RS intensifies monitoring of Asian soybean rust

Soybean rust monitoring in Rio Grande do Sul crops is completing two months. The action is part of the Rust Monitoring program, which installed 77 collectors in 75 municipalities in Rio Grande do Sul at the beginning of October 2024.

The disease is caused by the fungus Phakopsora pachyrhizi  and is considered the main disease of the crop worldwide. “In the first few weeks of monitoring, we noticed structures of the fungus in the collectors, possibly coming from other regions that plant soybeans before Rio Grande do Sul, or from neighboring countries, since the fungus spreads through air currents and many regions of the state had not yet started planting soybeans,” highlights the doctor in phytopathology from the Secretariat of Agriculture, Livestock, Sustainable Production and Irrigation (Seapi), Andreia Mara Rotta de Oliveira. 

However, the researcher highlights that in the last two weeks the amount of fungus particles in the collectors has decreased significantly. “And since this is a year with a predominance of the La Niña phenomenon, the trend is for a summer with less rain and therefore the expectation is for a harvest with fewer outbreaks of rust compared to the previous harvest, under the influence of El Niño”, says Oliveira.

Data from the Emater/RS Conjuntural Bulletin indicate that 80% of the soybean area has already been planted to date. The projection is for an area of ​​6 million 811 thousand hectares in Rio Grande do Sul. “Soybean is the main summer crop, which reinforces the importance of the Rust Monitoring Program as a public policy for the sector,” says the researcher. Asian rust is considered the most important disease in soybean crops, and can cause losses of up to 90% of crops.

The Rust Monitoring Program is a joint action by the Department of Agriculture, Emater/RS-Ascar, in partnership with state education and research institutions. The Department of Plant Protection (DDV) and three units of the Department of Agricultural Research and Diagnosis (DDPA) participate through Seapi: the phytopathology laboratory, which analyzes slides from collectors in 16 municipalities, and the agrometeorology and agricultural climatology laboratory, linked to the Center for Agronomic Research (Ceagro), in Porto Alegre, and the Centers for Seed Research in Júlio de Castilhos (Cesem) and Digital Agriculture and Irrigation in Vacaria (Cepadi), with collectors for monitoring.

The program

The RS Rust Monitor provides weekly information on the occurrence of spores of the fungus that causes Asian rust, allowing farmers to access updated data on areas with the highest risk of infection. On the program's website, it is possible to identify, based on data from the previous week, the locations most prone to the disease. In addition, a risk map, updated daily, provides information on the weather conditions that favor the incidence of the disease.