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Looking Ahead
Volume 61 Number 12 Date 07/21/2016 SOYBEAN APHID - Surveys indicate aphid pressure is still low. Of the 74 soybean fields examined in the last two weeks, none had an average density greater than 19 aphids per plant. Moderate to high counts of 200-350 aphids can be found on individual plants in localized areas within fields, but field-wide averages remain low. Insecticide treatment has not yet been justified for any site sampled by DATCP as of July 20. Monitoring of soybeans should be intensified in the next two weeks as more fields enter the intermediate reproductive stages (R3-R4) during which aphid populations usually peak. EUROPEAN CORN BORER - Moths are appearing in low numbers in the Columbia, Dodge, Fond du Lac, Marathon and Walworth County black light traps and have been observed in corn near Galesville, La Crosse, and Lancaster since the last report. The peak flight of summer moths is projected for July 24-August 4 in the south-central, southwestern and central areas and August 4-12 in the southeastern and east-central areas. The treatment window for second-generation larvae has reopened in advanced southern and western locations with the accumulation of 1,550 degree days (modified base 50°F). CORN ROOTWORM - Beetles have become more common since the first adults of 2016 were observed on July 5. Counts are still low at less than 0.2 beetles per plant. Corn with fresh silks should be inspected in the week ahead to ensure that pollination is not being impaired. A threshold of five or more beetles per plant has been established for fields where the silks have been clipped to less than ½ inch and pollination is incomplete. WESTERN BEAN CUTWORM - Moth activity has peaked or is expected to peak next week across the southern half of the state. As of July 20, the Wisconsin network of 72 pheromone traps has reported a cumulative total of 715 moths, already exceeding last year's cumulative capture of 644 moths in 96 traps. High counts in the past week were 42 moths in a pheromone trap near Markesan in Green Lake County and 32 moths in the Pardeeville (Columbia County) black light trap. CORN EARWORM - Minor moth flights were registered in Dane, Dodge and Fond du Lac counties again this week. Numbers were extremely low at only 1-2 moths per trap. Egg deposition on corn silks is occurring and is likely to increase as larger flights of migrants arrive in August. Regular scouting should begin in fields with green silks. -- Krista Hamilton, DATCP Entomologist 
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