Propelled Abrasive Grit for Weed Control in Organic Silage Corn

Core Ideas Air‐propelled corncob grit can control in‐row weeds in corn through abrasionA single grit application applied at V1 or V3 of corn increased silage yield.A single grit application applied at V5 or V7 suppressed weeds, but had lower silage yield. Weed management in organic farming requires many strategies to accomplish acceptable control and maintain crop yields. This 2‐yr field study used air propelled abrasive grit for in‐row weed control in organically certified silage corn (Zea mays L.). Corncob grit was applied as a single application at corn vegetative growth stages V1 (one true leaf; numbers correspond to number of true leaves at the corn vegetative stage), V3, or V5 (in 2013) and V3, V5, and V7 (in 2014) and in double and triple combinations at these stages. Between‐row weed control was accomplished by flaming or cultivation after the last grit application. Grit effects on weed efficacy and silage yield were quantified and compared with hand‐weeded and season‐long weedy treatments. Grit applications decreased in‐row weed biomass by >80% and increased yield up to 250% when compared with the weedy check. Single early applications (V1 and V3) increased yield, with additional treatments decreasing end‐of‐season weed density and biomass. Single late grit applications (V5 and V7) also decreased weed biomass, but silage yields were reduced compared with hand‐weeded and early treatments. Early grit applications may have value for growers to control in‐row annual weeds in organic silage corn without soil disturbance.