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Looking Ahead
Volume 56 Number 8 Date 06/16/2011 EUROPEAN CORN BORER - The most advanced corn is now susceptible to infestation by first generation corn borers. Leaf feeding and small larvae were observed during the past week on 2-5% of plants in Monroe and Richland counties. Early signs of damage, including leaf pinholes and shotholes, should be noticeable in southern and central Wisconsin corn fields in the week ahead. APPLE MAGGOT - Emergence could begin by June 23 near Janesville, June 30 near La Crosse, and July 13 near Racine. This annual event corresponds with the accumulation of 900 degree days (base 50°F) when soil moisture is adequate. Traps should be placed next week in perimeter trees adjacent to abandoned orchards or woodlots to capture the first male flies. SOYBEAN APHID - Early colonies were detected for the first time this season on June 7 in La Crosse County. Surveys in the last reporting period found aphids in 5 of 24 sampled fields. Densities were very low and ranged from 2-6 per infested plant on 1-8 per 100 plants. The aphids were noted in Dane, Monroe, Sauk and Waukesha counties. STALK BORER - Larvae ranging in size from ¼ - ½ inch caused light leaf injury to 1-6% of edge row plants in Dane, Monroe and Sauk County corn fields. Similar levels of infestation were documented last week in Columbia and Richland counties. The migration of stalk borer larvae from grasses and broadleaf weed hosts into corn is expected to accelerate next week. Spot treatment may be warranted for fields that show 10% of plants with feeding damage. SQUASH VINE BORER - Moth emergence and egg laying can be anticipated by June 23 in the southern areas, about the time chicory blooms. Pumpkins, squash, gourds and other vine crops should be examined daily for eggs and evidence of larval boring from 900-1,000 degree days (base 50°F). Insecticidal controls should be applied to the stems of plants when the adults are first noticed, especially while runners are less than two feet long. Repeat applications may be required throughout the three-week oviposition period. WESTERN BEAN CUTWORM - The first moth of the season was caught in the Arlington area of Columbia County on June 8. None were reported this week at the any black light or pheromone trap location. In preparation for the start of the adult flight period, traps are now being placed at selected sites statewide. Participants in the DATCP western bean cutworm network are reminded to submit datasheets with trap locations to Clarissa Hammond at clarissa.hammond@ wisconsin.gov no later than June 22. --Krista Hamilton, DATCP Entomologist 
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