Seven eriophyid mite species (bermudagrass mite shown here) are turfgrass pests that are challenging to manage. A new guide in the Journal of Integrated Pest Management reviews the mites’ biology, identification, and management strategies. (Photo by Matthew Brown)

By Matthew Brown

Matthew Brown

Many producers and managers of turfgrass do not recognize eriophyid mites or even their damage. These banana-shaped, four-legged, 0.2-millimeter long mites are an enigma even to acarologists. But those who have experienced the devastating damage caused by eriophyid mites know three things: First, they are hard to diagnose due to their small size and the fact that symptoms of their infestation closely resemble those caused by environmental stress (such as drought) or other pest infestation (such as nematodes). Second, we know very little about their biology and ecology, limiting our ability to develop effective management options. And, last, once you have an infestation, you are often stuck with it.

In turfgrass systems, seven eriophyid mite species infest bermudagrass, zoysiagrass, buffalograss, and other turfgrass species. Each mite species specializes in utilizing one or a group of closely related grass species and often causes distinctive, abnormal growth, such as the witches’ brooms caused by bermudagrass mite infestation. In addition, mite infestation weakens and thins out turf. These injuries slow recovery from wear and ruin the aesthetics of golf, recreational, and athletic turf, and they lead to losses on sod farms when the sod breaks during harvest.

In a new paper published this month in the open-access Journal of Integrated Pest Management, Carmen Blubaugh, Ph.D., J.C. Chong, Ph.D., and I review the ecology, identification, and available management strategies for turfgrass-infesting eriophyid mites. This review serves to educate turf industry professionals, improve their ability to identify mite infestations, and help them make the best pest management decisions.

Dorsal view of adult Aceria cynodoniensis mite under a low-temperature scanning electron microscope. (Photo by Gary Bauchan, U.S. Department of Agriculture-Agricultural Research Service; orginally published in Brown et al 2021, Journal of Integrated Pest Management)

Symptoms of bermudagrass mite (Aceria cynodoniensis) infestation. The mites produce gall-like structures called witches’ brooms. (Photo by Matthew Brown)

Symptoms of Aceria zoysiae infestation. The mites cause twisted leaf tips to get caught in folded, older leaves, producing an arched terminal leaf. (Photo by Blake Layton, Mississippi State University)

Turf severely damaged by bermudagrass mite (Aceria cynodoniensis). (Photo by Matthew Brown)

We do not know much about the biology of turfgrass-infesting mites in the family Eriophyidae. They have a short development period (7−10 days), which allows a large population to build up rapidly. All life stages live together, usually in parts of the plant that provide protection—for example, under leaf sheaths, within folded leaves, or in leaf grooves. Because the mites are tiny, turf professionals monitor the abnormal growth caused by mite infestation instead of the mite population itself. The correlation between the abundance of symptomatic grass and mite density is unknown. Researchers have not established an economic threshold because turf professionals do not monitor mite populations, and pest tolerance depends on visibility, use frequency, and aesthetic requirements in different turfgrass systems.

Turf industry professionals use synthetic miticides (such as abamectin and pyrethroids) to manage eriophyid mites. However, these chemicals are costly, marginally effective, and risk miticide resistance development and adverse non-target effects. Clearly, we need alternatives that incorporate cultural or biological control strategies. Maintaining healthy turf with proper irrigation and fertilizer application helps turf tolerate mite damage. Scalping, or mowing turf low to the ground, may help mechanically remove mite populations. Researchers have reported many mite species as potential natural enemies of eriophyid mites in turfgrass. However, their potential for biological control is currently unknown. Combining knowledge about mite ecology with proper identification of mite-induced symptoms and cultural and chemical control strategies can form the foundation of an effective integrated management program.

Matthew Brown is a Ph.D. candidate in the Department of Plant and Environmental Sciences at Clemson University, conducing research at the Pee Dee Research and Education Center in Florence, South Carolina. Email: msb5@clemson.edu.