Larval populations remained historically low in 2011. The seventieth annual fall abundance survey in September revealed a state average of 0.09 borer per plant, the fourth lowest since record-keeping began in 1942. Minor population reductions from 2010 were charted in the southwest, central and northeast agricultural districts and increases occurred in the south-central, southeast, east-central, north-central and northwest areas. Larval densities in the south-central district increased to 0.20 per plant, or 20 larvae per 100 plants. On the basis of the fall survey results, a continued low population trend is expected for 2012.
Soil Science Extension
University of Wisconsin Madison