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Looking Ahead
Volume 63 Number 12 Date 07/19/2018 WESTERN BEAN CUTWORM - Moth activity is expected to peak next week across the southern half of the state. As of July 18, the Wisconsin network of 55 pheromone traps has reported a cumulative total of only 82 moths, well below last year's capture of 440 moths in 69 traps. High counts in the past week were 17 moths in one pheromone trap each in Pepin and Rock counties, and 10 moths the Wausau black light trap. CORN ROOTWORM - Beetle emergence began approximately two weeks ago. Counts this week were very low at 0.1-0.3 per plant, with the beetles mostly limited to silking plants at the edges of advanced fields. Inspection of corn with emerging silks should be underway. 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. SOYBEAN APHID - Surveys indicate aphid pressure remains low. Of the 73 soybean fields examined in the last two weeks, none had an average density greater than 25 aphids per plant. Moderate counts of 100-250 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 continue weekly through mid-August. CORN EARWORM - Minor moth flights were registered in Dane, Columbia, Dodge and Fond du Lac counties again this week. Numbers were low at only 1-8 moths per trap. Egg deposition on corn silks is occurring and is likely to increase as more migrants arrive this month. Routine scouting is recommended for sweet corn with green silks. EUROPEAN CORN BORER - Moths continue to appear in low to moderate numbers in black light traps. The peak flight of summer moths is projected for the week of July 22 in the south-central, southwestern and west-central areas, and July 29-August 4 in the southeastern and central counties. 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). BROWN MARMORATED STINK BUG - As many as 10 BMSB adults and 25 nymphs were captured on a clear panel trap in Madison from July 14-18, confirming a marked increase in first-generation stink bug activity in Dane County. The appearance of nymphs also signals a potential for increased activity and fruit injury in southern Wisconsin apple orchards. Growers participating in the DATCP monitoring program are encouraged to closely check traps for BMSB next week. Any suspects should photographed and images sent to PJ Liesch at the UW Insect Diagnostic Lab for confirmation (pliesch@wisc.edu). -- Krista Hamilton, DATCP Entomologist 
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