Fall Armyworm Alert
Ken Wise from the NYS IPM Program reported a large infestation of fall armyworm larvae in a 50 acre alfalfa field in Eastern NY. Ken’s comments follow: “The larvae completely ate all of the alfalfa leaflets leaving only the stems on the 50 acres. They were in the 2nd to 3rd instar of development. This means they are still small. Fall armyworm normally go through 6 instars and will eat much more forage before they pupate. The range of the infestation was 5 to 15 larvae per square foot. Fall armyworm in other parts of the country has been causing issues this season. It would be best to go out and check your crops for fall armyworm. The threshold for fall armyworm in alfalfa is 1-3 larvae per square foot. Many of the Bt corn hybrids are resistant to fall armyworm. Fall armyworm will feed on many other grasses. It is best to get out and scout fields now!”
I have also received two reports similar to Ken’s in NWNY this week. A lot of alfalfa and alfalfa/grass fields are being cut for haylage this week. Those fields still standing should be scouted. Fall armyworm is a different species than common armyworm but it will feed just as voraciously. Soybeans are not safe either!
Ken has put together a list of labeled products for alfalfa, two of which can be used on mixed stands.
