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October 5, 2016

Confirmation of Soybean Rust Puts Brazilian Farmers on Alert

Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.

The disease Brazilian farmers worry the most about is soybean rust and Brazilian scientists have already confirmed nearly 30 cases of soybean rust on volunteer soybeans in Brazil. Volunteer soybeans are soybeans that were spilled either during the harvest process or when the grain was transported from the field to storage facilities. These spilled soybeans can then germinate with the first rains of the summer and act as host plants for the disease. The disease spores can then move into commercial soybean fields early in the crop's development.

There have not been any confirmed cases of soybean rust thus far in commercial soybeans in Brazil, but the forecast for wet weather during the first half of October, which could facilitate the spread of the spores, have many farmers on alert.

The Brazilian agricultural research service Embrapa has registered 26 cases of soybean rust in Brazil as of the end of September with all the confirmed cases of rust found in volunteer soybeans. The state of Sao Paulo has 16 cases, Parana has 7 cases, and Mato Grosso has 3 cases.

The first two cases of rust in Mato Grosso were confirmed in the cities of Primavera do Leste and Campo Verde (both located in southeastern Mato Grosso) on August 18th. The third case was also confirmed in Primavera do Leste on September 16th.

According to the Anti Rust Consortium, soybean rust costs Brazilian farmers an estimated US$ 2 billion per year in control costs and lost productivity, so it is imperative that farmers monitor their fields and report the first signs of rust. Scientists recommend that farmers plant short-cycle soybeans and that they plant them as soon as conditions permit so that the crop can be harvested as early as possible in order to hold down control costs. They also strongly recommend that farmers rotate the fungicide they use to control the disease. By rotating fungicides that have different modes of action, it will reduce the chances that the disease will develop resistance to any one of the chemicals.

Soybean rust can cause loses from 10% to 90% if not treated.