Selectivity of herbicides in pre- and post- transplantation in lettuce culture

Abstract

Evaluation of herbicide selectivity on transplanted lettuce cv. Elisa was undertaken in Maringá PR Brazil, from April through June, 1998. Experiment consisted of randomized blocks in a split plots scheme with four replications. The plots (6.3m x 1.2m) were divided into three subplots: one central subplot received herbicide treatments and the two lateral subplots were controls. Herbicides applied to pre-transplanted lettuce and evaluated were metolachlor, oxadiazon, oxyfluorfen, pendimethalin, thiobencarb and trifluralin; phenoxaprop-p-ethyl + clethodin, fluazifop-p-butyl, ammonium gluphosinate and imazethapyr were applied to post-transplantation culture. The experimental area was kept free from weeds during the whole period. Four to five weekly visual evaluations of phytotoxicity were performed for pre- and post- transplantation treatments. Marketable lettuce was evaluated too. The above two characteristics taken as a basis, treatments with thiobencarb, trifluralin, phenoxaprop-p-ethyl + clethodin, fluazifop-p-butyl and ammonium gluphosinate were defined as selective in the doses and the application modes delimited in the assay