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Looking Ahead
Volume 58 Number 12 Date 07/25/2013 WESTERN BEAN CUTWORM - The emergence of western bean cutworm moths continued this week at southern and central monitoring locations. Egg deposition on corn and dry beans has intensified. The high count for the reporting period of July 17-24 was 29 moths near Marcellon in Columbia County. SOYBEAN APHID - The first economic infestations of the year were found on July 22 in Waushara and Waupaca counties. Densities in 86 other fields sampled during the last reporting period ranged from 1-172 per plant, indicating wide variation in aphid pressure. Routine sampling is especially critical at this time. Populations must reach or exceed the 250 per plant threshold for fields to qualify for treatment. EUROPEAN CORN BORER - Moths of the second flight are appearing in very low numbers in black light traps. The peak of summer moth activity is projected for 1,733 degree days (base 50°F), or the week of August 4-10 across most of southern Wisconsin. The optimal treatment window for second generation larvae has opened in the warmest areas of the state with the accumulation of 1,550 degree days. CORN ROOTWORM - Beetles have become slightly more common in the past week. Peak emergence of the adult population is anticipated by early to mid-August. Corn acreage that has not been pollinated by early August will be at increased risk of silk clipping, reduced pollination and poor kernel set. A rescue treatment may be considered for infestations of five or more beetles per plant when the silks have been clipped to less than ½ inch and pollination is incomplete. Scouting should begin before 70% of plants are silking. APPLE MAGGOT - Emergence increased in a few apple orchards, while most have not yet captured any flies this season. The high count for the period of July 18-24 was six flies on an unbaited red ball trap at Gays Mills in Crawford County. On the basis of projected degree day accumulations, peak emergence of the fly population should occur in the next two weeks at most southern monitoring sites. -- Krista Hamilton, DATCP Entomologist 
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