#1.11:301/3 THORNLESS BLACKBERRIES FOR THE HOME GARDEN /fS^ UNITED STATES WW DEPARTMENT OF ^ AGRICULTURE HOME AND GARDEN BULLETIN NUMBER 207 PREPARED BY AGRICULTURAL RESEARCH SERVICE CONTENTS Page Thornless blackberry varieties 1 Planting sites 1 Preparing the soil 2 Spacing the plants 2 Setting the plants 2 Intercropping 2 Trellis construction 3 Training 3 Pruning 4 Fertilizing and watering 4 Cultivation 5 Cover crops 5 Herbicides 5 Harvesting 5 Preventing winter injury 6 Diseases and insects 6 Descriptions of thornless blackberries 7 Department publications contain public informa- tion. They are not copyrighted and may be re- produced in whole or in part with or without credit. Revised February 1975 Washington, D.C. Slightly revised October 1977 For sale by the Superintendent of Documents, U.S. Government Printing Office. Washington, D.C. 20402 THORNLESS BLACKBERRIES FOR THE HOME GARDEN By J. W. Hull (deceased ) and F. J. Lawrence, ARS research horticulturist For years home gardeners hesi- tated to grow blackberries in their backyard because of the annoy- ance of the thorns. Then two thornless blackberry varieties — Smoothstem and Thornfree — were developed by the U.S. De- partment of Agriculture. Two newer varieties, Dirksen Thorn- less and Black Satin, have also been introduced by the Depart- ment. Popular with home gar- deners and proprietors of "you- pick" enterprises, these produc- tive blackberries are easy to han- dle and require little summer pruning. The fruits are firm and highly flavored. TIIOKNLESS BLACKBERRY VARIETIES Smoothstem, Thornfree, Dirk- sen Thornless, and Black Satin are genetically thornless black- berries — all the cells have the thornless character. When new canes develop they retain this thornless characteristic. Other thornless blackberries, such as Thornless Young, Thorn- less Logan, and Thornless Ever- green, have a thornless character only in the outer cell layer of their canes. New canes originating be- low the crown have thorns. Thornless blackberries have trailing or semitrailing canes that are not self-supporting. They can be grown along the ground in their first season, but, thereafter, must be trained on trellises. Blackberries are planted in early spring in the North; in late winter or early spring in the South. Blackberries vary in their abil- ity to withstand cold, but none should be grown where temper- atures drop to F. and below. PLANTING SITES Planting sites for blackberries must offer plenty of soil moisture. This condition is especially neces- sary while the fruit is growing and ripening. 1 Horticultural Oregon 97331. Crops Research, Corvallis, Almost any soil type, except very sandy soil, is suitable for blackberries if the drainage is good — both on the surface and in the soil. Plants can be harmed at any season of the year if water stands around their roots. Preparing the soil Prepare the soil as you would for a vegetable or flower garden. If you are establishing a new planting, seed and plow under one or two green-manure crops of cowpeas or of rye and vetch. This will condition the soil, and the added organic matter and nitro- gen will help produce an early fruit crop. Spacing the plants Leave plenty of space between rows when planting blackberries, or severe competition for soil nu- trients and moisture will result. Smoothstem and Thornfree are vigorous varieties and should be set 6 to 8 feet apart in rows that are at least 8 feet apart. Less vigorous varieties, such as Thornless Young and Thornless Logan, should be set 4 to 6 feet apart in rows that are at least 8 feet apart. Aline plants carefully in the row to accommodate the trellis, which will be constructed. (See P. 3.) Setting the plants Do not let planting stock dry out. This condition can be pre- vented by heeling in the roots. To heel in, dig a trench in a shaded area deep enough to hold the roots. Open the bundles and spread the plants along the trench with the roots down. Cover the roots with moist soil and firm the soil down to eliminate air pockets. If the plants are dry upon arri- val, soak the roots in water for several hours before planting or heeling in. If you do not plant immediately, wrap the plants in polyethylene bags and place them in a refriger- ator until planting time. Before setting the plants, cut the tops (the old cane or "han- dle") back to about 6 inches. This is useful for handling the plants and serves to mark their location. After you make a planting hole, set the root of the plant so that it is about the same depth as it was in the nursery, or slightly deeper. Then firm the soil carefully to as- sure good contact with the roots. INTERCROPPING During the first summer after setting the blackberries, vege- tables such as beans, peas, or cab- bage can be grown in the spaces between rows. Their cultivation your garden to good use. Intercropping should not be done after the first year of plant- ing; when the blackberry plants are of bearing size they will need will benefit the blackberry plants all available moisture and nutri- and put the unused portion of ents. TRELLIS CONSTRUCTION After the first season, thornless blackberries should be trained on trellises. This will assure clean fruit, ease of picking, and help in disease control. Many trellis arrangements and training methods are satisfactory. To construct a simple and effec- tive trellis — • Stretch two wires (gage size 12 or 14) between heavy end posts set 15 to 25 feet apart in the row. String one wire 21/2 feet from the ground and the other about 5 feet from the ground. • Staple the wires loosely to all posts between the end posts. (Wires must be loose enough to allow for contraction in cold weather. ) • Tie trailing canes horizontally along the wires or fan them out from the ground and tie them where they cross each wire. Avoid tying the canes in large bundles. Thornless blackberries should be trained on a two-wire trellis. Set end posts 15 to 25 feet apart in the row. String one wire 2*/2 feet from the ground and the other about 5 feet from the ground. TRAINING During the first year, black- berry canes grow vegetatively and send out side branches. In the sec- ond year, these canes bear fruit, and then the canes die. (The canes arising from the crown are bi- ennial ; they live for only 2 years. The roots and crowns are peren- nial.) Methods of training black- berries largely depend on the length of the growing season and the degree of winter cold. In northern areas, leave trail- ing varieties of thornless black- berry canes on the ground, under the trellis, until their second sea- son. Then, before the buds swell, bring the canes up to the trellis wires, wrap them in groups of three or four, and tie. Tie semitrailing blackberry va- rieties to the wires in their first year. In the South, tie new canes of both trailing and semitrailing va- rieties to the trellis as soon as harvest is over. The old canes should be cut out immediately. PRUNING After harvest, prune away old canes and destroy them as a sani- tation measure. In certain areas of the South anthracnose and rosette, both serious diseases of blackberries, threaten crops. In these areas, all the canes should be cut out after harvest. Before tying canes to the trellis wire, remove any that are weak, spindly, or broken. Thin out to leave 12 to 16 new canes. Tie these to wires, or de- pending on the management plan being used, leave them under the trellis for the rest of the season. Thornfree and Smoothstem va- rieties require little summer prun- ing; they do not tend to branch freely and usually will not develop more than three or four canes. Before growth starts in spring, prune all side branches back to 12 inches. Side branches that are pruned will produce larger fruit than those that are not pruned. FERTILIZING AND WATERING Mixed fertilizers are satisfac- tory for blackberries. For best re- sults, apply fertilizer in early spring when growth starts and again in summer just after har- vest. Use a 10-10-10 commercial fertilizer mix or a 10-6-4 mix at the rate of 5 pounds per 100-foot row. For late-ripening varieties, such as Smoothstem and Thornfree, ap- ply the fertilizer mix no later than July. This is to avoid forcing a late season growth that will be subject to winter injury. For the first year or two, before the root systems of the plants de- velop fully, spread 3 or 4 ounces of the fertilizer mix in a 12-inch radius around the base of each plant. 4 Blackberry plants require plenty of moisture while the berries are growing and ripening. The amount of water needed is roughly equivalent to 1 inch of rainfall per week. Irrigate suffi- ciently to meet this requirement. Mulching reduces the frequency of watering. Good mulch mate- rials include : seed-free straw or prairie hay, pine needles, corn- cob, wood chips, or cotton hulls. Lawn clippings are not satisfac- tory. CULTIVATION Blackberry plants need thor- ough and frequent cultivation ; weeds and grasses compete for moisture and are difficult to con- trol. Cultvate thornless blackberries during the summer, and as often as necessary to keep the weeds down. To avoid harming shallow roots of the plants, cultivate only 2 or 3 inches deep near the rows. Unnecessary pruning of roots stunts plant growth. Discontinue cultivation at least a month before freezing weather begins. Cover crops Winter cover crops planted be- tween the rows help to maintain the structure of the soil, and re- duce erosion. If a legume cover crop is planted, valuable nitrogen will be added to the soil. Sow cover crops during the fall. The following cover crops are adapted to thornless blackberries : field rye, vetch (a legume) and rye, and spring oats. Drill or broadcast the seed by hand between rows. Plant at least 18 inches away from either side of the row to allow air circulation for the blackberry canes on the ground. Herbicides Herbicides can be useful, espe- cially in large plantings. Control recommendations depend on soil types, and weed species in various areas. Contact your county agri- cultural agent or State Agricul- tural Experiment Station for local recommendations. HARVESTING Blackberries that are picked at the proper time, handled carefully, and stored in a cool place will stay in good condition for several days. Overripe or injured berries spoil quickly. Harvest thornless blackberries at least twice a week, but do not pick thornless blackberries as soon as they turn black. It is bet- ter to wait 3 or 4 days and pick when the color has a dull appear- ance. This will assure a better flavor, color, and wholeness, es- pecially if you are canning the berries. Remember the following when harvesting the berries — • Pick berries in the morning while the temperature is still cool. Blackberries picked in the morn- ing do not spoil as easily as those picked in the afternoon. • Pick carefully and do not crush or bruise the fruit when placing them in berry baskets. • Pick when the berries are fully ripened but still firm. PREVENTING WINTER INJURY Winter protection is needed for blackberries in areas where winter temperatures are expected to go below 10° F. Cold-hardy varieties, however, need no special protec- tion in the winter. In areas with low winter tem- peratures and cold, drying winds, cover the canes with a layer of soil, straw, or coarse manure. _ This should be done after the canes have become dormant, and before the onset of severe cold weather. Remove this protective layer before growth starts in spring. Where winters are mild and moist, such as in western Oregon, canes of trailing varieties left lying on the ground will be damaged. It is best, in areas with similar conditions, to tie the canes to the trellis in early fall and al- low them to stay up through the winter. However, in areas with severe drying winds, canes tied to trellises are subject to winter in- jury. DISEASES AND INSECTS Diseases and insects vary in kind and severity from area to area. For information suited to your local conditions contact your county agricultural agent or State Agricultural Experiment Station. To keep disease and insect dam- age to a minimum — • Choose disease-resistant va- rieties adapted to your area. • Burn diseased plants or canes. • Remove old canes soon after harvest. • Remove all wild blackberry plants in the vicinity of your garden. • Prune out and burn canes that have been infested with insects. • Keep the garden free of weeds and fallen leaves. DESCRIPTIONS OF THORNLESS BLACKBERRIES The thornless blackberry varie- ties that follow are listed in their approximate order of ripening. Specific ripening dates will vary with location and season. All the varieties are partly susceptible to winter damage. The variety descriptions in- clude : the degree of hardiness (four degrees are given: Hardy, moderately hardy, less hardy, and tender) ; the duration of harvest; the characteristics of the plant; and the area of special adaptation. For local variety recommenda- tions consult your county agricul- tural agent or your State Agricul- tural Experiment Station. Thornless Logan. — Less hardy; harvest period is 10 to 15 days ; berry large, long, reddish, acid, high flavor; plant is vigorous, very productive. Grown on Pa- cific coast. Not adapted to East. Austin Thornless. — Moderately hardy; harvest period is 10 to 15 days; genetically thornless, berry is large, round, black, good flavor ; plant is vigorous but only moder- ately productive. Widely grown in the South. Thornless Young. — Moderately hardy ; harvest periods is 10 to 15 days ; berry large, soft, wine col- ored, very sweet; plant is vigor- ous and fairly productive. Adapt- ed in the South and Pacific States. Cory Thornless. — Less hardy; harvest period is 10 to 15 days; berry large, black, sweet, soft; plant is vigorous and fairly pro- ductive. Grown on Pacific coast. Thornless Boysen. — Moderately hardy; harvest period is 10 to 15 days; berry large, soft, wine col- lored, very sweet; plant is vigor- ous and fairly productive. Adapt- ed in the South and on Pacific coast. Black Satin. — Hardier than Thornfree and 12 to 14 days ear- lier. Harvest period lasts 3 to 4 weeks ; slightly more vigorous and productive than Dirksen Thorn- less (see below) but otherwise very similar in fruit and plant habits and in area of adaptation. Dirksen Thornless. — Hardier than Thornfree and about 3 weeks earlier. Harvest period lasts 3 weeks ; genetically thornless, berry medium-large, firm, black, slightly dull at full maturity, good flavor, very little astringency; plant is vigorous, healthy, and very productive. Winter hardy south of a line from Kansas City to Urbana, Illinois, to central Ohio to New Jersey and in the Pacific Northwest. Thornfree. — Hardy, harvest pe- riod lasts for about 1 month; genetically thornless, berry me- dium, firm, black, good flavor ; plant is notably healthy and very productive. Grown in central New Jersey, southern Pennsylvania, southern Ohio southward to North Carolina and west to Arkansas, Maryland to North Carolina along and in the Pacific Northwest. Atlantic coast. Smoothstem. — M oderately Thornless Evergreen. — Hardy ; hardy; harvest period lasts for harvest period lasts for about 1 about 1 month ; genetically thorn- month ; berry is large, exception- less, berry medium-large, black, ally firm, sweet, black; plant is good flavor ; plant is extremely vigorous, productive, and healthy, healthy and vigorous, very pro- Best adapted to Pacific North- ductive. Adapted from southern west. -ft U.S. GOVERNMENT PRINTING OFFICE : 1977 O— 244-113 8 UNIVERSITY OF FLORIDA 3 1262 08582 9264