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Forages & Grains
Volume 58 Number 12 Date 07/25/2013 POTATO LEAFHOPPER - Counts remain below two per sweep, despite this month's hot and mostly dry weather pattern. Surveys in Juneau, Monroe, Portage, Waupaca and Waushara counties yielded a range of 0.1-1.7 per sweep and an average of only 0.5. Systematic sampling is recommended as long as counts continue to be variable. PEA APHID - After several weeks of declining populations, individual alfalfa fields are again showing moderate to high numbers of aphids. Counts of 11-22 aphids per sweep were found at sites in Juneau, Monroe, and Waushara counties in the past week, although averages in most fields ranged from 1-3 per sweep. Pea aphid populations reached the highest levels of the season (20-29 per sweep) during the first two weeks of June and have been relatively low until now. Their resurgence in some fields suggests aphid fungal pathogens may not be regulating populations as conditions have become increasingly dry this month. GRASSHOPPER - Moderate to high populations exist in fields on sandy soils in the central area. Average counts in the past week varied from 1-4 per sweep, but exceptional fields contained as many as 9-10 per sweep. Grasshoppers, like pea aphids, have become abundant in recent weeks because the bacteria and fungi that normally provide natural control are not as effective under hot, dry conditions. Alfalfa growers are advised to monitor the edges of fields for initial signs of grasshopper activity. Problems usually begin in the field margins and extensive damage can occur quickly, before the grasshoppers are noticed. -- Krista Hamilton, DATCP Entomologist 
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