Chemical control alternatives for sourgrass (Digitaria insularis) resistant to glyphosate

Abstract

Herbicides alternatives for controlling sourgrass (Digitaria insularis) weed in infested citrus areas are limited, mainly due to the few options of registered herbicides and by the modalities in that these chemical products are used (directed applications). Thus it is important to evaluate other post-emergence herbicides, to be used in association with glyphosate, for the efficient control of glyphosate-resistant biotype of sourgrass (Digitaria insularis), resistant to glyphosate.  The experiment was conducted in Matão County, Sao Paulo State, in area belonging to Cambuhy Farm, during September to October 2009, in areas presenting biotypes of D. insularis resistant to glyphosate. Application occurred when sourgrass plants were with 3 to 5 tillers stage. Treatments consisted of different herbicides in association with glyphosate. It was conducted control visual assesments at 7, 14, 21, 28 and 35 days after application and collecting and weighting of weed dry mass dossel. Treatments that showed better results were glyphosate in association with clethodim, complemented by paraquat + diuron 7 days after the first application and glyphosate in association with clethodim complemented by  ammonium-glufosinate 7 days after the first application. Further, glyphosate treatments mixture to haloxyfop-methyl, glyphosate + fenoxaprop-p-ethyl + clethodim and glyphosate + tepraloxydim showed excelent performance, even with just one application.