Overton – Armyworms are marching in East and North Texas pastures, say Texas AgriLife Extension Service experts.
"Some producers trying to get another cutting of hay have found out that the armyworms have already harvested it for them,” said Ralph Davis, AgriLife Extension agent for agriculture in Kaufman County.
Dr. Vanessa Corriher, AgriLife Extension forage specialist based in Overton has been getting reports of fall armyworms for weeks.
The rain before and after the passage of Hurricane Ike will encourage further outbreaks, she said. Outbreaks typically happen in the and are worse when rains follow a drought.
Highly fertilized forage is also favored by fall armyworms, she noted.
Fall armyworm moths migrate northward from South Texas in the spring and summer. As part of its natural life cycle, each moth will deposit a clump of 50 to100 eggs on individual blades of grass, she said.
“Early detection and control is necessary to avoid crop loss,” Corriher said. “Early detection of larvae is the best management tool and is achieved by frequent, thorough inspection of pastures.”
When armyworm larvae reach about three-quarters of an inch long, they eat 80 percent of their total lifetime food. During this stage of their development, they can seemingly strip a pasture bare in a day or two, so early detection is the key, said Dr. Gerald Evers, Texas AgriLife Research forage management expert.
Evers found armyworms in his test-plot pastures soon after Hurricane Ike passed. He offered an easy way to detect armyworms early before they do damage.
"A good way to determine if you have armyworms before they do damage is to walk your pastures in the morning when dew is still on the grass in knee-high rubber boots," Evers said. "The worms will fall off the grass as you walk and stick to the wet boots."
Corriher and Evers gave the following recommendations:
– Thresholds in improved pastures and lawns vary with conditions, but treatment should be considered when counts average three or more worms per square foot. Three fall armyworms per square foot can consume 30 percent leaf area of a good stand of Coastal Bermuda grass.
– Insecticide choices labeled for use in pastures include (with product names and grazing restrictions in parentheses): – Carbaryl (Sevin) (14 days)
– Methomyl (Lannate) (seven days)
– Methyl parathion (15 days).
– Tracer (Zero days but let spray dry before grazing and a three-day wait before hay harvest.)
– 4 ounces carbaryl (Sevin plus 4 ounces of malathion per acre. (14 days)
“As with all insecticides, users should read and follow label instructions,” Corriher said. “Strict adherence to label instructions and observing the correct waiting period before harvest and grazing is particularly critical.”