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Corn
Volume 56 Number 15 Date 08/04/2011 EUROPEAN CORN BORER - The peak in summer moth activity should occur before August 12 in the southern and central counties and August 29 in the northern counties, a few days earlier than last predicted. Pupae and fifth instar larvae are still common in many corn fields, and these stages will contribute to the flight in coming weeks. The optimal treatment period for second generation larvae has opened in the southern and central counties where 1,550 degree days (base 50°F) were surpassed as of August 4. WESTERN BEAN CUTWORM - The phenology model for this insect suggests that 75% of the annual moth population has emerged as far north as Stevens Point in Portage County. Pheromone trap and black light trap counts have begun to decline across the southern half of the state. By contrast, emergence is only 50% complete in the north-central and northeastern counties where the peak flight is underway. High counts for the period of July 28-August 3 were 101 moths in the black light trap near East Troy in Walworth County and 93 moths in the pheromone trap near Arlington in Columbia County. CORN ROOTWORM - Corn surveyed in the southwest district yielded averages of 0-0.9 beetles per plant, with economic counts of 0.75 or more beetles per plant in only 3 of 14 fields sampled. An exceptional field near Bloomington in Grant County had an extreme population of 8.9 beetles per plant, but counts at other sites were still fairly low for early August. --Krista Hamilton, DATCP Entomologist 
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