Published online by Cambridge University Press: 12 June 2017
Greenhouse studies were conducted to investigate the basis for effective field control of yellow nutsedge (Cyperus esculentus L. var. esculentus) when atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-trizine] was applied late postemergence. Yellow nutsedge responded similarly to atrazine applied preemergence, early postemergence, or late postemergence. Yellow nutsedge growing with or without the presence of the mother tuber responded similarly to atrazine applied early postemergence. Atrazine application to the soil resulted in much greater yellow nutsedge injury than foliar application. The addition of oil enhanced atrazine activity when foliarly applied, but not when soil applied. Simulated rainfall immediately after postemergence applications enhanced yellow nutsedge control more than when simulated rainfall was delayed. The primary roots of yellow nutsedge appeared to be more important than other underground absorbing areas for atrazine uptake in young plants. Plants from tubers originating from lower soil depths produced secondary roots deeper, and these plants were less affected by atrazine applied preemergence than plants originating from tubers closer to the soil surface. A considerable reduction in atrazine activity was obtained when tubers were planted into soil 1 month after atrazine application.