Associação químico-biológico no manejo integrado de doenças foliares da soja

Abstract

Soybean is one of the main agricultural crops in Brazil and to obtain good productivity, the control of foliar diseases through biological and chemical fungicides is essential throughout the crop cycle. Therefore, the objective of this work was to evaluate the chemical-biological association in the integrated management of soybean foliar diseases. The work was developed at the phytopathology demonstration unit, located at the Federal University of Grande Dourados, in the city of Dourados-MS, during the 2024/2025 harvest in a randomized block design (DBC), with 6 treatments with 6 replicates, totaling 36 plots. The treatments were: 1- without fungicide application; 2- Bacillus velezensis –strain CBMAI 1301 and CBMAI 1304 in V4 (0.75 L ha-1 of p.c.) and Pyraclostrobin + Epoxiconazole + Fluxapyroxad and Mancozeb in R1 and R1+15 days (0.80 L ha-1 of p.c.) + 1500 g ha-1 of p.c.); 3- Propiconazole + Difenoconazole in V4 (0.15 L ha-1 of p.c.) and Pyraclostrobin + Epoxiconazole + Fluxapiroxad and Mancozeb in R1 and R1+15 days (0.80 L ha-1 of p.c. + 1500 g ha-1 of p.c.); 4- Bacillus velezensis – strain CBMAI 1301 and CBMAI 1304 and Propiconazole + Difenoconazole in V4 (0.75 L ha-1 of p.c. + 0.15 L ha-1 of p.c.) and Pyraclostrobin + Epoxiconazole + Fluxapyroxad and Mancozeb in R1 and R1+15 days (0.80 L ha-1 of p.c. + 1500 g ha 1 of p.c.); 5- Bacillus velezensis – strain CBMAI 1301 and CBMAI 1304 in V4 and R1 (0.75 L ha-1 of p.c.) and Pyraclostrobin + Epoxiconazole + Fluxapyroxad and Mancozeb in R1 and R1+15 days (0.80 L ha-1 of p.c. + 1500 g ha-1 of p.c.); 6- Bacillus velezensis – strain CBMAI 1301 and CBMAI 1304 in V4, R1 and R1+15 days (0.75 L ha-1 of p.c.) and Pyraclostrobin + Epoxiconazole + Fluxapyroxad and Mancozeb in R1 and R1+15 days (0.80 L ha-1 of p.c. + 1500 g ha-1 of p.c.). The evaluations performed were stand, severity of diseases such as septoria leaf spot, cercospora and target spot, thousand-grain weight and productivity, with severity being done according to the diagrammatic scales of septoria leaf spot, cercospora and target spot. The data obtained were subjected to the variance test, and the treatment means were compared by the Tukey test (p < 0.05), using Sanest. The area under the disease progression curve for septoria leaf spot was also calculated, as it had a higher occurrence in the area. Soybean septoria leaf spot control was observed in all treatments, but there was no significant difference between the treatments evaluated due to the low pressure of the disease. In addition, it was not possible to observe an increase in productivity and in the weight of a thousand grains with the integrated management of soybean foliar diseases. However, although in the present study there are no distinctions between the chemical-biological associations, their use is necessary due to the non-occurrence of resistance by the pathogen, in the case of selection pressure, and because it stimulates sustainability given the biological nature of these microorganisms present in the formulations.