Controle químico da antracnose da soja e sanidade de sementes

Abstract

Soybean is the main agricultural product worldwide, justifying investments to reduce limiting factors as anthracnose caused by Colletotrichum truncatum. Three field trials were conducted in order to evaluate fungicides for control of anthracnose, singly or in association, in the aerial part at two sowing dates in the harvest 2011/12 in the condition of Dourados and Maracaju-MS. The experimental design was randomized block with five replications. Treatments were: control, carbendazim 250 g i.a.ha-1, pyraclostrobin 66,5 g i.a.ha-1 + epoxyconazole 25 g i.a.ha-1, pycoxistrobin 60 g i.a.ha-1 + cyproconazole 24 g i.a.ha-1, carbendazim 250 g i.a.ha-1 + pyraclostrobin 66,5 g i.a.ha-1 + epoxyconazole 25 g i.a.ha-1 and carbendazim 250 g i.a.ha-1 + pycoxistrobin 60 g i.a.ha-1 + cyproconazole 24 g i.a.ha-1. Two applications of fungicides were done, the first at the time of detection of disease, in R2 stage of development, and the second 19 days after the first one. Disease incidence and severity, defoliation, plant height, insertion height of first pod, number of pods, yield and thousand grain mass. Data were analyzed jointly. Seed pathology was performed focusing on the incidence of C. truncatum. The use of carbendazim, singly or combined, controlled anthracnose of soybeans. Fungicide provides yield gain, reduced the percentage of diseased petioles, a greater number of pods, plant height and productivity gains. Carbendazim + cyproconazole + picoxystrobin in some cases provided greater control than carbendazim. A greater number of pods was found when using this association, however, due to adverse conditions such as rain, this did not reflect in higher yield. Carbendazim + cyproconazole + picoxystrobin applied in the aerial part controlled incidence of Colletotrichum sp., Phomopsis sp. and Fusarium sp. in seeds. However, there was no difference in the product carbendazim. In Dourados 2nd sowing time this mixture was the only one to control the incidence of Alternaria sp. in the seeds.