|
|
|
Posted 25 May 2006. Forage and Grazinglands. Armyworm Moths Blown in from Southern States Can Produce Forage-Eating Worms; Scouting Urged University of Missouri Columbia, MO (April 20, 2006) – Large numbers of armyworm moths rode recent high winds into Missouri from southern states, said an entomologist at University of Missouri. The grass-eating armyworms add more risk to drought-stricken pastures and wheat fields.
Farmers are urged to scout fields, said Wayne Bailey, University of Missouri Extension entomologist. Early detection is important; the worms can strip a field overnight once they become established. A full armyworm invasion can cause spectacular damage, Bailey said. "If larvae devour available food in an area, they will readily move in masses to another field of grass or wheat," Bailey said. "This movement, or march, is responsible for their name." Five years ago drivers found some Ozark highways slick and dangerous because of squashed masses of armyworms that tried to move across the roads, Bailey said. Three years ago an unusually widespread infestation affected north central Missouri. Crops most vulnerable to damage are tall fescue pastures and cereal crops. True armyworms are found more frequently in southern Missouri, but can cause damage throughout the state. The location depends on where the moths are blown. Armyworm moths are light tan to grayish-brown in color with a pinkish-white spot near the center of each forewing. Each female can lay up to 2,000 pale-green eggs, usually on green vegetation. The larvae hatch in a couple of weeks and start feeding. Larvae are yellow-brown in color with smooth hairless bodies and grow to more than an inch in length. They have dark horizontal stripes down each side and the back. In the past three weeks, large numbers of armyworms have been found in Kentucky and Arkansas, Bailey said. "This is an early warning for Missourians to check their fields." Scouting for early outbreaks of armyworm requires careful searching down into stands of forages to find the first worms. "Armyworm larvae avoid the light and spend most of the day hiding deep in the plant residue near the soil surface," Bailey said. "Feeding usually occurs during the night. Plants are defoliated from the ground up." A field that looks normal from the road one day can be reduced to a stand of stems by the next morning. "Two to four generations can occur in Missouri each year," Bailey said. "The first generation is responsible for the most damage in tall fescue and wheat." Fescue left for seed harvest is most vulnerable. Several insecticides are approved for control of the pests. Recommendations can be obtained at local MU Extension Centers. Control recommendations for all insect pests are available on the Internet at ipm.missouri.edu/pestguidelines. In the past, when heavy movements of armyworm have occurred in Missouri out-of-state aerial applicators flew in to help control the pest. Contact: Duane Dailey |
