Quizalofop-P-ethyl controlling sourgrass (Digitaria insularis) and goosegrass (Eleusine indica) in infested coffee areas

Abstract

Chemical control is the main weed management system in coffee crop. Herbicides alternatives controlling grass weeds in infested coffee areas are limited, mainly due to the few options of registered herbicides. Thus, it is important to evaluate selective post-emergence herbicide to control these important weeds in coffee crop. The objective in this work was to evaluate the selectivity, efficiency and agronomic viability of the herbicide quizalofop-P-ethyl compared to GLI OVER SL (glyphosate) on grass control in coffee crop. Two experiments were carried out in randomized blocks with four replicates in the municipality of Lavras and Santana da Vargem (MG - Brazil) in a commercial coffee crop cultivar “Mundo Novo” and “Catuai” to evaluate the herbicide effectiveness in the crop rows. The experimental design was a randomized block design with seven treatments and four replicates. Treatments consisted of the herbicide doses (25, 50, 75 and 100 g a.i. ha-1) compared to the standard glyphosate at the dose of 1,680 g a.i. ha-1 + Iharol at 0.5% v/v. Application occurred when sourgrass and goosegrass were at the beginning of development with up to 4 tillers (early vegetative stage) and in a second trial, at advanced stages of development (highly branched and /or flowering). Control assessments in percentage were performed at 7, 14, 21 and 28 days after application (DAA) of the treatments. A note of phytotoxicity was given following the European Weed Research Council (EWRC) patterns. The control of weeds was evaluated in each experimental plot using the visual notes scale, where: 0% represents no control, and 100% total control of the species in question, compared to the population present in the non-weed control. In general, the dose of 1,500 and 2,000 mL per hectare of quizalofop-p-ethyl (75 and 100 g a.i. ha-1) for the weeds at early vegetative stage presented the highest levels of controls (above 90%). The dose of 2,000 mL per hectare (100 g a.i. ha-1) was efficient at 28 DAA to control more developed plants. No symptoms of phytotoxicity caused by the herbicide quizalofop-P-ethyl were detected at any dose tested. Quizalofop-P-ethyl can be recommended for integrated weed management in coffee for sourgrass and goosegrass.