Non-Chemical Weed Management in Annual and Perennial Organic Cropping Systems

Abstract

Weedy pests, especially perennial weeds, are among the most challenging barriers to organic crop production. Improving non-chemical weed management tactics for established organic productions systems, like cool-season grains, and emerging crops like perennial flax could benefit producers. We compared three crop sequences for creeping perennial weed suppression in organic grains. Three years of alfalfa was associated with reduced densities and aboveground biomass of perennial weeds compared to sequences that alternated grain and cover crops. Interseeding cover crops with perennial flax for weed management was attempted, but neither flax nor cover established well. Flame weeding and cultivation in perennial flax were assessed in response to the failure of these cover crops. Greenhouse trial results suggested flaming could eliminate weeds without damaging shallowly planted flax seed, but emerged flax seedlings suffered greater mortality. Massive perennial flax mortality in subsequent field trials suggested flaming is a risky weed management tactic for the crop.