Revista Brasileira De Herbicidas 2000; 1(1): 53-56
Efficiency of lactofen in controlling Euphorbia heterophylla resistant to herbicides inhibitors ofthe enzyme acetolactate synthetase (ALS)
DOI: 10.7824/rbh.v1i1.315
The occurrence of resistant weeds is a process ofbiotype selection, with mutant genetic traits, which support applications of certam herbicides to which most of the population are susceptible. Imazethapyr, chIorimuron-ethyl, and oxasulfuron herbicides have the same mode of action; they are inhibitors ofthe acectolactate synthetase enzyme (ALS), which is responsible for the synthesis ofthree essential aminoacids: valine, leucine, and isoleucine. These herbicides are widely recommended and used for controlling Euphorbia heterophylla. However, biotypes of E. heterophylla which are resistant to those herbicides were identified in Central Western Brazil. This work was carried out with the objective of evaluating the efficiency of lactofen, applied singly and in mixture with imazethapyr, chlorimuron-ethyl, and oxasulfuron for the control of E. heterophylla biotypes which are resistant to ALS inhibitors. The results showed that sequential application oflactofen at 60 + 60 g/ha was efficient in controlling E. heterophylla. Lactofen mixtures with imazethapyr, chIorimuron-ethyl, and oxasulfuron showed good efficiency, thus demonstrating that mixing herbicides of different action mechanisms is a good strategy for controlling E heterophylla biotypes which are resistant to ALS inhibitors. Lactofen mixture with flumic1orac-pentil showed good control of E. heterophylla. The evaluated herbicides and mixture rates were not harmful to soybean plants.
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