The Importance of the Shoot of Giant Foxtail for Uptake of Preemergence Herbicides

Herbicides were mixed with Drummer silty clay loam soil in 1-inch layers in the shoot, root, shoot and root, or seed zones for giant foxtail ( Setaria faberii Herrm.). After 2 weeks in the greenhouse, foxtail tops were harvested and dry weights used as the measure of herbicidal effectiveness. All of the 11 herbicides evaluated caused a reduction in dry weight when placed in the shoot zone. When placed in the root zone, only 3-amino-2,5-dichlorobenzoic acid (amiben) caused a reduction in dry weight. Most herbicides were just as effective, or more so, in the shoot zone as in the seed zone. Only amiben and N -1-naphthylphthalamic acid (NPA) were more effective in the seed zone than in the shoot zone.