Lack of rain could intensify the incidence of powdery mildew in soybeans during the 2020/2021 harvest

The impacts of the La Niña climate phenomenon - marked by dry weather and irregular rains - threaten record estimates of soybean production in Brazil, mainly in the South and Central-West regions. According to the National Supply Company (Conab), the forecast for the 2020/2021 harvest confirms 135 million tons of grain, with an increase of 8,1% compared to the 2019/2020 period. However, in this drought scenario, the crop may be more vulnerable to the incidence of diseases, which are favored by low air humidity and mild temperatures. "In the last harvest, powdery mildew (Erysiphe diffusa), which, for a long time, had a secondary importance for soybean growers, had a considerable impact on crops in Rio Grande do Sul and, without a doubt, this could happen again this season", points out the agronomist and researcher at Agro Tecno Research, Carlos Alberto Forcelini.

The researcher also highlights that the frequency of rain, even in the initial phase of the crop, can influence the occurrence of the disease at any stage of soybean development - both in the vegetative and reproductive stages, and in the grain filling phase. "The studies carried out by Agro Tecno Research, in the last harvest, 2019/2020, demonstrated that powdery mildew can greatly impact the productivity of soybean crops, causing rural producers to fail to harvest 10 to 12 bags per hectare , depending on the selection of cultivars and also on management, especially when we are talking about the appropriate use of fungicides", highlights Forcelini.

Among the most common characteristics of the disease is the formation of a grayish-white mold on the leaves. The growth of the fungus ends up covering the leaf area, which impairs the photosynthetic activity of the leaves, hindering the plant's development and causing premature defoliation. "The fungus is easily dispersed by the wind. Once the disease is present in the area, the leaves produce spores, which can be dispersed and generate new infections. Therefore, under favorable conditions, powdery mildew can evolve quickly", adds the researcher.

According to Anildo Betencourt, Bayer's Market Development Manager for the South region, in addition to the use of cultivars resistant to the disease, chemical control is essential for the effective management of powdery mildew. "Monitoring the fungus must be weekly, starting from sowing. Therefore, with the identification of the infection, the assertive positioning of the fungicide has been essential to prevent damage at the most sensitive moments of soybean development", he explains.

Solution for controlling powdery mildew

Thinking about the challenge of controlling powdery mildew, Bayer developed the Fox Xpro fungicide, which has a triple formulation, including the active ingredient Bixafem (the company's new exclusive carboxamide). The formula acts in the different phases of the fungus' life cycle and provides health to the plants, helping soybean farmers to manage them intelligently and seek better results at harvest time.

"In the last harvest, we closely monitored 3.610 assisted areas, which represents 21% of the soybeans cultivated in Brazil. Out of every four areas analyzed, three had greater productivity with the use of Fox Xpro. In 45% of these areas, it was found that an increase of two to four bags per hectare and, an approximate general average, an increase of three more bags. This is because the consistency of Fox Xpro's results is impressive. We had this average result not only in commercial areas, but also in contracted protocols and studies from recognized institutions. Our recommendation is to start with the product in the first applications, protecting this lower middle third, which is so important for the producer's profitability at the end of the harvest", highlights Betencourt.