Forages & Grains
Volume 62 Number 11 Date 07/13/2017
POTATO LEAFHOPPER - Counts in some late second-crop alfalfa fields in western Wisconsin have surged above the economic threshold of two leafhoppers per sweep for stands 12 inches and taller. Notably, several 18-22 inch fields in Buffalo and Trempealeau counties sampled on July 10 had extremely high counts of 5-21 per sweep. Nymphs were very abundant in these fields and hopperburn was evident. Above-threshold populations have also developed in a few new alfalfa seedings in the northwest. In eastern Wisconsin, including Calumet, Fond du Lac, Manitowoc, Shawano, Winnebago counties, averages were far lower at less than 0.3 per sweep. Harvesting the second crop and monitoring third-crop regrowth are of particular importance at this time.
PLANT BUG - Levels of this insect vary considerably from field to field, but the average remains low at 0.7 per sweep. Nymphs in all developmental stages are common in sweep net collections.
PEA APHID - Alfalfa surveyed in the western counties contained very low populations ranging from 0.1-0.9 per sweep and averaging 0.4, or 40 aphids per 100 sweeps. Counts in the eastern areas were even lower at less than 0.2 per sweep. Populations of this insect have been consistently low since mid-June.
-- Krista Hamilton, DATCP Entomologist