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Forages & Grains
Volume 63 Number 8 Date 06/21/2018 POTATO LEAFHOPPER - Nymphs are appearing in second-crop alfalfa. Populations remain below economic thresholds, although a few 8-11 inch fields in Waushara and Waupaca counties had averages approaching one per sweep. Counts in other parts of central and southern Wisconsin were generally below 0.4 per sweep. Crop scouts are reminded that potato leafhopper nymphs are seldom recovered in the bottom of the sweep net with the adults, but are instead found around the collar of the net. The neon-green nymphs move sideways when disturbed. ALFALFA WEEVIL - Larval populations are now less than 0.2 per sweep and pupation is occurring across the southern and central areas of the state. The alfalfa weevil season is expected to end by late June. PLANT BUG - Surveys conducted in Columbia, Dane, Dodge, Marquette, Waushara and Waupaca counties yielded averages of 0.1-1.5 adults and nymphs per sweep, which is still low in comparison to the economic threshold of five per sweep in alfalfa. Both the alfalfa plant bug and tarnished plant bug species are common in sweep net collections. PEA APHID - Counts of this insect remain much the same as previously reported at around one per sweep. Pea aphid levels have increased throughout June in surveyed fields, which is contrary to their usual pattern of peaking by early June and then decreasing sharply before the end of the month. The recent heavy rain will likely lower populations in some areas. -- Krista Hamilton, DATCP Entomologist 
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