Armywormageddon: That’s the term Angus Catchot has coined this year for what he says is “by far been the biggest armyworm invasion we’ve ever seen in the Mid-South.” 

And the worm influx isn’t crop specific, he said at the joint annual meeting of the Mississippi Boll Weevil Management Corporation and the Mississippi Farm Bureau Federation Cotton Policy Committee.

“They’re in bermudagrass pastures, rice, corn, cotton, soybeans, milo — it doesn’t matter; we’ve sprayed them in every crop. They’re bad, and they’ve been coming since the beginning of May. These armyworms are the rice strain, or grass strain. They come to grass, kill the grass, and then move off to eat your crops.”

There is one difference for this year’s invasion, says Catchot, who is Extension entomology professor at Mississippi State University. “We’ve never before seen the grass strain hurt Bollgard II cotton; they’ve never eaten so much as a hole in a cotton leaf in the past. The standard advice, here and in other cotton states, was that if they’re in soybeans, corn, whatever, you’ve got to treat them if numbers are high, but if they’re in two-gene cotton, don’t worry about them.

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“But that’s not the case this year — in one cotton field we looked at, they caused extensive damage. Ernie Flint, regional Extension specialist at Kosciusko, texted me that one of his growers had to spray for the worms. I went and looked at the field, and the armyworms had hurt the cotton badly in a short period of time.

“It was small, six-node Bollgard II cotton, and they weren’t eating the leaves — they were eating the stems and cutting the plants off like cutworms. In bigger cotton, they were chewing the terminal out of the plants about five nodes down. But that cotton will be OK; it will branch out.

I’m no longer taking for granted that armyworms won’t hurt Bollgard II cotton,” Catchot says, “and I’m recommending spraying if numbers are high. I don’t know if something has changed with this pest, but we’ve never seen this strain hurt cotton before.

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“No matter what crop you have, if there is grass in it, and you’re going to make an application of Roundup or other herbicide, if you see armyworms in that grass, you can solve the problem easily — just tank mix a pyrethroid with the herbicide. The worms are easy to kill, and you can save yourself a tremendous amount of heartache by doing this. They’re not like the corn strain, they’re very sensitive to pyrethroids, and they’re super easy to control with low to mid-rates of pyrethroids.”

Although he doesn’t work with rice, Catchot says the armyworms “have been wearing out some rice. Dr. Jeff Gore, research and Extension entomologist at the Delta Branch Research and Experiment Station at Stoneville, has had numerous calls for armyworms in rice this year.”