Fall Armyworm in the Near Term.

Doug Johnson, Extension Entomologist


I am still receiving calls about fall armyworm (FAW) primarily as they affect pastures and especially reestablishment of grass fields and waterways. Most people are able to get control relatively easily, once the infestation is found; and by now quite a few folks are looking!

We have a few pieces of good news. The capture of moths in the UK-IPM trap at Princeton, KY has decreased significantly to 69 moths / trap-week. Additionally, we have a forecast of very cool temperatures and perhaps some significant frost. Both of these will have a generally debilitating effect on the FAW population.

It is quite reasonable to assume that FAW populations will decrease over the next week or so. Nevertheless, it is impossible to predict what will occur in a specific field or portion of a field. That is all completely dependent on how cold it gets and for how long that cold lasts. This is especially important for producers pushing up against the planting date window for newly seeded grasses. If you must plant / renovate in the near term then be sure that: 1.) There is no uncontrolled FAW infestation in your field. 2.) Make sure you begin checking your newly seeded grasses as soon as they begin to emerge for the presence of a new infestation.

For those producers planting winter wheat, waiting until after the Hessian fly free date, which from the date of this writing (Fri. 10/5/12) would be another week to 10 days, depending upon where you are located, could reduce your risk substantially. Again, this is almost completely dependent upon the weather, especially temperature, during this time frame.

Temperature forecast over the next ten days is about normal. There is a chance of frost on Sat. 10/6 and Sun. 10/7 but after that the temperatures will moderate once again. This weather is certainly not preferential for FAW growth and development and I would expect a continual decrease in the population size. However, I don’t see any immediate event in the next ten days that will remedy the problem for the season. So, for the time being, those with susceptible crops (all small grasses) should keep checking for the presence of this pest.