A simple change in the choice of grass varieties for many lawns in the United States could be a key tool for fending off fall armyworm infestations, according to new research.
St. Augustinegrass (Stenotaphrum secundatum) is the most common turfgrass species in the southeastern United States, and it is typically planted with a single cultivar across an entire lawn. But multiple cultivated varieties, or cultivars, of St. Augustinegrass are commercially available, and landscape entomologists at the University of Florida and the U.S. Department of Agriculture recently sought to find out which, if any, of those cultivars offered natural resistance to the fall armyworm (Spodoptera frugiperda), a caterpillar that commonly damages lawns.
Their tests found that none of the six common St. Augustinegrass cultivars rose above the rest in resisting fall armyworm infestation. But, when the cultivars were planted together in mixtures of two or four cultivars, it was a different story. The fall armyworm clearly preferred the single-cultivar plantings.
“We were most surprised by how clear the effect of cultivar diversity was on fall armyworm host selection and feeding,” says Ethan Doherty, biological scientist at the University of Florida’s Indian River Research & Education Center and lead author on the study. “The insects had a consistent preference for the cultivar monoculture plantings, and we saw that the effect of cultivar diversity became increasingly more pronounced as diversity increased from two to four cultivars. We didn’t expect such a clear result.”
Read more at Entomological Society of America
Image: The fall armyworm (Spodoptera frugiperda) is a moth species that, in its larval form, can feed on more than 80 plant species, but its preferred hosts are grasses, ranging from crops like corn and sorghum to turfgrasses such as Bermuda grass or St. Augustinegrass. St. Augustinegrass is one of the most common grasses planted in lawns in the southern United States, and a new study suggests that, while single St. Augustinegrass cultivar rises above the rest in resisting infestation, mixing varieties may confer some benefits, as fall armyworms clearly preferred single-cultivar plantings in a series of lab tests. (Credit: Russ Ottens, University of Georgia, Bugwood.org, CC BY 3.0 US)