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Forages & Grains
Volume 60 Number 3 Date 05/07/2015 ALFALFA WEEVIL - Larval emergence is expected to begin over the weekend in advanced southern and western locations. Regular sampling for larvae and leaf tip feeding should start around 300 degree days (sine base 48°F), or by May 8 near Janesville, May 11 near Hancock, and May 15 near Appleton. POTATO LEAFHOPPER - The first distinct migration occurred late last month and leafhopper adults are now distributed in very low numbers across southern Wisconsin. Migrants were collected from 9 of 59 (15%) alfalfa fields sampled as of May 6, as far north as Chaseburg in Vernon County. TARNISHED PLANT BUG - Adults are more numerous than last week, but counts in alfalfa remain low. Surveyed fields in Columbia, Dodge, Richland, Rock, Vernon and Walworth counties contained an average of nine per 100 sweeps compared to three per 100 sweeps last week. The economic threshold for plant bugs in alfalfa is extremely high at five per sweep (or 500 per 100 sweeps) and is seldom exceeded until July or August. PEA APHID - Alfalfa sampled this week contained counts of 1-49 aphids per 100 sweeps. Reproduction has not yet started. -- Krista Hamilton, DATCP Entomologist 
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