G.L. Graham1 and R. Tremblay1
Abstract: Three trials were established to evaluate the effectiveness of mesotrione in controlling weeds within the cranberry production system. Two trial sites were established at Maugerville, NB on mineral based soils with a layer of sand on the top. The Lamèque, NB site had a peat based soil with sand on top. Within each trial location, one square metre plot areas were randomly selected within the field area in order to include a broad range of weed species. A broadcast application of mesotrione at the rate registered for the emergency use was applied to the selected plot areas. Evaluations of weed control and crop injury were recorded. No crop injury was noted for any mesotrione application, demonstrating the lack of phytotoxicity to cranberry from this product. Mesotrione consistently provided early control of five fingered cinquefoil and vetch. Aspen, barnyard grass, creeping buttercup, clover, goldenrod, New York aster, milkweed, poplar, wild raspberry, wild strawberry and rush were suppressed at this early rating time. Only wild strawberry and vetch were adequately controlled at the later rating, while goldenrod, rush, milkweed, New York aster, wild raspberry and sedge were suppressed. Re-growth from early injury typically occurred for clovers, buttercup, cinquefoil and most tree species. This early season weed injury with late recovery could be an issue for producers. Control may be expected based on early season evaluations, but late season weed recovery could lead to yield reductions and harvest issues. Applications too smaller weeds may increase control, and this timing should be evaluated in the future for difficult to control weeds.
1NB Department of Agriculture and Aquaculture, Crop Development Branch, P.O. Box 6000, Fredericton, NB, E3B 5H1