A Review of Non-Chemical Management of Couch Grass (Elymus repens)

Abstract

Couch grass (Elymus repens) is a morphologically diverse, rhizomatous, perennial grass that is a problematic weed in a wide range of crops. It is generally controlled by glyphosate or intensive tillage in the intercrop period, or selective herbicides in non-susceptible crops. The aim of this review is to determine the efficacy of non-chemical strategies for E. repens control. The review shows that indirect control measures like crop choice, subsidiary crops, and fertilizer regimes influence E. repens abundance, but usually cannot control E. repens. Defoliation (e.g., mowing) can control E. repens growth, but efficacy varies between clones, seasons, and defoliation frequencies. Tillage in the intercrop period is still the main direct non-chemical control method for E. repens and its efficacy can be increased, and negative side-effects minimized by an appropriate tillage strategy. Some new tillage implements are on the market (Kvik-up type machines) or under development (root/rhizome cutters). Alternative methods that can kill E. repens rhizomes (e.g., steaming, soil solarization, biofumigation, hot water, flooding) often have high costs or time requirements. More studies on the effect of cropping system approaches on E. repens and other perennial weeds are needed.