Volume 60 Number 4 Date 05/14/2015
EUROPEAN CORN BORER - Degree day accumulations in advanced portions of southern Wisconsin have surpassed 374 (modified base 50°F) and conditions are now suitable for moth emergence. Black light traps should capture the first moths of the season next week, although the majority of spring adults are unlikely to emerge before early June.
PLUM CURCULIO - Beetle activity is expected to resume with the warmer weather. Apple growers are advised to begin checking early-blooming cultivars and orchard perimeter trees for crescent-shaped oviposition scars and adult weevils. Signs of infestation usually become evident in the first 10-14 days after petal fall.
TRUE ARMYWORM - Moth collections increased substantially at the Janesville black light trap location, where 289 moths were registered during the May 7-13 reporting period. Another 24 migrants were collected in the trap near Ripon in Fond du Lac County. These counts signal that a large flight has occurred and growers should anticipate armyworm larvae appearing in corn and wheat fields 2-4 weeks from now.
BLACK CUTWORM - The start of the primary corn cutting period is predicted for May 27 in far southern Wisconsin, based on degree day accumulations (modified base 50°F) since the first significant moth flight occurred late last month. Although the unusually small black cutworm migration this spring suggests a low risk for localized outbreaks, close inspection of corn, including Bt hybrids, for evidence of cutworm feeding is recommended from emergence until the V-5 stage.
SOYBEAN APHID - Colonization of the earliest emerging soybeans could occur in the week ahead. Reports indicate egg hatch on buckthorn has been under way for 2-3 weeks and the spring dispersal of winged aphids is expected to start as soon as soybean plants are available.
-- Krista Hamilton, DATCP Entomologist