Featured Article | GreenCast | Syngenta

Prevent fall armyworm damage

By Matt Giese, M.S., technical services manager for Syngenta

As summer continues, the threat of fall armyworm damage is looming. These destructive insects overwinter, typically as pupae, in southern Florida and along the Gulf Coast, where outbreaks can occur as early as April or May. The fall armyworm moth migrates northward in search of suitable sites to lay eggs. Armyworms typically arrive in the northern transition zone by June or July, and activity can continue well into the fall.

Fall armyworm adults (moths) lay clusters of 50 to 300 eggs on fence posts, tree leaves and bushes adjacent to turf and other structures. Each female may produce about 1,000 eggs during its lifetime. Larvae emerge and move into adjacent turf areas to feed.

Fall armyworm caterpillars (larvae) feed above the ground on the foliage of the turf, and an “army” of the caterpillars can quickly devour large areas of turf down to the soil. From a distance it may appear that the turf has become dormant, but closer inspection will reveal ragged turf with individual blades showing signs of chewing damage. Armyworm caterpillars prefer to feed on bermudagrass, but outbreaks can occur on other turfgrass species. Lush, actively growing turf is most desirable to the larvae; newly sodded or sprigged areas are particularly prone for this reason.

In the past, armyworm outbreaks were normally controlled on a curative basis with organophosphate or synthetic pyrethroid insecticides. These products provide rapid knockdown of the feeding larvae, but do not provide long-term prevention of subsequent outbreaks and therefore require repeated applications - as many as four to six per year.

Acelepryn® insecticide provides ultimate flexibility in fall armyworm management. With its systemic activity and long soil residual, Acelepryn not only provides rapid knockdown of existing outbreaks, but also provides extended residual control to prevent subsequent outbreaks.

Recommended treatment

  1. Apply Acelepryn at 2-4 fl. oz./A as a preventive application, or when fall armyworm larvae are observed. This application will provide rapid knockdown of existing outbreaks, as well as one to two months of protection against future outbreaks. For the best knockdown control, avoid irrigation for 24 hours after treatment to allow time for caterpillars to ingest the active ingredient.
  2. Applications of Acelepryn at 8-16 fl. oz./A to target white grubs will provide extended periods of protection against fall armyworm outbreaks for up to four months (see figure below). Sequential applications may be needed for late fall outbreaks.


The data above is based on the summary of 11 field trials that took place between 2005-2009 in Florida, Indiana, New Hampshire, New Jersey, North Carolina, Ohio, Pennsylvania and Rhode Island. Performance assessments are based upon results or analysis of public information, field observations and/or internal Syngenta evaluations. Trials reflect treatment rates commonly recommended in the marketplace.

For more information about fall armyworm control, contact your local Syngenta territory manager.

©2020 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties. Please check with your local extension service to ensure registration status. Acelepryn® and the Syngenta logo are trademarks of a Syngenta Group Company. Merit® is a trademark of Bayer Environmental Science.

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