Forages & Grains
Volume 62 Number 9 Date 06/22/2017
POTATO LEAFHOPPER - Nymphs are appearing in second-crop alfalfa. Populations remain below economic thresholds in 12-20 inch fields, with a few exceptions. Two fields in Richland County and one in Vernon County had averages above 2.0 per sweep, and mild hopperburn was evident. Treatment could be justified in these fields. Counts at other sites sampled in the southern and east-central districts were generally below 1.0 per sweep.
ALFALFA WEEVIL - Larval populations are now less than 0.3 per sweep and pupation is occurring across southern and central Wisconsin. No significant alfalfa weevil problems are anticipated for the remainder of the season.
PLANT BUG - Surveys conducted as far east as Brown, Oconto and Outagamie counties yielded averages of 0.1-2.4 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 decreased considerably in most fields since peaking at 37 per sweep in Kewaunee County during the first week of June.
-- Krista Hamilton, DATCP Entomologist