Persistence of imazethapyr in the soil and phytotoxicity to corn seeded as succeeding crop

Abstract

This work was carried out to evaluate imazethapyr persistence in the soil, as well as the phytotoxicity of this herbicide to the corn crop seeded in succession. Treatments were organized according to a factorial scheme with two types of soil (S; clay and sandy), three regimes of irrigation (I; daily, weekly and no irrigation) and four timing (T) of herbicide application (90, 60 and 30 days prior to corn seeding, besides check plots without application). For that, imazethapyr was applied at the unique rate of 100 g ha-1. Experimental design of completely randomized blocks was adopted, with four replicates and 96 plots. Each plot consisted of a 8,5L plastic pot, fulfilled with sieved soil. In synthesis, adequate water availability between herbicide application and corn seeding granted the lowest levels of crop phytotoxicity and the highest yield of dry matter. In clay soil, the lowest levels of crop phytotoxicity were observed. Thus, it was possible to infer that imazethapyr persistence in the soil is reduced whenever there are higher microbial activity, which is enhanced by higher temperature, water availability and, in lower degree, by the time of herbicide persistence in the soil.