Volume 62 Number 11 Date 07/13/2017
JAPANESE BEETLE - Numbers are increasing in fruit and field crops over much of the state. This beetle could become a serious problem this season since soil moisture levels have been very favorable for larval survival. Damage to fruit trees, ornamentals and field crops is expected to intensify this month and control may be necessitated. Spot treatment of individual trees or problem areas is usually an effective approach.
SPOTTED WING DROSOPHILA - Captures of flies have been recorded at all nine DATCP monitoring sites as of July 12, and fly emergence is accelerating. The high count during the past week was 125 flies in La Crosse County raspberries, while numbers at other sites ranged from 3-41 per trap. The appearance of flies signals that eggs are being laid on fruits and the small white larvae should be detectable. Berry growers are advised to finalize their management for this season's berry crops as soon as possible.
EUROPEAN CORN BORER - Pupation of first-generation corn borers has started in advanced southern and western areas. Black light traps could register the earliest moths of the summer flight in the week ahead. The treatment window for first-generation corn borers has closed over the southern two-thirds of the state following the accumulation of 1,100 degree days (modified base 50°F).
SOYBEAN APHID - Aphid pressure is intensifying in R1-R2 soybean fields, although the typical average is still very low at fewer than 10 aphids per plant. Monitoring efforts should be increased as soybeans advance through the early to intermediate reproductive growth stages.
APPLE MAGGOT - Counts of 1-5 flies per trap were reported in the past week from eight of 21 apple orchard locations. Fly emergence is expected to escalate throughout July and peak in August. Apple growers concerned about this pest should set a minimum of three traps per 10 acres at this time, increasing the density to one trap every 200-300 feet along the orchard perimeter as the season progresses. The traps should be hung at eye-level near wild hosts and early-ripening cultivars.
BROWN MARMORATED STINK BUG - UW-Madison Extension Entomologist PJ Liesch reports that second-instar brown marmorated stink bug (BMSB) nymphs were found near Middleton on July 2. This observation confirms the start of the first-generation of stink bugs in Dane County. BMSB is thought to have a single generation per year in Wisconsin depending on temperatures, although an early spring and summer heat could permit the development of two generations in warmer years.
CORN ROOTWORM - Beetles are emerging in southern Wisconsin. Both the northern and western species have been observed in Grant, Iowa, La Crosse, Richland and Sauk counties as of July 12.
-- Krista Hamilton, DATCP Entomologist