The persistence of imazaquin (preemergence) and imazethapyr (pre and postemergence) in the soil, and their effects on corn and cucumber plants were evaluated in two expriments in Londrina, Paraná State. Treatments of imazaquin 0,12, 0,15 (normal) and 0,30 kg./ha, and imazethapyr 0,1 (normal) and 0,2 kg/ha were arranged in a split-plot design. Six sowing dates (plots), including 0, 30, 60, 90 120 and 150 days after herbicide application (DAA) were arranged in blocks. Residual activity for corn (Pioneer 3072) was evaluated in the field, and for cucumber in a bioassay, in greenhouse. Corn plant phythotoxicity was visually evaluated and dry weight were recorded as well as dry weight and height for cucumber plants. Imazaquin (preemergence) and imazethapyr (pre and postemergence) phytotoxicity were not considered to be harmful to corn plants, when sowing occurred 90 DAA. Cucumber plants showed to be more sensitive to the herbicides than corn plants, especially to imazaquin. Symptoms disappeared 120 DAA for imazaquin, at normal dosis. After the same period, cucumber plant height recovered from imazethapyr phytotoxicity at the lowest dosis, but not its weight.
Residue; bioassay; phytotoxicity; Zea mays; Cucumis sativus