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Corn
Volume 59 Number 7 Date 06/12/2014 EUROPEAN CORN BORER - Moth emergence continued for the second week, but numbers in black light traps were still very low. Counts of 1-14 moths per trap were reported from Janesville to Chippewa Falls during the period of June 5-11. The European corn borer degree day model suggests that the spring flight should peak by June 15 in the southern counties, June 21 in the central counties, and approximately one week later in northern Wisconsin. Since most corn is less than 18 inches tall and cannot support larval development, oviposition is likely occurring on peas, peppers, potatoes, snap beans and various weed hosts. BLACK CUTWORM - Conditions remain favorable for localized cutworm outbreaks this month. Crop advisors and growers should continue to inspect fields for another two weeks or until corn plants have reached the five-leaf (V-5) stage, particularly sites affected by spring flooding or with previous grassy weed problems. Signs of cutworm activity have been encountered in a very small percentage of surveyed fields this month, but significant injury has not been reported or observed as of June 11. TRUE ARMYWORM - Minor infestations in corn were noted in eight of 54 fields sampled this week. Larvae ranging in length from ¾-1 inch were found in six fields. Although observed infestation rates were very low, actual populations may be larger and more widespread than indicated by our surveys. Continued scouting of corn and wheat is advised. A rescue treatment is justified if 25% of plants are infested with two or more small larvae (¾ inch or shorter) or 75% of plants are infested with larvae of any size. -- Krista Hamilton, DATCP Entomologist 
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