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October 30, 2013

Brazilian Farmers on Lookout for Corn Earworm and Soy Rust

Brazilian farmers have two pests that they need to monitor closely early in the 2013/14 growing season, the newly discovered corn earworm and their old nemesis, which is soybean rust.

The corn earworm (Helicoverpa amigera) is the one that worries farmers the most since it is new to most soybean farmers Brazil. In Sorriso, which is located in central Mato Grosso, farmers have been actively applying insecticides in an attempt to stop the insect from getting a foothold in their newly planted soybean fields even though the soybeans are still very small. Some soybean fields that were planted during the second half of September have already been sprayed three times with insecticides. When the worm is still tiny, it is easier to control so farmers are not wasting any time in an attempt to control the pests. Scientists are recommending that farmers rotate the type of chemicals they use to maximize control and that they spray in the evening or at night when the caterpillars are more active.

Chemicals that contain the active ingredient Benzoato de Emamectina seem to work the best in controlling the caterpillar in other countries, but farmers need to be very careful when using these chemicals due to its toxicity. Scientists are in the process of setting up series of 100 insect traps across the state of Mato Grosso to monitor the pest populations. The moth migrates very easily from one field to the next and these traps are designed to monitor that migration.

Controlling this new pest is going to be a "work in progress"a as farmers and scientists develop effective control measures. One thing they have in their favor is the experience in other countries where scientists have been able to keep the pest under control. When soybean rust appeared in Brazil in 2000/01, it came as a complete surprise and it took several growing seasons before scientists and farmers developed effective control measures. Farmers are certainly hoping that it does not take that long to develop effective control measures for the corn earworm.

As far as soybean rust is concerned, Embrapa has not yet reported any confirmed cases of the disease. Normally, the first confirmed cases of the disease are not reported until later in November or even early in December.