FEATURE
LOOKING BACK at the Fall Armyworm Invasion of 2021 By Ben McGraw, Ph.D.
Editor’s Note: Some turfgrass areas in western Connecticut and Massachusetts experienced Fall armyworm (FAW) feeding damage this fall. Given the opportunity to keep membership up-to-date with new or emerging insect pest concerns, Dr. McGraw was kind enough to allow us to update the article for our New England “eyes”.
It
would have been difficult to convince me in January 2021 that there would be a bigger insect news story than the emergence of 17-year periodical cicadas. These red-eyed menaces were the talk of the town early in summer with their near constant humming, driving those who work in landscapes to near madness over the course of several weeks. Little did we know at that time that a more insidious pest would be on the verge of invading states in the Northeast, including western Connecticut and Massachusetts, and about to cause turfgrass damage on a scale that has not been observed in many years. Here we look back at the Great Fall Armyworm (FAW)(Spodoptera frugiperda) Outbreak of 2021 to discuss what can be done in future years to prepare.
Homegrown problem: The majority of our destructive turfgrass insect pests are introduced species to North America. Invasive insects are believed to be more problematic outside of their native distribution since they are unlikely to occur along with their natural enemies, thus allowing for greater population growth. Unlike the majority of white grubs species, mole crickets, crane flies (leatherjackets), the FAW is native to the Americas. However, they are native to tropical or semi-tropical areas and incapable of persisting yearround in most areas in the United States. This means that no stage is capable of surviving in areas that experience freezing temperatures, limiting permanent populations to southern Texas and Florida. Each spring, moths in these areas deposit thousands of eggs that will hatch and become caterpillars. These voracious eating machines will feed on numerous host plants including corn, soybeans, rice, and turfgrasses (warm- and cool-season turfgrasses). The literature would suggest that most turfgrasses are susceptible, including Bermudagrass, fescues, ryes, and blues. The caterpillar develops through six to seven instars, pupates in the soil (forming a reddish brown cocoon), then emerges as a moth. Some moths will remain in the region, deposit eggs to become the 2nd generation of caterpillars. In the south, this scenario will play out continuously, making for year-round threats to turfgrass loss. However, some moths will be dispersed on the wind hundreds of miles which then become infestations in northern and western regions. The number of FAW generations a region may experience is largely dependent on the moth’s migration north. The Carolinas might have several FAW generations per year, whereas Pennsylvania and points north into New England may experience one generation per year. Surveillance of moths has shown FAW capable of being dispersed as much as 500 miles in 24 hrs! The Northeast does not typically experience FAW turfgrass damage, but rather observe boom years when southern storm activity is active in mid-summer.
24 • New England BLADE • Spring 2022
