Wednesday, June 17, 2009

Wheathead armyworms emerging

Yesterday's collection from the wheathead armyworm survey traps found zero (0) moths. As expected the larvae are starting to emerge, and are still relatively small.

Fields sweeping (10 - 180 degree sweeps) with an insect net resulted in finding some wheathead armyworm larvae at each site:

  • Site 1 - 1 armyworm
  • Site 2 - (in an adjacent field) 20 armyworms
  • Site 3 - 2 armyworms

Here are a few tips for scouting:

  1. Larva fed at night, and drop to the ground during the day, so scout in the late evening or early morning for the most accurate results,
  2. Scout at various locations throughout the field, as populations are often higher along the field edges,
  3. Larva will vary in color from greenish to cream and have white and brown stripes down the length of their bodies.

We do not have any solid research to show at what level populations becomes economical to treat with insecticides. There are various insecticides available with pre-harvest intervals ranging from 30 days to a little as 7 days. Read and follow label directions before selecting an insecticide, and/or applying.

In other wheat-growing states, this pest has not been a significant problem, nor stayed around long enough to develop any research to establish treatment thresholds. We are now into our third year of seeing this pest, and hope that it will not become a significant problem beyond this localized outbreak. Field monitoring and scouting remain our best option for making good management decisions.

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