Forages & Grains
Volume 63 Number 11 Date 07/12/2018
POTATO LEAFHOPPER - Counts in surveyed fields are well below the economic threshold of two leafhoppers per plant for alfalfa 12-inches and taller, and most sites have averages below 0.5 leafhoppers per sweep. Economic counts have not been found as of July 13. Nymphs are appearing more frequently in sweep nets indicating populations are increasing.
PEA APHID - Levels of this insect vary considerably by region of the state. Alfalfa sampled in northeastern Wisconsin (Brown, Oconto, Lincoln, Marinette counties) contained very high counts of 9-30 aphids per sweep, whereas numbers in the northwestern and west-central areas (Chippewa, Dunn, Pierce, Pepin, St. Croix counties) were much lower, ranging from 0.5-9 per sweep and averaging 3 per sweep. Pea aphid counts usually decrease abruptly by mid-summer.
PLANT BUG - Surveys conducted across the northern one-half the state yielded counts of 0.1-1.2 per sweep (average 0.4 per sweep), which are standard for this time of year and still very low in comparison to the economic threshold of five per sweep in alfalfa.
-- Krista Hamilton, DATCP Entomologist