Efeito de doses reduzidas de um herbicida de pós-emergência no controlo de infestantes e na produção de trigo em sementeira directa

Abstract

The purpose of this work was to study the efficiency of the herbicide Mesosulfuron & iodosulfuron & mefenpyr – diethyl, to control grass and broad-leaved weeds at post-emergence in wheat under direct drilling, combining three doses of herbicide (0,20; 0,30 e 0,40 kg/ha) with three water volumes (100; 200 e 300 l/ha), in two different weed development stages (beginning and complete tillering for the grass weeds and 3-4 and 5-6 pairs of leaves for the broad-leaved weeds). For our climatic and infestation conditions, the recommended doses are 0,30; 0,35 and 0,40 kg/ha, and the recommended water volumes vary between 350 and 600 l/ha. The study was carried out during the year of 2004/2005 on a private farm near Evora (South of Portugal). The results showed a great efficiency of this herbicide to control grass weeds. The efficiency to control broad-leaved weeds was lower than to control grass weeds, but for both weed types, the first application timing was better than the second one. The results indicate the possibility of the anticipation of the application of this herbicide to allow both reduction of doses and water volumes while maintaining the crop yield.