Chemical control of the soybean target spot (Corynespora cassiicola), in the cerrado of Tocantins, Brazil

Abstract

The fungus Corynespora cassiicola (Berk. & M.A. Curtis), the causal agent of the target spot in soybean, have occurred frequently in the North Central region of Brazil and may, under high temperature and high humidity conditions, cause serious damage to the crop. As the use of chemical fungicides is recommended in susceptible cultivars, the objective of this study was to determine the fungicide efficiency in the control of the soybean target spot in the cerrado of Tocantins, Brazil, crop 2014/2015. The experimental design was a randomized block with four replications. The treatments were differentiated by plant crop management, with the use of commercial synthetic fungicides applied alone or in combination with each other, plus a control (no application), a total of six different treatments. Were determined the area under the disease progress curve, the percentage of defoliation, thousand grains mass and grain yield. The application of fungicides promoted lower advance of the target spot in soybean, reduction in defoliation, greater thousand grains mass and higher productivity compared with the control. The treatment consists of two sequential applications Pyraclostrobin + Fluxapyroxad reduced by 36.7% the severity of the disease, as well as lower rate of defoliation of plants, promoting increase in mass of thousand grains and soybeans grain yield.