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Corn
Volume 58 Number 7 Date 06/13/2013 EUROPEAN CORN BORER - The spring flight of moths continued for the fourth week, with only a single moth registered in the black light trap near Janesville. The European corn borer degree day model suggests that the peak in moth activity has occurred near Beloit in Rock County and should occur before June 14 in the Madison area and June 21 near Hancock. Most corn is unsuitable for larval development at this time, so egg deposition is likely occurring on peas, peppers, potatoes, snap beans and various weed hosts. TRUE ARMYWORM - Minor feeding injury was noted in five of 60 cornfields sampled in the southern and west-central areas from June 6-12. Larvae ranging in length from ¾-1 inch were found in two of the fields. Although 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. SLUGS - Damage consisting of narrow, irregular longitudinal tracks or streaks in the lower leaves was observed in several damp, weedy fields in Dane, Green, Monroe, Rock and Walworth counties. These mollusks thrive during periods of wet weather and could become an increasing problem in no-till systems and very weedy corn where surface residue and high moisture favor their development. Emerging to four-leaf stage corn is at greatest risk of injury. CORN ROOTWORM - Larvae hatching from overwintered eggs during the next several weeks are likely to encounter saturated soils, potentially resulting in high mortality in areas affected by flooding. Corn rootworm larvae have difficulty accessing corn roots under extreme wet conditions. -- Krista Hamilton, DATCP Entomologist 
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