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Forages & Grains
Volume 57 Number 21 Date 11/08/2012 ALFALFA WEEVIL - Development was accelerated by historic heat in March and the first larvae were collected from Dane County alfalfa on April 10, exactly 36 days earlier than in 2011 and well ahead of normal. Counts increased in April to reach peak levels during the first three weeks of May. Pupation began at advanced sites by May 24. Surveys showed considerable regional variation in weevil pressure, with the highest counts and most severe defoliation observed in south-central and southwestern Wisconsin alfalfa fields. An early and timely alfalfa harvest reduced larval populations and prevented significant damage from occurring. Defoliation subsided by early to mid-June as the remaining larvae entered the non-feeding pupal stage. POTATO LEAFHOPPER - The earliest migrants arrived with southerly winds in March and were swept from Rock County alfalfa by mid-April. Successive migration events directed large numbers of leafhoppers into the state in April and May, with the first nymphs appearing in alfalfa as early as May 2. Populations escalated markedly by mid-June and controls continued until the drought halted alfalfa growth in late July. In contrast to the previous two years, leafhopper counts were very high this season and treatment was required for many fields in June and July. -- Krista Hamilton, DATCP Entomologist 
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