We are invaded! Well, at least some of our fields are overrun. And by some of our fields I mean mostly hay and pasture fields. So who are the invaders? Fall Legionaries.
Some background on this matter: About six weeks ago we had a large fall armyworm flight into Kentucky from the south. This has resulted in outbreaks of damage from worms feeding on pastures and hay fields, soybeans, etc. But their favorite plant for food is alfalfa. Corn, due to its current stage of maturity, is not very attractive to the worms that feed on it.
In Boyd County we don’t have a lot of row crops or alfalfa, but we do have a lot of other forage fields. However, some of our neighboring counties have quite a few acres of row crops and alfalfa.
And they are here, not just in our west. I got calls and pictures of them before I knew they were where they are. Many of our surrounding states consider this to be the biggest fall armyworm outbreak since the 1970s. So the worst it has been in 40-50 years. A unique and unwelcome event for some.
The best way to determine if you have Fall Armyworms is to go out into the fields and look for them. You can find small worms, larger worms, or egg masses of future worms.
Small worms are much easier to control than large worms. If you see egg masses, be aware that a female can lay up to 1,000 eggs, which can hatch within 48 hours of laying.
Small worms can be effectively controlled by spraying pyrethroids. Larger worms are much more difficult to control with pyrethroids and may require stronger and more expensive insecticides to control them.
If you have multiple generations in the field, you may have a mixture of small and large worms, as well as egg masses. If you see two or three worms per square foot, regardless of their size, you will likely need to spray an insecticide to avoid major damage.
There are several insecticides that can successfully control large worms, but most are restricted and require a license to purchase and use. If you decide to spray for them, regardless of their size, be sure to read the label and determine the length of time, if any, that you cannot graze or harvest the forage after spraying. This can be up to 14 days, depending on the chemical and rate used and the crop sprayed.
At first, it was believed that cutting and baling the forage would reduce the damage caused. However, it was revealed that even when baling, there was a significant number of live worms under the windrows. So this indicates that it may be essential to look for them as they can significantly damage the tender regrowth, which can lead to a loss of production for the next cut, even if it is next year, especially on legumes.
If you are storing fescue for grazing in late fall or early winter, be sure to watch and monitor these fields. They could lead to a reduction in mass, which means less grass to graze and more hay to feed.
If you or someone you know is planting wildlife food plots for hunting purposes or just to feed various wildlife, depending on what may have been planted, they might also feast on these plants.
Even if you don’t live on a farm, they can visit you. Butterflies lay eggs on the side of your home, on landscaping, etc. And they are certainly not above eating the herbs that grow in our backyards and our landscapes, and maybe some landscape plants.
Fall armyworms are actually an annual occurrence in many parts of Kentucky, usually in much lower numbers, so they don’t cause much damage and mostly go unnoticed. It turns out that this year they are here in great numbers.
The good news is, if you could call anything good associated with these pests, it’s that when we get a good hard freeze that should be the end of this infestation. But it also means that they could be with us feeding for the next six weeks to two months.
They cannot survive below freezing temperatures, so when temperatures start to drop, the butterflies will fly south to spend the winter in warmer weather, mainly in Texas and Florida. Much like insect equivalents of snowbirds, as they will return north next summer and fall to feed again. Hopefully that’s not in the numbers we’re seeing this year, but they’ll be back.
LYNDALL HARNED is Boyd County Agriculture and Natural Resources Extension Officer.