Protection of the bass is essential for the management of leaf spots in soybeans

On the eve of the start of soybean planting, expectations are high for the 2020/2021 harvest. With exports on the rise, Brazil is expected to reach a new record in crop production, harvesting more than 278 million tons of grains - an increase of 8% compared to the last cycle, according to data from the National Supply Company (Conab). For researcher Eder Moreira, from Fitolab Agricultural Research and Development, even in this promising scenario, the soybean farmer must be attentive to the management of foliar diseases at the beginning of the cycle, "these fungi, called necrotrophic, are present in residues and leftovers from the harvest previous, being able to resist after harvest and act as a source of inoculum for the following year", he reinforces.

In this context, among the producer's biggest concerns, spots have gained relevance in the first 35 days after emergence, including septoria ( Septoria glycones) target ax (Corynespora cassiicola), anthracnose (Colletotrichum truncatum) and Cercospora growth (Cercospora kikuchii) "Normally, these infections occur while the lines are open and incidences begin after the interline is closed, due to the formation of a microclimate favorable to the development of the fungus. However, this is not a rule and may occur in advance, depending on the production system (cotton, crotalaria, corn) and also the sensitivity of the cultivar", comments the researcher.

For Moreira, the assertive positioning of fungicides has been essential to prevent damage in the most sensitive moments of the crop, "it is recommended to carry out the first application when closing rows (15 cm for total closure). During this period it is possible to protect the leaves of the bottom, where infections occur and the beginning of the disease process. This phase is responsible for more than 60% of the grain filling, when compared to the upper portion of the plant, in which it represents only 40% of the filling - even with the photosynthetic limitation and shorter time to grain", comments the expert.

According to Eder, the spots have a greater capacity for damage, because they affect the plant from the initial phase to the end. "When not controlled at the right times in the cycle, they can reduce productivity by 5 to 15 bags per hectare, according to data collected in the 19/20 harvest", he reinforces. In the Cerrado, for example, where most of the national oilseed production is concentrated, the highlight is the target spot, which has caused significant losses.

The disease presents its first symptoms as small circular spots, with a yellowish halo and a black dot in the center. The evolution of the fungus can be rapid, leading to premature defoliation of the bottom, consequently affecting the weight of the grains. "The determining factors for managing the target spot: 1. Production systems (straw), 2. sensitivity of the cultivar, 3. Timing of applications and 4. use of efficient products associated with multisites", adds Eder.

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Thinking about the challenge of disease control, Bayer developed the fungicide Fox Xpro. The fungicide has a triple formulation, including the active ingredient Bixafem, the company's new carboxamide. The formula acts in the different phases of the fungus' life cycle and provides health to the plants, which translates into better results at the end of the harvest.

According to Cecília Melo, product launch manager at Bayer, "in the last harvest, we closely monitored 3.610 assisted areas, which represents 21% of the soybeans cultivated in Brazil. For every four areas analyzed, three had greater productivity with the use of Fox Xpro. In 45% of these areas, there was 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 the results Fox Xpro It's 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", he concludes.