South America Calling

Timely spraying has allowed Brazilian soybean farmers to effectively control the threat of the Asian rust fungus this season, although it has come at a cost.

Up until Monday, Brazil had registered 226 cases of the disease, down 15% from the same time last year, according to the Anti-Rust Consortium, a monitoring group led by Embrapa, a government research agency.

However, spending on controlling the disease is 14% higher at $2.21 billion, according to Embrapa numbers, which is partially offset by a 6% increase in planted area.

While much attention has been paid to the new threat posed by the spread of the corn earworm this season, Asian rust remains perhaps the biggest threat to the soybean crop. The fungus causes lesions on the leaves of soybean plants, which impede the formation of the bean and can result in massive yield losses. In more extreme cases, the fungus can kill the plant.

However, since it arrived in the first half of the last decade, Brazilian farmers have learned to manage the fungus' threat, spraying on the first reports of cases in their region rather than waiting for the telltale yellow mosaic to appear on their own plants.

While control of the fungus has been generally good across Brazil this season, there has been one black spot, in the southeast of Goias. The No. 4 soybean producing state accounts for 37% of all cases in Brazil this season.

The rust surge in Goias may have been due to the late application of fungicides, says Claudia Godoy, an Embrapa researcher.

Normally, rust propagates in January, but heavy rains fell in the state during November, which could have nurtured the fungus' spread earlier than expected.

February and March are traditionally the most dangerous months for rust as the spores multiply and attack plants in the later phases of development.

However, early planting this season will limit the impact in March. According to Agroconsult, a local consultancy, some 42% of the Brazilian crop will be ready to pick by the end of February.

Brazil's crop is in excellent shape with some local analysts forecasting output could be near 92 million metric tons.

Alastair Stewart can be reached at alastair.stewart@dtn.com

(AG)

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