Efeito de fungicida protetor clorotalonil sobre o mildio e outras doenças na cultura da soja

Abstract

The soybean is considered one of the most important crops in the world. The growing expansion of the oilseed in recent years has brought numerous problems of abiotic and biotic order, among which the diseases are one of the factors that can harm the culture and cause losses in productivity. Chemical control is one of the solutions currently found for the management of diseases. Site-specific fungicides are the most used, triggering the sensitivity of many pathogens. The use of multisite fungicides has been demonstrated as a tool to complement the management and to help reduce the selection of resistant pathogens. As a result, the objective of this work was to verify the control provided by the fungicide Chlorothalonil applied at different times and cultivars with different levels of resistance to Asian rust, in the reduction of damages caused by mildew, Asian rust and DFC's, as well as in components. The experiment was conducted in a 4x2 factorial scheme (different seasons x cultivars) with four replications. The entry times of the first application of the fungicide Chlorothalonil were in the phenological stages: V8, R1 and R4 and except in the control that received no application of this product. Soil rust severity (FAS), mildew and CFDs were analyzed weekly, used to calculate the area under the disease progress curve (AACPD), as well as yield variables such as height of first pod insertion, number of productive nodes, number of productive and unproductive pods, thousand grain weight and productivity. The cultivar TMG 7063 IPRO always obtained the lowest severity of the disease through AACPD regardless of the time of application. On the other hand, for the most part, late applications have proved to be less efficient for disease control. However, for the yield components most of the times no significant effect was observed.