Monday, June 22, 2009

Wheathead armyworm counts low it was cold and windy here in eastern Oregon, as I visited the wheathead armyworm traps for my weekly collection. There was only one moth in all the traps, so we have a continuing trend of very low moth counts for the third week in a row. Perhaps this is the year that things will take a turn for the better!

We also did sweeping with an insect net, looking for armyworm larvae. Only 1-2 larvae per 10 sweeps were found.
This monitoring program will continue as we are now on the countdown toward harvest. Hopefully, the low numbers will continue!

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.

Friday, June 12, 2009

Wheathead moth counts for June 3- June 10

The numbers of moths have dropped dramatically over the last week, June 3 - June 10. Last week I reported in moths/day. With moth numbers at less than 1/day, I will just give the total numbers.
Total moth counts over the 8 days:
  • Site 1 - 1 moth
  • Site 2 - 3 moths
  • Site 3 - 6 moths
We are not sure if we are dealing with one flight or more. We will continue to collect weekly up to mid July.

Thursday, June 11, 2009

Armyworm survey shows lower moth counts

I collected from the wheathead armyworm traps yesterday in the Helix area. There were very few moths in any of the traps this week. I will post the counts as soon as the numbers are confirmed by our entomologist, Silvia Rondon.
Last week's numbers were
  • Site # 1 near Myrick Rd - 19/day;
  • Site # 2 off Harper Rd - 12/day; and
  • Site 3 on field road 1 mile west of Helix - 13/day.
These counts were in the pheromone traps. The traps using a different attractant were low at 3 per trap total.
Under our current weather conditions, we expect to see larva emerging over the next week. If anyone finds larva when scouting their fields please post your findings to the blog or call my office with the information.
I will be collecting larva to rear again this year as there are questions emerging about if there are two species present and we hope to clarify that issue this season.

Friday, June 5, 2009

Wheat head armyworm (Faronta diffusa) survey

I collected moths from the armyworm traps on Tuesday. The pheromone traps seemed to be more effective at attracting our target species wheat head army worm (Faronta diffusa) than the attractant traps. There were more moths in them and less other insects or moths. Yesterday we had thunderstorms and a hard rain. I will go and check the trap conditions later today to see if they are still intact. More thunderstorms in the forecast for today.
I am not seeing any armyworm larvae yet. I did find low numbers of leafy feeding sawflies in one location near Myrick, Oregon. (2 larvae per 10 sweeps.)

If the populations of army worms reaches a significant population to damage wheat heads there are several control options. Preharvest intervals (PHI) are a concern and should be carefully followed. One option, zeta cypermethrin (Mustang Max) has a wheat only label, is known to be effective on armyworms in general, and has a 14 day PHI. For more recommendations check out the online version of the Pacific Northwest Insect Management Handbook.