The peach, Prunus persica (L.) Batsch, is native to China. From China, peaches were introduced to Persia, Greece, and temperate European countries including Italy, Spain, and France. Peaches were introduced to the southeastern United States more than 300 years ago when the Spanish visited the Florida region in the 1500s. It is believed that in the northeastern United States the early English and French settlers brought peach seeds with them.
Until the early 1900s, most peach varieties developed from chance seedlings. One cultivar, Chinese Cling, is the ancestor of Elberta; from Elberta, many of our first commercial varieties were developed. Some of the peach cultivars selected between 1850 and 1900 are still grown commercially. These include J. H. Hale and Belle of Georgia. Today there are more than 200 peach varieties available for home and commercial production.
Commercial peach production in the Southeast expanded rapidly in the early 1900s. Improvements in transportation, such as the introduction of refrigerated boxcars, tractor trailers, and air freight greatly increased the marketing potential of many commercial crops. Today South Carolina and Georgia rank second and third, respectively, among the nation's peach-producing states. California is the nation's top producer of both fresh and processed peaches. North Carolina ranks approximately ninth in peach production, growing an average of 35 million pounds of fruit annually for the fresh market.
Commercial peach production in the Southeast, as well as the Northeast, has been plagued by various problems in recent years. Spring frosts and freezes have adversely affected commercial production in the Southeast during the last decade. Another difficulty is peach tree short life (PTSL), a disease complex most severe on replant sites with sandy soils. PTSL is the greatest threat to Southeastern peach producers. A 10-point PTSL management program has been devised to minimize the probability of PTSL. Adherence to the 10-point program is a good strategy for both home and commercial peach growers, especially in lighter and sandy soils.
Before planting a peach orchard, a grower must identify market outlets for the fruit. Many growers who have not identified markets before planting have been disappointed by initial sales. In addition, consistent annual full cropping has not occurred in the state during the last decade. If you are concerned about the economic efficiency of your peach orchard, consult your local Extension agent, who has a copy of a computer software package called Budget Planner. You will need to supply production records and equipment lists to run the program to get an accurate estimate of your production costs.
It is important to realize that North Carolina peach growers have been caught in a difficult situation because of low prices and the lack of consistent cropping for large-scale shipping. At present, most of the peaches produced in North Carolina are sold at roadside retail outlets which provide greater returns to the grower. However, to survive economically, North Carolina peach growers must compete in the marketplace with a quality product. Growers must continue to ensure that producing a quality product remains their ultimate goal.
The bottom line is: Do your homework before you plant an orchard!
Successful peach growing depends primarily on the site selected for the orchard. The site must have good air drainage to minimize the risk of late winter and early spring frost and freeze injury (Figure 1). The windiness of the site also should be considered. Level land is suitable if the area has good air drainage or if there is little chance of spring frost. Planting next to wooded areas, windbreaks, or high hedgerows is not advised because these obstructions will impede air drainage, allow frost pockets, and increase shading that will reduce crop yield and increase the chance of disease and insect problems. To minimize these problems, plant at least 80 feet from wooded areas for optimal conditions.
Peach trees can withstand fairly cold temperatures (about -12°F); however, hardiness is affected by the preconditioning the trees receive before being exposed to winter temperatures. If the tree is late in going into dormancy, or hardening off, it will be more susceptible to cold winter temperatures. For example, excessive levels of nitrogen fertilizers in late summer can delay the onset of dormancy and increase the tree's susceptibility to winter cold injury. If a tree is cropped too heavily, its reserves are depleted and the tree may be susceptible to winter injury.
The cold sensitivity of peach flower buds is highly correlated with variety. Some varieties are known to be hardy, such as Reliance or Surecrop. The time of bloom for a given variety is determined by the length of the chilling requirement and the weather conditions in the spring. Chilling is fulfilled between 33°F and 45°F and is necessary for the tree to bloom and grow properly. Varieties that require 850 to 1,000 hours of chilling tend to bloom later than those with a shorter chilling requirement. In North Carolina, varieties with less than a 750-hour chilling requirement are not recommended because they may bloom too early and the flowers could be killed by frosts or freezes. Table 1 lists the chilling requirements as well as many of the fruit characteristics of selected peach varieties. (Refer to the Sources of Additional Information section for other pertinent publications.)
|Variety||Freestone or Clingtsone||Browning Tendency||Maturity||Chilling Requirement (hours)||Bacterial Spot Resistance||Comments|
|Derby||Cs||Low||Early||750||+++++||NC variety; medium to large fruit.|
|Candor||Cs||Very low||Early||950||++++||NC variety; medium-size fruit.|
|Dixired||Cs||Low||Early to mid||950||++++||Late-blooming variety.|
|Pekin||Semi-Cs||Low||Mid||950||+++++||NC variety; medium-size fruit.|
|Reliance||Semi-Cs||Low||Mid||1,000||++++||Late-blooming variety; poor quality, soft flesh.|
|Redhaven||Semi-Cs||Low||Mid||950||+++||Industry standard; recommended for freezing.|
|Clayton||Semi-Cs||Very low||Mid||950||+++++||NC variety; small-size fruit, excellent flavor.|
|Norman||Fs||Very low||Mid||850||++++||NC variety; medium to large fruit; good for canning and freezing.|
|Carolina Belle||Fs||Very high||Mid||750||++||NC white-fleshed variety, large fruit.|
|Raritan Rose||Fs||---||Mid||1,000||++||White variety; softens rapidly.|
|Topaz||Fs||Low||Mid||750||+++||Recommended for canning and freezing; flower buds are cold sensitive.|
|SungloN||Fs||Very high||Mid||550||+||Nectarine; susceptible to bacterial spot.|
|Nectar||Fs||---||Mid||1,050||++||White peach variety; late blooming.|
|Winblo||Fs||Very low||Mid||800||+++||NC variety; medium to large fruit; good for canning and freezing.|
|RedgoldN||Fs||Low||Mid||800||+||Nectarine; susceptible to bacterial spot.|
|Ellerbe||Fs||Low||Mid||850||+++||NC variety; medium to large fruit; good for canning and freezing.|
|Contender||Fs||Low||Mid||1,050||+++||NC variety; large fruit size; very cold tolerant.|
|Summer Pearl||Fs||---||Mid to late||900||+||White variety; very susceptible to bacterial spot; high quality.|
|Biscoe||Fs||High||Mid to late||900||++++||NC variety; large, high-quality fruit; recommended for canning.|
|Belle of Georgia||Fs||---||Mid to late||850||++||White variety; freezes well; popular for local markets.|
|Elberta||Fs||Very high||Mid to late||850||+++||Favorite yellow variety, especially for local market.|
|Encore||Fs||---||Late||900||+++||Hardy, late-blooming variety.|
|Monroe||Fs||High||Late||750||+||Susceptible to bacterial spot.|
|Emery||Fs||Very high||Late||900||++++||NC variety; medium to large fruit.|
|Legend||Fs||Low||Late||950||+++||NC variety; large fruit size.|
|Parade||Fs||Low||Late||850||++||Very-late-maturing California variety.|
|+++++ = very high resistance + = low resistance N = Nectarine|
Soil types. Peach trees, like many fruit trees, prefer deep, well-drained, fertile soils with a pH of 6.0 to 6.5. They do not grow well in heavy, slow-draining soils. Peach trees, however, can be grown on a wide range of soil types --- even when soil conditions are less than ideal --- if pH, drainage, and fertility are modified. If the pH is less than 5.5, preplant liming with deep incorporation (12 to 18 inches) is recommended. Poor drainage can be modified by planting the trees on raised beds or berms. A raised bed 1 to 2 feet high and 4 to 6 feet wide is sufficient to improve drainage. However, irrigation is recommended with raised beds because of increased soil moisture evaporation from a larger exposed surface area. Soil drainage also can be improved by adding drain tiles and ditches. Soil fertility must be adjusted before planting. Adjustments should be based on soil test results.
When choosing a peach variety, the main features to consider are the chilling requirement, the time of ripening, and the intended market for the crop. The characteristics of various peach and nectarine varieties are listed in Table 1. As mentioned previously, varieties with less than a 750-hour chilling requirement should not be planted in North Carolina because of the risk of crop loss due to spring frosts or freezes. Time of ripening is especially critical for commercial growers who sell to local markets, roadside retail, or have pick-your-own operations. It is recommended that growers select multiple varieties that will ripen over a six- to eight-week period. Thus, the harvest season can be extended, and repeat business is possible. For roadside retail sales, it is essential to have varieties with overlapping maturity dates for a continual supply of fruit. Variety selection should be tailored to consumer demands in a given locale.
Two rootstocks are recommended for North Carolina peach orchards: Lovell and Halford. These rootstocks have performed well in a variety of soil types and weather conditions, and are the only rootstocks suitable for North Carolina. Other rootstocks, such as Nemaguard and Siberian C, have not proven to be winter hardy in North Carolina and are not recommended. Lovell and Halford are not nematode resistant; preplant fumigation is necessary on sandy soils with a history of root-knot or ring nematode problems. A promising new rootstock that performs well on PTSL sites in South Carolina and Georgia may be available in North Carolina within the next three years.
Before planting the trees, take a soil sample and have it analyzed for pH nutrient requirements and nematode populations. Instructions for soil sampling can be obtained from your county Extension Center. Results from the soil test will determine the amendments necessary to correct nutrient deficiencies and improper pH.
Trees can be planted from late fall (after Thanksgiving) until early spring. Late-fall-planted trees may be more prone to winter injury, and late spring plantings (after mid-April) are not recommended. Early winter (late December to early January) is the optimal time for planting in North Carolina. The trees' roots should never be exposed to freezing temperatures or drying conditions before or during planting.
When the trees arrive from the nursery, open the package. If the roots are dry, moisten them immediately. If the trees are to be planted within 24 hours, soak the roots in water until planting. Trees that are to be held for more than 24 hours before being planted should be heeled in. This is done by digging a trench, placing the roots in the trench, and covering them with soil. If refrigerated storage is available, soak the roots and place the trees (with their roots wrapped in plastic and moist sawdust or paper) in a storage room at 35°F to 40°F until planting time. Do not place the trees in the same storage room with apples because apples give off ethylene gas, which can harm the peach trees. For the same reason, ventilate an empty apple storage area completely before using it to store trees. Make sure that the soil used for heeling in is not infested with nematodes, especially in areas with sandy soils.
Peach trees planted in a residential setting should be approximately 18 to 20 feet apart. Avoid planting in shade from neighboring trees and buildings.
Recommended planting distances and number of trees per acre for large or commercial plantings are listed in Table 2.
|Planting Distance (feet)||Number of Trees (per acre)|
|12 by 20||181|
|15 by 20||145|
|18 by 20||121|
|20 by 20||108|
Before planting the tree, dig a hole large enough to accommodate the root system without curling or cramping the roots. Use of an auger is not advised for heavy clay soils because the hole will act like a clay pot and restrict root growth. Prune off the ends of any large roots that are twisted, too long for the hole, or damaged. It is much better to cut roots back than to curl them up to fit into the hole. Dig the hole deep enough so that the graft union will be 1 to 2 inches above the soil line when finished planting.
Place some of the native topsoil into the bottom of the hole and then the tree. Cover the roots with soil, making sure that the graft union is 1 to 2 inches above the soil line after planting. Water the tree to firm the soil and get rid of air pockets.
CAUTION: Do not put fertilizer into the planting hole as it may "burn" the roots. Allow the soil to settle before applying fertilizers around the tree.
Fertility requirements should be determined by visual analysis, soil analysis, and foliar analysis. Trees putting on 12 to 18 inches of terminal growth per year usually require less fertilizer in heavier soils. Foliar samples for analysis should be collected from mid-July through mid-August. Instructions on sampling can be obtained from your county Extension Center. A small fee is charged for each sample submitted for analysis. Table 3 lists the recommended foliar concentrations of key elements for peaches.
|Nitrogen||2.0 to 3.0 percent|
|Phosphorus||0.1 to 0.3 percent|
|Potassium||1.5 to 3.0 percent|
|Calcium||1.0 to 1.8 percent|
|Magnesium||0.2 to 0.4 percent|
|Iron||50 to 100 ppm|
|Manganese||50 to 100 ppm|
|Zinc||20 to 40 ppm|
|Copper||5 to 10 ppm|
|Boron||20 to 40 ppm|
|Source: G. Cummings, North Carolina State University|
General rule-of-thumb fertilization rates for peach trees are shown in Table 4. The principal nutrients needed are nitrogen and potassium, but it may be necessary to supply other nutrients as well.
|Age (years)||Annual Amount of 10-10-10 Fertilizer (pounds per tree)*|
|Newly planted||0.25 to 0.5|
|1 to 2||0.5 to 1.0|
|3 to 5||1.5 to 3.0|
|5 to 10||3.0 to 5.0|
|Over 10||5.0 to 7.0|
|NOTE: Adjust the rate for your trees' overall vigor.
* Other formulations are appropriate; adjust the amount applied for the nitrogen-phosphorus-potassium content.
Nitrogen. This nutrient must be applied regularly to both nonbearing and bearing peach trees. Bearing trees need enough nitrogen to ensure good terminal growth (12 to 18 inches per year), fruit production, and fruit size. If a peach tree does not receive sufficient nitrogen during its nonbearing years, its growth will be weak. The amount of nitrogen needed is determined by the tree's age, overall vigor, crop load, and weed competition. Too much nitrogen can stimulate excessive vegetative growth (such as watersprouts), increase susceptibility to winter injury, and decrease fruit color and flower bud formation.
Nitrogen can be applied in early winter (mid December) on heavy soils or in the early spring before bud swell. On sandy soils in North Carolina, it is best to apply nitrogen in the spring just before or during bud break. Summer nitrogen applications are not recommended. For orchards on piedmont soils that have a high native fertility, the lower rates of nitrogen in Table 4 should be adequate for good tree growth and fruit production. On sandy soils, the higher rate should be used.
A split application of nitrogen fertilizer is highly recommended in North Carolina because of the high probability of a spring frost or freeze in many locations. Half of the fertilizer is applied in late February or early March; if a crop is set, the other half is applied in late April or early May. For trees on sandy soils, a third nitrogen application may be necessary. Nitrogen should not be applied after June 15 to avoid winter injury and decreased fruit quality.
If terminal shoot growth is too vigorous (more than 12 to 18 inches), reduce the amount of nitrogen applied. If terminal growth is weak (less than 6 to 8 inches), increase the amount of nitrogen.
Potassium. If soil and leaf analyses indicate a deficiency, potassium can be added in the late fall or spring. Although the most common potassium source is muriate of potash, other potassium sources will work equally well. Cost may be the deciding factor. Excessive potassium can interfere with calcium and magnesium uptake and is therefore undesirable.
Other Nutrients. Many North Carolina sites may need additional phosphorus, calcium, and magnesium. Soil and leaf analyses are the best means to determine what is needed to correct deficiencies.
Weed control can help reduce competition for water and nutrients between weeds and young trees. Also, certain weeds are hosts for disease-causing organisms, including fungi, viruses, and nematodes, as well as catfacing insects. For this reason, only grasses are recommended in peach orchards with a vegetation-free strip down the tree row.
Mulching. Mulching under trees --- alone or combined with chemical weed control --- is an excellent home orchard management tool. Using a mulch:
- Controls weeds and erosion
- Conserves water
- Improves soil structure
- Adds nutrients and organic matter.
Pine straw and hay are among the many materials that can make good mulches. The mulch should be applied under trees to a depth of 4 to 5 inches.
However, this practice holds risks for commercial peach growers. Disadvantages may include the cost of labor to apply the mulch, scarcity of mulching materials, and the increased possibility of fire and rodent damage. Therefore, mulching is not advised for commercial peach orchards because it increases the potential for vole damage and collar-rot injury to trees.
If chemical weed control methods are used, you may need to reduce the amount of nitrogen fertilizer to avoid excessive tree growth. The appropriate herbicides labeled for use on peaches should be selected for specific weed problems. Certain herbicides are labeled only for nonbearing trees; it is illegal to use these herbicides on bearing trees. Consult your county Extension agent; AG-146S, Peach and Nectarine Disease and Pest Management Guide; or the current North Carolina Agricultural Chemicals Manual for herbicide recommendations.
Most peach varieties, with the exception of some varieties like J. H. Hale and Marsun, are self-fertile. Peaches can thus be planted in solid blocks of one variety if desired.
Bees and other wild insects are the main agents involved in transferring pollen among trees in an orchard. Care should be taken during bloom to spray only those chemicals that will not harm bees and other beneficial insects. Many insecticides are toxic to bees and should be avoided during bloom. Also, remove blooming vegetation from the orchard to minimize competition for bees and to avoid bee kills from pesticide applications.
Fruit thinning is a practice required for increasing fruit size and balancing crop load.
Peaches have a tendency to overbear, and the trees commonly split if the crop load is too heavy. Trees should not be allowed to bear fruit for the first two years after planting as this can decrease the tree's growth and bend the framework branches or scaffolds. Once the trees begin to bear, fruit thinning is necessary for producing high-quality, marketable peaches --- there are no shortcuts.
Thinning is a labor-intensive process. The early-maturing clingstone peach varieties may require several thinning treatments, and the cost of labor may become a major concern. Early varieties should be thinned first, before mid- or late-season varieties.
Timing is critical for thinning to be beneficial. With all varieties, it is recommended that thinning be done before pit hardening, which is within 40 days of bloom. Thinning early varieties after the pit hardens does not increase fruit size substantially. With mid- and late-season varieties, thinning can be delayed until after the first drop through June drop (the second period of fruit drop) but no later than pit hardening. Under North Carolina conditions, it is best to thin peaches as early as possible.
The amount to thin from a tree depends on the tree's size and bearing capacity. Obviously, trees in poor vigor should not be allowed to bear as much fruit as moderately vigorous trees. If a tree has set a uniform crop of fruit, a general rule of thumb is to thin fruit 6 to 8 inches apart on the shoot. After a spring freeze, however, the crop is sometimes borne on the basal portion of the shoots. In this case, only light thinning is recommended. Clusters of fruit should be broken so that orchard sprays can cover the fruit well.
Thinning relies heavily on hand labor. Beating the trees with a rubber hose or plastic baseball bat to knock the fruit off is the most popular thinning method. High-pressure water sprays, tree shakers, and rope drags have been relatively unsuccessful.
Research has been conducted on blossom and fruit thinning with growth regulators and other chemicals. Currently no chemicals are labelled for peach bloom or fruit thinning.
Peach trees are easy to train and prune in contrast to apple or pear trees. The first three years of growth should be devoted to training the peach tree to a shape that will allow it to bear a full crop. If trees are left unattended, fruit production will initially be good, but as light becomes limited in the interior portion of the tree, the crop will be borne only on the tree's periphery. Pruning keeps the tree open to light, which helps maintain fruit production close to the trunk. Pruning also:
- Helps keep the tree at a desirable height
- Decreases the incidence of certain diseases by allowing the foliage and fruit to dry more quickly
- Allows spray to more readily penetrate the tree's canopy and cover the leaves and fruit
- Removes dead, damaged, and diseased wood.
Peach trees are trained to the open center system in the Southeast. The open center system is designed to give the tree an open, vaselike shape. Peach trees are trained to an open center to optimize light distribution within the tree. Trees with this vaselike form should be strong enough to bear an optimal crop load. Figure 2a shows an overhead view of an open center tree. Concentric circles approximate the yearly development of the tree. Note the scaffold branch orientation. Figure 2b shows a side view of an open center tree with concentric circles approximating the yearly development.
Summer pruning is strongly encouraged, especially for removing watersprouts, rootsuckers, and diseased wood. Summer pruning also can be very beneficial during the first three years of tree growth to produce the desired tree shape and promote earlier production. Undesired growth should be removed in early summer when the growth is 3 to 6 inches long or after harvest between late July and mid-August. The goal of summer pruning is to thin out growth rather than head back (Figure 2a and Figure 2b). Heading back cuts may stimulate new growth in the area of the cut; this growth will be susceptible to winter injury.
Peaches bear most of their crop on last year's wood, so it is important when pruning not to remove an excessive amount of one-year-old wood. During the dormant season, one-year-old wood is distinguished by its reddish tinge.
Dormant pruning should be done in late winter or early spring (late February to early March) as close to bloom as possible and as soon as the risk of a hard freeze is over.
At planting, the newly set tree should be headed, or cut back, to a height of 24 to 30 inches from the soil surface. This forces the tree to form new side branches approximately 18 to 24 inches above the ground. During the following winter (when the tree is entering its second growing season), select three to five scaffold branches with wide angles (45 to 60 degrees). These branches, or primary scaffolds, also should be headed back to a length of 24 to 36 inches. These primary scaffolds should not arise from one point along the trunk. Ideally, they should be spaced 6 to 12 inches apart, with the lowest scaffold 18 to 22 inches above the ground. Scaffolds should not be directly opposite or above each other as limbs in these positions will be more likely to break once they begin to bear a normal crop load. When viewed from above, the scaffolds should form angles of approximately 90 to 120 degrees, giving the tree balance (Figure 2a).
During the dormant season of the second year, the scaffolds should be cut back to an outward and upward growing lateral branch approximately the same diameter as the scaffold being pruned. Lateral branches from the scaffolds also should be selected approximately 18 to 20 inches from the trunk. These lateral branches may be pruned back to promote secondary branching. All upright growth not removed during summer pruning should be removed, as well as growth below horizontal.
During the dormant season of the third year the primary scaffolds can be pruned so that there are two secondary scaffolds arising from each approximately 3 feet from trunk (Figure 2b, inner circles). These secondary scaffolds should be pruned to outward and upward growing laterals if needed to maintain the open center system of the tree.
On each secondary scaffold, approximately 3 feet from the first split, another split may be required to form tertiary scaffolds (Figure 2b, outer circle). Lateral branching from all of the scaffolds is to be encouraged for fruit production. One of the problems with peach trees is that lateral branching from the scaffolds closer to the trunk is discouraged because of excessive shading. (This problem can be eliminated with summer pruning.) At this time all vigorous upright shoots not removed during summer pruning also should be removed along with the shoots growing downward.
By the fourth year, the basic framework of the tree should be completed. Prune moderately to thin out undesirable branches; peach trees will suffer from reduced yields if pruned too severely. Also, remember that moderately pruned trees bear sooner than heavily pruned trees. However, allowing trees to bear excessive crop loads before establishing the tree's framework can stunt the tree as well as destroy its shape.
The bearing peach tree is pruned to maintain a good balance between vegetative growth and fruit production. The first two years should be spent on training only. Beginning in the third and fourth years, the trees can be moderately cropped.
Pruning bearing trees is critical if you want to maintain healthy, fruiting wood. Remove weak, shaded-out wood, diseased or dead wood, watersprouts, and rootsuckers. Tree height can be controlled by cutting back the top portion of the tree to weak, outward growing branches or to a side branch. It is important to maintain a consistent tree height or the entire crop may be too far above ground for convenient picking and pest control.
All branches of the tree should be exposed to adequate sunlight to ensure good flower bud production. This can be a challenge in the lower portion of the tree. On the secondary scaffolds, it may be better to tip the terminal shoots of these branches during the spring rather than cut them back to laterals. If fruit quality and yield diminish in older trees, heavy, careful pruning may be necessary to restore tree shape and allow more sunlight to penetrate the tree's interior.
Remember that peach trees need to be pruned for many reasons. Pruning produces and maintains a desirable tree shape and size, and allows for good flower bud development and fruit quality. Pruning also aids in disease and insect control because the leaves and branches can receive a more efficient spray distribution.
Diseases and insect pests of peach trees and fruit must be controlled if you wish to produce an attractive product. Many pests and diseases also threaten the survival of the peach tree, so proper control is highly recommended. Consult the 10-point PTSL management program if you are locating your orchard in a replant site or a site with known nematode infestations. Your county Extension Center should be contacted for current pest control recommendations. Also, the publications listed in the Sources of Additional Information section will be useful.
Proper orchard spray equipment is essential for disease and insect control. For orchard operations, an airblast sprayer is most effective. For any operation of more than 5 acres, an airblast sprayer is highly recommended. Backpack sprayers are simply not adequate for large orchards because their coverage is limited. Consult your county Extension agent for equipment recommendations for your operation.
Bacterial spot affects fruits, leaves, and twigs of susceptible varieties; it is a serious disease in the sandhills and coastal plain. It is less of a concern in the piedmont. When planting an orchard, avoid highly susceptible varieties. Some of the most susceptible varieties are Sunhigh, Jerseyland, Elberta, Southland, and Blake. Relatively resistant varieties include Candor, Dixired, Norman, Pekin, Winblo, Biscoe, Emery, Redhaven, Redskin, Contender, and Legend.
Peach Leaf Curl
Peach leaf curl will not kill a tree but can cause foliar damage in the spring. Control consists of one fungicide application in the fall or early spring before bud swell.
Rhizopus rot is primarily a postharvest disease, although some orchard infections may occur. Maintain fungicide applications up until harvest and cool fruit immediately after harvest. Do not allow the fruit to become overripe before picking. If you use a hydrocooler, make sure the water is clean. Chlorination of hydrocooler water may be necessary.
Brown rot effects blossoms, young shoots, and fruits. It can be controlled with properly timed fungicide applications. Orchard sanitation is very important for adequate control. Clean up and destroy mummified fruit (mummies) and infected plant material. Also, avoid bruising the fruit at harvest. Hydrocooler water should be kept clean; dirty dumptank water can actually increase brown rot as well as rhizopus rot infections. Prune and maintain adequate vigor in the trees; excessive vigor can increase the incidence of brown rot infections.
Peach scab is a fungus and infects fruit just after shuck split. However, the symptoms do not appear on the fruit until mid- to late-May as small, shallow, greenish black spots. With severe infections, the fruit may crack. Control measures depend on properly timed fungicide applications. Fungicide treatments are especially important during the four to six weeks after shuck split.
On heavy piedmont soils, stem-pitting virus has been a problem in the past. This virus is transmitted by nematodes, which feed on alternate hosts such as dandelions. Control measures include obtaining clean plant material from a reputable nursery, eliminating wild hosts (including wild cherries and plums), controlling broadleaf weeds, and maintaining good cultural practices.
Nematodes are microscopic wormlike organisms rather than insects, and can transmit viruses affecting peaches. The ring nematode is associated with the PTSL disease complex. Ring and root-knot nematodes are especially troublesome in sandy soils. A nematode analysis is strongly recommended before planting to determine if preplant fumigation is necessary. There is a small fee for an analysis. Consult your county Extension Center for sampling instructions. See the section on the 10-point PTSL management program for a discussion on nematodes.
White peach scale attacks peach trees; in severe infestations, young trees can be killed. This scale insect primarily damages shoots and larger branches. White peach scale eggs and overwintering adults can be controlled with one dormant oil spray in the early spring before budbreak. If the infestation is severe, two dormant oil sprays applied two weeks apart, as close to bloom as possible, are recommended for control.
San Jose scale also can attack peach trees. Control measures are the same as for white peach scale.
Several species of mites can attack peach foliage. They feed on the leaves, which then become bronzed or blackened. In severe mite infestations, defoliation may occur and fruit development may be abnormal.
Orchard mite populations usually increase during warm, dry weather. As many as eight or nine generations may develop in one growing season. Mites can be controlled with an approved miticide.
Stink bugs and lygus bugs are sucking insects that attack the peach fruit. They can cause premature fruit drop and misshapen fruits (catfacing). These insects overwinter in winter annual broadleaf weeds including vetch and chickweed. Broadleaf weed control in the orchard can assist greatly in minimizing damage from this type of insect.
Peach Tree Borer
Borers can attack young or old trees; this insect is generally attracted to diseased or stressed trees. Severe infestations can kill young trees. An accumulation in the spring of brown gum and brown frass around the trunk of the tree at the soil line is evidence of the presence of peach tree borers. Prevention is the best way to avoid infestations. Application to the tree trunk of an approved insecticide in late summer, combined with sound cultural practices in the orchard, will diminish the chances of peach tree borer infestations.
Oriental Fruit Moth
The oriental fruit moth attacks most of the stone fruit species as well as apple and pear trees. The most characteristic symptom of this insect's presence is shoot death at the terminal end. Fruit injury also may occur in some instances. A regular insecticide program will control the adult moth.
The plum curculio feeds on and lays eggs in almost all pome and stone fruits as well as blueberry, grape, and wild persimmon. Adults may attack the fruit at any time but prefer young peaches or mature peaches that are about two weeks away from harvest. Very few peaches are attacked during the pit hardening stage. Control consists primarily of insecticides, but orchard sanitation helps considerably. Remove volunteer peach trees along roadsides as well as abandoned orchards. Destroy thickets of wild hosts if they are located near the orchard.
This section presents recommended practices for sound orchard management and should be considered by all peach growers.
- Preplant Phosphorus and Lime Application. The soil pH should be adjusted to at least 6.0 --- preferably 6.5 --- before planting the trees. Lime and phosphorus move slowly through soil, so deep incorporation of these materials is recommended before planting. Always base application rates of lime and phosphorus on soil test results.
- Preplant Subsoiling and Backhoeing. Subsoiling helps improve soil drainage and promotes better root growth. It also helps soil amendments to move through the soil profile better. Backhoeing is recommended to break up severely compacted soil and to remove residual tree roots. Backhoeing must be done carefully in sites with heavy clay soils; if done improperly, the soil structure may be damaged. After either subsoiling or backhoeing, let the soil settle naturally before planting a new orchard.
- Preplant Fumigation. Preplant fumigation is highly recommended for replant sites. Research has shown that tree survival is greatly enhanced, as are tree vigor and yields. Fumigation is good for controlling most nematode species, but most nematicides do not control root rots and crown gall. If necessary, a broad spectrum fumigant may be used. Preplant nematicides and fumigants are extremely toxic and must be applied carefully. Also, adequate time should be allowed for soil ventilation before planting new trees; the trees may die if the soil has not been properly aerated.
- Nursery Stock. Purchase trees from a reputable nursery. Nursery stock should be certified virus free and true to type. Purchasing trees from an unreliable source can also lead to problems with nematodes and peach tree borers. The bottom line is: Quality pays!
- Rootstock selection. As discussed in a previous section, the only recommended rootstocks for North Carolina are Lovell and Halford. Nemaguard is resistant only to root-knot nematode, and trees on Nemaguard survive poorly in North Carolina. If planting in a replant site, preplant fumigation is necessary as neither Lovell nor Halford are nematode resistant.
- Nutrition. Nutrient deficiencies have been associated with tree stress, which may make the trees more susceptible to winter injury or any of the other factors associated with PTSL. Maintaining adequate soil pH and good soil drainage can prevent nutrient stress. Preplant liming and incorporation is essential to increase subsoil pH as lime moves through the soil very slowly (about 1 inch per year). A split application of nitrogen, which aids in controlling tree vigor during a crop loss, is recommended.
- Time of Pruning. Pruning at the wrong time of the year results in excessive tree mortality in North Carolina. Do not dormant prune trees from October through mid-January. Trees are more susceptible to winter injury and PTSL during this time. Summer pruning should consist of thinning cuts --- never heading back --- for tree training purposes. Avoid heavy summer and dormant pruning. Pruning is not a substitute for fruit thinning and should not be used for this purpose.
- Orchard Floor Management. Herbicides are preferred to disking or cultivating for weed management. Peach roots are close to the soil surface and may be injured by disking. Weed control also is recommended for two other reasons: weeds compete directly with trees for water and nutrients, and many weeds are hosts for virus-transmitting nematodes and catfacing insects. Research has shown that many broadleaf weeds, such as dandelions, are hosts for nematodes that carry the stem-pitting virus. Ring and root-knot nematodes have a wide host range, so absolute avoidance may be impossible. Weed control will ultimately keep the trees vigorous and help improve survival.
- Postplant Nematicides. Routine nematode analysis should be conducted either in early spring or late summer or, if possible, both times each year. If test results indicate that postplant treatment is necessary, make sure that an appropriate postplant nematicide is used.
- Orchard Sanitation. Dead or diseased wood and prunings should be removed from the orchard during every winter season. Also, dead or diseased trees should be removed from the orchard. Infested plant material harbors diseases and insects that can attack healthy trees still in the orchard.
About 80 percent of the peach crop in North Carolina is marketed via roadside markets and pick-your-own operations, so shipping quality and maturity standards are not as important as they are to commercial growers in larger peach-producing areas. However, roadside markets are able to supply a tree-ripened peach to the consumer. The biggest challenge we face in North Carolina is maintenance of good postharvest quality. Few people have access to hydrocoolers, so they depend on refrigerators to keep fruit cool.
Control of diseases, especially brown rot and rhizopus rot, is essential for preventing postharvest disease problems. Too often, preharvest sprays are neglected and these diseases become serious problems. Sanitation in the packshed is necessary to prevent disease problems. Picking containers and storage boxes should be cleaned after every harvest season. Infected fruit should be culled so that repeat infestations can be avoided. Also, a fungicide dip can prevent infections if the fruit was not previously infested in the orchard. The best practice is to continue cover sprays until harvest and cool the fruit as rapidly as possible. Harvesting peaches in the early morning or later in the evening when the fruit temperature is lower also is recommended to prolong the storage potential of peaches.
Deciding when to harvest peaches is a matter of personal preference if sales are limited to the roadside market. Consumers prefer tree-ripened fruit, but fruit at this stage has an extremely short shelf life. As a compromise, it may be better to pick the fruit two to four days before it is fully ripe. The fruit will continue to ripen normally, and the taste will be unaffected.
Peaches that are almost fully ripe can be stored at 40°F for several days with no adverse effects on fruit quality or ripening. However, if they are stored for longer than two weeks at 40°F, they may not ripen properly and can develop internal breakdown. Almost ripe peaches can be stored at 32°F for two to three weeks, but internal breakdown may be a problem if they are stored longer than three weeks.
Peaches are highly perishable and care should be taken to maintain the highest quality possible whether you have a pick-your-own operation or a local roadside stand. Repeat sales can occur only if the consumer is pleased with your product.
Westwood, M. N. Temperate Zone Pomology. Third edition. San Francisco: W. H. Freeman and Co., 1993. 523 pp.
North Carolina Agricultural Chemicals Manual. Raleigh, N.C.: College of Agriculture and Life Sciences, North Carolina State University. Revised annually.*
Peach Production Handbook. Available for $20 from the Agriculture Business Office, 215 Conner Hall, University of Georgia, Athens, GA 30602.
Bulletins and Leaflets
Epperson, D. L., et al. Weather and Climate in North Carolina. AG-375. North Carolina State University, 48 pp. *
Johnson, G. L., and K. M. Williams. Risk of Frost and Freeze Damage for North Carolina Fruit Crops. AG-403, North Carolina State University, 15 pp. *
Johnson, G. L., and K. M. Williams. Low-Temperature Probability Data for North Carolina . AG-403S. North Carolina State University, 91 pp. *
Perry, K. B. Frost/Freeze Protection for Apple Orchards. AG-303. North Carolina State University, 6 pp. *
Perry, K. B. Frost/Freeze Protection for Horticultural Crops. HIL-705-A. North Carolina State University, 7 pp. *
Ritchie, D., and J. Meyer. Peach Diseases and Insects in North Carolina. AG-146. North Carolina State University, 16 pp. *
Ritchie, D. et al. Peach and Nectarine Disease and Pest Management Guide. AG-146 Supplement. North Carolina State University, revised annually. *
Ritchie, D., T. B. Sutton, and K. Sorensen. Spray Guide for Diseases and Insect Control in the Home Orchard. Plant Pathology Information Note No. 238. North Carolina State University, 3 pp. **
Ritchie, D. Peach Scab. Plant Pathology Information Note No. 216. North Carolina State University, 2 pp. **
Ritchie, D. Nematode Control on Peaches and Management of the Peach Tree Short Life Complex. Plant Pathology Fruit Disease Information Note No. 8. North Carolina State University. 3 pp. **
Sneed, R., and C. R. Unrath. Irrigation for Apple Orchards. AG-306. North Carolina State University, 8 pp. *
Hoag, D., et al. Budget Planner. 1987. Available at your county Extension Center. The software package is also available from the North Carolina State University Department of Economics and Business at $50 per copy.
*For price and ordering information contact your county Extension agent or Agricultural Publications, North Carolina State University, Campus Box 7603, Raleigh, NC 27695-7603.
**Available from the Department of Plant Pathology, North Carolina State University, Campus Box 7616, Raleigh, NC 27695-7616
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.
AG-30 Publication date: Jan. 1, 2000