ISHS Acta Horticulturae 112: Symposium on Breeding and Machine Harvesting of Rubus
QUACKGRASS CONTROL IN RASPBERRIES |
| Author: | Jack A. Freeman |
| Abstract:
Several herbicide treatments were tested for quackgrass (Agropyron repens (L.) Beauv.) control in raspberries (Rubusidaeus L.) over a 6-year period. Both glyphosate and pronamide gave good quackgrass control. Glyphosate appeared more effective when applied in late fall while pronamide appeared more effective when applied in early spring. The addition of simazine to glyphosate caused little or no improvement in grass control. A paraquat-simazine mixture did not give satisfactory grass control. Pronamide applied either in the fall or spring caused a reduction in the new cane growth with 3.36 kg/ha in the spring causing a significant reduction in the number of raspberry sucker plants. Grass competition in the unweeded check plots reduced the number of canes and yield of berries. The crop was not affected adversely by the herbicide treatments. The pronamide-treated plants tended to give the highest yields. However, retarding to complete kill of the canes resulted when glyphosate and glyphosate + simazine were applied in the spring after the primocanes had emerged. Glyphosate translocated to the current year's fruiting canes causing interveinal leaf chlorosis and necrosis. The reduction in primocanes reduced the number of fruiting canes the following season and yield decreased. The primocanes in the following season were also affected with up to 55% of the canes showing deformity (epinasty, marginal leaf chlorosis and terminal leaves narrowed and elongated). Pronamide also caused some primocane injury at the time of spraying and there was some translocation to the current year's fruiting canes. However, sufficient canes developed and although height was reduced, yields were not affected detrimentally. There was little or no effect by any treatment on fruit quality, although there was a trend for glyphosate and the glyphosate-simazine mixture to decrease total soluble solids and for pronamide to decrease ascorbic acid content. | |
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