Writer: Karie Fehler (409) 862-1556,
Contact: Dr. Clifford Hoelscher (979) 845-6812, c-hoelscher@tamu.edu
COLLEGE STATION — Fall is approaching quickly and so are one of small grain crops’ worst enemies. Fall armyworms pose a monstrous threat to Texas pastures and grain crops each year, but entomologists say this year’s conditions may be especially favorable for the ravenous larvae.
Fall armyworms can cause serious damage in one to two days before the damage is even noticed. The larvae attack small grains in large numbers and devour all plant material in their path. Texas Agricultural Extension entomologist Clifford Hoelscher says early detection and preventative measures are essential for successful small grains crops this season.
“We expect heavy infestations in wheat and oats in the next five or six weeks in much of East, North and Central Texas,” he said. “Early detection is key because small larvae are much easier to control than large larvae. Producers should also look at getting some protection with insecticides before plant stands are killed or greatly reduced.”
The fall armyworm is a pest that strikes during late summer and early fall. The larvae feed mainly at night on plant foliage, and on cloudy days, one may observe them feeding. Hoelscher said the larvae hide just under the surface of the soil in bright sunlight and feed on the growing parts of the plants.
Though many assume that a preventative pesticide treatment will remedy the problem, Hoelscher suggests other tactics.
“We do not suggest that producers try to pre-treat areas because these infestations can be sporadic and some areas may not be affected,” he said. “Once your small grains are planted and are up to a stand, we suggest farmers check them twice per week for the presence of small larvae and also plant damage.”
The fall armyworm larvae range in color from pale green to brown to black and are often striped with yellowish lines from head to tail.
Hoelscher said scouting grain fields can indicate the level of treatment necessary and can save farmers time and trouble in the long run.
“You should inspect six to eight areas in the field randomly to determine the number of larvae per square foot in the field,” he said.
“You can take a small wire frame that is one foot in diameter and place it down in the field to make an inspection. Divide the number of locations you inspect by the number of larvae found.”
Hoelscher says if there are four larvae to five larvae per square foot, an insecticide treatment is recommended. Small grain insecticides include Lannate, ethyl parathion, methyl parathion and Sevin; there are three formulas of Sevin recommended for armyworms. These include XLR Plus, 4-Oil and 80S formulations.
Hoelscher explained there can be a waiting period and general guidelines to follow with most insecticides.
“Producers are urged to specifically read the label for the crop that they’re treating to get grazing and harvesting intervals,” he said.
“Sevin is the only material that can be put out where grazing can be continued — there’s 0 days from treatment to grazing.”
But Hoelscher suggests another form of prevention: listening to nature’s cues. As the nights get cooler and the temperatures drop, armyworm egg deposition and feeding is restricted.
“If producers can wait to plant their small grains until after Oct. 15, there’s less likelihood of having fall armyworm infestations,” he said. “It’s been fairly dry until recently, so producers may need extra small grains for grazing. If you plant them in mid-September, you will have a greater likelihood for armyworm infestations.”
-30-
ENTO TOP