By Justin Walker
Communications Specialist
Fall armyworms could be more prevalent following rainfall from Tropical Storm Barry, according to a Texas A&M AgriLife Extension Service expert.
Armyworms have been reported in Central and East Texas hayfields and pastures over the past few weeks, Dr. Vanessa Corriher-Olsen, AgriLife Extension forage specialist in Overton, said. Farmers and ranchers in these areas can expect to see more, especially with rain and cooler temperatures from Barry.
“I’ve seen a few reports about armyworms, and this expected rain could mean an explosion in their populations,” she said. “Armyworms can devastate grazing and forage production pastures quickly. So, producers need to be mindful to watch their pastures for the pest. It is shaping up to be a good hay production year following such a poor season, and it would be a shame to lose a cutting or valuable grazing to armyworms.”
Armyworms have a rapid reproduction rate, according to a report by AgriLife Extension entomologist Dr. Allen Knutson. Armyworm moths can lay up to 2,000 eggs, which will hatch two to three days later. It is not uncommon for the pest to grow four to five generations per year.
The caterpillars tend to be picky eaters, Corriher-Olson said. They prefer high-quality, fertilized forage in hay fields but can also be found in Bermuda grass, sorghum, corn, wheat and ryegrass, among other crops.
To help protect against infestation, growers should check their crops each morning, Corriher-Olsen said. Armyworms are night feeders, avoiding the rising temperatures during the day. The green, brown and black pests can be identified by white inverted Y on their head.
Armyworms should be treated immediately in a pasture when three or more are found per square foot, Corriher-Olsen said. She recommends insecticides labeled for armyworm control in pastures and hayfields and stresses that all label instructions are followed properly.
“You don’t need to wait a day if their numbers are at threshold,” she said. “They are going to do a lot of damage quickly. If you find them in the morning, spray that day.”