Effect of 2,4-D and Dicamba Residues on Following Crops in Conservation Tillage Systems

Abstract

Dicamba and 2,4-D, which are used prior to seeding in conservation tillage systems, were applied in late fall and early spring to determine their residual effect on subsequent spring-seeded crops. The herbicides 2,4-D ester and 2,4-D amine with dicamba or glyphosate, applied 0 or 15 d prior to spring seeding, damaged canola, peas, lentils, and alfalfa. The legumes were damaged by spring-applied dicamba. There was also a slight reduction in the total dry matter yield of wheat and barley by 2,4-D applied in spring prior to seeding. All crops tested, except lentils, were tolerant of recommended fall applications of 2,4-D for the control of winter annual flixweed and field pennycress.