Protocol for Seasonal Production and Pest Management
In our experience, a commercial primocane crop is not possible in the planting year when tissue-cultured plants are established (0.6 m in the row). However, commercial crops should be expected the year after planting. A simple, two-wire trellis is recommended to prevent the vigorous canes from bending over and to prevent wind breakage (Strik and Thompson 2009). The following production and pest management practices should be followed:
At green tip, apply pre-emergent herbicide for weed/grass control
At green tip, 6-inch shoot, prebloom and petal fall, implement disease management for anthracnose and cane blight only at prebloom (Bordeaux, copper-based products, Captan, Pristine, Tilt).
Shortly after green tip, cut all floricanes at ground level and remove from within the planting.
In May and June, soft-tip primocanes as they grow to 3 ft (remove tips from field to minimize spread of broad mites). In addition, double-tipping, where primocane branches are soft-tipped also, shows great promise for increasing production (Thompson and Strik, 2007). Tipping will produce higher number of branches per cane, five on average, that results in threefold more flowers and yield than per untipped canes (Strik et al. 2008, Thompson et al. 2007, 2008).
Petal fall, apply soil drench of Admire Pro for prevention of rednecked cane borer or keep Surround treated plots whitewashed to minimize egg laying and possibly delay broad mite buildup (a research question being addressed).
Late May on, walk planting weekly looking for bronzing of terminal leaves that indicates presence of broad mites. Apply Agri-Mek if broad mites are present on bronzed terminals.
As needed in July, apply insecticide (Sevin) or keep Surround treated plots whitewashed during Green June beetle and/or Japanese beetle flight and feeding.
Green fruit to harvest, walk planting weekly looking for stink bugs on fruit. If mostly wingless nymphs are present, apply bifenthrin or pyganic or keep Surround treated plots whitewashed.
Ripening and through harvest, apply insecticide (Brigade, Danitol, Delegate, Mustang Maxx) weekly for prevention of spotted wing drosophila infestation of fruit. In 2017, the Surround whitewash of blackberry plants and fruit did not appear to reduce fruit infestation by spotted wing drosophila.
Late October, apply soil drench of insecticide (Brigade or Altacor) around blackberry plants to kill newly hatched raspberry crown borer larvae that overwinter on canes below soil surface.
December leaf fall, remove and compost all fallen blackberry leaves from planting to minimize numbers of overwintering broad mites.
Sources or Citations:
Smith, S. 2018. Arkansas small fruit management schedule. Univ. of Arkansas Division of Agriculture Res. & Ext. MP467.
Strik, B.C., J.R. Clark, C.E. Finn, and G. Buller. 2008. Management of primocane-fruiting blackberry to maximize yield and extend the fruiting season. Acta Hort. 777:423–428.
Strik, B.C., and E. Thompson. 2009. Primocane-fruiting blackberries: potential for extending harvest season and production regions. Hortscience 44(1):23-24.
Thompson, E. 2007. Primocane-fruiting blackberries: the effect of summer-pruning, tipping, and chilling on primocane morphology, fruiting season, and yield. M.S. thesis, Dept. of Horticulture, Oregon State University, Corvallis.
Thompson, E., B.C. Strik, J.R. Clark, and C.E. Finn. 2007. Flowering and fruiting patterns of primocane-fruiting blackberries. HortScience 42:1174–1176.
Thompson, E., B.C. Strik, J.R. Clark, and C.E. Finn. 2008. Flowering and fruiting morphology of primocane-fruiting blackberries. Acta Hort. 777:281-288.
Dr. Donn T. Johnson
Department of Entomology
University of Arkansas