The Pacific Northwest (PNW) region produces most of the North American crop of processed red raspberry (Rubus idaeus L.) annually, with Washington accounting for 58% of the region’s 45,000 t of fruit produced in 2015 (Raspberry Industry Development Council, 2016; USDA-NASS, 2016). Red raspberry has perennial roots and biennial aboveground shoots. It produces primocanes in the first year, which overwinter and became floricanes in the second year (Crandall, 1995). Although both primocanes and floricanes are capable of producing berries in primocane-fruiting raspberry, floricane-fruiting raspberry, which produces berries only from floricanes, is predominantly grown in the PNW where the climate is relatively cool and mild (Pritts, 2008). In floricane-fruiting raspberry, photosynthates produced by primocane leaves contribute more to root growth than to floral development (Fernandez and Pritts, 1993, 1994). Although floricane leaves tend to have higher CO2 assimilation rates than primocane leaves, floricanes are often shaded by primocanes in midsummer, reducing floricane leaf photosynthesis (Fernandez and Pritts, 1996). In the cultivars exhibiting the most floricane shading, strong competition for photosynthates exists between roots, primocanes, and floricanes, especially during flower bud initiation and flower development (Alvarado-Raya et al., 2007), so early removal of primocanes may often increase raspberry yield.
Caneburning is the practice of chemically removing the first primocanes emerging in spring with the goal of increasing raspberry yield (Crandall, 1973, 1977; Norton, 1973, 1974, 1980). Caneburning improves floricane exposure to sunlight during flowering and fruiting, reduces labor cost for dormant-season pruning and training, decreases incidence of certain raspberry diseases, and increases machine-harvest efficiency and berry yield (Freeman and Daubeny, 1986; Howard et al., 1989; Lawson and Wiseman, 1983; Norton, 1980). Caneburning also aids early season weed control in crop rows (Miller et al., 2008). When first developed in the 1970s, up to three applications of dinoseb were applied per season to the most popular red raspberry ‘Willamette’, increasing berry yield by an average of 52% (Norton, 1973, 1980; Sheets, 1973). Since that time, the herbicides carfentrazone and oxyfluorfen have replaced dinoseb for this use in the PNW, ‘Meeker’ has replaced ‘Willamette’ as the most widely grown raspberry cultivar in the PNW, and more efficient berry harvesters have been developed (Howard and Cameron, 1990; Howard et al., 1989). However, growers believe that the conditions and outcomes described in these older reports are still applicable to current PNW raspberry production practices and cultivars. Yet, even in initial trials cited above, caneburning was not universally effective at increasing berry yield. Of seven PNW raspberry cultivars tested since the late 1970s, caneburning consistently increased berry yield of only four: ‘Willamette’, ‘Chilcotin’, ‘Nootka’, and ‘Skeena’ (Freeman and Daubeny, 1986; Howard and Cameron, 1990; Lawson, 1980; Miller et al., 2008; Norton, 1980, 1981). The objectives of this study were, therefore, to assess and compare 1) the effect of caneburning herbicide application for weed control, 2) the reproductive response of three current red raspberry cultivars to caneburning, and 3) to determine whether caneburning is still a beneficial practice for PNW red raspberry production.
Alvarado-Raya, H.E., Darnell, R.L. & Williamson, J.G. 2007 Root to shoot relations in an annual raspberry (Rubus ideaeus L.) production system HortScience 42 1559 1562
Crandall, P.C. 1995 Bramble production: The management and marketing of raspberries and blackberries. Food Product Press, an imprint of the Haworth Press Inc., Binghamton, NY. p. 213
Fernandez, G.E. & Pritts, M.P. 1994 Growth, carbon acquisition and source-sink relationships in ‘Titan’ red raspberry J. Amer. Soc. Hort. Sci. 119 1163 1168
Fernandez, G.E. & Pritts, M.P. 1996 Carbon supply reduction has a minimal influence on current year’s red raspberry (Rubus idaeus L.) fruit production J. Amer. Soc. Hort. Sci. 121 473 477
Howard, S.W. & Cameron, J.S. 1990 The applied aspects of cane burning with dinoseb alternatives Proc. West. WA Hort. Assoc. 1990 108 109
Lawson, H.M. & Wiseman, J.S. 1983 Techniques for the control of cane vigor in red raspberry in Scotland: Effects of timing and frequency of cane removal treatments on growth and yield in cv. ‘Glen Clova’ J. Amer. Soc. Hort. Sci. 58 247 260
Miller, T.W., Klauer, S.F. & Nicholson, M. 2008 Effects of primocane suppression programs on weed management and productivity of ‘Meeker’ red raspberry Acta Hort. 777 267 274
Raspberry Industry Development Council 2016 Fraser Valley processed red raspberry production. 28 Sept. 2016. <http://bcraspberries.com>
Shaner, D.L. 2014 Herbicide Handbook. 10th ed. Weed Science Society of America, Champaign, IL
USDA-NASS 2016 Processed red raspberry in the US and Washington, 2015 summary. 28 Sept. 2016. <https://www.nass.usda.gov>