By Scott Stewart
West Tennessee pastures are experiencing high levels of fall armyworms.
Pastures greening up after the prolonged drought are attractive to moths. They start showing up about this time of year anyhow.
Bermudagrass is especially attractive to fall armyworms, but other pasture grasses may also be at risk. With the previous lack of forage owing to the drought, we need to protect this crop.
The University of Tennessee recommends treatment for armyworms in pastures when three to four larvae are found per square foot. Any fields a week of harvest can be rather than treated with insecticide. Larvae will not feed on cut hay.
There are many good treatment options. Several pyrethroids insecticides including Baythroid XL, Karate or Warrior II and Mustang Max provide effective control and have short preharvest application restrictions and no grazing restrictions. Other products that have short or no pre-harvest grazing restrictions include Intrepid, Tracer, Prevathon and Besiege. A complete list of recommended insecticides and suggested rate can be found in the 2012 Pasture Insect Control Recommendations for Tennessee.
I sometimes get calls where people will say, "I'm going to let the worms 'cylce' through because most are pretty big."
This is usually a mistake because a larva will consume more than 8)% of its total food needs in the last few days before it pupates.