Effect of differential levels of simulated overhead irrigation on residual herbicides applied to wheat straw–covered soil for barnyardgrass control

Abstract Crop residue can intercept and adsorb residual herbicides, leading to reduced efficacy. However, adsorption sometimes be reversed by rainfall or irrigation. Greenhouse experiments were conducted evaluate the effect of differential overhead irrigation level on barnyardgrass response acetochlor, pyroxasulfone, pendimethalin applied bare soil wheat straw–covered soil. Acetochlor resulted in 25% 40% control, 30 50 more plants 213 cm −2 , greater biomass than applications, regardless amount. Barnyardgrass suppression pyroxasulfone applications improved with increased irrigation; however, weed control levels similar not observed after any densities from decreased but did change Aboveground amounts both applications; efficacy was alleviated Pendimethalin only herbicide tested that displayed when approximately 0.3 1.2 applied; applications. No differences between for densities. These data indicate increase acetochlor pyroxasulfone. Optimal required are specific, some such as pendimethalin, may adversely affected