Herbicides are commonly used in agriculture for weed control. Since they are applied in the field, target plants and other organisms are exposed to their action. This exposure may have distinct effects on crop plants, either by predisposing them to plant pathogens or affecting the pathogen's ability to cause disease. The effect of herbicides on the development of disease usually results from direct action on the pathogen and indirectly by the activation of plant response. The objective of this study was evaluate the effect of herbicides, clorimuron-ethyl, fomesafen + mineral oil, cletodim + fenoxaprop-P-ethyl, lactofen on urediniospores of Phakopsora pachyrhizi. Germination and germ tube length were evaluated at the exposure times of 1, 2, 4, 8 and 24 h. All herbicides inhibited urediniospore germination. Chlorimuron-ethyl, cletodim + fenoxaprop-P-ethyl, fomesafen + mineral oil, glyphosate and lactofen reduced germ tube length of urediniospores, indicating that these products were toxic to the spores of P. pachyrhizi.
Asian soybean rust; urediniospores; chemical control