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Forages & Grains
Volume 63 Number 12 Date 07/19/2018 POTATO LEAFHOPPER - Alfalfa fields surveyed in Dodge, Fond du Lac, Sheboygan, Washington and Winnebago counties contained low counts of fewer than 0.3 adults and nymphs per sweep, with an average of only 0.1 per sweep. Economic populations above two leafhoppers per sweep (for 12-inch alfalfa) were not observed by DATCP this week, though a report from Chippewa County indicates that leafhopper counts there have exceeded thresholds in new alfalfa seedings. Immature nymphs can be found in most fields at this time. PEA APHID - Levels of this insect in eastern Wisconsin alfalfa were generally low at less than 3 aphids per sweep. The July 12-18 average of 2.5 per sweep is far below the high counts of 9-30 aphids per sweep recorded during the previous week in the northeastern region. PLANT BUG - Mixed populations of alfalfa and tarnished plant bugs currently average 0.4 per sweep, which is very low in comparison to the 5.0 plant bug per sweep threshold. The week?s highest count was noted in Winnebago County. UW Entomologist PJ Liesch reports that tarnished plant bug fruit damage has been noted this month in south-central Wisconsin, and this species is also suspected to be the cause of distorted strawberries in Portage County. ALFALFA CATERPILLAR - Larvae are prevalent in field collections, especially in southern and western alfalfa fields where counts occasionally average 0.2-.4 per sweep (20-40 per 100 sweeps). Adults are also common in alfalfa, signaling that egg laying is occurring and more larvae should appear soon. -- Krista Hamilton, DATCP Entomologist 
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