Níveis de danos na soja com diferentes intensidade do oídio na cultura

Abstract

Soybean (Glycine max L.) is one of the main oilseeds produced in Brazil and in the world, being of great economic importance, due to its use mainly in the manufacture of Oil. With climate change resulting from the La Niña phenomena, there has been periods of drought in the South region and with this the development of powdery mildew has been favored. Currently, observations in the field indicate that the disease is more destructive and there is no safe recommendation for the positioning of products to control chemical. Therefore, this work aimed to evaluate the level of damage and efficiency of chemical control at different intensities of powdery mildew in soybean crops. The experiment was conducted on a rural property located in the municipality of Pato Branco-PR, in the period from September 2022 to February 2023, with the soybean cultivar used being BMX Zeus IPRO. The experimental design used was randomized blocks, with four replications, where each plot had nine rows of six meters, and spacing between rows of 0.45 cm and distance of 1.5 m between each plot. The experiment had five treatments formed due to increasing intensities of the powdery mildew disease, being: 0% (T1); 10% (T2); 20% (T3); 30% (T4) and 40% severity (T5), with assessment being carried out weekly after the appearance of first signs, in five plants of each plot. To assess the level of damage, samples were taken the plants in the four central rows of each plot. The data was subjected to analysis of polynomial regression. Greater soybean productivity increased inversely proportionally the intensity of the disease. The lower the intensity of the disease at the time of control chemical, the less damage and, consequently, greater economic return.