Forages & Grains
Volume 57 Number 12 Date 06/28/2012
POTATO LEAFHOPPER - Adults and nymphs are numerous throughout much of the state, especially in the central and southern areas. Counts in Green Lake and Fond du Lac counties ranged as high as 3.9 per sweep this week and averaged 2.6 per sweep, which is well above the threshold of 2.0 per plant for 12-inch alfalfa. Numbers in Columbia, Dodge, Green, Jefferson, Lafayette, Rock and Sauk counties were more variable at 0.2-4.5 per sweep, but still comparatively high in untreated fields. Economic counts of 2.0 or more per sweep were noted in 18 of 42 (43%) fields checked in these counties from June 21-27. Above-average temperatures accompanied by dry conditions have caused a marked increase in populations and damage this month, and controls are being applied. Regular monitoring of the third crop will be required next month.
GRASSHOPPERS - Populations of this pest, like the potato leafhopper, have increased in response to the hot, dry weather. Several Adams, Columbia, Juneau and Monroe County alfalfa fields ranging from 11-21 inches tall contained as many as 4-6 per sweep along the field margins. Severe damage has not been noticed thus far, but the grasshoppers are expected to migrate to corn, soybeans and other crops as alfalfa is harvested.
VARIEGATED CUTWORM - Larval infestations have largely been reduced by pupation and treatment of many fields in the past 2-3 weeks. Another generation is anticipated next month or in August. The pupal stage usually lasts 2-4 weeks before second brood moths emerge.
--Krista Hamilton, DATCP Entomologist