Weed Control in Sunflowers (<i>Helianthus annuus</i>) with Desmedipham and Phenmedipham

Abstract

Desmedipham [ethyl m -hydroxycarbanilate carbanilate(ester)] controlled wild mustard ( Sinapsis arvensis L. ♯ 3 SINAR) and redroot pigweed ( Amaranthus retroflexus L. ♯ AMARE) more effectively than phenmedipham (methyl m -hydroxycarbanilate m -methylcarbanilate). A synergistic interaction occurred with all tank-mix combinations of the two herbicides for wild mustard control, except combinations containing 0.71 kg ai/ha of desmedipham. The magnitude of the synergism decreased as the rate of desmedipham was increased and increased as the rate of phenmedipham increased. Both herbicides caused injury symptoms of leaf necrosis and height reduction to sunflowers ( Helianthus annuus L.). Crop injury and sunflower heights were affected more by desmedipham than by phenmedipham. Injury effects were temporary and had no influence on sunflower yields.