November 13, 2009


Wetness in Brazil soy belt may lure in more soy rust



Brazilian soy producers may have a tougher fight against soy rust this year as above-average rains may attract more of the fungus, a plant pathologist said Thursday (Nov 12).


It was still early in the season to know how the plant disease would behave under the current weather conditions, said Rafael Moreira Soares, soy rust specialist at the government's crop research company Embrapa.


Brazil's soy belt has been wetter than usual this planting season, and the region is entering the rainy season.


Soy rust first appeared in Brazil in 2001 on some farms in the south, but quickly spread nationwide. From 2003 to 2005, Brazil lost more than four million tonnes of soy to rust. Soy rust can destroy 80 percent of a crop field if left untreated.


Farmers now use fungicides to fight the rust, but the tactic could prove useless if rains persist, which would paralyse all efforts in controlling rust.


The government has taken precautions by forbidding producers from planting soy during the winter months to reduce the spread of rust from one season to the next. The policy was relatively successful, but farmers were careless in cleaning up voluntary soy that crops up around fields from spilled beans over the winter months, which serves as a host to carry the disease over into the next season, said Soares.


Soares said signs of rust would not show up until the soy crop begins to flower. As plants divert more energy to bean production, their natural defenses weaken and rust can easily set in. Flowering will begin in early December in some places.


Brazil is projected to harvest a record 64 million tonnes of soy this year, up from 57 million in 2008-09.


Soares said producers on average had enough fungicide for two sprays, but they need to spray as many as five times to control rust during a particularly bad outbreak.


There is a risk that producers will not have sufficient fungicide on hand as they try to keep costs down, he said.


If rust shows up, immediate spraying is required. If producers order the chemicals after the rust appears, it will be too late, Soares warned.

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