In fields that had heavy white mold in 2009, no-till is the best tillage option. Tilling these fields with bury the sclerotia in the soil which increase the survival rate of the white mold fungus. The sclerotia can survive in the soil for up to seven years. Sclerotia within the top two inches of the soil surface will germinate and produce spores even in the corn. Getting as many of these sclerotia to germinate in corn so they are not able to colonize the soybean crop in 2011 is a critical step in managing this disease for future years.
Crop rotation is also critical. Fields with heavy pressure in 2009 should not be planted to soybean in 2010. The risk of an infection of white mold is too high to plant beans on beans in 2010.
Variety selection is the best tool we have to reduce the incidence of white mold problems. There are drastic differences in tolerance to white mold in varieties, but all beans are susceptible under very high pressures like we saw in 2009. Row spacing and population are two cultural practices than can easily be managed to control the canopy density and reduce the risk of white mold.
Chemical controls include soil applied Contans before the crop is planted. This biological control agent breaks down the sclerotia in the soil so they cannot germinate. There are also several fungicides now labeled for suppression of white mold, but timing is critical with application of these products. Another chemical option is the use Cobra herbicide to improve the plants natural defense against white mold. With any chemical control agent it is important to read and follow label directions.
Talk to you Trelay DSM on the best control options and soybean varieties for your farm in 2010
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