Agricultural News
Scouting for Armyworms- Here are Pictures to Know What to Look For
Thu, 23 Sep 2010 5:59:59 CDT
Oklahoma wheat growers need to watch their newly planted wheat fields closely in the next few weeks- at least until the first killing frost of the season- so says OSU entomologist Dr. Tom Royer.
Dr. Royer dropped us an email on Wednesday afternoon and provided a couple of pictures as well to help us show you what the enemy looks like.
"Thanks for getting the word out. I have been checking some wheat fields over the past few days as well as fielding some phone calls on fall armyworm infestations and have received reports of infestations from SE Kansas, Logan and Murray counties. I took some pictures in a Logan county field that to show what to look for in newly planted wheat.
"The windowpaning picture shows the kind of injury producers should be looking for (scraped tissue). This is what small armyworms do until they get big enough to chew through the leaves. The FAW2 picture shows 3 larvae (one very small) and one partially hidden behind a weed. The third shows a caterpillar beginning to crawl up a seedling plant. If producers notice damage early before they start taking out plants, and the larvae are small, control will be much more effective. (The windowpaning picture is at the top- picture two and three are below.)
"I have been suggesting a treatment threshold of 3-4 worms per row foot (6-8 per square foot) if application costs run from $7-$9 per acre. If application costs are higher ($10-$12 acre), I would bump up the threshold to 4-6 per row foot (8-12 per square foot) Most of the chemicals listed in our Current Report 7194 are effective, based on my field evaluations over the past few years. Personally, I would go for the pyrethroids (lambda or gamma cyhalothrin or zeta cypermethrin) and use generics if they are cheaper. I kind of leave that decision up to the producer and the dealer. Thresholds in Texas are sometimes higher, but our fields are seedling wheat and we are more often intending to use them for dual purpose instead of graze out, so I tend to be a bit on the conservative side.
"It is very important that fields be checked regularly. We will probably continue to see moth egg lay as new fields emerge. As fields accumulate more forage and weather gets cooler, they should be able to take higher worm pressure, and once we get a killing frost, any remaining worms will be toast!"
Click here for contact info for Dr. Tom Royer at OSU.
Damage can be seen in the very top picture- the next two pictures show larvae that can cause lots of damage.
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