David Himelrick | 12/20/2017 3:41:13 PM
Blackberries are adapted to most regions of Louisiana. They are a good addition to the home fruit garden and can be grown with fewer inputs than most other fruit crops. Furthermore, their fruit is flavorful and nutritious. Varieties developed by the University of Arkansas fruit breeding program are recommended for use here. These varieties have an upright growth habit and do not require the use of an elaborate trellis system. They are grown in a hedgerow-type system with the first crop harvested the year after the planting is established. Many soil types are suitable for blackberry production. However, the preferred soil pH ranges from 5.5 to 6.5, and good soil drainage is essential. Sites with water standing for long periods of time should be avoided.
If possible, begin preparing the soil a year prior to the projected planting date. Perennial weeds and established sod should be eliminated before planting. The soil should be cultivated deeply, and several passes with a tiller may be needed to kill weeds and thoroughly incorporate plant residues. Blackberries will respond to increased levels of organic matter in the soil, especially under non-irrigated conditions. If the soil requires additional drainage, the rows can be established as raised beds. The beds should be 6 to 10 inches high and 2 to 3 feet wide. The row middles will be maintained as sod strips.
Blackberries are established from root cuttings or plants. Rooted plants are often used for thornless varieties because of the reduced level of sprouting from root cuttings that occurs for thornless varieties compared to thorny varieties. Plant blackberry roots or rooted plants at any time in the spring before the soil warms. Later planting can reduce plant growth. Root cuttings should be pencil size in diameter or slightly larger and 4 to 6 inches long. Plants grown from good root cuttings are usually strong and can come into production as early as 1-year-old plants. Space root cuttings 2 feet apart in the row in a horizontal position and cover with soil to a depth of 2 to 3 inches. Place plants 2 to 3 feet apart in the row at the same depth they grew in the nursery or container. The objective is to produce a continuous hedgerow for the full row length desired. Do not let the cuttings dry out. If the plants or cuttings are slightly dry when received, soak the roots in water for several hours before planting them or heel them in. If plants or roots are extremely dry, reject the shipment.
Apply fertilizer following recommendations based on soil tests. If soil tests are not available, a general recommendation for the first year is to apply 5 pounds of a complete fertilizer, such as 10-20-10, per 100 feet of row after the newly set plants have started growing or after root cuttings begin to emerge. The second year, and thereafter, fertilizer should be applied alongside the rows in February with applications based on soil test recommendations. Side-dress with ammonium nitrate after harvest at 5 pounds per 100 feet of row. Increase or decrease fertilizer in response to cane growth. Cultivation should begin as soon as plants are set in the spring. Cultivate often enough to keep the ground free from weeds and grass until late summer. Generally, little pruning is required the year of planting. However, lateral growth may need to be trimmed to keep the plants within the rows. Blackberry plants send up new canes from crowns or from buds formed on the roots. These canes grow through one season, produce a crop of fruit the second year and then die soon after harvest. Remove old canes immediately after harvest so that the new shoots develop sturdy canes. Top the ends of new canes during the summer at a height of 36 to 48 inches. This limits cane height and forces side laterals, which bear the fruiting clusters the following year. During the summer, it is very important to remove suckers growing up outside of the desired row. Summer-prune the remaining laterals or side branches to a manageable length. Winter-prune the laterals to 14 to 16 inches for convenient harvesting and larger berries (Figure 1). Winter removal of excessively wide summer growth removes the most fruitful canes. In late winter, remove the remaining dead and weak wood. Leave healthy, vigorous canes spaced about six canes per foot in a row about 12 to 18 inches wide. Irrigation of blackberries is required during the first season and is needed during dry periods in most years. Irrigate equivalent to 1 inch of rainfall per week. If drip irrigation is used, apply 2 to 3 gallons of water per day to mature plants during dry periods. Increase or decrease the amount of water applied based on plant response.
Blackberries begin bearing one year after they are planted. First-year growth of erect blackberries is low and non-erect. This often causes concern among beginning blackberry growers, but by the second year, all growth is erect. A planting may produce for more than 15 years, but production is usually best during years three through eight and often begins to decrease after that.
Erect-type blackberries are pruned twice each year. Summer topping is used to limit the height of the plants to 3 to 4 feet. Cut and remove approximately 6 inches off the tip of the primocane when it reaches about 3 feet high. This will induce lateral branches to form below the cut. Dormant pruning takes place in the winter. At this time, cut out spent floricanes at ground level. Shorten lateral branches to 12-18 inches. A simple two-wire T-bar trellis will help to keep rows neat.
Blackberries are highly perishable. They should be harvested as soon as ripe, handled very carefully and either placed in cold storage or used without delay. It may be necessary to harvest daily to prevent loss of fruit and the spread of molds and other diseases.
Spraying for weed control may be necessary. Blackberries tend to have only two common diseases: double blossom rosette and orange rust. There are no effective homeowner sprays. The disease cycle of double blossom rosette can be broken by mowing the plants to the ground in the winter. This will result in a loss of production for one year. Orange rust can be controlled by digging and removing diseased plants.
Blackberries are unusual in that they have a perennial root system and biennial tops (canes). Individual canes live for two years and then naturally die. Historically, in the first year, they produce only vegetative growth (primocanes). In the second year, these same canes, now called floricanes, produce fruit. The floricanes will die after fruiting. The new primocane-fruiting blackberry varieties also bear fruit on current-season canes. This new type of blackberry could greatly change blackberry production. The first commercial primocane-fruiting blackberry cultivars were released by the University of Arkansas in 2004. The second important consideration is whether the variety has either thorned or thornless canes. Those with no thorns have an obvious appeal.
Varieties recommended for home fruit production in Louisiana are summarized below. All these varieties were developed by the University of Arkansas fruit breeding program.
Thorny. High yielding with large fruit. Disease-resistant to anthracnose and orange rust. Mid-season harvest with medium storage potential. Requires approximately 500 chill hours.
Thorny. High yielding with medium fruit size. Disease-resistant to anthracnose and orange rust. Early ripening. Low storage potential.
Thorny. High yielding with medium to large fruit size. Disease-resistant to anthracnose and orange rust. Early to mid-harvest season with low storage potential.
Thornless. High yield with large fruit. Disease-resistant to anthracnose and double blossom. Late harvest season with high storage potential. Requires approximately 800-900 chill hours.
Thornless. Moderate yield with medium-sized fruit. Disease-resistant to anthracnose and double blossom. Early to mid harvest season. High storage potential.
Thorny, erect with very large fruit. Ripens over a long period. The longest fruiting of the Arkansas varieties. Storage and handling potential very good. Among the best of the thorny varieties. Requires approximately 200-300 chill hours.
Thornless. Moderate yield with small to medium-sized fruit. An excellent variety. Consistently rated the highest of the Arkansas varieties. Disease-resistant to anthracnose and double blossom; susceptible to orange rust. Late harvest season with very high storage potential. Requires approximately 800-900 chill hours.
Thornless, with very erect canes. Early to mid-season ripening. Resistant to double blossom/rosette. High storage potential. Requires approximately 400-500 chill hours.
Primocane-fruiting. Thorny, erect. Floricane yields comparable to floricane-fruiting thorny and thornless varieties. Primocane yields vary greatly by location; best in North Arkansas. Floricanes susceptible to double blossom/rosette, but primocanes avoid this disease because the disease does not appear until the second season on the canes. No orange rust observed and only slight anthracnose observed. Low storage potential. Recommended only for home garden use and very limited commercial trial. Requires approximately 300- 400 chill hours.
Primocane-fruiting. Thorny, erect. Similar to Prime- Jim. Requires approximately 300-400 chill hours.
Thornless, floricane-fruiting. Medium-sized fruit. Good flavor. Good postharvest storage.
Primocane-fruiting. Thornless, erect. Medium-sized fruit.
Primocane-fruiting. Thornless, erect. Large fruit.