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Forages & Grains





Nursery & Forest

Degree Days

Volume 58 Number 6 Date 06/06/2013

SPOTTED TENTIFORM LEAFMINER - Moth counts are expected to increase abruptly by mid-June as the second flight begins. Counts were low in the past week and ranged from 1-146 per trap, except at the Oneida and Raymond monitoring sites where 450-582 moths per trap were reported. The economic threshold for STLM increases from 0.1 to 1.0 mine per leaf for the second generation of sapfeeder larvae.

PLUM CURCULIO - Beetle activity continued in southern and central orchards. Two adults were collected in traps at an orchard near Rio in Columbia County and oviposition scars are appearing on fruits. According to Orchard IPM Specialist John Aue, examination of fruits for oviposition scars should be under way in apple orchards beyond petal fall, while sampling for adults using a beating tray is the preferred method for northern orchards where tree development is less advanced. Female weevils show a strong preference for early-sizing fruits and any fruits beyond 10 mm will be most attractive. John reminds organic growers that kaolin clay (SurroundŽ WP) may have an unintended stress effect on trees and is not recommended as a plum curculio deterrent. Instead, he suggests the use of Pyganic applied at dusk on the next warm evening since most oviposition occurs at night.

OBLIQUEBANDED LEAFROLLER - The first of two flights this season is likely to begin next week in southern Wisconsin with the accumulation of 600 degree days (base 43°F). Sampling of 10 fruit clusters and 10 terminals in the outsides, centers, and tops of five trees per orchard should occur on a weekly basis after pheromone traps verify that emergence of the summer brood has started. Control is warranted for populations averaging three or more larvae per tree.

CODLING MOTH - A significant increase in codling moth activity was charted in the last week. Counts varied from 0-21 per trap, with an average of five per trap. The biofix was set at most southern Wisconsin orchards from May 19-29. Controls directed against first generation larvae should be applied from 250-350 degree days (base 50°F) post-biofix.

-- Krista Hamilton, DATCP Entomologist