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Looking Ahead
Volume 62 Number 12 Date 07/20/2017 WESTERN BEAN CUTWORM - Moth activity has peaked or is expected to peak next week across the southern half of the state. As of July 19, the Wisconsin network of 69 pheromone traps has reported a cumulative total of 440 moths, well below last year's capture of 701 moths in 72 traps. High counts in the past week were 87 moths in the black light trap near Sparta in Monroe County and 40 moths in a Green Lake County pheromone trap. CORN EARWORM - Minor moth flights were registered in Adams, Columbia, Dodge, Fond du Lac and Rock counties again this week. Numbers were low at only 1-10 moths per trap. Egg deposition on corn silks is occurring and is likely to increase if migrants continue to arrive this month. Regular scouting should begin in sweet corn fields with green silks. EUROPEAN CORN BORER - Moths have been observed in corn near Reedsburg and Richland Center since the last report. The peak flight of summer moths is projected for July 30-August 5 in the south-central, southwestern and west-central areas, and August 6-12 in the southeastern and central counties. The treatment window for second-generation larvae will reopen over the weekend of July 22-23 in advanced southern and western locations, with the accumulation of 1,550 degree days (modified base 50°F). SOYBEAN APHID - Surveys indicate aphid pressure remains low. Of the 67 soybean fields examined in the last two weeks, none had an average density greater than 21 aphids per plant. Moderate counts of 100-200 aphids could be found on individual plants in localized areas within fields, but field-wide averages were low. Insecticide treatment has not yet been justified for any site sampled by DATCP in July. Scouting to assess soybean aphid densities should be underway and continue weekly through mid-August. SPOTTED WING DROSOPHILA - SWD captures in western Wisconsin have increased markedly since early July and now exceed 100 per trap per week in raspberries in La Crosse and Trempealeau counties. Extremely high weekly captures of 392 and 592 flies have been reported from two Trempealeau County monitoring sites. These counts indicate a heightened risk of severe maggot infestation on farms and in gardens where SWD control programs are not in place. CORN ROOTWORM - Beetles have become more common since the first adults of 2017 were observed two weeks ago. Counts this week were variable at 0.1-5.0 per plant, with the beetles mostly limited to silking plants at the edges of advanced fields. Inspection of corn with emerging silks should start in the week ahead. An average of five or more beetles per plant and silks that have been clipped to less than ½ inch suggest pollination is being impaired. -- Krista Hamilton, DATCP Entomologist 
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