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Forages & Grains
Volume 63 Number 7 Date 06/14/2018 ALFALFA WEEVIL - The peak larval damage period is expected to end by late June as populations transition into non-feeding pupal stage. Larvae remain common but not abundant in late first-crop alfalfa and second-crop regrowth. Weevil numbers have been low this spring. The average count from June 7-13 was below 0.2 per sweep and leaf tip feeding was less than 20% in most surveyed fields. PEA APHID - Densities generally range from 1-2 per sweep in surveyed fields. The rainy, humid weather of the past week favors the spread of fungal pathogens that will likely contribute to aphid population decline later this month. POTATO LEAFHOPPER - Counts in 8-14 inch regrowth were less than 0.3 per sweep in all fields sampled this week, though development and reproduction are expected to increase by late June and the economic threshold of 1.0 per sweep in 6-12 inch alfalfa and 2.0 per sweep in alfalfa taller than 12 inches may be exceeded in some fields. Continued sampling of alfalfa regrowth is advised. MEADOW SPITTLEBUG - The adult stage of this insect is appearing in alfalfa sweep net samples, signaling that the population has matured. Meadow spittlebug damage is rare but occasionally occurs on first-year alfalfa seeded into small grain stubble. This insect has a single generation per year in Wisconsin, and the risk of damage ends once the adults emerge. -- Krista Hamilton, DATCP Entomologist 
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