With soybeans as the row crop, no herbicides are registered for use on soybeans and wheat. With intercrop sorghum, 2,4-D is registered for use on sorghum and wheat. However, wheat injury can occur from 2,4-D application during wheat jointing. Buctril can be applied up to boot stage of both wheat and sorghum, but susceptible weeds must be less than 6 inches high. If weed growth is excessive after small grain harvest, cultivation and postemergence herbicides are the only options.
More herbicides are available for soybeans than for sorghum.
Basagran, Blazer, Butyrac, Cobra, Classic, and Pinnacle can be used on broadleaf weeds in soybean. Poast, Fusilade, Assure, and Option can provide grass weed control. However, such herbicide treatments may not be effective because the weeds will likely be too large for control. It is better to strive for good weed control in the winter wheat, properly timed herbicide applications when wheat and the intercrop are growing together, and use of supplemental cultivation of the row crop if necessary. To make cultivation possible, harvest wheat with a combine equipped with a chopper-spreader.