EN 
PT_BR According to Anti-rust ConsortiumThe 2025/2026 soybean crop has 144 reported cases of Asian soybean rust, one of the most severe diseases affecting soybean crops: 88 cases in Paraná, 44 in Mato Grosso do Sul, 5 in Rio Grande do Sul, 4 in São Paulo, 2 in Santa Catarina, and 1 in Minas Gerais. Comparing this to the same period last year, Paraná had registered 41 cases at the beginning of January. Therefore, Paraná has double the number of occurrences compared to the previous crop. "The increase in the number of reports does not indicate a loss of control of the disease, but rather that rust has been identified in the region and needs to be managed properly. It is a sign that spores are circulating and that producers need to use fungicides effectively to manage the rust," emphasizes researcher Cláudia Godoy, from Embrapa Soja.
According to the researcher, the higher occurrence of reports of Asian soybean rust in southern Brazil is related to the greater survival of volunteer soybean plants during the off-season, the planting window in the region, and disease monitoring. The researcher states that the wetter climate during the winter in the South favors the survival of volunteer soybeans—plants that sprout spontaneously after harvest—and, consequently, of the fungus that causes rust. “With rainfall in the winter, there is greater survival of volunteer soybeans, in which the fungus ends up surviving,” she explains. “In the Cerrado, where the winter is drier, this survival is lower,” says the researcher.
Photo: Fernando Dias/Ascom Seapi
The sanitary break, a 90-day period during which soybean planting is prohibited, mandates the elimination of soybean plants. “Even so, there is a significant presence of these plants among other crops in the Southern region, which contributes to the maintenance of the disease,” she says. Another factor pointed out by the researcher is the planting window. “States like Paraná begin planting as early as September 1st, as do regions of Paraguay. The earlier the planting, the sooner rust begins to appear, especially when there is proximity to sources of inoculum,” states Cláudia.
Furthermore, the high number of reports in the South is also linked to the registration methodology. The data from the Antiferrugem Consortium are counted by municipality, and Paraná, for example, has a larger number of municipalities compared to other states. “The registrations are voluntary and depend on the work of technicians and agronomists in the field. And regions with a strong presence of cooperatives, as is the case in Paraná, end up presenting a higher number of notifications,” explains Cláudia.
In the Brazilian Midwest, on the other hand, the harvest is approaching and rust tends to have less impact. “Producers are managing to ‘escape’ the disease more effectively. However, in this region, other diseases, such as target spot, have greater economic relevance,” Claudia points out.
Guidelines for producers
With the increasing resistance of the Asian soybean rust fungus to fungicides, there is a need to use multi-site products in combination. These fungicides attack the fungus at multiple points in its metabolism simultaneously, therefore, the risk of the fungus developing resistance to them is lower. "This strategy is fundamental to increasing the efficiency of control and prolonging the useful life of available fungicides," he states.
Producers can download the Antiferrugem Consortium app at Google Play and Apple Store and monitor the data from the Antiferrugem Consortium. The effectiveness of fungicides available on the market can be consulted in the application “Classification of the effectiveness of chemical and biological fungicides: soybean module” on the network's website. tropical plant health (RFT), with information based on cooperative trials of four growing seasons. Technical circulars with detailed trials for Asian soybean rust are available at RFT website.
The publication Efficiency of fungicides for the control of Asian soybean rust, Phakopsora pachyrhizi, in the 2024/2025 crop season: summarized results of cooperative trials. It provides up-to-date information to support producers' management strategies.
