Effect of the interaction between soil moisture and growth stage of weeds on the efficacy of herbicides applied at different doses

摘要

The pot experiment under controlled environment was carried out to evaluate the influence of the interaction between soil moisture (60 and 30%) and growth stage (2-4 and 6-8 leaves) of Anthemis arvensis L. and Papaver rhoeas L. on the efficacy of herbicides. Under optimal conditions (growth stage of 2-4 leaves and soil moisture 60%), high efficacy for both doses of the mixture 2,4-D + florasulam and full dose of the mixture 2,4-D + dicamba was observed. Dose reduction of the second mixture contributed to poorer weed control. Low soil moisture and advanced growth stage of weeds decreased the efficacy of the mixture 2,4-D + florasulam against P. rhoeas. However, A. arvensis at the growth stage of 2-4 leaves was efficiently controlled under low soil moisture conditions. The mixture 2,4-D + dicamba applied under optimal conditions was efficient only against A. arvensis. Regardless of weed species, a decrease of herbicide efficacy for reduced dose was noted under above conditions. Application of the mixture 2,4-D + dicamba at the growth stage of 6-8 leaves resulted in poor herbicide effect despite the soil moisture. Water deficit in soil also significant decreased the herbicide efficacy.