Forages & Grains
Volume 63 Number 13 Date 07/26/2018
POTATO LEAFHOPPER - Populations of this alfalfa pest have been low to moderate throughout July. Surveys from July 19-25 found counts of 0.2-1.1 per sweep in 12 to 32-inch fields, with an average of o.4 per sweep. Continued monitoring of third- and fourth-crop alfalfa throughout August is recommended.
PLANT BUG - Counts are similar to last week at 0.1-1.2 adults and nymphs per sweep. Most fields contain 0.5 plant bugs or fewer per sweep, a fraction of the economic threshold of five per sweep. Nymphs remain more abundant than adults in alfalfa, indicating that populations may build.
PEA APHID - Levels have decreased to 1-3 per sweep in alfalfa fields surveyed in central and western Wisconsin.
ALFALFA CATERPILLAR - This insect continues to be common in southern and western Wisconsin. Counts vary considerably from field to field, but the average is about 12 per 100 sweeps. As noted last week, adults are also prevalent, and an increase in larvae and feeding injury should be anticipated early next month. Significant damage is rare but can develop if heavy egg laying occurs in recently-cut fields and larvae defoliate the regrowth.
-- Krista Hamilton, DATCP Entomologist