CHEMICAL CONTROL OF SOYBEAN AND COTTON VOLUNTEER PLANTS RESISTANT TO DICAMBA

Abstract

This work was conducted with the objective of evaluating alternatives for chemical control of soybean and cotton volunteer plants, comparing glyphosate-resistant commercial cultivars to new transgenic cultivars resistant to dicamba, in two growth stages. Four independent trials were designed in the greenhouse, repeated for two consecutive years. Infestation of cotton and soybean volunteer plants was simulated in plastic pots with two distinct genetic materials. For cotton, a glyphosate-resistant (Roundup Ready Flex®) and a dicamba and glufosinate-ammonium tolerant (DGT) cultivars were used. The same experiment was repeated on plants with two or four leaves. For soybean, a glyphosate-resistant cultivar (Intacta®) and a glyphosate and dicamba-resistant cultivar (Xtend®) were evaluated. The same experiment was repeated on plants with two or four completely expanded trifoliate leaves. In conclusion, the timing of application and herbicide rate are most important factors for consistent control of volunteer plants with different technologies, especially for contact herbicides. When herbicides were applied in early growth stage and using the recommended rate, no differences were observed across technologies present in the cultivars. Therefore, independently of the technology present in cultivars, cotton plants can be controlled by 2,4-D, paraquat and flumiclorac, while soybean plants can be controlled with 2,4-D, paraquat and atrazine.