Cane burning, chemically removing the first primocanes produced by red raspberry in the spring, is commonly practiced in the Pacific Northwest. The practice was first described by scientists in Washington and Oregon in the early 1970’s, and was developed to aid in the machine harvest of the predominant raspberry cultivar at the time (‘Willamette’) using the herbicide dinoseb. This practice is now used on approximately 95% of raspberries in Washington. Dr. Tim Miller, weed scientist at WSU’s Northwestern Washington Research and Extension Center in Mount Vernon has led a three-year study to determine whether cane burning current Pacific Northwest red raspberry cultivars with currently available herbicides improves berry yield as dramatically as did when it the practice was first developed. Dr. Tom Walters and graduate student Yushan Duan participated in the research. Some of their conclusions are:
Berry Yield. Cane burning increased berry yield of ‘Meeker’ in two years of three, averaging 29 to 47% greater yield in treated plots over three years. At least some of this increase resulted from weed control, as residual herbicide alone increased yield by 22%. Conversely, ‘Cascade Bounty’, ‘Coho’, ‘Saanich’, and ‘Chemainus’ berry yield was not significantly increased by cane burning. There was a trend in the data suggesting that yield was marginally better in treated plots, but the numerical increase was within the margin of error for each trial. Although yield of individual cultivars was not greater with cane burning, when ‘Meeker’ and ‘Cascade Bounty’ yields were averaged together, raspberry yield was increased by treatment with either Goal or Aim herbicide during two of three years.
Primocane Growth. Primocane growth rate was slowed by use of cane burning products for about 70 to 80 days. Goal slowed growth rate slightly longer than did Aim in both ‘Meeker’ and ‘Cascade Bounty’. Biomass of pruned primocanes that had to be removed during the dormant-season did not differ between Goal and Aim treatments, although pruned primocane biomass tended to be marginally greater with Aim than with Goal.
Product Choice. There did not appear to be much difference between Aim and Goal in the cultivars used in this trial when applied at the tested rates. Goal slowed primocane growth longer than did Aim, but yield was not statistically increased. These products were generally inadequate for weed control unless a residual product was also used. This was particularly true in fields were weed pressure was higher, in particular when common chickweed was present, where Goal performed more poorly than Aim.
Cultivar Choice. In side-by-side comparisons, ‘Meeker’ produced 18% more fruit than did ‘Cascade Bounty’. ‘Cascade Bounty’ also produced about 30 to 40% more primocane biomass that had to be removed during dormant-season pruning. Despite this, ‘Meeker’ required significantly more time to prune and train than ‘Cascade Bounty’, about 20% longer in both years. In their first two harvests, ‘Saanich’ and ‘Cascade Bounty’ produced more fruit than ‘Chemainus’ or ‘Meeker’. This is an indication of the relative precociousness of these cultivars, although it may also be partly due to more winter injury suffered by ‘Meeker’ than other cultivars.
Dormant Season. In 2010-11, pruning and training ‘Meeker’ took 20% longer than ‘Cascade Bounty’, equivalent to about 15 additional hr/a. Total time spent on ‘Meeker’ was reduced 18% by cane burning. Both Aim and Goal were equally effective for reducing training time of ‘Meeker’. Training time for ‘Cascade Bounty’ was not improved by cane burning, although there was a trend toward reduced training time after treatment with Goal. In 2011-12, pruning and training time was not reduced by cane burning for either cultivar. Similar to the previous year, ‘Meeker’ took 22% longer to prune/train than did ‘Cascade Bounty’.
Miller earned his B.S. degree in Range Management in 1981, and his M.S. and Ph.D. degrees in plant science in 1987 and 1995, respectively, all at the University of Idaho. He joined the faculty in the Department of Crop and Soil Sciences at WSU in 1997 and is stationed at the Northwestern Washington Research and Extension Center in Mount Vernon. His extension duties involve conducting trials for improving weed management in western Washington crops, such as vegetable seed (spinach, beet, cabbage, and others), ornamental bulbs (tulip, daffodil, and iris), small fruit (blueberry, raspberry, and strawberry), cucurbits (cucumber, squash, and pumpkin), and potato. His research has focused on primocane management of red raspberry and how those programs affect yield and growth of raspberry. Since 1997, Miller and his staff have conducted 621 trials including nearly 14,000 individual treatments. He has given over 500 presentations to over 40,000 people on a host of weed, herbicide, agricultural, and horticultural topics. Other recent work includes evaluation of biodiesel crops for western Washington production as well as control trials on various regional noxious weeds.