Dec 10, 2009
El Nino Rains Are Expected To Aid Spread Of Soybean Rust
Author: Michael Cordonnier/Soybean & Corn Advisor, Inc.
Now that the soybean planting is complete in the state of Parana, soybean producers in the state have turned their attention to scouting their fields for any sign of soybean rust. Since the rains started earlier than normal this year in southern Brazil, the disease started earlier than normal as well. The first case of the disease was found on volunteer soybeans in the northern part of the state in late September, just as the soybean-planting season began. The abundant rainfall associated with El Nino is expected to result in ideal conditions for the spread of the disease.
During the 2008-09 growing season, farmers in Parana averaged two application of fungicide aimed at controlling the disease. The 2008-09 growing season in southern Brazil was dryer than normal, which slowed down the spread of the disease. Scientists believe that the abundant rains associated with El Nino could result in an average of three fungicide applications or more being applied this growing season. For some of the later maturing soybean varieties that take longer to mature, four applications may be required.
The first soybeans to be planted in Parana are always in the western part of the state and those soybeans are now starting to flower and set pods. Once a soybean plant enters the reproductive phase, the plant is more susceptible to rust infections. Seventeen cases of rust have been reported in the state and that number is expected to multiply quickly as more soybeans enter their reproductive phase.
If multiple applications of fungicides are required to control the disease this growing season, it doesn't necessarily mean that soybean yields will be impacted. If done correctly, the control measures developed in Brazil work quite well. It would mean though, that the farmers would encounter higher costs at a time when their margins are already thin.