Size of Planting
The size of planting will depend on the amount of fruit desired. An average red raspberry plant will produce from 1-2 lbs. of fruit (when it has filled in a 2 sq. ft. area) while purple and black raspberries will produce about 3 lbs. per plant and blackberries 5-7 lbs. per plant.
Care of New Plants Before Planting
Tissue cultured plants are recommended because of freedom from disease. These plants will need some extra care, however. Order them to arrive soon after the last frost date. Tissue culture plug plants will be actively growing when they arrive. Put them in a partly shady location to acclimate. Gradually decrease shade until they can take full sun. Plant, water carefully and mulch with straw, shredded newspaper or other organic material. Tissue cultured plants will need frequent watering until the roots become established.
Soil Preparation and Fertilization
The soil should be tilled well in advance of planting. Adjust pH to approximately 6.5 and add potassium and phosphorus before planting based on your soil analysis. Do not fertilize with nitrogen until the plants have been planted for several weeks. Fertilizer amount varies with the type of plant and soil conditions. Use the following table to determine the amount of ammonium nitrate needed. If you use 10-10-10, you will need to use three times the amount indicated. Apply fertilizers in early spring or as split applications in March and May for fall-bearing plants.
Table 1. Amount (in ounces) of ammonium nitrate to apply per five linear feet of row (assuming rows 2 ft wide).
Table adapted from: Bramble Production Guide, Northeast Regional Agricultural Engineering Service, Marvin Pritts and David Handley (eds). 1989.
Red raspberries should be planted 2-3 feet apart in rows as far apart as required. As root suckers come up, the row should fill in to be 2 feet wide. Red raspberries have an erect growth habit and can be grown without a trellis if pruned to about 36 inches. A simple trellis of two wires about 36 inches high along either side of the row to hold taller canes up is all that is required if no heading is done. Red raspberries are not topped, unless there is no trellis. Pruning consists of removing at the ground all older canes after they have fruited. This can be done soon after fruiting or in the winter. All dead, damaged and weak canes should also be removed at that time. Vegetative canes come up all summer long and will quickly fill any space. These canes should be thinned to 4-6 inches apart within the desired row as they come up. If thinning is done early, it can be done with a hoe or by hand; if done later, clippers will be needed. It is important that the new vegetative canes receive optimum light and water for production of next year's crop. Fall-bearing raspberries can be mown off 2 inches from the ground after the fall fruiting if only a fall crop is desired. The plants will regrow the following year with new vegetative canes that will fruit in the fall. If both summer and fall crops are desired, treat the same as other red raspberries.
Black raspberries are planted 3 feet apart in rows as far apart as required. Black raspberries do not produce root suckers and will not fill in a row. Instead, basal buds will produce the new canes. Black raspberries have an arching growth habit and should be trellised for maximum production, but they can also be pruned back to 36 inches if no trellis is desired. Trellises can be simple two-wire trellises, or more elaborate, to separate fruiting and non-fruiting canes and increase light exposure, to facilitate harvesting, or to create a narrow row with easy harvest and good light exposure. During the summer, as the canes reach 40-50 inches, the top 3 inches should be cut off to stimulate branching and increase the strength of the cane. Later topping at this height should be avoided as it will result in a larger wound that is susceptible to cane blight. If a tall trellis is used, canes may be topped at the top wire (up to 60 inches) as long as no more than 3 inches is removed. In the winter, head back all branches to 7 inches; remove all dead, diseased or weak canes; remove all old fruited canes; and thin remaining canes to 5-10 per plant.
Blackberry plants should be set 3 feet apart in rows at least 8 feet apart. Some varieties are erect and need no trellising; others will require trellising to obtain maximum yields. Trellises are similar to those described for black raspberries. Like red raspberries, erect black berries produce primocanes from crown buds and root suckers. They should be thinned to 10 inches apart in the row during the dormant season, and in the summer headed back to 48 inches; the laterals should be cut to 18 inches. Trailing blackberries produce primocanes only from crown buds, like black raspberries, and will require trellising. They should be summer tipped at about 6 inches above the highest trellis wire and tied to the wire to induce branching. During the dormant season, select five to eight of the strongest canes on each plant and remove all others. Also remove all laterals on the lower 3 feet of the canes and tip back remaining laterals to 12-18 inches because fruit weight will pull these down to the ground.
Raspberries and blackberries have a very short shelf life. Very gentle treatment is required to obtain marketable fruit. Berries should be picked in the morning while it's cool, but after the dew has dried on the fruit. Fruit are normally picked directly into the containers they are to be marketed in to reduce handling. Containers should never allow the fruit to be more than four deep. Clear plastic containers with narrow slits are the most popular type. Picker aprons that support a tray holding eight half-pint containers are useful. The planting should be harvested every two days to ensure all fruit are picked just as they turn completely red, in the case of red raspberries, or black, in the case of black raspberries and blackberries. Picked berries should be cooled immediately to remove any field heat. This can be done by using fans to pull the warm air off the fruit and replace it with cool air in a corner of the cold storage room. Once fruit temperatures are brought down to about 35 oF, the fruit should be moved to a storage area without rapidly moving air, and air temperature should be maintained at 32 oF. Under these conditions, storage life may be up to a week, and slightly longer for blackberries.
The information in this section is taken mainly from the Bramble Production Guide (NRAES-35) produced by the Northeast Regional Agricultural Engineering Service (NRAES). This guide contains color photographs of more bramble diseases and pests. Please use it for further reference. It can be purchased for $45.00 by calling 607/255-7654, faxing 607/254-8770, or e-mailing firstname.lastname@example.org
Anthracnose is a fungal disease that is common on all brambles but is especially destructive on blackberry, black raspberry and, to a lesser degree, purple raspberry. The first symptoms of anthracnose occur on the canes as small, slightly sunken purple spots that enlarge, becoming oval in shape and turning gray in the center with dark raised borders. Sometimes the spots grow together to form a large irregular lesion. The spots sometimes cause the canes to crack. Badly affected canes are weak and prone to winter injury. The foliage from affected canes is weak and fruit is often small and shrivels before harvest, especially during dry spells. The stems supporting the fruit may become infected and the whole fruit cluster lost, or individual drupelets of the berry may become brown and scabby with infection.
The spores produced in the infection sites are spread by splashing rain, reinfecting any succulent new growth. The infection is worse with higher temperatures and the longer the canes remain wet.
Control strategies are the same for all cane diseases of brambles:
Verticillium wilt is caused by a fungus and can be extremely severe on black raspberries. Red raspberries are generally not as affected and susceptibility of blackberries is variable.
The first year of infection, lower leaves become yellow and drop prematurely. Sometimes the plant appears to recover during cool fall weather, but the following year some buds will not break on infected canes and all lower leaves wilt and die. The canes are stunted and may develop streaks of blue in the bark before they finally wilt and die. Symptoms may occur on only one side of the plant at first, but eventually the whole plant will collapse. Red raspberry root suckers from infected canes may be free of the disease although numbers will be reduced. Infection occurs when healthy or wounded roots come in contact with the fungus. The fungus travels up the water-conducting cells of the root and plugs them, causing wilting and death.
Disease severity depends on the population of Verticillium in the soil at planting. A history of susceptible crops in the field is very important because dangerous levels of fungus are likely to occur with susceptible crops, such as potato, tomato, eggplant, pepper, squash, melons, strawberries, stone fruit trees, and such weeds as pigweed, nightshade, horse nettle, ground cherry and lamb's quarters. Such fields should be fumigated with an approved material active against fungi or planted for three to four years with a nonhost crop.
Crown gall is a tumorlike disease of plants caused by a bacterium. It occurs on a wide variety of plant species, including all brambles. Crown gall may stunt and weaken seriously infected plants, but causes little economic damage in most fields.
The bacteria cause rough gall to grow on plants at or below the soil line. Bacteria persist in and on infected plant tissue in the soil and are moved with soil. They enter a plant through wounds on the roots or crowns caused by growth cracks, insect feeding, winter injury or cultivation. As the galls grow, they shed outer layers filled with bacteria.
To control, plant only nursery stock which is free of any sign of galls on crowns or roots. Do not plant into a field where crown gall has occurred previously unless a nonhost crop, such as strawberries or most vegetables, has been grown for at least two years. Also, minimize injury to root and crown systems during farm operations. A biological control organism, Agrobacterium radiobacter, strain K-84, is available. It is only useful when applied to clean plants at planting, and will not cure infected plants.
Orange rust is a serious fungal disease on all brambles except red raspberries. Symptoms are most apparent in the spring when young shoots first look pale, weak and spindly. Within two to three weeks, blisters form on the lower surface of the leaves, which then rupture and produce masses of powdery, rust-colored fungal spores. Affected leaves wither and drop off and new leaves appear normal. However, the following spring infected canes will produce spindly shoots with no blossoms. The fungi are systemic throughout the infected plants and can be transferred by nature root grafting and by spores borne on the wind.
There is no cure for infected plants; they must be dug from the planting and destroyed. Any root suckers that arise from infected plants will also be infected, so it is important to dig out the whole infected plant and root system. Elimination of all sources of new infections is the only way to control this disease. There is no effective fungicide for orange rust. Established plantings should be examined for orange rust every year during the first weeks of growth when symptoms are easiest to diagnose. Wild brambles near the planting should also be inspected and destroyed if infected.
Late rust is caused by a fungus that affects only red and purple raspberries. It is completely different from orange rust and the two should not be confused. Late rust does not develop until late summer, unlike orange rust. It is only of minor importance on summer-fruiting cultivars, but can destroy the fall crop of fall-fruiting cultivars. Symptoms first appear as small yellow spots on the upper surface of mature leaves in late summer or early fall. Small blisters filled with powdery, rust-colored spores form on the leaf undersides. Fruit infections may also occur on individual or several drupelets of berries.
The fungus is not systemic like orange rust, but overwinters in infected canes. White spruce is an alternate host, but is not required. Periods of wetness are presumed necessary for infection, but little is known of the disease cycle.
No specific control measures are currently available, nor are they needed on summer-fruiting cultivars. Several new fungicides look promising for use on fall-bearing cultivars. See your spray guide for future developments.
Raspberry Cane Borer
The raspberry can borer is a slender beetle, about 1/2-inch long and black except for a bright orange thorax with two or three black spots. The insects require two years to complete their life cycle. Adults appear in early June and may be present until late August. Before laying an egg, the female punctures the stem with her mouthparts in a girdling fashion, creating two puncture rings around the cane, about 1/2-inch apart and about 6 inches from the can tip. The egg is laid between the rings. At hatching, the larvae burrow down the cane, reaching the base by fall and the crown by the next summer. The larvae spend the next season underground, then pupation occurs the second spring. The damage is first observed when cane tips wilt and die. This can be especially damaging in fall-bearing cultivars.
To control, the girdled stems should be removed a few inches below the lower girdle ring. Damaged canes and roots should be removed and burned during the dormant season. Sprays are directed at adults and are applied at late pre-bloom, just before blossoms open. Consult your spray guide for chemicals and rates.
Raspberry Crown Borer
The adult is a clear-winged moth resembling a yellow jacket, with a wingspan of 1 inch and bright yellow bands across the abdomen. This insect also requires two years to complete its life cycle. Adults appear in early August and are present through September. Reddish-brown eggs are laid on the undersides of leaves. The larvae move to the crown after hatching where they tunnel in for the winter. The next spring the larvae continue tunneling through the crown and roots; they overwinter in the roots and pupate the second summer. Visible symptoms on the plant are the swelling on the crown from the tunneling and withering, wilting and dying of the cane foliage, often with half-grown fruit still attached. The crown must be opened to find the larvae infesting it.
As with all crown- and cane-boring insects, the main control is to remove and destroy any dying canes, canes showing symptoms of boring and canes with swellings. All wild brambles in the area should be eliminated. Insecticides are applied as a heavy drench in the early spring to kill larvae, and as a spray between mid-October and mid-November to kill adults.
Japanese beetle adults are about 1/2-inch long and shiny metallic green. They emerge from the soil from June to September and feed on ripe bramble fruit and leaves. Eggs are laid on the ground and the larvae feed on roots of grasses and other plants. These beetles are serious pests of lawn, turf, vegetables, roses and nursery stock. Plantings near turf are especially susceptible to infestation. A chemical spray may be needed at late pre-bloom, just before the blossoms open. Pheromone traps for beetles attract the beetles to your planting, and if used, should be placed away from your planting to lure the insects away. Using milky spore on grassland will destroy the larvae, but it must be used over a wide area to effect any control, as the adults will migrate long distances in search of food.
Mites are barely visible to the unaided eye, but can be seen on close observation on the undersides of affected leaves. Affected leaves turn bronze-colored and may dry up and fall off. At this stage fine webbing and mites can be seen on the undersides of the leaves. The mites will feed on the leaves, reducing the yield and quality of fruit during the current season, stunting primocane growth and reducing next year's crop. Mites will also feed on the fruit. Mite damage is more likely in hot, dry seasons and the drier sections of fields.
Several predatory mites are being tested and may be useful in controlling mites. Miticide sprays are applied as the mite density on the leaf increases, and several sprays with thorough underleaf coverage may be necessary.
Blackberry psylla look similar to aphids, and cause the leaves and stems of blackberries to grow twisted and distorted. They move from conifer trees, the overwintering host, into the field slightly before, during or after bloom. Insecticides may be applied when adults first appear, and curled leaf clusters should be removed and destroyed.
For more information, contact your local county extension office.