NC State Extension Publications

Site Preparation

Thoroughly destroy perennial weeds and established sod before planting. Ideally this would occur one year before the caneberry crop is to be established. Kill wild caneberries with an herbicide and remove the residue from the field. Perform several ground tillings before planting to destroy weeds and loosen the soil. Plow the land again to prepare for planting. Preplant land preparation should be completed by mid- to late February in the coastal plain and by March or in the preceding fall in the mountains.

If possible, avoid planting caneberry fruits on a site previously planted to fruit crops, such as peaches, apples, grapes, raspberries, or blackberries. The soil could harbor pathogens from previous plantings.

Many blackberry varieties are susceptible to viruses, double blossom disease, and orange rust, so cultivated plants should not be planted near wild blackberries.

If possible, at least one year before planting caneberries, grow a summer cover crop (such as Sudangrass) or a winter cover crop of rye, oats, or wheat. A cover crop will suppress weeds and increase organic matter. Test soils for fertility and nematodes. Apply lime and nutrients according to soil test recommendations.

Fumigation and the use of black plastic on raised beds will give newly set blackberry and raspberry plants an advantage by killing most weed seeds and soil pathogens. Fumigation is highly recommended if nematodes are present in the soil, with or without the use of black plastic mulch.

The durability of black plastic mulch limits the number of years that the plastic will be useful. Over time, the plastic and drip tubes used for irrigation will break down. Check labels when using herbicides in the presence of black plastic mulch.

Soil Tests

Most roots of blackberries and raspberries are found in the upper 12 to 18 inches of the soil. Soils should be tested six months to a year or more in advance of planting to enable application and incorporation of recommended amendments. Lime, phosphorus, and potassium tend to move down into the soil very slowly, if at all. Therefore, waiting to apply needed amendments until after the planting has been established is not effective because incorporation of these amendments will no longer be an option. In most cases, the basic soil test consisting of pH, phosphorus, potassium, calcium, and magnesium plus a test for organic matter content should provide sufficient information. Knowledge of soil organic matter content will be valuable in determining how much nitrogen to apply.

Soil test at two depths—0 to 8 inches and 8 to 16 inches—to determine the status of both the topsoil and the subsoil. Knowing calcium and magnesium levels in the soil will be valuable in determining whether to apply either calcitic or dolomitic limestone. Determine the amount of lime, phosphorus, and potassium to apply by adding the recommendation for the 0- to 8-inch sample to the recommendation for the 8- to 16-inch sample. Rototill or disk this amount into the top few inches of soil and then deep plow the field to get the amended soil down into the lower depths. In the event that large amounts of lime or nutrients are needed, add two-thirds of the total recommended amount and incorporate as described. Once this is done, apply the remaining one-third to the soil and disk or rototill it in. After planting, soil test on a regular basis, perhaps every other year, to monitor soil pH levels.

Nematode Tests

Plant-parasitic nematodes cause direct damage to roots and can transmit viruses that may significantly suppress yield and fruit quality in caneberries. The only reliable way to determine if nematodes are present in a site is by collecting a soil sample and submitting the sample to a nematology laboratory for assay (see Appendix 1). Thoroughly sample fields during the summer or early fall to determine the types of nematodes that are present and their population density. Guidelines for proper sampling and sample handling procedures are available through local N.C. Cooperative Extension centers.

Planting

Order plants a year before you intend to establish your new planting. Several types of nursery stock are available (Figure 7). Bare root dormant nursery stock or tissue culture plants are usually available from November to March. A limited amount of nurseries are able to ship for fall planting. Be sure to contact nurseries to determine shipping dates.

Purchase only stock plants from reputable nurseries to increase chances of getting healthy plants of the desired cultivars. Healthy planting stock is key to the cost-effective production of caneberries. Healthy plants will produce higher crop yields and better crop quality than common planting stock. Healthy planting stock is necessary for your planting to remain economically viable.

The most efficient approach to producing healthy planting stock is through programs that screen valuable plant selections for viruses and other diseases that can be spread by contaminated plant stock. Quarantine services provided by clean stock programs reduce the chance of introduction of exotic pests that can be difficult and costly to control. Ask your plant nursery if they are part of the National Clean Plant Network. Visit the National Clean Plant Network’s website for more information.

The use of clean, healthy plants cannot be emphasized enough. New bare rootstock should be purchased from nurseries that have grown plants in a greenhouse or on fumigated land well isolated from other caneberries. The plants should have been sprayed regularly for insect and disease control and inspected by state officials. Early spring planting of dormant stock is acceptable in most regions. Plants set late in the spring may be adversely affected by drought or drying winds. In warmer areas, early fall planting is possible provided the soil is still warm and not excessively wet. Fall planting enables a good root system to develop. Avoid planting on wet soil. When planting both bare rootstock and tissue-culture plugs, give plants a thorough drenching with water, especially if the soil is dry and the weather is hot. After planting, cut off the stem of bare root plants at least 3 to 4 inches from the ground.

Bare root nursery stock (Figure 8). Plants should arrive just a day or two before planting. Do not keep plants in a cooler for an extended period of time or let the roots dry out. If the bare root plants are dry upon arrival, soak the roots in water for several hours before planting. If they will not be planted immediately, heel in the plants by digging a trench deep enough to contain the roots. Spread the plants along the trench, roots down, and cover the roots with moist soil. Plants can be held in this manner until buds begin to swell (usually in a couple of weeks). Always keep the bare roots covered and moist. To plant, dig a hole large enough for the root system to be spread in the hole. Cover the roots of bare-root plants with soil to a depth of 2 to 3 inches, and firm the soil around the roots.

Tissue-culture plug plants (Figure 9). Tissue-culture plants should be allowed to harden off in a protected and shaded location outdoors. When planting, take only the number of plants that can be transplanted in half a day to the field. Be sure to water the plants well prior to planting. Set tissue-culture plants in holes so that the top of the root ball is even with the soil surface. Push a thin layer of soil around the top of the plug’s root system. Growers have found that tissue culture plants perform well in the Southeast.

Tip layered canes. These types of plants are produced when growing tips come in contact with the ground and form roots. Once root systems are well established, the newly formed plants are cut from the mother plant and stored for shipping at a later date. This type of propagation method is most often used in black raspberry. These plants should be hardened off similarly to the tissue-culture plants.

Root section. A root section (root cutting) should be about 3 to 4 inches in length and 14 to 38 inch in diameter. Plant the root section about 2 to 3 inches in depth. New canes will originate from adventitious buds on the root section. A new planting can be established as quickly and successfully using root cuttings as it can with rooted suckers.

Figure 7.

Figure 7. Three types of nursery stock. A: bare root; B: tip-layering; C: tissue cultured.

Raspberry and Blackberry Production Guide: For the Northeast, Midwest, and Eastern Canada, NRAES-35.

Figure 8. Bare root nursery stock.

Figure 8. Bare root nursery stock.

Jon Traunfeld, University of Maryland Extension

Figure 9. Tissue-culture plug plants.

Figure 9. Tissue-culture plug plants.

Karen Blaedow, NC State University

Establishment

Alleys

Maintain alleys with a ground cover or with cultivation in areas where soil erosion and high temperatures do not occur. Perennial grass species are preferable in most areas because they are not hosts for botrytis and verticillium. A good ground cover will serve as a deceleration/diffusion strip for run-off water and as support for equipment used in caring for the crop. If sod is allowed to develop in between rows, it should be kept mowed. Tall fescue is well adapted to non–coastal plain regions of the Southeast and has proven to be an effective ground cover in the piedmont and mountains of North Carolina.

A 4-foot-wide, weed-free strip must be kept in the plant row, either by physical or chemical means, to prevent weed competition with the caneberry plant (Figure 10). Chemical weed control, used correctly, can be very effective. The choice of herbicide depends on soil type, weed species present, season of the year, herbicide application timing, and bearing status of the planting. The correct herbicide must be used at the proper time, or serious injury to the caneberry plants may result. For detailed information on managing weeds and using herbicides, see the Southeast Regional Caneberries Integrated Management Guide, located on the Southern Region Small Fruit Consortium’s IPM/Production Guides web page.

Spacing—Blackberry

Optimal spacing between plants and rows varies depending on plant type, training method (trellis type), terrain, and size of farm equipment. Allow at least 10 to 12 feet between rows to facilitate tractor operations. On sloping ground, the wider spacing is recommended. Space erect blackberries 2 to 4 feet apart in the row, and allow primocanes to fill in the spaces between plants. Both semi-erect and trailing types require 4 to 8 feet between plants to accommodate their very long canes. In southern Georgia, many cultivars have fewer canes than farther north, and a spacing of 2 to 3 feet between plants is recommended. Generally, maximum row length should not exceed 600 feet. When planting before trellises are erected, align plants carefully in the rows to accommodate the trellises. To calculate how many plants you will need for each acre, refer to Table 4.

Spacing—Raspberry

Primocane-fruiting raspberries can be set at 2 to 3 feet apart in the row, while floricane-fruiting types should be set at 3 to 4 feet apart within a row. The row-width range is from 8 to 15 feet, depending on equipment. However, rows should be spaced as closely as possible to ensure the highest possible planting yields.

To calculate how many plants you will need per acre, multiply the distance between plants in a row by the distance between rows and divide 43,560 square feet per acre by this number, or simply refer to Table 4.

Table 4. Number of plants required per acre using different spacing within and between rows.
Spacing between Rows (ft)
Spacing within Row (ft) 8 10 12 13 14 15
2 2,722 2,178 1,815 1,675 1,556 1,425
3 1,815 1,452 1,210 1,117 1,037 968
4 1,360 1,090 907 838 778 726
5 1,090 870 726 670 662 581
6 907 726 605 558 519 484
8 680 544 453 419 389 363
10 544 435 362 335 311 290

Figure 10.

Figure 10. A perennial grass in alleyways provides a durable surface for equipment and competes with weeds.

Absalom Shank, NC State University

Authors

Extension Specialist (Small Fruits)
Horticultural Science
Professor
University of Arkansas
Professor
University of Tennessee

Publication date: Oct. 30, 2015
AG-697

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