Yesterday we discovered that armyworms have infested our lawn. Apparently, there are a variety of chemicals that are effective against armyworms, so I called Dr. Chris Cooper at the Extension Office to ask his recommendation. I had one of the products he suggested (Ortho Bug B Gon) in the garage, and I also took a trip to Lowes to purchase one of the others (Spectracide Triazicide). While in Lowes, I ran into a friend who is the Plant Specialist in the garden center. I told her why I was there and she remarked that people had been coming in all day to buy treatment for armyworms.
Yesterday, Jack mowed the grass and raked where the clippings were heavy. Since armyworms tend to feed in the morning and late afternoons, we waited until about 6:00 p.m. to spray. The Spectracide chemical I bought was a hose-end, ready-to-spray formulation that covered 5,000 sq ft area. This was enough to spray the area where we saw the caterpillars and a wide margin around that area. A large number of caterpillars like we have will eat all the green in an area (except the broadleaf weeds that we wish they would eat), then systematically march to the adjacent green areas to continue wreaking destruction. Thus, the name armyworms. I read somewhere that they can increase the margins of an affected spot by as much as 3 feet overnight.
I suspect that the lawn services in our area are treating entire yards, not selected areas as we did. Treating the entire lawn makes sense for a lawn service because armyworms can move quickly across the turf. In addition, they may already be in areas that are not showing damage yet. But Jack and I wanted to the minimize use of chemicals as much as possible, while still achieving some control. As homeowners, we have the ability to check the turf every day and spray as needed.
One indication that we may need to do additional spraying is an unusually large number of birds on the lawn. We did not spray the backyard (where no damage was evident yesterday), but this morning there were about 6-8 robins feeding there. I went out to check the grass but did not see any caterpillars. Birds can serve as an early indication that armyworms may be present, but they cannot eat enough to control a large infestation.
The other yardwork we did today was to put the final application of fertilizer and a pre-emergent herbicide on our lawn. (This summer, we have used more lawn chemicals than we usually do, hoping to encourage a thick lawn that will not require a lot of chemicals to suppress weeds in the future.) Had we not been visited by armyworms, we probably would have waited a few more weeks for this, but we wanted to encourage re-growth in those bare spots and to stop the germination of weed seeds that are now getting plenty of sunshine. Or will be soon when we get rid of these clouds. We put those chemicals down this morning, hoping that the forecasted rain will come in this afternoon and water them in for us.
I'm curious about how widespread this armyworm outbreak is. I live in Germantown, and many people in my neighborhood have them. What about your area of the county?