Selectividad de herbicidas y control de malezas para establecer una asociación Brachiaria brizantha-Leucaena leucocephala

Abstract

A study was carried out at Mococha, Yucatan, Mexico with the objective of determining whether the application of bentazon, imazethapyr or metribuzin would improve postemergence (POST) weed control without damaging a huaxin (leucaena, guaje, leadtree, wild tamarind) {Leucaena leucocephala (Lam.) de Wit} and insurgente grass (Brachiaria brizantha Richard Stapf) association. In both June 2004 and 2005, insurgente grass (INS) and huaxin (HUA) were seeded in an arrangement of two by one rows, respectively. Herbicide treatments were a single application of bentazon, imazethapyr or metribuzin at three different rates each, and the same herbicides at a single rate but applied sequentially two and three times during the growing season. Metribuzin damaged INS (10 to 95 %) and HUA (55 to 100 %) in both years. Overall, both forage species were tolerant to bentazon and imazethapyr. In 2004, both bentazon and metribuzin showed a greater weed control (82 %) than imazethapyr (70 %), in 2005, weed control was similar for all three herbicides (P>0.05), which averaged a moderate 65 %. This study shows that an increase in 1,000 kg DM ha-1 of weed biomass, decreases forage yield for this association by 190 kg DM ha-1. Forage yields with bentazon applied three times at a 0.8 kg a.i. ha-1 rate were similar to those in the weed-free control. In tropical areas, bentazon should be an interesting option for weed control in insurgente-huaxin associations.