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Looking Ahead
Volume 63 Number 8 Date 06/21/2018 EUROPEAN CORN BORER - Larvae are primarily in the first and second instars and will begin entering the midribs of corn leaves next week. The treatment window for first-generation corn borers will close by June 28 in the far southern counties and 1-2 weeks later elsewhere, following the accumulation of 1,100 degree days (modified base 50°F). APPLE MAGGOT - Flies are likely to begin emerging next week. Apple growers concerned about this pest are advised to set a minimum of three traps per 10 acres before the end of the month, increasing the density in July to one trap every 200-300 feet along the orchard perimeter. The traps should be hung at eye-level adjacent to wild hosts and near early-ripening cultivars. JAPANESE BEETLE - Adults are appearing in the southern counties. Damage to fruit trees, ornamentals, nursery stock and field crops can be expected for the next two months across most of the state, with peak beetle emergence expected by mid- to late July. Soil-applied systemic insecticide treatments must be made 3-4 weeks in advance of beetle emergence and are no longer advised. WESTERN BEAN CUTWORM - The first moths of the season were captured in pheromone traps this week, signaling the start of the annual flight. One was caught near Ripon in Fond du Lac County and three others were collected near West Salem in La Crosse County. Scouting corn plants for egg masses and small larvae is recommended at 25% moth emergence, predicated for the week of July 8-14 in southern Wisconsin. CODLING MOTH - Egg hatch has peaked in most apple orchards. First-generation larvae are presently in the early to intermediate growth stages, and now is an opportune time to check fruits for entry holes and frass to assess codling moth control programs. Moth counts in pheromone traps varied widely this week from 1-37 per trap. SPOTTED WING DROSOPHILA - Emergence of flies has been confirmed in Dane and Sauk counties as of June 21. The appearance of SWD adults should be viewed as an early warning to fruit growers to increase monitoring efforts and make preparations for SWD management. TRUE ARMWORM - A significant capture of 214 moths documented in the Janesville black light trap from June 14-20 suggests that egg laying has intensified. More larval armyworms can be expected in corn, wheat and other crops by early to mid-July. -- Krista Hamilton, DATCP Entomologist 
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