Nov 08, 2021

Soybean Rust Identified in Paraguay and Parana, Brazil

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

Scientists in Paraguay have identified the presence of soybean rust on volunteer soybeans and kudzu vines. In the state of Parana, Brazil soybean rust spores have been found in special collecting devises. Even though soybean rust spores are present, no cases of the disease have been identified in commercial soybeans fields in either Brazil or Paraguay, but it is just a matter of time, because the disease generally does not infect soybean plants until they start to flower.

At the end of October, authorities in Paraguay identified soybean rust on volunteer soybeans and on kudzu in the department of Itapua in far southeastern Paraguay, which is one of the main soybean producing regions of Paraguay. The National Vegetation and Seed Quality and Sanitation Service of Paraguay (SENAVE) sent out an alert to farmers in the region informing them that soybean rust has been found and that they should start monitoring their fields for the presence of the disease, especially in the earliest planted soybeans.

In the state of Parana Brazil, the Institute for Rural Development in Parana (IDR-Parana) identified rust spores in some of their special collection devises on October 26 in the city of Santa Helena in far western Parana, just across the Parana River from Paraguay.

For many years, Brazil has had in place a "Soybean Free Period" from early June to early September during which all live soybean plants must de destroyed to eliminate host plants where the disease can survive from one growing season to the next. That has generally worked very well, but other plants such the kudzu vine can function as hosts as well and they are much harder if not impossible to eliminate.

Soybean rust was first identified in Brazil in 2001 and is considered the most severe soybean disease capable of causing losses as high as 90% if not controlled. Soybean rust originated in Asia and it is unclear how it arrived in South America, but the main suspect are soybean hulls that were used as packaging material for products that arrived in Paraguay from China.