Monitoramento do agente causal do oídio na soja via coletor de esporos e o efeito no controle químico

Abstract

Currently, the occurrence of powdery mildew in soybeans, especially when environmental conditions are favorable to the development of the disease, has been affecting the crop and causing significant damage to grain yield, even increasing production costs. In the southwest region of Paraná, the last harvests were marked by periods of water deficit, and this condition favored the occurrence and intensity of powdery mildew. Once this is known, and in the absence of resistant cultivars or when it is impossible to use them, chemical control with fungicides is essential. However, it is remarkable the exaggeration in the number of applications for its control and that consequently lead to environmental damage. This high number of applications can be explained by the lack of tools and information to help rural producers and agronomists make decisions about the correct moment for chemical control. In this sense, this work aimed, together with an alternative tool (spore collector), to generate information for farmers, agronomists and other interested people for decision-making on the chemical control of Microsphaera difusa Cke Pk in soybeans, aiming at a possible reduction in the number of applications of fungicides maintaining productivity and reducing production costs. To make this possible, the arrival of Microsphaera difusa Cke Pk spores in the field was monitored using a spore collector provided by the Instituto de Desenvolvimento Rural do Paraná (IDR-Paraná). A comparison was made between three different types of treatments, the first being the conventional or scheduled treatment, in which the producer usually performs 4 fungicide applications, the second the fungicide applications only happened after the detection of spores on the present microscope slide in the collector and the third in the absolute control, where no fungicides were applied. The experiment with the TMG7062 IPRO soybean cultivar was conducted in a randomized block design, with 7 replications, totaling 21 plots, each plot with 9 𝑚2. As a result, we obtained a greater productivity in the blocks with fungicide application, even through the economic analysis it was observed that the monitored control via collector has a greater return. The reduction in applications contributes to a reduction in costs for fungicides and application costs for farmers, while also preserving their health, taking into account the risks of contact with agrochemicals. The evaluated data were subjected to analysis of variance at a 5% error probability level followed by Tukey’s test.