January 31, 2012

Mato Grosso and Goias Account for 80% of Rust Cases in Brazil

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

The wet weather in Mato Grosso and Goias over the last several weeks has been ideal for the spread of soybean rust. Currently there are 139 cases of rust confirmed in Brazil with 66 cases in Mato Grosso and 46 cases in Goias. These two states combined now account for 80% of all the confirmed rust cases in Brazil.

Its unprecedented for these two states to account for 80% of the rust in Brazil and it is due to a number of factors including: ideal weather for the spread of the disease in central Brazil, the ongoing drought in southern Brazil which has reduced the spread of the disease, a more lax attitude toward the disease after two consecutive years when the disease was not much of a problem, and farmers trying to save money by purchasing cheaper and less effective fungicides.

Even if the weather would dry out somewhat going forward, the harvesting of early and super-early maturing soybeans is also helping to disperse the spores to nearby fields of later maturing soybeans. Therefore, it's the later planted soybeans that are most at risk from the disease this growing season.

The amount of loses caused by rust this growing season is yet to be determined, but in the hardest hit areas, agronomists are estimating the loss in the range of 5 to 8 sacks per hectare or 300 to 480 kg/ha (approximately 4 to 7 bu/ac). During the 2010/11 growing season, Mato Grosso averaged 52 sacks per hectare 45.2 bu/ac.

For the last two years, the number of fungicide applications in central Brazil for rust control has been averaging less than two applications per season and this has led to a more relaxed attitude this year toward the disease. These two applications were probably applied approximately 30 days apart. In the hardest hit areas of central and northern Mato Grosso, agronomists are now advising farmers to wait no more than 15 days between applications. Additionally, the heavy rains tend to wash off

In addition to reduced yields caused by diseases, the wet weather is also increasing production costs by forcing farmers to harvest their soybeans at higher moisture content resulting in additional drying costs.