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Forages & Grains
Volume 59 Number 10 Date 07/10/2014 POTATO LEAFHOPPER - Counts in second-crop alfalfa remain much the same as previously reported, except in the southernmost counties where populations appear to be increasing. Of the 84 fields surveyed in the past two weeks, 52 (62%) had fewer than 0.5 leafhoppers per sweep, 26 (31%) had 0.6-1.0 per sweep and six (7%) had 1.1-1.7 per sweep. The average was 0.5 per sweep. Economic counts of 2.0 or more leafhoppers per sweep for alfalfa 12 inches or taller were not observed. Circumstances have not justified treatment in any alfalfa field surveyed as of July 9. ALFALFA WEEVIL - Larval populations are now less than 0.1 per sweep and pupation is occurring statewide. No further alfalfa weevil problems are anticipated this season. PLANT BUG - Surveys conducted as far north as Marathon and Shawano counties yielded counts of 0.2-1.6 per sweep, which are standard for this time of year and still low in comparison to the economic threshold of five per sweep in alfalfa. PEA APHID - Populations of this insect collapsed abruptly since the last report was issued and now average only 0.5 per sweep compared to 4.9 per sweep two weeks ago. The prevailing wet, humid weather of late June and early July favors the spread of fungal pathogens that regulate pea aphids and likely contributed to the population decline observed. -- Krista Hamilton, DATCP Entomologist 
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