenandoah medium-long medium medium hand/machine (similar to Cross Country), HR
Vlaspik long medium medium machine, MR
Vlasset medium dark medium hand, strong vine, MR blocky, high-quality fruit, HR
Vlasstar medium-long dark high hand/machine, MR
Wellington medium-long medium medium hand/machine, short-vined, long, small-sized fruit, HR
a Fruit L/D ratio was measured as length over diameter and was determined using five 2B-size fruits. Short-medium = 2.6 to 2.8, medium = 2.8 to 3.0, medium-long = 3.0 to 3.2, long = 3.2 to 3.5.
b Color: Dark green fruit might be more suitable than medium green fruit for fresh-market sales.
c Yield potential: Medium indicates that consistent good yields can be expected, yet they typically are somewhat lower than high-yield-potential cultivars.
d Indicates suitability for hand or machine harvest, shorter vines for easier harvest, and other pertinent characteristics. Anthracnose resistance: HR = high resistance, MR = moderate resistance, S = susceptible. (Contact your county Extension center for cultivar updates.)
e Fruit length, color, and yield relative to Calypso, a standard pickling cultivar grown in North Carolina.

# Slicing Cultivars

Market acceptance. Cultivars should be chosen and a seed source identified several months before planting to ensure availability of high-quality seed. Slicing cucumbers must meet the standards set by the packer, wholesaler, retailer, and consumer. Thus, growers should investigate these standards before choosing a cultivar.

Yield. Average yield for slicing cucumbers in North Carolina is 200 to 250 bushels per acre, but better yields (600 to 650 bushels per acre) can be obtained when growing a crop on plastic which is fertigated.

Fruit quality. High-quality fruit must always be packed according to end-user specifications. (Specific grades are discussed in the Grades section of this publication.)

Disease. There are some differences among slicing types noted in the comments in Table 2.

Table 2. Recommended slicing cucumber cultivars for North Carolina.
Cultivar Fruit Lengtha Earlinessb Yield Potentialc Commentsd
Centurion medium-long M medium spring/fall
Dasher II medium-long M high NC standard cultivare
Daytona (trial, 1998) medium-long M high ZYMV, PRSV, WMV
General Lee medium-long M high spring/fall
Indy (trial, 1998) medium-long M high ZYMV, PRSV, WMV
Lightning long E high dark green
Meteor medium-long M medium angular leaf spot
Pointsett 76 medium L medium monoecious, open-pollinated, most Southern foliar leafspot resistant slicer cucumber, fall planting
Revenue long M medium spring/fall
Slice Nice medium-long M medium spring/fall
Speedway medium E high spring
Striker M long L medium spring/fall
Thunder long E high less vine mass
Turbo medium-long L high spring/fall
a Fruit length: medium = 7.5 to 8 inches, medium-long = 7.8 to 8.2 inches.
b Refers to time when most fruit maturity occurs relative to Dasher II: E = early, M = midseason, L = late.
c Yield potential: Medium indicates that consistent good yields can be expected, yet they typically are somewhat lower than high-yield potential cultivars.
d Indicates superior disease resistance (ZYMV = zucchini yellow mosaic virus, PRSV = papaya ringspot virus, WMV = watermelon mosaic virus) and best seasons for planting (Contact your county Extension center for cultivar updates.)
e Fruit length, earliness and yield relative to Dasher II, a standard slicing variety for North Carolina.

# Factors That Affect Flowering of Pickling and Slicing Cucumbers

Commercially grown cucumbers are predominantly gynoecious or monoecious. Predominantly gynoecious cultivars produce mostly female flowers. Monoecious cultivars produce a similar proportion of male and female flowers. A seed blend of 85% to 90% predominantly gynoecious cultivar plus 10% to 15% monoecious cultivar results in high yields, good pollination, and quality fruit (Miller 1976). This ratio provides the optimum proportion of male flowers for pollen production, and female flowers for fruit production (Plate 3). For more detailed information on terminology and plant types, see the Terminology and Application section of this publication.

Certain stressful environmental conditions influence the proportion of male and female flowers produced on cucumber plants. Conditions that can influence those proportions are plant density (Lower et al. 1983; Nienhuis et al. 1984), plant damage (Cantliffe and Omran 1981), low light intensity and temperatures (Tiedjens 1928; Cantliffe 1981). Yields may be reduced due to the production of more male flowers, fewer female flowers, or both. For example, high plant populations may stress the plants for water, nutrients, or light and cause an increase in the number of male flowers. Injury caused by insect feeding or blowing soil or a combination of low-light and high-temperature conditions (this may occur in the fall) may also reduce the number of female flowers.

Ethrel and other chemicals have been used to increase female flowering and fruit set (Cantliffe and Phatak 1974; Cantliffe and Phatak 1975). However, these treatments are not always effective nor are their effects consistent due to varying environmental conditions and different stages of plant growth at time of application. Most recommended cultivars today are predominantly gynoecious and produce nearly all female flowers. Mistakes in production (e.g., overplanting, lack of timely irrigation, etc.) often cause too few female flowers or too many male flowers to be produced. If a stressful environment causes an overabundance of male flowers, the situation will usually correct itself in more favorable weather. Once excessive male flowering is discovered, it is usually too late to correct the flowering imbalance problem by spraying Ethrel. The use of Ethrel for inducing female flowering is not recommended for commercial cucumber production.

Plate 3. Male flower (far left) and female flower development (remaining).

# Site Selection and Preparation for Pickling and Slicing Cucumbers

Soil type. Cucumbers are adapted to a wide range of soils, but grow best on fertile, well-drained, loamy soils. Plantings on poorly drained soils can result in significant plant loss (Plate 4). Soil type should be as uniform as possible within a field so that plant establishment, crop development, and harvest are also uniform. If you are considering once-over destructive harvest of pickling cucumbers, this is especially critical because fruit development must be at the same stage to achieve profitable yields. Sandy, well-drained soils warm early in the spring, resulting in early production. They often allow mechanical operations for harvest the day after a rain. These soils require frequent irrigation and careful fertilizer management. Cucumbers grown in soils high in organic matter (e.g., Blacklands in eastern North Carolina) have the advantage of good nutrition and increased water-holding capacity; however, the soil tends to stick to fruit after harvest.

Soil and nematode samples. At least four months before planting (the fall before planting season is preferable), a soil analysis and a nematode assay should be made to determine fertilizer and fumigation needs. Root-knot nematode populations generally increase as the growing season progresses. The nematode assay is an inexpensive way of predicting yield and profit loss from nematode damage. For best results, ask your county Cooperative Extension agent for instructions on getting a proper sample and interpreting the test report. Samples can be submitted to:

Agronomic Division
(Soil or Nematode Lab)
North Carolina Department of Agriculture & Consumer Services
Raleigh, NC 27607-6465

(Specify on the envelope whether the sample should be delivered to the Soil or the Nematode Lab.) To get accurate results, sample carefully. Test results can be used to prescribe fumigant and fertilizer needs.

Weeds. Choose fields that do not contain high populations of yield-reducing weeds such as common cocklebur, nutsedge, morningglory, or sicklepod. Previous cropping history is also important as some fields may contain residues of herbicides used in previous crops. There are several herbicides that could cause severe cucumber injury or reduce plant stands and yield due to carryover. Atrazine, Canopy, Pursuit, Scepter, Squadron, and Zorial are examples of herbicides that should not be followed by cucumbers for 12 to 24 months. A tobacco sucker control, PrimePlus, can cause injury to cucumbers, especially when high rates were used the previous year. Follow the herbicide label carefully to avoid carryover injury.

Rotation. Crop rotation is another important consideration. Cucumbers should not be planted within at least two years of a crop of cucurbits (cucumbers, squash, melons, watermelon, or gourds). Plant residue from these related crops serves as a host for plant diseases and insects that may infect or infest the next crop. Recommended rotation crops include cabbage, collards, sweetpotato, sweet corn, tobacco, wheat, rye, corn, or other grain crops.

Tillage. Plant debris should be turned and completely buried at the bottom of the furrow to facilitate decomposition. A well-tilled field will help produce a smooth, fine seed bed for uniform planting and emergence. Several weeks before planting, ridges approximately 6 to 8 inches high should be formed to insure adequate moisture for seed germination and emergence, to improve drainage after heavy rains, and to help warm the soil (Figure 3). Ridging also facilitates cultivation, which is usually necessary. Tillage should not be done when soil is heavy or wet; soil structure is impaired resulting in compaction, poorer drainage, and crusting.

Plate 4. Cucumber field showing poor drainage.

Figure 3. Ridging bed prior to planting provides many benefits: improved stand establishment, drainage, and soil warming.

# Fertilization for Pickling and Slicing Cucumbers

Tissue samples. Fertilizer requirements for cucumbers will vary widely depending on soil fertility, soil type, and fertilization of the previous crop. Plant tissue analysis can be beneficial in diagnosing or preventing nutrition problems. To take a tissue sample, remove the first fully expanded leaf behind the growing point (terminal leaf) of the cucumber plant (Figure 4). About 10 leaves should be collected in a similar manner to create a representative sample of the planting or problem plants in the field. Samples can be submitted for analysis to the North Carolina Department of Agriculture & Consumer Services (NCDA&CS) in Raleigh for a nominal fee. Submit samples to:

Agronomic Division
Attention: Tissue Lab
North Carolina Department of Agriculture & Consumer Services
Raleigh, NC 27607-6465

The foliar sufficiency range for cucumber is given for the major and minor nutrients in Table 3. Tissue samples should be taken every two weeks starting three to four weeks after planting to monitor crop nutrient status.

Table 3. Foliar nutrient sufficiency range for cucumber.
Major Nutrient Percent
Nitrogen 5.0-6.0
Phosphorus 0.3-1.0
Potassium 4.0-5.0
Calcium 1.2-3.5
Magnesium 0.3-1.0
Sulfur 0.2-0.8
Minor Nutrient Parts per Million
Boron 25-75
Iron 50-200
Manganese 25-200
Zinc 20-75
Copper 5-35
Adapted from Sanders et al. 1995.

Liming and pH. One of the most common causes of poor growth and low yield in cucumbers is unbalanced nutrition from low pH (acid) soils. Soil pH for a cucumber crop should be between 6.0 and 6.5. Liming is recommended for soils below pH 6.0. If lime is needed, incorporate it thoroughly at least two to three months before the expected seeding date. Dolimitic lime is a good lime source because it contains magnesium as well as calcium. Sufficient magnesium levels are necessary for deep green fruit color. If magnesium levels in the soil are adequate, calcitic lime can be used for raising the pH.

Minor nutrients. Cucumbers also need small quantities of micronutrients (minor nutrients) for normal plant growth and development. Manganese and zinc can be deficient in mineral soils, while copper tends to be deficient more often in soils high (5% to 10%) in organic matter. Boron is leachable and may be deficient in some North Carolina soils. Micronutrients should only be applied as indicated by soil and plant tissue testing results because high rates are often toxic. If needed, micronutrients can be broadcast before planting or applied foliarly during the growing season. Broadcast application involves spreading fertilizer over the entire field and incorporating it into the soil. Broadcast application before planting is preferred because plants take up nutrients more readily through the root system than the leaves. An adequate supply of these nutrients is then available to the seedling at planting.

Major nutrients. The major nutrients, or macronutrients, required for plant growth are nitrogen (N), phosphorus (P), potassium (K), calcium, magnesium, and sulfur. Soil test results should be used to customize a fertilizer program resulting in economic and environmentally safe use of fertilizer. In most sandy soils in North Carolina, growers should consider using supplemental sulfur. In a typical situation, 20 to 30 pounds per acre of sulfur broadcast is sufficient. Sources of sulfur are ammonium sulfate, potassium sulfate, gypsum, superphosphate, or elemental sulfur. For magnesium, magnesium sulfate could be used rather than dolimitic lime. Gypsum, lime, or calcium nitrate can be used as a supplemental calcium source.

The fertilizer program described in Table 4 will meet N, P, and K fertilizer requirements of cucumbers grown on most soils in North Carolina. The program recommends using either broadcast application before planting (option 1) or sideband application before or at planting (option 2). Some fertilizer is wasted with broadcast application because some fertilizer is placed between rows, in ditches, and on field borders. Injury, however, is less likely because fertilizer is incorporated evenly throughout the bed.

Sideband or sidedress application is more efficient than broadcast application because it involves placing fertilizer precisely near the seed or developing plant. This reduces fertilizer leaching and waste, but is less forgiving of error in application rate.

Starter fertilizer. Seedling emergence and early season growth can be improved by sidebanding a "starter" fertilizer containing phosphorus (30 to 40 pounds P2O5 per acre) 2 inches below and beside the seed and should be used in conjunction with option 2. Phosphorus, in particular, should be sidebanded near the seed drill because movement in the soil is limited. A starter fertilizer is especially helpful in improving plant stands and earliness under cool growing conditions.

Option 1 broadcast and a sidedress application. For most North Carolina soils, a preplant broadcast application (7 to 10 days before planting) of 80 to 100 pounds per acre each of nitrogen, phosphorus (P2O5), and potash (K2O) is usually adequate (Table 4). The fertilizer should be thoroughly incorporated in the soil. Following broadcast application, one sidedress band application is suggested just before layby (about four weeks after planting, before the vines begin to grow into the row middles). For sidedressing, there is no difference in crop response to liquid or dry fertilizer materials. Do not apply more than 40 pounds of nitrogen per acre as a sidedress application because plants can be burned or killed at higher rates. At least half of the nitrogen should be in the nitrate form to reduce the chance of foliar burn and blossom end rot.

Option 2 sideband and sidedress applications. If fertilizer is to be sidebanded, reduce nitrogen and potash preplant rates at least 50% (Table 4). At these rates of nitrogen and potash, fertilizer should be placed 3 to 4 inches to the side and 2 to 3 inches below the seed to prevent salt injury. An additional sidedress application is needed at the next cultivation (10 to 14 days after planting) to meet crop need for nitrogen and potash (approximate total of 70 pounds per acre). Just before the vining stage, regardless of whether you are using option 1 or 2, recommendations call for a final sidedress application of 20 to 30 pounds of nitrogen per acre. About 20 to 30 pounds per acre of potash may be beneficial in soils low in potassium.

 Nutrient Requirements Method Application Time N-P-K (lb/acre)a Option 1 - Initial Application Broadcast before Planting 1. Broadcast Preplant (7-10 days) 80-100 N, P and K 2. Sidedress Before vines fall over and run (before layby) 20-30 N and Kb Option 2 - Sideband Application 1. Sideband At planting 40 N and K 30-40 P (9-12 gal/acre 18-34-0 or 65-90 lb/acre 18-46-0) 2. Sidedress 10 to 14 days after planting 20-30 N and K 3. Sidedress Before vines fall over and run (before layby) 20-30 lb N and Kb a N = nitrogen, P = phosphorus (P2O5), K = potassium (K2O) b Only low in K2O soils

Late application with full-vine coverage. Supplemental nitrogen applications later in the season may still be warranted because of heavy rainfall or a long harvesting period. Application of nitrogen, or any other fertilizer material, over the top of growing plants is extremely hazardous because fertilizer particles remaining on the leaf will burn the plant tissue. If supplemental fertilization is needed to sustain plant growth and fruit production when soil is completely covered with vines, it should be applied when the foliage is dry to reduce foliage injury. Use a conservative rate of fertilizer with a low salt index (e.g., 200 pounds per acre calcium nitrate), and irrigate immediately after application to minimize foliage burn.

Fig. 4. The first fully expanded leaf indicated by arrow) behind the growing point should be used for foliar tissue analysis.

# Planting of Pickling and Slicing Cucumbers

Temperature. Cucumbers require warm temperatures for maximum growth and production. The crop grows and yields best when germination is quick and growth is rapid. Cucumber seed will not germinate when soil temperatures are below 60°F. Some weeds germinate at a lower temperature, which makes their control more difficult. Daily average soil temperatures 3 to 4 inches deep should be over 60°F at planting. This means that the highest daytime soil temperature and lowest nighttime temperature, when added together, should total 120°F or more for 7 consecutive days. About 9 to 16 days are required for seedlings to emerge at slightly above 60°F, but only 5 to 6 days are required at 70°F. Optimum temperature for plant growth is between 65°F and 75°F (Lorenz and Maynard 1980).

A light frost is very damaging to cucumbers and can severely retard plant growth and reduce yield. Even temperatures below 40°F after plants have emerged can result in chilling injury and can stunt cucumber growth. In a cucumber field, chilling injury is easily diagnosed by leaves and cotyledons that are chlorotic or white.

Seed quality. To obtain the most vigorous, best germinating seed, purchase new seed every year. If you plan to store seed for the next year, store it in dry (25% to 40% relative humidity), cool (38 to 50°F) conditions. Percentage germination and seed vigor are reduced if seed is stored for more than one year (Haanwen et al. 1995). A germination test should be done before planting old seed to ensure a good plant stand. The Seed Testing Laboratory of the North Carolina Department of Agriculture & Consumer Services will also test your seed for free. Send samples to

North Carolina Department of Agriculture & Consumer Services
Plant Industry Division
Seed Section
216 West Jones Street
Raleigh, NC 27611

Seed count. Seed count for most cucumbers is about 16,000 seed per pound or 1,000 seed per ounce. The amount of seed needed will depend on the plant spacing, which depends on method of harvest; method of growing (soil or plastic mulch); type of cucumber; and type of seeder used. For traditional plantings for hand harvest, approximately two pounds of seed per acre is needed to establish a good cucumber stand.

Sowing seed. Plant cucumber seeds 12- to 34-inch deep. Deeper seeding may result in delayed and nonuniform emergence and reduced plant stands. Soils should have ample moisture at planting. Dry soils should be irrigated before sowing to facilitate fast, uniform plant emergence. A surface crust can form in soil making seedling emergence difficult, particularly after a heavy rain or if spray-gun irrigation equipment is used. In such cases, light cultivation or irrigation to break or soften the soil crust will help seedlings emerge.

Precision seeding. Hybrid seed is expensive. Precision seeding can significantly reduce costs by reducing the amount of seed needed because individual seeds are placed at a precise depth and spacing. In addition, precision seeding improves plant uniformity, which leads to better plant stands, uniform harvest (note, this is particularly important for once-over harvest), and increased yields. Also, the requirement for plant thinning is eliminated.

High-quality seed must be used along with proper land preparation to maximize the benefits of precision seeding. Sufficient moisture must also be provided for the planted seed. Good establishment practices must be carefully followed to assure a complete, uniform plant stand.

Belt, plate, and vacuum precision seeders are suitable for planting cucumbers. With belt seeders (e.g., Stanhay), circular holes are punched at intervals along a belt to achieve desired spacing. Pelleted seed (seeds encased in an inert material and made round for easy planting) should be used with belt planters to obtain better singulation (one seed as opposed to two or more seeds sown at a specific depth and distance apart). Although singulation is improved with pelleted seeds, they are bulky and cost more than seeds that have not received this treatment. Seeding is much slower with a belt seeder than with a plate or vacuum seeder; however, it is more accurate than a gravity feed seeder (e.g., Planet Jr.).

With plate-type seeders (e.g., John Deere 33), seed catch on a notch in the plate, then drop from the seed hopper to the ground. Spacing can be adjusted by gearing the rate at which the plate turns. Some precision is lost due to the long drop of the seed from the hopper to the ground.

A vacuum seeder (e.g., Stanhay, Monosem, Gaspardo, John Deere) provides very accurate precision seeding. The vacuum column holds a seed against a vertical plate with holes. When the vacuum is broken, the seed is dropped. The seeder employs various mechanisms to remove excess seed and drop one seed per vacuum hole (singulation). The number of holes per plate, as well as gearing, can be varied to achieve desired spacing. Spacing (plant population density) is most easily adjusted with this type of planter.

# Plant Spacing/Population for Hand-Harvested Pickling and Slicing Cucumbers

Best plant spacing will vary considerably depending on harvest method and cultural practices (Table 5). Under conventional hand-harvest culture, row widths may vary from 30 to 48 inches (Table 6). Most prevalent are 36- to 42-inch rows with plants 6 to 8 inches apart in the row. With irrigation, regardless of row width, growers should strive for 30,000 plants per acre for pickling cucumbers and 25,000 plants per acre with slicing cucumbers. This will require approximately two pounds of seed per acre. Higher plant populations can sometimes result in plant stress due to inadequate nutrition and moisture. High plant populations can also result in short fruit with light color, and dense vine growth can make harvest difficult. Thinning, however, should only be done in extreme cases of overpopulation.

Table 5. Recommended plant population, spacing, and quantity of seed for multiple-hand harvest on bare soil and plastic-mulched soil, and once-over machine harvest on bare soil.
Harvest/Culture Plant Population 1,000/acre Spacing (inches) Seed lb/acre
In-row Between-row
Hand/Soil 25-30 5-10 30-48 2
Hand/Plastic 20-30
double row (18 inches between rows on bed)
10-14 60 2
Machine/Soil 50-70 3-4 24-28 4-5

Table 6. Number of plants per acre (in thousands) by between-row and in-row spacing.
Between rows (inches) In-row inches
3 4 5 6 7 8 9 10
24 87.1 65.3a 52.3a 43.6 37.3 32.7 29.0b 26.1b
30 69.7a 52.3a 41.8 34.8 29.9b 26.1b 23.2 20.9
36 58.0a 43.6 34.8 29.0b 24.9b 21.8 19.4 17.4
42 49.8 37.3 29.9b 24.9b 21.3 18.7 16.6 14.9
48 43.6 32.7 26.1b 21.7 18.7 16.3 14.5 13.1
a = approximate recommended plant populations per acre for once-over machine harvest
b = approximate recommended plant populations per acre on unmulched soil for hand harvest

# Plant Spacing/Population for Machine-Harvested Pickling Cucumbers

For once-over (machine) harvest, recommended plant populations are much higher (50,000 to 70,000 plants per acre) than for multiple-hand harvest (Table 5). Rows are usually planted 24 to 28 inches apart (three rows per bed) with plants spaced 3 to 4 inches apart in-row.

# General Considerations for Earliness

In most cases, little is gained by planting early in the spring, particularly for pickling cucumbers for which growers have a contract set price. The first harvest for pickling cucumbers in eastern North Carolina is usually June 1 to 5, while slicers are usually ready by June 10 to 15 if they are planted by mid-April. An early crop harvest might have a price advantage with fresh-market cucumbers for a short period of time. Special growing practices should be employed to achieve an early harvest.

# Earliness for Fresh-Market Pickling and Slicing Cucumbers

Early harvests can by achieved by use of containerized transplants, rye/wheat windbreaks, row covers, and plasticulture.

Transplants should only be considered if market considerations warrant (when profits exceed added transplant costs). Choose only containerized transplants with at least a 1.5-inch diameter cell size. Cucumbers are very sensitive to root disturbance so transplants should be handled very gently. Rough handling can result in severe stunting, thus losing the advantage of earliness. The use of transplants is not common due to the extreme sensitivity of cucumber transplants to rough handling.

Windbreaks, provided by seeding rye or wheat between every four to six rows in the fall, offer protection from cold prevailing winds and minimize sandblast injury to plants. Windbreaks also can improve earliness by reducing heat loss and plant injury and usually are not cut until about three to four weeks after seeding. Windbreaks can harbor aphids and thrips; growers should scout for these pests early in the season.

Row covers provide a warm microclimate and protection from light frost. However, they must be removed to allow bee flight and pollination. Black plastic, or infrared transmissible plastic, can be used for soil warming and weed control. When cucumbers are planted on plastic in early spring, generally 7 to 10 days earliness is gained.

# Scheduling Harvest for Pickling and Slicing Cucumbers

Favorable planting conditions usually occur between April 10 and 20 in the coastal plain of North Carolina, between April 21 to 30 in the central Piedmont, and between May 1 to 15 in the mountains and foothills (Figure 5). For optimum yield before frost, seeding for the fall crop should be completed by August 5 in eastern North Carolina, July 25 in the central Piedmont, and mid-July in western North Carolina. For more specific weather and climate information for your location, refer to bulletin AG-375, Weather and Climate in North Carolina (Epperson et al. 1988).

Plantings should be carefully scheduled so that labor and machinery are used efficiently and harvests from each planting will not overlap. Scheduling harvests can also result in more timely production for higher price market windows.

A heat unit (HU) model (Perry and Wehner 1996) has been developed which better predicts cucumber harvest dates than the standard model. A ceiling of 90°F is used in the new model because cucumber plant growth stops or is inhibited above this temperature. To compute HUs for each day, get the maximum air temperature for each day, then use one of the following equations:

1. If maximum air temperature is 90°F or lower
HUs = maximum temperature - 60°F
or
2. If maximum air temperature is equal to or higher than 90°F
HUs = [90-(maximum temperature - 90)] - 60

To use this model in North Carolina, growers must use tables of daily normal HU accumulation and the associated harvest dates. See Table 7 for a sample prepared for Clinton. To acquire the climatological data for your location, contact your county Extension center. Table 7 is designed for use with mid-season, pickling-type cultivars which have an HU target of 1,125. However, certain slicing and even some pickling-type cultivars may have different maturities. Thus, scheduling will need to be adjusted to HUs for a particular cultivar (Table 8).

Table 7. Predicted heat unit (HU) accumulation, harvest date, and total days from planting to harvest (DTH) for pickling cucumbers planted in Clinton, NC, from March 1 to September 2.
Planting Date HU Harvest Date DTH
March 1 149 May 2 81
March 2 155 May 2 80
March 3 161 May 2 79
March 4 168 May 22 79
March 5 175 May 22 78
March 6 182 May 22 77
March 7 186 May 22 76
March 8 192 May 23 76
March 9 198 May 23 75
March 10 202 May 23 74
March 11 209 May 23 73
March 12 216 May 24 73
March 13 225 May 24 72
March 14 237 May 25 72
March 15 247 May 25 71
March 16 256 May 25 70
March 17 262 May 26 70
March 18 266 May 26 69
March 19 273 May 26 68
March 20 281 May 27 68
March 21 290 May 27 67
March 22 297 May 27 66
March 23 301 May 28 66
March 24 308 May 28 65
March 25 315 May 28 64
March 26 322 May 29 64
March 27 328 May 29 63
March 28 337 May 29 62
March 29 346 May 30 62
March 30 358 May 30 61
March 31 370 May 31 61
April 1 384 May 31 60
April 2 397 June 1 60
April 3 412 June 1 59
April 4 428 June 2 59
April 5 443 June 3 59
April 6 454 June 3 58
April 7 465 June 3 57
April 8 476 June 4 57
April 9 486 June 4 56
April 10 495 June 5 56
April 11 506 June 5 55
April 12 521 June 6 55
April 13 537 June 6 54
April 14 552 June 7 54
April 15 567 June 8 54
April 16 583 June 8 53
April 17 596 June 9 53
April 18 609 June 9 52
April 19 624 June 10 52
April 20 641 June 10 51
April 21 657 June 11 51
April 22 673 June 12 51
April 23 690 June 12 50
April 24 707 June 13 50
April 25 723 June 14 50
April 26 739 June 14 49
April 27 755 June 15 49
April 28 774 June 16 49
April 29 791 June 16 48
April 30 807 June 17 48
May 1 825 June 18 48
May 2 843 June 19 48
May 3 861 June 19 47
May 4 878 June 20 47
May 5 896 June 21 47
May 6 914 June 21 46
May 7 935 June 22 46
May 8 954 June 23 46
May 9 972 June 24 46
May 10 988 June 24 45
May 11 1,006 June 25 45
May 12 1,028 June 26 45
May 13 1.050 June 27 45
May 14 1,072 June 27 44
May 15 1,093 June 28 44
May 16 1,113 June 29 44
May 17 1,135 June 30 44
May 18 1,155 July 1 44
May 19 1,176 July 1 43
May 20 1,199 July 2 43
May 21 1,220 July 3 43
May 22 1,242 July 4 43
May 23 1,265 July 5 43
May 24 1,290 July 6 43
May 25 1,311 July 7 43
May 26 1,331 July 7 42
May 27 1,352 July 8 42
May 28 1,373 July 9 42
May 29 1,396 July 10 42
May 30 1,420 July 11 42
May 31 1,445 July 12 42
June 1 1,471 July 13 42
June 2 1,496 July 14 42
June 3 1,522 July 15 42
June 4 1,544 July 16 42
June 5 1,568 July 16 41
June 6 1,593 July 17 41
June 7 1,619 July 18 41
June 8 1,645 July 19 41
June 9 1,670 July 20 41
June 10 1,696 July 21 41
June 11 1,719 July 22 41
June 12 1,743 July 23 41
June 13 1,768 July 24 41
June 14 1,793 July 25 41
June 15 1,818 July 26 41
June 16 1,844 July 27 41
June 17 1,869 July 28 41
June 18 1,894 July 29 41
June 19 1,919 July 30 41
June 20 1,946 July 31 41
June 21 1,972 August 1 41
June 22 1,997 August 2 41
June 23 2,021 August 3 41
June 24 2,048 August 4 41
June 25 2,074 August 5 41
June 26 2,099 August 6 41
June 27 2,125 August 7 41
June 28 2,150 August 8 41
June 29 2,176 August 9 41
June 30 2,204 August 10 41
July 1 2,230 August 11 41
July 2 2,256 August 12 41
July 3 2,282 August 13 41
July 4 2,308 August 14 41
July 5 2,335 August 15 41
July 6 2,360 August 16 41
July 7 2,386 August 17 41
July 8 2,412 August 18 41
July 9 2,438 August 19 41
July 10 2,464 August 20 41
July 11 2,490 August 21 41
July 12 2,516 August 22 41
July 13 2,542 August 23 41
July 14 2,569 August 24 41
July 15 2,595 August 25 41
July 16 2,621 August 26 41
July 17 2,647 August 27 41
July 18 2,674 August 28 41
July 19 2,701 August 29 41
July 20 2,727 August 30 41
July 21 2,752 August 31 41
July 22 2,777 September 1 41
July 23 2,802 September 2 41
July 24 2,829 September 3 41
July 25 2,855 September 4 41
July 26 2,883 September 5 41
July 27 2,909 September 6 41
July 28 2,936 September 7 41
July 29 2,962 September 9 42
July 30 2,988 September 10 42
July 31 3,015 September 11 42
August 1 3,041 September 12 42
August 2 3,068 September 13 42
August 3 3,095 September 14 42
August 4 3,121 September 15 42
August 5 3,147 September 16 42
August 6 3,173 September 17 42
August 7 3,200 September 19 43
August 8 3,227 September 20 43
August 9 3,253 September 21 43
August 10 3,280 September 22 43
August 11 3,305 September 23 43
August 12 3,331 September 24 43
August 13 3,357 September 26 44
August 14 3,384 September 27 44
August 15 3,409 September 28 44
August 16 3,436 September 29 44
August 17 3,462 October 1 45
August 18 3,487 October 2 45
August 19 3,512 October 4 46
August 20 3,536 October 5 46
August 21 3,561 October 6 46
August 22 3,587 October 8 47
August 23 3,610 October 10 48
August 24 3,637 October 11 48
August 25 3,662 October 13 49
August 26 3,688 October 15 50
August 27 3,716 October 17 51
August 28 3,742 October 19 52
August 29 3,768 October 21 53
August 30 3,794 October 23 54
August 31 3,818 October 25 55
September 1 3,842 October 27 56
September 2 3,868 October 29 57

 Pickling Cucumber Cultivars Early Season Maturing HU = 1,053 Midseason Maturing HU = 1,125 Blitz Panorama Clinton Calico Pikmaster Pennant Calypso Pinnacle Saladin Carolina Regal SMR 58 Cascade Reliance Sumter Castlepik Salvo Triple Pak Chemset Sampson Wisconsin SMR 18 Commander Score Earlipik 14 Southern Belle Explorer Tamor Fremont Target Greenpak Tempo Gynomite Totem Lucky Strike Triple Crown Medusa Triplemech Multipik Slicing Cucumber Cultivars Early Season Maturing HU = 1,154 Midseason Maturing HU = 1,246 Late Season Maturing HU = 1,337 Lama Dasher II Ashley Raider Castlemaster Comanche 7 Revenue Centurion Early Triumph Slice King Cherokee 7 Marketmore 76 Slice Nice Coolgreen Marketsett Slicemaster Guardian Pacer Sprint 440 Jet Set Poinmarket Medalist Pointsett 76 Slice Mor Slice Verino Super Slice Note: Some cultivars may no longer be available, but can be used to determine heat units to harvest for similar or related cultivars.

The following procedure enables the user to update harvest prediction based on daily observed air temperatures:

1. Calculate HUs for each day using equations 1 and 2 above.
2. Keep a running total of these HUs beginning on the planting date.
3. Update the harvest prediction date by subtracting the current total from 1,125. Add the result to the accumulated HUs from the table for the current day. Find the number closest to this result in the HU column of Table 7 to determine the associated harvest date.

Example of harvest scheduling
Planting date is April 10 at the Clinton location. At planting, the initial predicted harvest date is June 5, which assumes the average weather conditions on which the table is based.

When summing HUs accumulated by April 25 using steps 1 and 2 above, it is determined that 400 HUs have accumulated. This is substantially more than an average year, thus the predicted harvest date would change. Normally, the total HUs accumulated would be 723 - 495 = 228. (Note, the amount accumulated from March 1 to April 10 must be subtracted to determine the units accumulated for April 11- 25.)

1. 1,125 - 400 = 725
2. 723 + 725 = 1,448
3. Closest number to 1,448 is 1,445
4. Updated harvest date prediction is May 31 (Note: When using the table to update your prediction, use the planting date column.)

Scheduling is especially critical if once-over machine harvest is used because the harvest window is usually only one to two days for highest yield and profit. (See the Machine Harvest section for more detailed information.) Mechanical harvesters can ony harvest about 10 acres a day, so if large acreages are being grown, they must be scheduled carefully to allow time for each separate acreage to be harvested. For example, for mechanical harvest, about 25 HUs accumulated between spring plantings leaves one day between harvests provided that best cultural practices are followed. Approximately 300 HUs are needed to accumulate between spring plantings to space beginning harvests about 14 days apart, whereas about 500 HUs are required for beginning harvests for each planting to be about 21 days apart. Planting such that harvest intervals are two to three weeks apart will help to maintain a continuous supply of good-yielding hand-harvested cucumbers. Use Table 7 and the example above to predict harvest for mid- to late-summer plantings as daily HUs become more variable late in the growing season.

Figure 5. Average last frost dates. Adjust last frost dates according to distance from date lines.

# Pollination of Pickling and Slicing Cucumbers

The process of transferring pollen from the male flower to the female flower is called pollination. It is essential for cucumber fruit development and deserves the full attention of the grower. Pollination is done mostly by bees visiting open flowers. A limited amount of pollination is done by other insects.

Honey bees are excellent pollinators. When they extend their tongues into male flowers to eat the nectar, pollen sticks to their hairy bodies. When the bee visits a female flower, some of that pollen touches the sticky stigma allowing pollination to occur. Honey bees also serve as excellent pollinators because their numbers can be controlled and they can be forced to work cucumbers, which have less nectar than other plants. The honey bee, unlike many other pollinating insects, gathers pollen and nectar from one type of plant (for example, only cucumbers) at a time.

Honey bees may not be needed in small fields (3 acres or less) that are adjacent to natural, undisturbed areas where plenty of wild bees nest. In these cases, bumble bees can be sufficient pollinators. Bumble bees are much more efficient pollinators than honey bees because fewer visits to the flower are required for pollination (Stanghellini et al. 1997). Large fields, or small fields that are not near natural areas, will probably require the use of honey bees for good pollination and high yields. Yield increases of 25% to 30% are common when honey bees are introduced into the field. An indication of adequate bee activity in a field is being able to hear the bees buzzing.

Generally, one strong hive of honey bees (25,000 to 30,000 bees) is recommended per acre for hand-harvested cucumbers. For higher plant populations (as in machine harvest), three to four hives per acre may be required. An average of one bee per plant is recommended. Cucumbers require large numbers of honey bees for adequate pollination because the female flower is only receptive for part of a day (morning and early afternoon). Each flower requires an average of 11 bee visits to produce a well-shaped cucumber. However, the bees will often visit the flowers more frequently. Occasionally, the number of bee visits is not sufficient for adequate pollination resulting in misshapen fruit (Figure 6).

To obtain maximum benefit from honey bees, proper management is critical. Consider the following suggestions:

1. Place the hives evenly around the edge of the field in groups of four hives or less. The hives should be spaced so that no place in the cucumber field is farther than 300 feet away from a hive.
2. Do not place hives in the field until cucumber flowers are present for three to four days.
3. Position the hives so that they face east and are shaded during mid-day and afternoon (Figure 7).
4. Locate hives upwind of any pesticide application when possible.
5. Avoid placing hives in high-traffic areas.
6. Keep a container of clean water near the hive if another source of water is not near. Place some floating sticks or similar objects in the water so that the bees can land while they are drinking their water.
7. Be careful when applying insecticides to cucumbers because insecticides can kill bees. Apply only when necessary and when bee activity is low, in the late afternoon (at least after 2 p.m.) or evening if possible. Use formulations that minimize drift downwind of the bee hives.
8. Destroy or mow nearby flowering weeds that attract bees away from the field. Honeysuckle, clovers, and buckwheat create competition for the attention of pollinating bees.
9. Do not remove hives from the field until sufficient pollination has occurred. For once-over harvesting, 6 to 10 days of good bee weather (at least 70°F and minimal rainfall) is usually sufficient. Bees should remain in the field for hand harvest until two to three days before the last harvest.
10. Irrigate either early in the morning (before 8 a.m.) or delay until late afternoon or evening (at least 4 p.m.) to minimize the impact on bee activity and optimize fruit set. Bee visits can be reduced 80% when overhead irrigation occurs during times of high bee activity.

Contact your beekeeper well in advance so that adequate hives can be placed in the field at the right time for good pollination. Rental fees will vary; however, costs are usually less in spring than summer or fall because less pesticides are used during crop production.

Sugar or pheromone-based bee attractants are not effective for increased bee activity, better fruit quality, or increased yields (Schultheis et al. 1994). Bee hive placement in fields is the most reliable method of meeting crop pollination needs.

Figure 6. Misshapen fruit resulting from insufficient pollination. Note the lack of seed development at the stem end.

Figure 7. Beehives are placed adjacent to cucumber field and in shade to reduce midday heat.

# Irrigation of Pickling and Slicing Cucumbers

Cucumbers have a high water requirement and are very susceptible to water stress. Lack of water can result in reduced fruit quality and yields. Under normal conditions, the crop needs approximately 1 inch of water per week. When the crop is fruiting especially during periods of hot, dry weather, under windy conditions, or both up to 2 inches of water per week may be required by the crop.

Uniform soil moisture is especially critical during plant establishment. If the soil lacks good moisture at planting, 12 to 34 inches of water should be applied to provide uniform moisture. This will result in more uniform, complete plant stands which in turn result in improved, concentrated fruit yields and efficient use of machinery and labor. If soil is dry and requires irrigation after seeding, reduce water droplet size by increasing delivery pressure. Large water droplets often lead to soil crusting, which can inhibit plant emergence. Soil crusting leads to reduced stands that are not uniform. Obtaining a complete, uniform stand is especially critical because plant and fruit development must be uniform throughout the entire growing season to maximize yield.

If cucumbers do not receive sufficient rain or irrigation, fruit quality and yield are reduced and symptoms are indistinguishable from poor pollination (Plate 5). Irrigation can increase yield by more than 50% in years of medium to low rainfall. Irrigation rate will depend on soil type but applications should not exceed 0.40 inch per hour for sandy soils, 0.30 inch per hour for loamy soils, and 0.20 inch per hour for clay soils. Higher rates will waste water and cause soil erosion and fertilizer runoff.

Plate 5. Various gradations of misshapen fruit resulting from poor pollination.

# Plasticulture for Hand-Harvested Pickling and Slicing Cucumbers

Use of plasticulture (black plastic and drip irrigation) is a viable option for producing cucumbers, especially slicing cucumbers. The economics of using plastic mulch for producing only one crop of pickling cucumbers is questionable. When double cropping, however, it may serve well as a second crop option (Plate 6). Use of plastic mulch with drip irrigation tape increases production cost, but offers certain advantages such as increased yield, weed control, better quality, and earliness. A crop produced with plasticulture can increase yields two-fold over a crop produced with good growing practices without plastic but with irrigation, and yields nearly five times more than an average North Carolina crop with limited or no irrigation (Sanders et al. 1995). A more consistent yield can be expected with plasticulture because moisture and fertilizer can be applied whenever needed. In addition, plastic helps control many weeds, improves fruit quality, and reduces belly rot (see Disease Management section) by reducing fruit contact with the soil. It can also result in 7 to 10 days earlier production, permits more efficient fertilizer retention and placement, and reduces water logging by draining excess water away from plants. In high-organic-matter soils, plastic should be considered to reduce soil adhering to fruits. It will also help reduce fruit rots (Jones 1961).

As mentioned earlier, soil preparation is a very important part of growing a productive cucumber crop. This also holds true with plasticulture. Failure in the plasticulture system can often be traced back to poor soil and bed preparation. Soil must contain adequate moisture, and be loose and free from trash (rocks, plant debris, etc.) so that plastic and soil are in direct contact and form a smooth bed. The plastic mulch should be laid tight to form a tight bed. The bed height should be near 6 inches with the center of the bed about 112 inches higher than the sides of the bed so that rain will not accumulate on the plastic. There are several bed presses available that can be used to form close contact between the plastic mulch and the soil surface.

When growing on plastic mulch, plant populations of 20,000 to 30,000 plants per acre are suggested (Table 5). Double rows should be planted approximately 6 to 8 inches to each side of the centrally placed drip tape. In-row spacing should be 10 to 14 inches between plants. Avoid having more than one plant per hole as multiple plants reduce yields.

With drip irrigation, micronutrients, phosphorus, and approximately 30% of the nitrogen and potassium should be incorporated into the bed before covering it with plastic. Commonly used nitrogen fertilizer sources for pre-bedding application include ammonium nitrate, calcium nitrate, and potassium nitrate. For potassium, common sources include potassium chloride, potassium nitrate, and potassium sulfate. Potassium sulfate is a good choice for sandy soils that are deficient or low in sulfur. Superphosphate (normal and triple) is a good source of phosphorus.

The remainder of the nitrogen and potassium should be applied through the drip system to coincide with plant growth and development through the season. Fertilizer applied with water through the drip tube (fertigation) should be high quality greenhouse grade so that the drip tube does not become clogged. Calcium nitrate and potassium nitrate are the most common forms of nitrogen and potassium fertilizer used for fertigation. However, ammonium nitrate, sodium nitrate, urea, diammonium phosphate, and nitrate of soda potash are also used.

Fertigation can be automated for a wide range of frequency from daily to biweekly. There is debate between researchers about the best frequency for fertigation; however, more frequent application could be closer to plant needs. Beginning when four true leaves have developed, tissue samples should be taken and analyzed every two weeks to determine the nutrient status of the crop. Results of that analysis should be compared with the foliar nutrient sufficiency range for cucumbers (Table 3) and fertilizer adjustments made accordingly. A total of three tissue samples during a production season should be sufficient.

Table 9. Suggested fertigation schedule for cucumber (N:K; 1:2).
Days after planting Daily nitrogen (lb/acre) Daily potash (lb/acre) Seasonal nitrogen (lb/acre) Seasonal potash (lb/acre)
(preplant) 45.0 45.0
0-7 0.9 1.8 31.3 62.6
8-14 0.9 1.8 37.6 75.2
15-21 1.3 2.6 47.7 83.4
22-28 1.3 2.6 57.8 101.6
29-35 1.5 3.0 68.3 122.6
36-42 1.5 3.0 78.8 143.6
43-49 1.5 3.0 89.3 164.6
50-56 1.5 3.0 99.8 175.6
57-63 1.5 3.0 110.3 196.6
64-70 0.7 1.4 115.2 206.4
71-77 0.7 1.4 120.1 216.6
Note: N = nitrogen, K = potassium as K2O
Adapted from Sanders et al. 1995.

In Table 9, a fertigation schedule is given as a starting point. This may need to be modified according to crop status, soil type, weather, etc. Other fertigation schedules have worked successfully in North Carolina. The University of Florida fertigation schedule recommends a 1:1 ratio of N and K2O over a 10-week period (Table 10). In addition to 24 pounds of preplant fertilizer, a total of 120 pounds of N and K2O are applied through the drip tape during the season. For more specific information on use of plasticulture in vegetable production, refer to bulletin AG-489, Plasticulture for Commercial Vegetables.

Table 10. Alternative fertigation schedule for cucumber (N:K; 1:1), option from Florida.
Days after planting Daily nitrogen (lb/acre) Daily potash (lb/acre) Seasonal nitrogen (lb/acre) Seasonal potash (lb/acre)
(preplant) 24.0 24.0
0-7 1.0 1.0 31.0 31.0
8-14 1.5 1.5 41.5 41.5
15-21 1.5 1.5 52.0 52.0
22-28 2.0 2.0 66.0 66.0
29-35 2.0 2.0 80.0 80.0
36-42 2.0 2.0 94.0 94.0
43-49 2.0 2.0 108.0 108.0
50-56 2.0 2.0 122.0 122.0
57-63 2.0 2.0 136.0 136.0
64-70 1.5 1.5 150.0 150.0
Note: N = nitrogen, K = potassium as K2O
Adapted from Hochmuth and Clark 1991.

Plate 6. Black plasticulture can be used for two sequential crops (e.g., pepper followed by cucumber).

# Machine Harvest of Pickling Cucumbers

Production of once-over-harvest pickling cucumbers requires precise cultural management practices that are quite different from those required for hand-harvested pickling cucumbers.

A well-drained, uniform field with sandy or loamy soil should be selected so that the crop develops uniformly and machine operations are possible following a day with significant rainfall. Also, those soils aren't as likely to cling to the fruit. If harvesting is delayed, crop value can be drastically reduced because cucumbers can oversize very quickly (Cargill et al. 1975).

Generally, machine-harvest pickling cucumber cultivars have a greater length-to-diameter ratio (Table 1). The high plant populations used in machine-harvest regimes produce shorter fruit, which means longer-fruited cultivars are needed.

High plant populations of 50,000 to 70,000 plants per acre are recommended to concentrate the number of fruit for a one-time destructive harvest (Table 6). Higher plant populations increase plant competition for water and nutrients. Thus, a grower must have irrigation that can be applied in a timely manner.

Seeds for once-over-harvest plantings are typically planted in three-row beds from 24 to 28 inches apart. Because the standard pickle harvester head is 7 feet wide, 28 inches between rows is most common. Ideal plant spacing within rows is 3 to 4 inches. A precision seeder should be used to achieve uniform spacing. Uniform spacing reduces nutrient and water stress and can result in increased yields. Any type of water stress can result in more misshapen fruit and reduced marketable yields.

Once-over-harvest pickling cucumbers are usually planted in large fields to allow for easy access and movement of machinery. Because the fields are large and contain a higher plant population, more bee hives (for pollination) must be placed beside the fields. Approximately three to four strong bee hives are needed per acre to assure good pollination, fruit quality, and yield.

Harvesting should be done when 5 to 10% of fruit reach oversize diameter (2 or more inches) (Miller and Hughes 1969). A suggested sampling technique for determining when to harvest is to pick all fruits in a 3 foot square section from a representative part of the field, then determine the percentage oversize fruit (Figure 8). Harvest at this stage of development often results in greater monetary return. In hot weather, fruit will size quickly, resulting in more production of the larger sized fruit of lower value. As much as 20% income loss can occur if harvest is delayed one day. A higher percentage of smaller fruit is often lost with machine harvesting compared to a hand-harvest operation. A good, profitable yield for machine harvest is 200 bushels per acre. One machine generally can harvest about 10 acres per day.

Figure 8. Determine oversized fruit using a 2-inch grading board for proper timing of mechanical harvest.

# Harvesting and Handling

Harvesting Pickling and Slicing Cucumbers

The spring-crop harvest begins about June 1 in southeastern North Carolina and continues for as many as six weeks. However, cultivars introduced during the past decade provide a more concentrated fruit set which often reduces the number of harvests. In the North Carolina mountains, harvest usually begins in early July and concludes in mid-August. Under optimum growing conditions, individual fields may be harvested as many as three times per week over a two- to three-week period. Crops planted during late spring and early summer should be ready for harvest in 36 to 40 days depending on the cultivar, the weather, etc. The first harvest date may be reliably predicted by counting forward 8 to 10 days from the first fully open female flowers. With good growing conditions, the fruits may exceed marketable size by the 12th day. These times may vary a few days due to environmental conditions, cultural practices, etc. Every effort should be made to harvest the fruits as they develop on the vines. Leaving large cucumbers on the vines will cause the plants to stop setting fruit (Table 11). Avoid harvesting pickling-type fruits of less than 12-inch diameter, and pick pickling-type fruit before they reach 2 inches in diameter and slicing-type fruit before they reach 2 inches in diameter.

Table 11. Effect of harvesting scheme on yields of pickling cucumbers.
Yields Per Acre
Treatment Bushels Dollarsb Number of Fruits
Per Acre (1,000x) Per Plant
All fruit 12-inch diameter or larger (Grade 1) removed at each harvest 688 (88)a 2,014 311 9.84
All fruit 1116-inch diameter or larger (Grade 2) removed at each harvest 682 (196) 1,567 197 6.25
All fruit 134-inch diameter or larger (Grade 3) removed at each harvest 602 (428) 1,161 113 3.60
Data from Greene County field test (Hughes et al. 1979).
a Values in parenthesis are bushels of oversize fruits, culled out at grader.
b Determined by processor prices received for fruit grades 1, 2 and 3.

Fruits should be "pushed" or twisted from the vine to avoid vine injury. Pulling fruit from the vine results in broken vines or pulled-up plants. Cucumbers should be delivered to the buying station or market the same day they are harvested. Holding fruits overnight results in excessive weight loss and increases the risk of fruit rots. Cucumbers should always be handled carefully to avoid bruises and punctures.

Grades and sizes for pickling and slicing cucumbers are established by the United States Department of Agriculture. Single copies of these standards may be obtained at no cost by writing to

Standardization Section
AMS, F&VD, Fresh Products Branch
United States Department of Agriculture
P.O. Box 96456, Room 2056 South
Washington, DC 20090-6456

Pickling cucumbers

The USDA/NCDA&CS size designations of pickling cucumbers (Plate 7) are

• U.S. Grade No. 1: Less than 11/16-inch diameter
• U.S. Grade No. 2: 11/16-inch diameter to less than 11/2-inch diameter
• U.S. Grade No. 3: 11/2-inch diameter to less than 2-inch diameter
• Oversized: 2-inch diameter and greater

Fruits larger than 2 inches in diameter are called "culls" or "oversize" but they do not constitute an official grade. There are no length requirements for those fruits. In addition to the grades above, most buyers separate the fruit at the grading or receiving station into two or more subgrades (Plate 7). These grades are for the convenience of the processor only and are not NCDA&CS or USDA official grades. Growers are often paid on the basis of subgrades.

Slicing cucumbers

The following is a summary of the US standards for slicing cucumbers

• U.S. Fancy: No more than 2 inches in diameter and no less than 6 inches long.
• U.S. Extra No. 1: No more than 2 inches in diameter and no less than 6 inches long.
• U.S. No. 1: No more than 2 inches in diameter and no less than 6 inches long.
• U.S. No. 1 Small: No less than 11/2 or more than 2 inches in diameter. No length requirement.
• U.S. No. 1 Large: No less than 21/4 inches in diameter and no less than 6 inches long.
• U.S. No. 2: No less than 2 inches in diameter and no less than 5 inches long.

Note that there is no size difference between the first three grades: The difference between U.S. Fancy (the best grade), U.S. Extra No. 1, and U.S. No. 1 lies in quality (color, shape, and defects allowed). U.S. Extra No. 1 is a combination of at least 50% U.S. Fancy with the remainder being U.S. No. 1 grade. Size is the only difference between U.S. No. 1, U.S. No. 1 Small, and U.S. No. 1 Large. To maximize yield, harvesting should be done to obtain the maximum number of U.S. Fancy and U.S. No. 1 cucumbers per acre.

Labor for Pickling and Slicing Cucumbers

At present, virtually all of the North Carolina cucumber acreage is hand harvested (Figure 9). One advantage of hand harvesting is the ability to pick more small fruit which are often lost during mechanical harvest. The harvest labor requirement of cucumbers is quite high, frequently being more than 50% of the cost of production. The amount of labor required to hand harvest an acre will depend on yield, number of times harvested, and the amount of vine growth. As an example, in prolific fields, an individual can pick 300 pounds (up to 6 bushels) of pickling cucumbers each hour. Approximately 24 hours of labor per acre will be needed for each harvest. A field with plants that have a high yield potential is an excellent enticement to labor since no one wants to pick from low-yielding plants.

Growers should secure picking labor well before harvest. Having sufficient labor is critical to the success of a farm operation. More stringent labor rules have been adopted and enforced in recent years. For more information, contact your county Extension center or the US Department of Labor, Wage and Hours Division.

North Carolina has several different arrangements for paying harvest labor. Most of the harvest labor is migrant crews. For pickling cucumbers, pickers usually receive a share (50% to 60%) of the gross sales for payment. For slicing cucumbers, a piece-work arrangement may be used where pickers are paid an amount per bushel. The disadvantage of a piece-work arrangement is the tendency for pickers to harvest only large fruits, especially with pickling cucumbers because smaller fruit have greater value.

As labor costs continue to escalate, harvesting aids and mechanical harvesters have attracted more interest. Harvesting aids are often farmer-built or rebuilt from tobacco equipment and are designed to eliminate stoop labor by allowing pickers to work in a more comfortable sitting position. The efficiency of harvesting aids varies widely, but growers usually find recruiting and supervising labor easier when these machines are used. Once-over and multi-pass mechanical harvesting aids are frequently used elsewhere but at present are used in North Carolina only on a limited basis (Figure 10). These machines could substantially reduce per-unit harvesting costs of pickling cucumbers, but growers might have to sacrifice some quality because fewer small-sized cucumbers are harvested than with hand-harvested fruit.

Plate 7. Commercial pickling cucumber grades and subgrades: (left to right) 1A, 1B, 2A, 2B, 3A, 3B.

Figure 9. Hand harvesting cucumbers.

Figure 10. Once-over mechanical harvesting in Delaware.

# Postharvest Handling of Pickling and Slicing Cucumbers

Proper instruction and careful supervision of the picking crew is essential to the success of any harvesting operation. Postharvest quality control begins in the field. Growers should have a responsible person supervise the picking operation at all times. Harvested cucumbers should be handled as gently as possible and never be allowed to remain in the sun for extended periods. Quick grading and cooling immediately after harvest are essential for top quality.

Although most pickling cucumbers are processed within a day or so of harvest, they may be successfully stored for longer periods of time under optimum conditions. If stored at 45-50°F and 90-95% relative humidity, cucumbers may be held in good condition for 7 to 10 days.

Chilling injury (water spots, pitting, tissue collapse) will result if the fruit is held at temperatures below 45°F (Plate 8). However, rapid ripening may occur if cucumbers are stored at temperatures above 50°F. Cucumbers should not be stored with other commodities that produce ethylene, (e.g., tomatoes, apples, and melons). The presence of even tiny amounts of ethylene can greatly accelerate ripening. Adequate humidity must be provided at all times because pickling cucumbers are especially susceptible to dehydration and shrinkage.

All cucumbers should be cooled as soon as possible after harvest. Hydrocooling with chilled water is the preferred method for pickling cucumbers; however, forced-air cooling has been used successfully where hydrocooling is unavailable. In the absence of sophisticated cooling arrangements, growers often resort to drenching the fruit with cool well water to prevent the build-up of respiration heat in bulk containers or loads. More information on forced-air cooling and hydrocooling for cucumbers and other types of fresh produce is available in the AG-414 series of publications at your county Cooperative Extension Service center.

Plate 8. Chilling injury.

# Pest Management

Integrated pest management (IPM) is an approach designed to keep pest populations below economically damaging levels by using selected control tactics, including certain cultural practices, plant resistance, and chemical and biological control. With many pests, especially diseases and weeds, growers must use preventive control strategies to eliminate the potential for infection before the crop is established. In contrast, most insect pests can be controlled after a field is infested, and scouting fields for the presence of economically damaging insect populations is a good way to eliminate unnecessary pesticide applications. For most pests, a combination of one or more strategies is often required for successful control, and the crop must be closely monitored to determine the need and timing of various control practices.

Some logical steps to follow in an IPM program are identifying insects, diseases, and weeds; keeping records of pest problems, field locations, pesticides used, weather conditions, etc.; scouting and monitoring for pests to determine pest and action levels; proper selection, handling and disposal of pesticides; safe and effective application of pesticides; and an integration of any and all control tactics and strategies.

Some essential strategies for integrated pest management follow:

• Keep records
• Select adapted cultivars with disease resistance and insect tolerance
• Practice a 24-month, non-cucurbit crop rotation
• Select fertile, well-drained fields
• Sample fields annually for pH, nutrients, nematodes, soil insects, and weeds
• Use certified seed treated with fungicides and insecticides
• Seed 1/2- to 3/4-inch deep on raised beds after soils warm to 60°F to "outgrow" pests
• Place bee colonies in fields after blooms are present
• Apply a general purpose fungicide shortly after emergence and include an insecticide as needed
• Diagnose all leaf spots and plant abnormalities promptly
• Use a high-pressure (200+ psi) sprayer
• Irrigate fields to ensure 1 inch of water each week
• Monitor migration of pickleworms with sex-pheromone trap and spray as needed
• Reapply nitrogen and potassium after leaching rain
• Harvest cucumbers three times a week
• Avoid injuries during harvesting and handling
• Use chlorine in all dump, wash, and handling water

Specific and more detailed information on insects, diseases, and weeds is readily available through local county Cooperative Extension centers. County agents and Extension specialists offer assistance with identification, farm tests, publications, control recommendations, and related advisory services.

Because pesticide regulations change rapidly, few materials and no application rates have been included in this publication. Ask county Extension staff for any additional information you need on cucumber pesticides or consult the North Carolina Agricultural Chemicals Manual for current materials and recommended rates. In all cases, follow directions on the pesticide label and use pesticides safely.

# Weed Management

The major weeds associated with North Carolina cucumbers are common lambsquarters (Chenopodium album), annual and perennial grasses (Poaceae), pigweeds (Amaranthus species), common ragweed (Ambrosia artemisiifolia), common cocklebur (Xanthium strumarium), and annual morningglory (Ipomoea species) (Toth et al. 1994). Weeds are usually more prevalent in the spring cucumber crop than in the summer cucumber crop.

Weeds reduce cucumber yield and quality, and are hosts for insects (e.g., cucumber beetle), and animals (e.g., box turtles, mice, etc.). Stress caused by weed competition can also make cucumbers more susceptible to disease. Cucumbers must be maintained nearly (99-100%) weed free to prevent yield and quality reductions. For example, if 95% of the weeds in a field are controlled and 5% of the weeds are not, then up to a 50% yield or quality reduction may occur. Cucumbers are most vulnerable to yield loss to weeds between 14 and 32 days after emergence (Friesen 1978). Thus, cucumbers must be near weed free between 14 and 32 days after emergence to prevent reductions in yield or quality.

A specific weed management program must be developed for controlling weeds specific to each field. Successful weed management programs should include a well-planned and implemented strategy of cultural (e.g., cover crops, cultivars, plastic mulch), mechanical (e.g., two to three cultivations, one to two hand weedings) and chemical (e.g., preplant, preplant incorporated, preemergence, and/or postemergence herbicides) methods. Species identification, density, and control strategy must be known (Tables 12 and 13). Growers should record the weed species in each field and use these records to detect any weaknesses in the weed management program used from year to year. Once weaknesses or weed escapes are detected, then adjustments must be made in the weed management program to achieve control of these weeds.

 Severity of Infestation (Number of plants/100 square feet)b,c Scouting Timea Light Moderate Heavy No. Strategy No. Strategy No. Strategy Annual Grasses Crabgrass Su, F 1-5 B 5-15 B 15 B Goosegrass Su, F 1-5 B 5-15 B 15 B Barnyardgrass Su, F 1-5 B 5-15 B 15 B Fall panicum Su, F 1-2 B 2-10 B 10 B Johnsongrass (seedling) Su, F 1-2 B 2-4 B 4 B Crowfootgrass Su, F 1-5 B, C 5-15 B, C 15 B, C Broadleaf signalgrass Su, F 1-5 B, C 5-15 B, C 15 B, C Foxtails Su, F 1-2 B 2-10 B 10 B Annual Broadleaves Common lambquarters S, Su 1-2 B 2-4 B 4 B Carpetweed S, Su 2-5 B 5-15 B 15 B Common purslane S, Su 2-5 B 5-15 B 15 B Redroot pigweed S, Su 1-2 B 2-4 B, C 4 B, C Common ragweed S, Su 2-4 B 4-8 B, C 8 B, C Common cocklebur S, Su 1-2 C 2-4 C, D 4 C, D Pickly sida S, Su 1-5 D 5-15 A 15 A Morningglories S, Su 2-4 D 4-8 A 8 A Sicklepod S, Su 1-2 D 2-4 A 4 A Perennials Common bermudagrass Su, F 1-2 B 2-4 B, C 4 B, C Johnsongrass (rhizome) Su, F 1-2 B 2-4 B, C 4 B, C Nutsedges Su, F 2-4 A 4-8 A 8 A a Scouting procedures should be conducted the year or season before planting cucumbers. S = spring; Su = summer; F = fall. b Number of specified weed plants in a 100-square-foot (10-by-10-foot) block. c Weed control strategies for A = Avoid planting cucumbers if possible if land is fallow and weeds are perennials. Use glyphosate (Roundup) site preparation techniques or other effective herbicides the previous year if applicable. B = Available herbicide programs plus cultivation will control this weed during the growing season. If infestation is light, cultivation alone may suffice. No action necessary in previous season. C = Destroy before seeds mature by disking, mowing, hand-pulling and herbicide use. This will eliminate seed from current weed crop, but a reservoir of weed seed for this particular weed probably exists in the soil. D = Same as C except none of the registered herbicides provide adequate control of this weed. If cucumbers are to be grown in this area, provisions for frequent cultivation, supplemented by hand hoeing, need to be made.

 Herbicide and Time of Applicationa Glyphosate Paraquat Prefar Prefar + Alanap Curbit Alanap Curbit + Alanap Poasat + Crop Oil Species PREPLANT PREPLANT PPI PPI PRE PRE PRE POST Weed Annual Grasses Crabgrass E E E E E G E E Goosegrass E E G E E G E E Barnyardgrass E E E E E G E E Foxtails E E E E E G E E Fall panicum E E E G E F E E Broadleaf signalgrass E E G F-G E F E E Crowfootgrass E E G F-G E F E E Johnsongrass (seedling) E E G E E G E E Annual Broadleaves Common lambsquarters E E E E E E E N Carpetwood E E P E E E E N Common purslane E E G E E E E N Redroot pigweed E E G G E G E N Common ragweed E E P G P G G N Common cocklebur E G P G P G G N Prickly sida E G P P P P P N Sicklepod E G P P P P P N Morningglories F-G G P P P P P N Perennials Common bermudagrass E P P P P P P E Johnsongrass (rhizome) E P P P P P P E Nutsedges G P P P P P P Notes: E = 90% control or better. G = 76-90%. F = 50-75%. P = 50% or less control. N = No control Relative ratings are based on the assumption that environmental (temperature, rainfall, etc.) and soil conditions are suitable for optimum herbicide activity proper application techniques are used proper rate adjustments are made for soil texture (depth, distribution, etc.) herbicides are used in accordance with labeled directions. See current edition of the North Carolina Agricultural Chemicals Manual for rates and recommendations. a PREPLANT = Paraquat should be applied before cucumber planting; with glyphosate allow at least 3 days between application and planting. Preplant herbicides are non-selective and kill emerged weeds. PRE = preemergence (herbicide applied immediately after cucumber seeding). Preemergence herbicides prevent susceptible weeds from emerging. PPI = prepant incorporated (herbicide applied and incorporated in soil before seeding cucumber). Preplant incorporated herbicides prevent susceptible weeds from emerging. POST = postemergence (herbicide applied after weeds and cucumbers have emerged).

# Insect Management

A number of insects can injure pickling and slicing cucumbers. Among these are aphids, flea beetles, seedcorn maggots, leafminers (Plate 9, Figure 11a, Figure 11b, Figure 11c) spider mites (Plate 10, Figure 12), white flies, cabbage loopers, thrips (Plate 11, Figure 13), cucumber beetles (striped and spotted), squash bugs, squash vine borers, melonworms, and pickleworms. Beetles and pickleworms pose the most serious threats.

Correct identification and knowledge of the insect's life cycle are essential for effective control. County plant clinics and the North Carolina State University Plant, Disease, and Insect Clinic can assist with identification. More detailed information on insect biology is in "Insect and Related Pests of Vegetables" (Sorensen and Baker 1994).

Two critical periods for insect activity are the prebloom stage for seedcorn maggots and cucumber beetles, and the flowering stage for pickleworms.

Seedcorn maggot (Hylemya platura) is a primary cause of poor stands in cool, wet springs and especially on heavier soils with an abundance of nondecomposed plant trash. First evidence of this pest's presence will be wilted plants or malformed cotyledon leaves. Maggots can be found either inside the old seed or in young plants. They are legless, whitish insects about to inch long (Figure 14a, Figure 14b). The adult seedcorn maggot resembles the common housefly and can be found in a characteristic death position with its legs attached to objects such as limbs, posts, wire, or tall grass. Insecticide-treated seed, application of soil insecticide, or both can help control these pests. Proper planting depth at optimum soil temperatures promotes rapid germination, plant establishment, and growth, all of which overcome attack by seedcorn maggots.

Cucumber beetles, striped (Acalymma vittatum) (Plate 12) and spotted (Diabrotica unldecimpunctata howardi) (Plate 13), overwinter as adult beetles and are one of the first insects to attack young cucumber plants in the spring (Plate 14). In addition, this pest deposits eggs in the soil and around young plants in large numbers. The young larvae feed on plant roots and stems. These insects, known as rootworms, are common on field corn. Adults are known to be primary transmitters of bacterial wilt (Plate 15a) and cucumber mosaic virus. Growers should check fields for adult beetles during the cotyledon stage to assess pest status and implement control strategies. Traps containing attractants and killing agents can be used to monitor beetles as well as to offer some control. Control most often requires the application of an insecticide. Rapid germination and plant establishment are significant factors in reducing the severity of beetle attack. The bacterium that causes bacterial wilt overwinters in the adult of this beetle.

Pickleworm (Diaphania nitidalis) is the most destructive insect pest of cucumbers in middle and late summer. Each year, migration of adult moths from areas south of North Carolina provides initial infestations. These populations become larger as the insects pass through their life cycle and go through four to five generations per season (Plate 16).

Pickleworms often pass unnoticed inside fruit, and may not be found until after the fruit is harvested or processed. Buyers and processors have zero tolerance for pickleworm.

Worm-like larvae first attack buds and tender terminals and later complete their growth in fruits or stems (Plate 17). Young larvae have many black spots scattered over their bodies. Full-grown larvae are green or coppery with brown heads. The adult pickleworm can be confused with melonworm (Plate 18). Melonworm adults have white hind wings while larvae have white body stripes and feed on the surface of the fruit (Plate 19).

The pickleworm can be controlled with timely and thorough applications of insecticides. Be careful that ends of rows and rows adjacent to woods or ditch banks are well covered with insecticides. In general, after July 15, growers should begin spraying just before any blooms open in a given field. When pickleworm sex-pheromone traps are employed, growers can begin and continue sprays as long as moths are collected (Figure 15). Growers can detect pickleworm early by close and periodic examination of young, tender vines. Squash is the preferred host of this insect, and a row of squash planted nearby and inspected regularly provides a good way to detect initial infestations of pickleworm. Apply insecticides at five-day intervals, always after picking. Check the insecticide label for rates and time limitations before harvest. Apply sufficient volume of water (30 to 100 gallons per acre) with high-pressure (200+ psi) and hollow-cone nozzles. This will ensure thorough coverage and provide continual protection to the developing plant. Apply insecticides in the evening (after 4 p.m.) for best results and minimal loss of pollinating insects.

With a sex-pheromone monitoring system for pickleworm moths in the final stages of development, a forecasting network throughout the southeast can be established. This network will monitor moth presence and absence and determine relative populations over time. This will eliminate unnecessary sprays and improve the time of essential sprays. This sex-pheromone trapping network should be available within the next several years and will be a welcome addition to cucumber integrated pest management.

Figure 11b. Vegetable leafminer larva.

Figure 11c. Vegetable leafminer pupa.

Plate 9. Leafminer damage.

Plate 10. Spider mite damage. Note webbing and mites between leaf robes.

Figure 12. Two-spotted spider mite life stages.

Plate 11. Thrips injury.

Figure 14b. Seedcorn maggot.

Plate 12. Striped cucumber beetle.

Plate 13. Spotted cucumber beetle.

Plate 14. Cucumber beetle feeding damage on cotyledons.

Plate 15a. Bacterial wilt.

Plate 15b. Slime string test.

Plate 16. Early and late instar larvae, pupa and adult male top right) and female (bottom right) pickleworm.

Plate 17. Cross section of fruit showing internal pickleworm damage and various larval stages.

Plate 19. Pickleworm (left) and melonworm (right) larvae.

Figure 15. Pickleworm sex-pheromone traps (Harstack screen trap) are used to determine the presence of adults. When adults are collected, sprays are necessary.

# Disease Management

Diseases of cucumber are caused by plant pathogens such as viruses, bacteria, fungi, and nematodes. In North Carolina, most of these pathogens survive from one season to the next and build up to enormous populations as the growing season progresses. Management (control) of cucumber diseases is based on excluding or keeping pathogen populations at low levels. In some cases, plants can be partially protected from diseases by timely application of chemicals. However, chemicals (fungicides, nematicides, and bactericides) are usually not effective under high disease pressure and disease-favorable weather.

The "secret" of disease control is prevention and timely application of management practices. The only way to accomplish this is to carefully monitor the first occurrence of the disease in the field and in adjoining production areas. Control and implementation of management strategies should be based on the weather, crop status, and economic considerations.

In general, foliar diseases start slowly in spring and increase as the growing season progresses. Usually by fall the inoculum level has reached such numbers that both cultivar resistance and chemicals are needed to protect the foliage from destruction. This is especially true during wet weather.

Crop rotation. Do not plant cucumbers on land that was planted to cucurbits (muskmelon, cucumber, watermelon, squash, pumpkin, or gourd) or cotton the preceding year because most cucumber pathogens can survive (overwinter) one or more years in the soil. It is even preferable to wait two to three years. Corn and small-grain crops are excellent crops for rotation. Tobacco, sweetpotato, peanuts, peas, soybeans, and tomato are satisfactory for rotation provided that root-knot nematode population is very low. However, these recommendations do not consider herbicide carryover which may last up to 2 years depending on the type of herbicide, its dosage, and weather considerations.

Field selection. Select fields that are well drained, fertile, warm, and have good aeration. Avoid fields near other cucurbit crops (see Site Selection and Preparation section).

Sanitation. Avoid cultivating or harvesting while the cucumber plants are wet. Immediately after the last harvest, disk the field to promote rapid decay of the crop and destruction of disease-causing pathogens.

Soil treatment. Surveys have shown that most sandy soils in commercial cucumber production in eastern North Carolina should be treated with a nematicide. Growers should always follow chemical label directions. Soils can be sampled and assayed to determine the need to treat for nematodes. Sampling should be done in the fall of the preceding year for the spring crop, and in late spring for the upcoming fall crop. Time of sampling is critical to obtaining reliable results.

Seed selection. Always purchase seed from a reliable seed source. Insist that the seed be produced under disease-free conditions and treated with a protective fungicide and insecticide. Select cultivars that have as much disease resistance as possible, consistent with horticultural and market requirements (see Pickling Cultivars and Slicing Cultivars sections).

# Specific Diseases and Their Control

Angular leaf spot is caused by the seed-borne bacterium Pseudomonas syringe pv. lachrymans which causes straw-colored spots with well-defined angular shapes on leaves (Plate 20). The organism occasionally attacks the fruits and may cause rotting. The disease is favored by cool, wet weather. There are resistant cultivars. Two pickling cultivars with resistance are Endeavor and Freemont, however these cultivars are shorter than most cultivars used by the processing industry. Sprays with a copper fungicide may be beneficial.

Anthracnose is caused by the fungus Colletotrichum obiculare that may be seedborne and may live for one or more years in the soil on crop debris. Leaf spots are light brown or salmon colored with irregular margins (Plate 21). The centers of the spots tend to drop out. Stems and fruits are also affected but this is rare in North Carolina. The disease is favored by warm, wet weather. Most cultivars recommended have some level of resistance (Tables 1 and 2). However, cultivar resistance is not always satisfactory under severe disease pressure. A two-year crop rotation with non-cucurbit crops is an essential practice and often must be supplemented with a regular spray program, especially for mid- and late-season crops.

Bacterial wilt is caused by the bacterium Erwinia tracheiphila that causes a progressive wilting of the plant and subsequent die-back of the vines (Plate 15a). The disease is easily recognized in the field. Individual wilted plants occur randomly which reflects beetle transmission. Often, only a single vine or half a vine will wilt, indicating the point of infection by the beetle.

To confirm diagnosis, cut off a portion of the wilted runner near the first wilted leaf. Check for the presence of bacteria in the vascular system by cutting the stem piece in half. Realign the two cut surfaces, press together, and slowly separate to about 0.1 inch. The test is positive for bacterial wilt if thin slime strings are seen between the two cut surfaces (Plate 15b). Normal sap (e.g., without bacteria in it) will not form a slime string. Try several samples on different plants. This disease is present throughout the state.

The bacterium overwinters in cucumber beetles and is spread by them. Most cultivars recommended do not have bacterial wilt resistance; some notable exceptions are Marketmore 80Bw (slicing type) and County Fair 87 (pickling type). Bacterial wilt can be prevented by controlling cucumber beetles with timely sprays of insecticides when beetles are present.

Cercospora leafspot and target spot. Cercospora leafspot is caused by the fungus Cercospora citrullina and causes pale spots on leaves surrounded by a dark ring and a chlorotic halo. A similar disease, target spot, is caused by the fungus Corynespora cassiicola. Target spot (Plate 22) produces a similar but more angular leaf spot. Both diseases are favored by wet and warm weather and are controlled by timely fungicide sprays.

Damping-off and seed rot can be caused by Pythium spp., Fusarium spp., Rhizoctonia solani, other fungi, and bacteria. Symptoms consist of poor emergence caused by seed decay in the ground and rot of the seedling at or near the soil surface. These result in spotty stands of plants. Most often damping-off and seed rot are problems during cool, rainy weather and are especially serious where water does not drain freely from a field and seed germination and seedling growth are delayed or inhibited. There are no resistant cultivars. Application of a soil fungicide or broad-spectrum soil fumigant before seeding may be helpful in problem fields.

Downy mildew is caused by an air-borne fungus Pseudoperonospora cubensis (Plate 23), the spores of which are blown northward each spring from overwintering areas in warmer climates. The fungus usually appears in mid-summer. Characteristic symptoms are yellow spots with a purplish, downy growth on the underside of leaves. The disease can be a problem during rainy periods after mid-season. Most commercial cultivars are highly resistant, which is especially useful in late summer and fall (Tables 1 and 2). Growers should follow a good fungicide spray program.

Fruit rots are caused by different soil-inhabiting fungi such as Pythium spp. (cottony leak) (Plate 24) and Rhizoctonia solani (belly rot) that affect fruit in the field and after harvest (Plate 25 and Plate 26). Fruit rots are favored by wet weather. Harvested fruit should be cooled as soon as possible. There are some cultivars and breeding lines with moderate resistance to belly rot. Marketmore 76 (slicing type) is the most resistant (Uchneat and Wehner 1998). Fungicidal sprays may be helpful.

Gummy stem blight is caused by two related fungi (Didymella bryoniae and Phoma cucurbitacearum) that can be seed borne and overwinter on old plant material in the soil. Symptoms are large, dark brown spots that often appear on the leaf margin (Plate 27), and lesions on the stems. The disease is favored by wet weather and there are few cultivars with some resistance. The cultivar Slice (slicing type) is the most resistant to gummy stem blight.

Mosaics are caused by different viruses (cucumber mosaic [CMV], watermelon mosaic [WMV], papaya ringspot [PRSV-W], squash mosaic [SqMV], zucchini yellow mosaic [ZYMV]), and tobacco ringspot [TRSV] and tomato [TmRSV] ringspot) and usually are only minor problems in North Carolina. Symptoms vary considerably, but plants are usually stunted, their leaves and fruits mottled and distorted (Plate 28). Occasionally plants appear to outgrow symptoms. The viruses are usually spread by aphids. Most recommended cultivars are resistant to cucumber mosaic (Tables 1 and 2), while some slicer cucumber cultivars also have resistance to other viruses (Table 2). In western North Carolina, soils should be treated for nematodes to control TRSV and TmRSV. In all cases, growers should follow a good insect control program. Use of reflective plastic mulches and stylet oil sprays may reduce the incidence of aphid-borne viruses.

Powdery mildew is caused by the fungus Sphaerotheca fuliginea and occasionally by Erysiphe cichoracearum and is rarely a problem in North Carolina because most commercial cultivars are resistant. Powdery mildew can be recognized by a white, superficial, powdery growth that usually starts on the underside of older leaves (Plate 29). The disease can spread rapidly on all green plant surfaces except the fruit. Unlike many other diseases, powdery mildew may develop rapidly during dry weather. Management of the disease is based on growing resistant cultivars and spraying of a recommended fungicide if necessary.

Scab is caused by the fungus Cladosporium cucumerinum and produces dark gray, crater-like spots on fruits. On the leaves, spots are irregular with yellow margins and brown centers. The disease is favored by cool, moist weather and is a problem primarily in western North Carolina. Resistant cultivars are essential in that area. Most recommended cultivars have resistance (Tables 1 and 2). Management of the disease is based on a two-year crop rotation with non-cucurbit crops and a fungicide spraying program.

Root-knot is caused by soil-borne parasitic nematodes (Meloidogyne spp., especially M. incognita) which cause swellings or galls on the roots (Plate 30 and Plate 31). The disease is more common and serious on sandy soils than on clay soils; crop injury is more serious during dry seasons than seasons with adequate rainfall. Root-knot is one of the most common and serious diseases of cucumbers in North Carolina (Main and Gurtz 1989), and all growers should practice control measures. Soils can be assayed for nematodes by the Nematode Advisory Section (there is a nominal fee per sample). Send samples to

Agronomic Division, Nematode
NC Department of Agriculture & Consumer Services
Raleigh, NC 27607-6465

Private laboratories can also assay soils for nematodes.

Growers should treat soils with a nematicide, if recommended. Currently, there are no resistant commercial cultivars.

Plate 20. Angular leafspot caused by Pseudomonas syringae pv. lachrymans.

Plate 21. Anthracnose caused by Colletotrichum orbiculare.

Plate 22. Target spot caused by Corynespora cassiicola.

Plate 23. Downy mildew caused by Pseudoperonospora cubensis.

Plate 24. Cottony leak caused by Pythium spp.

Plate 25. Belly rot caused by Rhizoctonia solani.

Plate 26. Belly rot caused by Rhizoctonia solani. Note dry, sunken, irregular lesions.

Plate 27. Gummy stem blight caused by Didymella bryoniae.

Plate 28. Slicing cucumber fruit with a mixed virus infection of WMV and ZYMV.

Plate 29. Powdery mildew caused by Sphaerotheca fuliginea.

Plate 30. Root-knot nematode galls on cucumber seedlings.

Plate 31. Root-knot nematode galls on developed root system.

# Sprayers

Adapted from Sumner and Sneed 1994.

Sprayers are used for applying insecticides, fungicides, herbicides, and foliar fertilizers. Boom sprayers, with the aid of drop nozzles, provide better coverage of the plant canopy than air-blast sprayers.

Most materials applied by a sprayer are in a mixture or suspension. Continuous agitation is needed when applying pesticides that settle out, even when moving from field to field or when stopping for a few minutes. Jet or mechanical agitators may produce that agitation.

Three factors to consider in selecting the proper pump for a sprayer are

1. Capacity — The pump should be of proper capacity or size to supply the boom output and to provide agitation (5 to 7 gallons per minute (gpm) per 100-gallon tank capacity).
2. Pressure — The pump must produce the desired operating pressure for the spraying job to be done. Pressures are indicated as pounds per square inch (psi). Piston or diaphragm pumps are recommended because they achieve high pressure.
3. Resistance to corrosion and wear — The pump must be able to withstand the chemical spray materials without excessive corrosion or wear. Use care in selecting a pump if wettable powders are to be used, as these materials will cause pump wear.

Nozzle tips are the most neglected and abused part of the sprayer. Because clogging can occur when spraying, nozzle tips and strainers should be cleaned and tested before each application. When applying chemicals, proper ground speed, operating pressure, and boom height should be maintained. This will ensure proper delivery of the recommended amount of pesticide to the plant canopy. Use a flat-fan nozzle to apply broadcast herbicides. When applying insecticides and fungicides, use solid or hollow-cone nozzles.

When applying insecticides and fungicides, completely cover both sides of all leaves with spray. Properly selected nozzles should be able to apply 25 to 125 gallons per acre when operating at a pressure of 60 to 200 or higher psi. Sprayers should be calibrated at 2 to 4 miles per hour. Calibration should be conducted every 8 to 10 hours of operation to ensure proper pesticide application. A good calibration procedure is given in the section entitled "Calibration of a Field Sprayer" in the North Carolina Agricultural Chemicals Manual, available through your county Extension Service center.

# Marketing

Pickling cucumbers. Cucumber production and sales can be an important source of income in an agricultural enterprise, especially for growers in the southeastern United States. Pickling cucumbers provide approximately $134 million in farm revenue to North Carolina growers. North Carolina and Michigan are the two largest suppliers of pickling cucumbers in the United States. US pickle consumption has decreased slightly from 5 pounds per person in 1990 to 4.8 pounds per person in 1995. Slicing cucumbers. Led by Florida and Georgia growers, the southeastern US states provide nearly two-thirds of US-grown fresh-market cucumbers during the late spring, summer, and early fall. Other important suppliers of slicing cucumbers include California, Texas, and Michigan while Mexican and Honduran growers also ship late fall, winter, and early spring cucumbers to US cities. USDA estimated that the 1995 farm value for fresh cucumbers exceeded$164 million in farm revenue to growers. North Carolina ranks third in domestic planted acreage and tenth in production of fresh cucumbers (Food Institute and Research Center 1996).

Favorable spring and fall temperatures in North Carolina provide favorable growing conditions and market window opportunities for growers. Each year, North Carolina growers plant around 6,000 acres of fresh-market cucumbers (spring and fall). During the 1990s, growers have benefitted from increasing US fresh cucumber consumption, with per capita consumption expanding 20 percent to 5.6 pounds per person by 1995.

Marketing Options for Pickling Cucumbers

Marketing options are limited for most pickling cucumber growers. Oftentimes, pickle packers and processors contract directly with growers. Contract terms usually dictate many production and cultural practices to be followed. At harvest time, the pickling cucumber crop is delivered by the grower to a local buying station where the crop is graded, sized, and evaluated for quality and condition. Contracts often include terms that indicate how the price paid to growers will be determined at the time of delivery and how crop-quality discounts and premiums will be paid to growers.

In recent years, an increased proportion of pickling cucumber acreage has been sold directly to retail grocery stores who offer "fresh-market pickling cucumbers" for sale in their produce departments to customers who wish to make their own pickles or simply prefer the taste of unbrined pickles. Table 14 offers a worksheet detailing pickling cucumber revenue and operating expenditures as an example for developing a marketing plan.

Table 14. Pickling cucumbers: Estimated revenue, operating expenses, annual ownership expenses, and net revenue per acre.
Operating Inputs Units Price Quantity Value Your Value
Cucumber Seed 1,000 Seed $1.44 32.0$46.08
Contract Harvest Bushel .90 250.0 225.00
Bee Hive Rental Each 35.00 1.0 35.00
Preemergence Herbicide Acre 14.13 1.0 14.13
Postemergence Herbicide Acre 24.50 1.0 24.50
Contact Insecticidea Acre 5.81 1.0 5.81
Contact Insecticidea Acre 8.63 1.0 8.63
Contact Insecticidea Acre 7.38 1.0 7.38
Fungicide Acre 13.75 1.0 13.75
Nematicide Acre 55.56 1.0 55.56
10-10-10, dry bulk CWTb 7.30 8.0 58.40
34-0-0 CWTb 11.00 2.0 22.00
Annual Operating Capital Dollars 0.09 45.3 4.08
Machinery Labor Hours 7.50 5.7 43.19
Other Labor Hours 7.50 5.0 37.50
Machinery Fuel, Lube, Repairs Dollars 48.04
Total Operating Costs $649.05 Fixed Costs Amount Value Your Value Machinery Interest at 10.0%$273.98 $27.40 Depreciation, Taxes, Insurance 32.02 Equipment Interest at 10% 180.00 18.00 Depreciation, Taxes, Insurance 123.24 Total Fixed Costs$200.66
Production Units Price Quantity Value Your Value
Cucumbers, pickling Bushel $3.75 250c$937.50
Total Receipts $937.50 Returns Above Total Operating Cost$288.45
Returns Above All Specified Costs $87.79 Note: Assumes fruit grade distribution of 15% No. 1s, 40% No. 2s, 35% No. 3s, 10% oversize (No. 4s) to obtain weighted price. Fall production; 6-10 fungicide and insecticide sprays are necessary. Bulk bins prorated over 3 years. a Application number and prices vary with season and insecticide type used. b CWT = hundredweight c Average yield for North Carolina Prepared by E. Estes, Extension Economist, and J. Schultheis, Extension Horticulturist, January 1998. Marketing Options for Slicing Cucumbers Slicer producers can sell directly to consumers (farmers markets or roadside stands), directly to retail grocery stores, or to wholesalers. The direct marketing approach often represents the highest price available to local growers. However, direct selling to consumers is often limited because of large distances between cities and the farm, the limited volume that most markets can handle, and the amount of time and labor associated with selling direct. One of the biggest challenges facing small- to medium-size growers is trying to sell fresh cucumbers to chain stores and wholesalers. Wholesale standards for size, maturity, color, shape, and pack uniformity are high and exact. Many growers have difficulty satisfying the quality considerations without culling substantial portions of their crop. In addition, wholesale prices received for cucumbers can be favorable one day but within hours or days can fall below cost of production levels. Because of buyer volume and quality considerations, selected local growers also have the option of selling cucumbers to local shipper-packers. Shippers consolidate quantities provided by several growers, offer grading and packing services, and arrange market transport, pre-cooling, and other services needed by buyers. How can a grower locate wholesale buyers, shippers, or both in an area? Perhaps the best way is by word of mouth. Most wholesalers and packers have been in business for a number of years and are well-known by other growers, North Carolina Department of Agriculture & Consumer Services marketing specialists, and your county Extension agents. Ask others in the industry for recommendations. The Red Book (Vance Publishing, Shawnee Mission, Kansas) and the Blue Book (Produce Reporter Company, Wheaton, Illinois) contain names, phone numbers, and financial information of buyers, shippers, brokers, and first-handlers as well as other critical marketing information such as instructions on filing a PACA (Perishable Agricultural Commodity Act) claim. Keys to Successful Marketing of Pickling and Slicing Cucumbers Unfortunately, there is not a single method or set of practices that will ensure success in marketing cucumbers. What may be successful for one individual grower may fail for another grower. Growers need to examine a variety of approaches, develop a marketing plan (Table 15), and collect as much marketing information as they can. Pickling and slicing cucumber production is a profitable venture for a number of North Carolina farmers, but it will not be successful and profitable for all who plant a crop. It is important to recognize that cucumber production can be profitable only if growers (1) carefully investigate changes in consumer tastes, buying habits, and preferences, such as a consumer's desire to purchase pickling cucumbers for fresh consumption; (2) identify market window opportunities when supplies are less plentiful but demand is sufficient to attract buyer interest and a favorable price; and (3) always try to produce and pack the highest quality cucumbers possible. Table 15. Slicing cucumbers: Estimated revenue, operating expenses, annual ownership expenses, and net revenue per acre. Operating Inputs Units Price Quantity Value Your Value Cucumber Seed 1,000 Seed$2.81 24.0 $67.50 Custom Harvest/pack Bushel 2.10 220.0 462.00 Bee Hive Rental Each 35.00 1.0 35.00 1.1 Bu Shipping Carton Each 1.00 220.0 220.00 Postemergence Herbicide Acre 14.13 1.0 14.13 Postemergence Herbicide Acre 24.50 1.0 24.50 Contact Insecticidea Acre 5.81 1.0 5.81 Contact Insecticidea Acre 8.63 1.0 8.63 Contact Insecticidea Acre 7.38 1.0 7.38 Fungicide Acre 13.75 1.0 13.75 Nematicide Acre 55.56 1.0 55.56 10-10-10, dry bulk CWTb 7.30 8.0 58.40 34-0-0 CWTb 11.00 2.0 22.00 Annual Operating Capital Dollars 0.09 48.8 4.40 Machinery Labor Hours 7.50 5.7 43.19 Machinery Fuel, Lube, Repairs Dollars 48.04 Total Operating Costs$1,090.28
Fixed Costs Amount Value Your Value
Machinery
Interest at 10.0% $273.98$27.40
Depreciation, Taxes, Insurance 32.02
Equipment
Interest at 10.0% 135.00 13.50
Depreciation, Taxes, Insurance 92.43
Total Fixed Costs $165.35 Production Units Price Quantity Value Your Value Cucumbers, Pickling Bushel$7.25 220c $1,595.00 Total Receipts$1,595.00
Returns Above Total Operating Cost $504.72 Returns Above All Specified Costs$339.37
Note: Blend price for all grades harvested. Fall production; 6-10 fungicide and insecticide sprays are necessary. Includes container assembly; bulk bins prorated 3 years.
a Application number and prices vary with season and insecticide type used.
b CWT = hundredweight
c Average yield for North Carolina
Prepared by E. Estes, Extension Economist and J. Schultheis, Extension Horticulturalist, January 1998.

Developing a Marketing Plan for Fresh-market Sales (Pickling and Slicing)

While development of a marketing plan cannot ensure marketing success, it can reduce the chances for failure. The first phase in developing a plan is collecting information. Marketing information on cucumbers is not abundant, but it is especially valuable when it (1) is timely and relevant to a particular situation, (2) is used to help make a decision, and (3) provides answers to questions. General knowledge that cucumber production or consumption is increasing may not be particularly relevant marketing information unless it is accompanied by more specific information such as "Which summer week are slicer supplies most abundant? Least abundant?" Information should be supplemented by personal visits with buyers, supermarkets, and other growers to evaluate competition and to learn what quality is needed to satisfy buyers.

Another inexpensive but effective technique is using market window analysis to examine marketing opportunities. Market window analysis involves collecting historic market price and cost data for specific locations over a defined time period (often weekly). From that information, a grower can observe regular trends in supplies and prices. This procedure helps identify periods when niche market opportunities exist. Follow-up conversations with brokers, buyers, and other farmers could support or refute the existence of a market window opportunity.

The bottom-line measure of conducting effective marketing analysis is profit. Over time, farm profits will improve with careful attention to the needs of consumers and anticipation of products and services that buyers desire. It is important to recognize that the market will not consistently provide a profit for whatever crop is planted. However, market planning and analysis will provide a grower with a reasonable expectation of a crop's market potential and the extent of profits offered by that crop. Because cucumber production is a highly competitive enterprise, prices and market contacts can change rapidly. Marketing plans must be developed, evaluated, and changed every year. Only by careful attention to all marketing details can long term profits be achieved.

# Terminology and Application

Advances in cucumber breeding have prompted introduction of several terms to describe cucumber cultivars. Cucumbers can exhibit different flowering and vining characteristics.

Flowering

Predominantly gynoecious cultivars produce almost all female flowers on the same plant, so they must be interplanted with monoecious pollenizer plants that produce mostly male flowers. Such cultivar blends usually have 10 to 15% pollenizer to ensure an adequate supply of pollen. In cucumbers, all predominantly gynoecious cultivars are hybrids but not all hybrids are predominantly gynoecious.

Monoecious cultivars produce separate male and female flowers on the same plant. An example of a hybrid monoecious inbred is Poinsett 76.

Hybrids are the offspring derived by crossing two unique inbred lines. Seed from fruits produced from hybrid seed cannot be saved because two specific inbred lines must be used exclusively to obtain hybrid seed. Seed companies do not publicize inbred (parents') identities of superior cultivar hybrids so that hybrids can be sold exclusively for profit.

Inbred (sometimes referred to as open-pollinated) cultivars are true-breeding cultivars which are self pollinated with male and female flowers on the same plant (called monoecious). Seed can be saved from an open-pollinated cultivar. That seed will produce the same cultivar when grown the following season. Because hybrids bring greater revenue from seed sales, most commercially sold cultivars are hybrids and not inbreds.

Parthenocarpic cucumber cultivars do not require pollination (pollen transfer from the male to the female flower) to set fruit. Nonfertilized fruits are seedless. Commonly grown parthenocarpic cultivars are the "burpless" or "European" cucumber types (10 to 14 inches long) typically produced in the greenhouse. Some field-grown cultivars are parthenocarpic. However, these cultivars usually are not seedless because flowers are often pollinated by wild bees. An example of a field-grown parthenocarpic cultivar is H-19, a little-leaf type.

Pistillate flowers are female flowers that produce fruit. The flower has an ovary below the petal (Plate 3).

Monoecious cultivars are used as pollen sources or pollenizers for the predominantly gynoecious cultivars to ensure that adequate pollination occurs, resulting in good fruit set and well-formed fruit. Many seed companies have developed their own monoecious pollenizers to blend with certain cultivars although Sumter and Poinsett 76 cultivars are often used. A good pollenizer should have plenty of male flowers to provide sufficient pollen for adequate pollination, have male flowers that open before the female flowers on the predominantly gynoecious cultivar open, and yield well and produce fruit similar in quality to the predominantly gynoecious cultivar. The seed label should indicate how much and what pollenizer seed is blended with the seed of the predominantly gynoecious cultivar. Approximately 10 to 15% pollenizer seed should be blended with seed of the predominantly gynoecious cultivar to maximize yields (Miller 1976).

Staminate flowers or male flowers have no ovary attached (Plate 3) but are necessary because they provide pollen for pollination. Male flowers must open (anthesis) when female flowers open for pollination, fruit set, and production of quality fruit.

Vining

In determinate plants, vine growth of the main stem ceases after a period of time (Denna 1971) with formation of floral tissue at the vine terminal (Staub and Crubaugh 1995). Determinate plant types have less vine growth, more concentrated fruit set, and fruit produced nearer to the base of the plant than indeterminate types. Determinate-type plants must be managed more intensively than the indeterminate (vining) type because they are more sensitive to environmental stress (from increased fruit load on smaller plants). With determinate plant types, fruit are easier to pick and high yields have often been obtained, particularly when grown on black plastic mulch.

Indeterminate, or vining types, continue to grow indefinitely as flowers are produced continuously throughout plant growth. Vining types typically produce fruit farther from the base of the plant than determinate types. Indeterminate plants are larger and more tolerant of stress conditions because they usually have more leaves to support fruit growth and development.

Little-leaf is a mutant line that was reported in Arkansas in 1980. It produces a plant with leaves that have one-fourth to one-half less leaf area than standard cucumber cultivars (Goode et al. 1980) (Plate 32a and Plate 32b). The little-leaf plant type has a multibranching habit which coincides with fruiting, which might result in increased yield. One little-leaf cultivar (H-19) was made available to the processing industry but was not widely accepted commercially because of seed maturation (hard seed) in grade 3-size fruit. Reduced maturation of seed in grade 3 fruit in little-leaf types is currently being addressed by breeders.

Plate 32a. Normal leaf cucumber (top) and little-leaf cucumber (bottom).

Plate 32b. Normal leaf (right) and little leaf (left).

# Production Plan

The purpose of this outline is to pull together in a readily usable form pertinent points made in this publication. Dates for this production plan are for the coastal plain area for spring-planted cucumbers. Growers located farther west need to delay these dates one to four weeks.

As early as practical in the fall

1. Select a field that has not had cucumbers, watermelons, cantaloupes, pumpkins, or squash for two to three years. The field should be fertile, well drained, and uniform.

2. Note predominate weed species and check susceptible crop roots for root-knot nematode presence.

3. Take soil samples for nematode assay and fertilizer recommendations.

4. Apply lime and incorporate, if recommended.

By April 1

1. Have soil turned and disked as necessary to cover plant refuse.

By April 15

1. Broadcast recommended fertilizer, plus soil insecticide, if necessary, and disk in.

2. Apply nematicide (if recommended) and form rows.

3. Wait 10 to 14 days before planting if treated with certain nematicides. (Some nematicides require no waiting period.)

Between April 15 and 30, or when the average soil temperatures reach 60°F at a 4-inch depth and remain for one week

1. "Strike-off" bed top and seed 12- to 34-inch deep.

2. Sow seed. Before planting, consider plant type and harvest method (hand harvest or machine harvest).

3. Apply herbicide. (Note, preplant herbicides should have been incorporated before seeding.)

When seedlings have completely emerged

1. Scout for disease and insects. If present, apply a recommended insecticide and fungicide. Additional applications should be geared to insect and disease pressure.

2. Scout field thoroughly and at least weekly.

When plants are 4- to 6-leaf stage

Sidedress with 20 to 30 pounds per acre of actual nitrogen. Additional sidedressing will be necessary after heavy, leaching rains.

When blooming is evident (about May 20 to 30)

Place bees in field.

Starting between May 30 and June 10

1. Harvest cucumbers at least three times each week.

2. Allow small fruit to reach at least 12-inch in diameter before picking.

3. Do not hold harvested fruit overnight or expose them to hot sun.

Throughout growing season

1. Provide supplemental irrigation, if necessary, to supply a total of about 1 inch of water per week.

2. Provide 2 inches of water per week at flowering and during fruit development.

3. Maintain an insect and disease spray program consistent with pest population pressure as determined by weekly field scouting by a qualified scout.

# Common Problems

Plants white or yellow and stunted in areas of the field. These symptoms are most often caused by frost or chilling. During cool, moist weather, growth is likely to be white or yellow and stunted in the low areas of the field where cold air tends to settle. The same areas are likely to have more vigorous growth in warm, dry spring weather.

If areas in fields are observed during summer or early fall, pull some plants and examine them for root-knot galls.

Young plants wilt and fall over. Wilting may be caused by nematodes or "damping-off." If "damping-off" is the cause, you will notice some evidence of rotting at or near the soil line. Another possible cause is the seedcorn maggot, which can be found feeding on the roots or inside the stems of young seedlings.

Vines produce only male flowers. This is a very common problem, especially during the spring crop; it is most often associated with monoecious cultivars. Cool temperature and excessive nitrogen may also be related to this problem. Usually the problem is temporary and will be resolved when lateral vines develop to produce female blooms with normal frequency.

Desiccated (dried up) areas on the upper surface of leaves that appear light in color. Such areas occur regularly in early spring and fall when the humidity is low. These areas are caused by wind-blown sand, leaves rubbing together, or both. This abrasive action ruptures the leaf tissue causing the plant sap to evaporate and the tissue to die.

Young fruits turn brown and shed. This condition is usually caused by lack of pollination brought on by inadequate numbers of bees, excessively hot and dry conditions, and, in some cases, plant diseases.

Meandering paths or trails on leaf surface. These paths are feeding trails of a small insect larvae (leafminer) inside the leaf. They are rarely a serious problem. With care, the very small brownish larvae can be lifted out with the point of a knife. Leafminer injury is sometimes a point of entry for disease-producing organisms. Crop protectants are available for control.

Young plants emerge, become chlorotic, and die back to soil level while roots appear normal. Problem appears intermittently along the row. Some parts of the row not affected. This condition is typical of triazine herbicide injury and most often results when cucumbers are planted after corn that was treated with a triazine herbicide.

# Literature Cited

• Cantliffe, D. J. 1981. Alteration of sex expression in cucumber due to changes in temperature, light intensity, and photoperiod. J. Amer. Soc. Hort. Sci. 106:133-136.
• Cantliffe, D. J., and A. F. Omran. 1981. Alteration of sex expression in cucumber by partial or total removal of cotyledons. J. Amer. Soc. Hort. Sci. 106:303-307.
• Cantliffe, D. J., and S. C. Phatak. 1974. Response of cucumber to soil and foliar application of ethephon. HortScience. 9:465-466.
• Cantliffe, D. J., and S. C. Phatak. 1975. Use of ethephon and chlorflurenol in a once-over pickling cucumber production system. J. Amer. Soc. Hort. Sci. 100:264-267.
• Cargill, B. F., D. E. Marshall, and J. H. Levin. 1975. Harvesting cucumbers mechanically. Bulletin No. E-837. Michigan State University Extension.
• Denna, D. W. 1971. Expression of determinate habit of cucumbers. J. Amer. Soc. Hort. Sci. 96:277-279.
• Epperson, D. L., G. L. Johnson, J. M. Davis, and P. J. Robinson. 1988. Weather and climate in North Carolina. AG-375. North Carolina Cooperative Extension Service.
• The Food Institute Information and Research Center. 1996. Food markets in review 1996 fresh vegetable. May:113-123.
• Friesen, G. H. 1978. Weed interference in pickling cucumbers (Cucumis sativus). Weed Science. 26:626-628.
• Goode, M. J., J. L. Bowers, and A. Bass, Jr. 1980. Little-leaf, a new kind of pickling cucumber plant. Arkansas Farm Research, May and June:4.
• Hochmuth, G. J., and G. A. Clark. 1991. Fertilizer application and management for micro (or drip) irrigated vegetables in Florida. Florida Cooperative Extension Special Series Report. SS-VEC-45.
• Huanwen Meng, H., Z. Cheng, H. Cui, and E. Shang. 1995. The relationship between storage time and viability of cucumber seeds (Cucumis sativus L.). Cucurbit Genetics Cooperative Report. 18:17-18.
• Jones, J. P. 1961. Control of soil rot of cucumber by plastic mulch and certain fungicides. Proc. Fla. State Hort. Soc. 74:180-182.
• Lorenz, O. A., and D. N. Maynard. 1980. Knott's handbook for vegetable growers. New York: Wiley-Interscience Pub.
• Lower, R. L., O. S. Smith, and A. Ghaderi. 1983. Effects of plant density, arrangement, and genotype stability of sex expression in cucumber. HortScience. 18:737-738.
• Main, C. E., and S. K. Gurtz (eds.). 1989. 1988 Estimates of crop losses in North Carolina due to plant diseases and nematodes. Special Publication No. 8. Raleigh, N.C.: Department of Plant Pathology, North Carolina State University.
• Miller, C. H. 1976. Effects of blending gynoecious and monoecious cucumber seeds on yield pattern. HortScience.
• Miller, C. H., and G. R. Hughes. 1969. Harvest indices for pickling cucumber in once-over harvested systems. J. Amer. Soc.
• Nienhuis, J., R. L. Lower, and C. H. Miller. 1984. Effects of genotype and within-row spacing on the stability of sex expression in cucumber. HortScience. 19:273-274.
• Perry, K. B., and T. C. Wehner. 1996. A heat unit accumulation method for predicting cucumber harvest date. HortTechnology. 6(1):27-30.
• Sanders, D. C., W. P. Cook, and D. Granberry. 1995. Plasticulture for commercial vegetables. AG-489. North Carolina Cooperative Extension Service.
• Schultheis, J. R., J. T. Ambrose, S. B. Bambara, and W. A. Mangum. 1994. Selective bee attractants did not improve cucumber and watermelon yield. HortScience. 29:155-158.
• Sorensen, K. A., and J. R. Baker. 1994. Insect and related pests of vegetables. AG-295. North Carolina Cooperative Extension Service.
• Staub, J. E., and L. Crubaugh. 1995. Selection for multiple lateral determinate cucumber genotypes. Cucurbit Genetics Cooperative Report. 18:5-6.
• Stanghellini, M. S., J. T. Ambrose, and J. R. Schultheis. 1997. The effects of honey bee and bumble bee pollination on fruit set and abortion of cucumber and watermelon. Amer. Bee J. 137:386-391.
• Sumner, P. E., and R. E. Sneed. 1994. "Sprayers." In Commercial Production of Edible Beans and Southern Peas. Eds. Adams, D. B., J. R. Schultheis, and C. D. Monks. North Carolina Cooperative Extension Service. pp. 14-16.
• Tiedjens, V. A. 1928. Sex ratios in cucumber flowers as affected by different conditions of soil and light. J. Agric. Res. 36:721-746.
• Toth, S. J., Jr., C. W. Averre, D. W. Monks, J. R. Schultheis, and K. A. Sorensen. 1994. Cucumber pest management 1990. AG-499. North Carolina Cooperative Extension Service.
• Uchneat, M. S., and T. C. Wehner. 1998. Resistance to belly rot in cucumber identified through field and detached fruit evaluations. J. Amer. Soc. Hort. Sci. 123:78-84.
• United States Department of Agriculture. 1958. United States standards for grades of cucumbers. U.S. Government Printing Office.
• United States Department of Agriculture. 1995. Vegetables 1994 summary. National Agric. Statistics Serv., Washington, D.C.

Crop protectant and variety recommendations may change from year to year. Certain publications are updated more frequently and are listed. Other related publications which provide more detail in various subject areas are also listed.

• Ambrose, J. T. 1995. Cucumber pollination. Dept. Entomology Insect Note No. 7B. North Carolina Cooperative Extension Service.
• Asgrow Seed Company. 1984. Modern cucumber technology. Asgrow Seed Co. Kalamazoo, Mich.
• Averre, C. W. 1993. Fruit rots of pickling and slicing cucumbers. Plant Pathology Information Note. Vegetable Disease No. 1. North Carolina Cooperative Extension Service.
• Averre, C. W., and S. F. Jenkins. 1991. Anthracnose of cucurbits. Plant Pathology Information Note. Vegetable Disease No. 11. North Carolina Cooperative Extension Service.
• Averre, C. W., and S. F. Jenkins. 1991. Gummy stem blight and phyma blight of cucurbits. Plant Pathology Information Note. Vegetable Disease No. 8. North Carolina Cooperative Extension Service.
• Averre, C. A., K. A. Sorensen, C. J. Eckenrode, and G. R. Hughes. 1986. Know and control cucumber pests (color poster). North Carolina Cooperative Extension Service and North Carolina Pickle Producers Association, Inc.
• Boyette, M. D., L. G. Wilson, and E. A. Estes. 1991. Introduction to proper postharvest cooling and handling methods. AG-414-1. North Carolina Cooperative Extension Service.
• Boyette, M. D., L. G. Wilson, and E. A. Estes. 1991. Design of room cooling facilities: Structural & energy requirements. AG-414-2. North Carolina Cooperative Extension Service.
• Boyette, M. D., L. G. Wilson, and E. A. Estes. 1994. Forced-air cooling. AG-414-3. North Carolina Cooperative Extension Service.
• Boyette, M. D., E. A. Estes, and A. R. Rubin. 1992. Hydrocooling. AG-414-4. North Carolina Cooperative Extension Service.
• Boyette, M. D., D. F. Ritchie, S. J. Carballo, S. M. Blankenship, and D. C. Sanders. 1993. Chlorination and postharvest disease control. AG-414-6. North Carolina Cooperative Extension Service.
• Motes, J. E. 1975. Pickling cucumbers. Production harvesting. Bulletin No. E-837. Michigan State University Extension.
• North Carolina Cooperative Extension Service. North Carolina Agricultural Chemicals Manual. North Carolina State University, College of Agriculture and Life Sciences.
• Sanders, D. C., C. W. Averre, D. W. Monks, and K. A. Sorensen. 1995. Producing commercial transplants. AG-337. North Carolina Cooperative Extension Service.
• Schultheis, J. R. 1998. Cucumbers for fresh market. Hort Information Leaflet No. 14. North Carolina Cooperative Extension Service.
• Schultheis, J. R. 1998. Pickling cucumbers. Hort Information Leaflet No. 14-A. North Carolina Cooperative Extension Service.
• Sorensen, K. A. 1985. The seedcorn maggot. Vegetable Insect Note 31. North Carolina Cooperative Extension Service.
• Sorensen, K. A. 1993. Pickleworm management. Dept. Entomology Insect Note No. 1. North Carolina Cooperative Extension Service.
• Wehner, T. C., and C. H. Miller. 1985. Effect of gynoecious expression on yield and earliness of a fresh-market cucumber hybrid. J. Amer. Soc. Hort. Sci. 110:464-466.
• Wehner, T. C., and R. R. Horton, Jr. N.C. State University cucumber breeding report (Annual). North Carolina State University, Department of Hort. Science.
• Zitter, T. A., D. L. Hopkins, and C. E. Thomas (eds.). 1996. Compendium of cucurbit diseases. St. Paul, Minn.: The American Phytopathology Society.

# Authors

Department Extension Leader and Specialist, Sweetpotato/Curcurbits/Sweet Corn
Horticultural Science
Professor Emeritus
Plant Pathology
Philip Morris Professor
Biological & Agricultural Engineering
Professor Emeritus
Agricultural & Resource Economics
Specialist (Vegetables)
Plant Pathology
Assistant Director
Agricultural Research Service
Extension Specialist (Fruits & Vegetables)
Entomology

Publication date: Jan. 1, 2000
AG-552

North Carolina State University and North Carolina A&T State University commit themselves to positive action to secure equal opportunity regardless of race, color, creed, national origin, religion, sex, age, veteran status or disability. In addition, the two Universities welcome all persons without regard to sexual orientation.