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Other insect populations of minor concern at this time are reports of variegated cutworm problems in alfalfa, bean leaf beetle in first planted soybean, and relatively high numbers of European corn borer moths in light traps. Variegated cutworm is an occasional pest of alfalfa following removal of first cutting. High numbers of moths earlier this season have resulted in a limited number of fields where this pest has reached economic levels. The identifying characteristic for variegated cutworm larvae is a row of small yellow spots or diamonds running down the length of the back. Problems typically occur when larvae grow to a large size and feed on developing tillers as they emerge from the crown of the alfalfa plants following first harvest. Feeding by this pest can delay regrowth of alfalfa plants by two to three weeks. In addition, lack of the alfalfa canopy often results in excessive weed (non host plants for cutworms) growth. Variegated cutworm are present in most years, but are often killed by insecticide applications for alfalfa weevil or potato leafhopper. Bean leaf beetles have required control in some early planted fields where beetles have congregated as they move to soybean fields from overwintering sites in wooded field borders. Bean leaf beetles are good flyers and readily seek out early planted soybean fields. European corn borer moths are being captured in relative high numbers in blacklight traps. Numbers are not as high as 10 years ago and prior to Bt ECB corn varieties, but they are much higher than captures during the past three years. These elevated populations may not develop into economic infestations of this pest, but growers should scout for first generation eggs and larvae if they are not using a Bt ECB corn variety. Additional information on scouting and thresholds for ECB will be provided in the next newsletter.

Wayne Bailey
573-864-9905 (cell)
BaileyW@missouri.edu