Submitted to: Annual Cumberland Shenandoah Fruit Workers Conference
Publication Type: Proceedings
Publication Acceptance Date: 3/30/2001
Publication Date: 7/10/2001
Citation: Takeda, F., Hummell, A.K. 2001. Primocane management in eastern thornless blackberry iii. relationship between pruning level and productivity. Annual Cumberland Shenandoah Fruit Workers Conference. Interpretive Summary: There is increased interest in growing blackberries in the United States for fresh market. More than 350 and 230 labor-hours per acre are needed to hand pick the fruit and for training and pruning of cane, respectively. A mechanical harvester with a potential to harvest blackberries with fresh market quality can reduce the cost of harvesting. To improve the machine harvestability, we developed a new trellis system called the "rotatable cross-arm" (RCA) trellis. We have determined growth parameters that would maintain high productivity of plants trained to the RCA trellis. The results of our studies suggest it is the number of lateral canes, not the number of primocanes from which these laterals develop, that is the more important determinant of plant performance. Managing blackberries for two primocanes resulted in reduced plant maintenance labor and meant that primocane training will be completed prior to fruit harvesting. Management tstrategies that will not conflict with labor-intensive harvest operations, mitigate labor costs or scarcity of labor will improve the economic viability of eastern thornless blackberry.
Technical Abstract: The "rotatable cross-arm" (RCA) trellis was developed to ease mechanical fruit harvesting of eastern thornless blackberries. The rotation of the cross-arm following bloom: (1) positions all the fruit on the floricanes to one side of the trellis in a plane underneath the cross-arm and (2) permits new primocanes to be trained to the side without the fruit. To maintain productivity, the number of lateral shoots that arise from primocanes must be maximized. In this study, we examined the relationship between pruning level and productivity in "Chester Thornless" blackberry. Plants with two floricanes had fewer nodes and racemes, more fruit per raceme, larger fruit size, but 82% of the productivity compared to plants with six floricanes. It also meant that retention of two primocanes reduced labor costs for summer cultural work by 50% and allowed primocane manipulation to be completed prior to fruit harvesting. Blackberry management strategies that twill not conflict with labor-intensive harvest, or mitigate labor costs, o scarcity of labor will improve the economic viability of this crop.