Producers, Homeowners battling armyworms

Writer: Adam Russell, 903-834-6191, adam.russell@ag.tamu.edu
Contact: Dr. Vanessa Corriher-Olson, 903-834-6191, vacorriher@ag.tamu.edu
 

Hay and forage producers and homeowners around the state are battling armyworms following rains and cooler weather, according to Texas A&M AgriLife Extension Service experts.

The fall armyworm is a common pest of Bermuda grass and many other crops in Texas, Dr. Vanessa Corriher-Olson, AgriLife Extension forage specialist, Overton, said. Given their appetite, numbers and ability to move, fall armyworms can consume entire fields or pastures in a few days.

“I highly, highly recommend producers scout their pastures,” she said. “We’ve been dry and recently received rain, and that combination is a sign that armyworms will follow. Nine out of 10 calls I’ve received in the last several days were regarding armyworms, so producers need to be diligent and protect their pastures.”

Corriher-Olson said limited forage and hay production this summer makes protecting hay fields and winter pasture seedlings critical.

army worms and grass

Late summer rains are often followed by fall armyworm outbreaks in pastures and hay fields. Much of the regions around Texas have reported armyworm activity during the past few weeks. (Texas A&M AgriLife Extension Service photo)Late summer rains are often followed by fall armyworm outbreaks in pastures and hay fields. Much of the regions around Texas have reported armyworm activity during the past few weeks. (Texas A&M AgriLife Extension Service photo)

Armyworm caterpillars are picky eaters that prefer high-quality, fertilized forage typically found on fields maintained for hay production or pasture, she said. They are a common pest of Bermuda grass, sorghum, corn, wheat, rye grass and many other crops in north and central Texas.

Producers should scout each morning for armyworms, she said. Armyworms are night feeders that try to avoid daytime temperatures.

Armyworms are green, brown or black in color and can be identified by the white inverted Y on their head. They can grow up to 1 inch in length when mature. The pest got its name because they appear to march across hay fields, consuming the grass in their path.

Improved hay pastures with dense canopies and vigorous growth are often more susceptible to armyworm infestations than less fertilized fields, Corriher-Olson said. Irrigated fields are also susceptible to infestations, especially during drought conditions.

“Look for fall armyworms feeding in the crop canopy during the late evening and early morning and during cool, cloudy weather,” she said. ‘When fields are wet with dew, armyworms can stick on rubber boots while walking through the field.”

The key to managing fall armyworms is frequent inspection of fields to detect infestations, she said. Armyworm moths can lay up to 2,000 eggs that hatch in two to three days, according to a 2018 report by AgriLife Extension entomologist Dr. Allen Knutson, based in Dallas. There are four to five generations per year.

The threshold for insecticide spray treating a pasture is three or more armyworms per square foot, Corriher-Olson said. Armyworms in those numbers should be treated immediately because armyworm caterpillars consume 85 percent of their diet in the last two to three days of their larvae stage.

Corriher-Olson recommends insecticides labeled for armyworm control in pastures and hayfields. She said applicators should always follow all label instructions on pesticide use and restrictions.

For more information about armyworms, go to https://bit.ly/2xlWpDP.

“Armyworms have been a problem and will continue to be a problem,” she said. “Producers just need to make scouting, especially following any rain event, part of their routine. The key is to be ready to treat for armyworms as soon as they are present because they can cause serious damage in a short amount of time.”

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