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Forages & Grains
Volume 59 Number 9 Date 06/26/2014 ALFALFA WEEVIL - Damage is expected to subside by early July as remaining third and fourth instar larvae enter the non-feeding pupal stage. Larvae are common but not numerous in second-crop alfalfa. The average count from June 19-25 was less than 0.1 per sweep and leaf feeding ranged from only 0-5%. PEA APHID - This insect continues to be abundant in most alfalfa fields in the southern half of the state. Densities currently range from 1-20 per sweep and average 4.9 per sweep. The rainy, humid weather of the past two weeks promotes the spread of fungal pathogens that regulate these aphids and could cause an abrupt population collapse next month. POTATO LEAFHOPPER - Counts in alfalfa remain low in most fields and moderate at a few sites. Surveys conducted in Columbia, Dane, Green, Green Lake, Iowa, La Crosse, Marquette, Trempealeau and Waushara counties found 0.2-0.8 leafhoppers per sweep, with an average of 0.4 per sweep. Levels in Calumet, Fond du Lac and Winnebago counties in the east-central area were much lower at only 0-0.02 per sweep. Nymphs were collected in about 10% of alfalfa fields checked and populations appear to be increasing. MEADOW SPITTLEBUG - The adult stage of this insect was swept from alfalfa in Columbia, La Crosse and Trempealeau counties, signaling that the population has matured and their characteristic spittle masses will not reappear until next spring. The highest number collected from second crop alfalfa this week was two per 10 sweeps. -- Krista Hamilton, DATCP Entomologist 
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