After a year of low activity, the Bermuda grass stem maggot has returned and is spreading quickly across lush pastures in Texas.
“Since 2013, this pest has rapidly expanded its range in Texas and is now found throughout much of East, Central and South Texas, and as far west as Abilene and San Antonio,” said Dr. Allen Knutson, Texas A&M Agrilife Extension entomologist in Dallas.
As the pest is relatively new to Texas, most farmers and ranchers may not recognize the early signs of damage.
Damage is first evident as the top two or three leaves turn white or brown, but the remainder of the plant remains green,” Knutson said. “The top dead leaves are easily pulled from the stem. Infested fields may appear ‘frosted.’”
Management recommendations developed in Georgia and Alabama suggest that if damage is found, the best course of action is to harvest the crop as soon as possible, AgriLife Enstension forage specialist Dr. Vanessa Corriher-Olson said.
“Once the damage becomes apparent, the crop is unlikely to add a significant amount of yield if left to further develop,” Corriher-Olson said. “The damaged crop should be cut and baled and removed from the field as soon as weather conditions allow. Leaving the damaged crop in the field will only compete with any attempts by the plant to regrow and decrease the opportunity that the next cutting will have time to accumulate dry matter.”
Knutson said maggots feeding within the stem will die once the crop is cut and dried for harvest.
However, without treatment, flies will emerge from pupae in the soil and re-infest the field, he said. “To protect the regrowth from infestation, apply a pyrethroid insecticide about seven days after cutting hay to kill adult flies. A single application is usually sufficient. There are yet no effective methods for sampling Bermuda grass stem maggot fly or larvae or guidelines for when an insecticide treatment is needed.”