Volume 58 Number 18 Date 11/21/2013
PEST HIGHLIGHTS OF 2013WESTERN BEAN CUTWORM - Moth counts decreased significantly from 2012 levels, according to the statewide trapping program. The 2013 cumulative capture of 663 moths was an 80% reduction from 3,290 collected last season. Larvae resulting from the flight were also less common this year, although a few individual fields in Adams, Chippewa, Clark, Eau Claire, Dunn and Marquette counties had infestations affecting 2-14% of the ears.
SPOTTED WING DROSOPHILA - Infestations were confirmed in 25 Wisconsin counties and suspected in another four in 2013. The current known distribution of spotted wing drosophila in the state includes the counties of Ashland, Bayfield, Brown, Columbia, Crawford, Dane, Door, Eau Claire, Fond du Lac, Grant, Iowa, Jackson, Jefferson, Kewaunee, La Crosse, Lafayette, Manitowoc, Marathon, Marinette, Monroe, Pierce, Polk, Racine, Rock, Sauk, Trempealeau, Vernon, Washburn, Winnebago and Wood, for a total of 30 confirmed counties since this invasive Asian vinegar fly was first identified in Wisconsin in 2010.
CORN ROOTWORM - Corn surveyed in August yielded a state average of 0.5 beetle per plant, a minor decrease from 0.6 per plant in 2012. Counts declined or remained the same in eight of the nine agricultural districts, with the exception of the northwest where the average increased from 0.5 to 0.7 beetle per plant. Heavy spring rain and extensive use of Bt-rootworm corn are presumed to have contributed to this year's lower beetle populations.
CORN EARWORM - An early migration beginning on May 29 and continuing throughout July produced scattered infestations in corn across southern and central Wisconsin by late June. The primary flight from early August to mid-September led to a second round of more damaging larval populations that persisted into October. The annual moth count of 6,568 in 15 traps was 38% lower than in 2012, although surveys indicated corn earworm problems were much more prevalent this year.
EMERALD ASH BORER - The spread of this ash pest greatly accelerated in 2013, especially in southeastern Wisconsin where the first infestation was discovered six years ago. Emerald ash borer was detected in four new counties this year---Dodge, Douglas, Sauk and Winnebago---and now occurs in portions of 18 Wisconsin counties.
GYPSY MOTH - DNR aerial surveys documented 12,248 defoliated acres statewide this season: 7,320 acres in Bayfield County, 4,324 acres on the Bad River Reservation in Ashland County, and 604 acres on several small parcels throughout the state. Approximately 12,200 acres were considered lightly defoliated and about 48 acres were rated as heavily defoliated. Last year, larvae defoliated 14,500 forested acres in Ashland, Bayfield and Marinette counties.
-- Krista Hamilton, DATCP Entomologist