As Arkansas Wheat Crop Grows, So Do Pests

MONTICELLO, ARK.
   Warm weather has not only accelerated growth of Arkansas’ winter wheat, but also that of hungry armyworms. Extension entomologist Scott Akin said Tuesday that he and fellow extension entomologists Gus Lorenz and Glenn Studebaker were all getting calls about armyworms from producers around the state.
   “Normally, armyworm populations build late in the wheat-growing season, after heading has already occurred,” he said. “However, we seem to have had an early spring here in Arkansas, and armyworms have been showing up early as well.”
   Armyworms have been reported in Arkansas, Desha, Ashley, Chicot, Lincoln, “and I suspect anywhere we look hard enough, at least in the southern part of the state,” said Steve Kelley, extension soybean and wheat verification coordinator with the University of Arkansas System Division of Agriculture.
    For armyworms, there’s plenty to eat. Statewide, 35 percent of the wheat crop has developed seed heads, according to Monday’s crop report from the National Agricultural Statistics Service. It’s much farther along in Prairie County where 95 percent of the crop is headed, while 60 percent is at the milk stage, when the seed grains begin to fill – all very attractive to pests.
   “Folks looking at wheat this morning and were picking up several worms on the southern end of Prairie County,” Extension Staff Chairman Brent Griffin said Tuesday. Lafayette County Extension Staff Chair Joe Vestal said he found a few in a wheat verification field last week as well.
   Armyworms are sneaky, feeding on leaves at night and starting from the bottom of the plant and eat their way up through the leaves.
   “It is not uncommon for these lower leaves to be completely consumed before they make their way up the plant,” Akin said. “Because these pests feed primarily at night, armyworms can often be found under debris, at the base of plants or in cracks of soil. Check these areas to ensure armyworms are still present and in fact the responsible culprit prior to making a treatment decision.”
   Another factor to consider before treatment is the wheat’s growth stage. Akin said that when wheat reaches late-stage development, the plants can withstand complete defoliation without a measurable loss of yield.
   “However, in rare situations, armyworm densities may be so high that they may cut the stem just below the head,” he said. “Obviously, serious yield damage would result in these situations; thus, fields should be observed closely to determine if head cutting is occurring.”
   Griffin said stinkbugs were also appearing in wheat, but not yet at levels requiring any action. Stripe rust, which had been reported in 20 counties is responding to control methods.
    For treatment recommendations, see www.uaex.edu/Other_Areas/publications/HTM L/MP-144.asp, or contact your county agent. Δ 
Armyworms work their way along the stems of winter wheat plants in Prairie County, Ark. Warm weather not only accelerated wheat growth, but that of wheat pests.
U of Arkansas System Division of Agriculture photo by Brent Griffin
 Hungry armyworms work their way up the stems of winter wheat plants on April 3, 2012, in Prairie County, Ark.
U of Arkansas System Division of Agriculture photo by Brent Griffin