1a. Objectives (from AD-416)
1. Enhance productivity in strawberry. 2. Enhance blackberry yield and survival.
1b. Approach (from AD-416)
Small fruits require high labor and chemical inputs. Improvements in cropping efficiency and out-of-season fruit production of strawberries and blackberries are needed to foster commercial expansion of these small fruits and help mitigate production factors limiting profit potential. In the current global economic market, it is difficult for the small fruit industry in the United States to maintain a profitable operation with ever-increasing competition and market share by fruits being imported from countries to the south. Studies will be conducted to: 1) determine the efficacy of novel cultural and chemical treatments to mitigate low temperature damage, and effects of primocane and environmental manipulations to accelerate and intensify floral bud initiation and subsequent reproductive development, 2) improve the understanding of mechanisms controlling flower development in strawberry and blackberry, and growth processes involved in regulating the flower size and inflorescence development, and 3) analyze the effects of plant material source and environmental conditions during transplant propagation to devise management strategies aimed at producing high quality, superior yielding strawberry transplants. Research into alternative production systems and evaluation of novel germplasm materials is expected to provide new technology and to create new opportunities to produce blackberries for fresh market. Research on season extension techniques for strawberries will provide new technology for the management of strawberries without the need for pre-plant soil fumigation and also opportunities to produce strawberries from October to December in the mid-Atlantic coast region. Technology transfer efforts proposed in this project are expected to improve viability of small fruit farming and rural vitality in several regions of the United States.
3. Progress Report
Under Objective 1, we made significant progress in developing a technique to delay and prevent flower bud development in day-neutral strawberry cultivar by altering the quality and intensity of red light. An experiment was conducted at a commercial strawberry nursery in which red LED lights were programmed to come on at dusk, midnight, or dawn to affect the phytochrome system and flowering response in day-neutral strawberry. The results of this study would benefit the California strawberry nursery industry that spends as much as $500 per acre each year to remove flowers by hand. Under Objective 2, we made significant progress in enhancing blackberry productivity and developing a new propagation method for blackberries. We used the rotating cross-arm (RCA) trellis and cane training system to increase the number long lateral canes. Methods were developed to improve rooting and flower bud development in long-cane plants. Research showed that plant yield can be improved by modifying the cutting date and temperatures at which they are grown. Such plant material should be useful for growing blackberries in southern United States where winters are too mild for outdoor blackberry production. The commercialization of this technology will benefit a large number of small acreage farmers developing niche market for specialty crops and expand blackberry production into a sub-tropical region and offer new ways to produce blackberries in out-of-season. The technology to develop these novel plant material was submitted in a patent application (S/N: 12/887,851) titled, "Long-cane blackberry plants for out-of-season fruit production". Alternative cane training systems for two USDA-ARS trailing blackberry (Black Diamond and Obsidian) were grown with the RCA trellis system. The selection of strawberry materials with high potential to produce fruit in fall and spring was made with a strawberry breeder in Beltsville, MD. In 2011, a greenhouse propagation method was used to produce large numbers of plug plants for a replicated field trial.
1. New, improved technology for producing long-cane blackberry plants. The U.S. blackberry growers want to produce blackberries in off-season as shipments of blackberries from Mexico increase during late spring to summer when the U.S. blackberry production is peaking. ARS researchers at Kearneysville, WV, used a unique trellis and cane training system to propagate many single-cane blackberry plants which can be manipulated to produce off-season fruit which command a higher price. The new propagation system increased plant output five- to seven-folds over the current commercial propagation technique. The long-cane plants can be established in a warm area such as southern Florida in late winter to obtain a crop in March and April. For late season fruit production, they could be held in cold storage until summer and then grown in a warm environment so that the fruit matures from August to October. The new propagation method is efficient for producing a large number of blackberry plants that can be manipulated to produce fruit in the off-season and should be useful to both growers and nurserymen.