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
Experimental plantings of 'Strawberry Festival' strawberry transplants for fall and winter fruit production were established in Queenstown, MD, Knoxville, TN, and Salisbury, NC. Plants rooted in early July produced about 1/4 to 1/2 lb of fruit from 24 Oct to 5 Jan in Maryland and Tennessee. In Salisbury, NC, July-plugged transplants began flowering earlier than commercially propagated and "conditioned" transplants. The novel strawberry transplant propagation method developed by ARS scientists has potential to condition plants for early flowering without the need for chilling and short-day length "conditioning" treatment, and will be a useful tool to produce transplants that will crop in both fall and spring. The canes of trailing 'Siskiyou' blackberry were positioned either upright or horizontal on the rotatable cross arm trellis in winter. In both cane training systems, plants were either covered with floating rowcover or left uncovered. The objective was to evaluate the effects of cane orientation and rowcover treatment on winter injury. Plants that had canes oriented horizontally, and covered with floating rowcover, produced more than 10 lbs. All uncovered plants and plants that had canes oriented upright and covered in winter produced low yields. An effective winter protection system will help to expand the blackberry production areas in which USDA-developed 'Siskiyou' and other trailing blackberries can be grown. A collaboration to develop modular trellis systems for brambles based on the rotating cross-arm trellis system developed by ARS scientists studied the effects of cross-arm rotation and shade net for reducing sun-burn damage. Placement of strawberry transplants under red and blue shade nets delayed reproductive development in short-day strawberry. Extramural funding was obtained from the USDA-CSREES Specialty Crop Research Initiative (Award No. 2008-51180-19579) to determine the effects of plant architecture modifications on machine harvestability and ground loss reduction in rabbiteye and southern highbush blueberries.
1. Regulation of fall flowering in short-day type strawberry cultivars reduces labor costs. The labor for removing flowers on nursery plants by hand costs about $500 per acre. The 'Strawberry Festival' transplants for the study were produced from runner tips that were harvested in early July and plugged into small rooting containers and transplants were either placed under red or blue colored photoselective shade net from 1 to 28 August or left uncovered (control). The control plants started flowering in late September and more than 90 percent had bloomed by November. Flowering in plants that were under red and blue net did not occur until early January. The results of this study showed that a simple change in greenhouse management can delay bloom by several months, reduce production costs and increase grower profits.
5. Significant Activities that Support Special Target Populations
Target populations, including small farms, and underserved farms were addressed through presentations at national and regional grower conferences in California, Ohio, and Pensylvania.