Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2003
Publication Date: 6/1/2003
Citation: TAKEDA, F., HUMMELL, A.K., PETERSON, D.L. CHARACTERIZATION OF PRIMOCANE GROWTH IN 'CHESTER THORNLESS' BLACKBERRY TRAINED TO THE ROTATABLE CROSS-ARM TRELLIS. HORTSCIENCE. 2003. 38(3):373-376 Interpretive Summary: Growing blackberries in the United States for fresh market is increasing. We developed the USDA rotatable cross-arm (RCA) trellis which facilitates more efficient means to harvest the fruit. Here we describe the growth of primocanes that were trained onto the RCA trellis. Cane training occurred from May to July. All plants developed at least 2 primocanes, but only 94, 73, 60, and 42% of plants developed 3, 4, 5, and 6 primocanes. The canes that developed early in the season produced 8 to 9 medium to long lateral branches, while the late ones developed only a few, short lateral branches. We found that the number of lateral branches, not the number of primocanes from which these laterals develop, was more important for plant productivity. Managing blackberries for two or three primocanes resulted in less labor input and completion of cane training prior to fruit harvesting. These management strategies that will not conflict with labor-intensive fruit harvesting and mitigate labor costs or scarcity of labor will improve the economic viability of eastern thornless blackberry.
Technical Abstract: A study was conducted to characterize vegetative growth of mature 'Chester Thornless' blackberry plants trained to the rotatable cross-arm (RCA) trellis in which up to six primocanes was retained. Cane emergence occurred from mid-April to late-May. The first (oldest) primocane attained a sufficient height to be trained in early May in 40% of plants and subsequently other primocanes trained until late July. However, only 94, 73, 60, and 42% of plants developed three, four, five, and six primocanes, respectively. In primocanes that were tied during the first three weeks of training period (14 May to 3 June), as many as eight to nine medium (0.7 m to 1.3 m) to long (>1.3 m) lateral branches developed. Primocanes tied during week 4 through week 9 (4 June to 16 July) averaged less than six lateral branches that were mostly of medium and short categories. Primocanes trained after 16 July produced only two short (< 0.7 m) lateral branches. The results indicated that training of only the primocanes from May to mid-June may be advantageous for 'Chester Thornless' blackberry trained on the RCA trellis to minimize labor costs.