Unusually warm weather is pushing up the start of the alfalfa-
weevil scouting season in parts of Ohio – to now, says Ron
Hammond, entomologist with Ohio State University (OSU)
Extension. Ordinarily, Ohio growers wouldn’t need to be
concerned about alfalfa weevils for another 10 days to three
weeks, says Hammond. This year, though, heat-unit accumulations
for weevils were above 250 in the southern part of the state and
200 in central Ohio as of early last week. He recommends the
following scouting procedure: - Collect a series of three,
10-stem samples selected randomly from various locations in a
field and place the stem tips in a bucket. - Shake the bucket
vigorously to dislodge the late third- and fourth-instar larvae,
which cause most of the foliar injury. Inspect the stem tips
closely to detect the early first- and second-instar larvae. -
Count the larvae in the bucket and record the height of the
alfalfa. The economic threshold for treatment is based on the
number of larvae per stem, their size and the a