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Forages & Grains
Volume 61 Number 4 Date 05/19/2016 ALFALFA WEEVIL - Larval counts in the southern half of the state remain low. Alfalfa surveyed in Dane, Dodge, Green, Jefferson, La Crosse, Monroe, Richland, Rock, Sauk, Trempealeau and Vernon counties contained only 1-36 weevils per 100 sweeps, and 50% (25 of 50) of fields sampled still had no apparent larval population. Based on the low number of larvae collected and the fact that alfalfa harvest has started, significant damage should not develop before most first-crop alfalfa is cut, except in rare fields or if harvest is postponed beyond the first week of June. Routine sampling for larvae and leaf tip feeding should be under way and continue through first harvest and early second-crop regrowth. PEA APHID - Densities varied widely from 9-1,200 aphids per 100 sweeps and averaged 262 per 100 sweeps, which is a considerable increase from last week's average of 68 per 100 sweeps. The appearance of winged females, an indicator of imminent dispersal from alfalfa into nearby pea and vegetable fields, was noted in several fields surveyed from May 12-18. TARNISHED PLANT BUG - Counts of this insect are low and range from 2-25 per 100 sweeps, with an average of seven adults per 100 sweeps. The first small nymphs should begin appearing in sweep net collections before the end of the month. MEADOW SPITTLEBUG - Nymphs and their characteristic frothy spittle masses were observed in alfalfa earlier this week. Populations are currently less than four per 100 stems. -- Krista Hamilton, DATCP Entomologist 
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