Bermudagrass mite, Eriophyes cynodoniensis (Fig. 1) is eriophyid mite species only infest and feed on bermudagrass (Cynadon spp.). It can develop into a serious problem in golf courses, athletic fields, sod farms, and residential and public lawns. The bermudagrass mite infestation can reduce the aesthetic value of the turfgrass, as it can cause thinning and poor grass growth. On severe infestations, extensive thinning of bermudagrass can cause economic challenges to golf course superintendents, sod producers, park managers, and homeowners. Over the last few years, problems with bermudagrass mites have increased in several counties in Georgia. Bermudagrass mite is reported from ~11 states in the United States.
The size of bermudagrass mite poses a real challenge in identifying and monitoring the population over time in the field. They hide under the leaf sheath and feed from the stem. Generally, eriophyid mites are microscopic, about 0.2 mm long or less. Unlike spider mites, the shape of bermudagrass mites is tubular or elongated barrel. The spider-like mites are about 1 mm long and can be seen with or without a hand lens, such as the two-spotted spider mite, Tetranychus urticae.
Biology and lifecycle
The stages of bermudagrass mites are egg, larva, nymph, and adult (Fig. 2). Bermudagrass mites lay eggs under the leaf sheath. Once eggs hatch, they molt into two immature states before molting into adulthood. Depending on temperature, bermudagrass mites can complete the lifecycle from egg to adult within 5-10 days. In Georgia, the bermudagrass mite is active during the growing season. Eriophyid mites are typically dispersed by wind.
Damage
Because mites have piercing and sucking mouthparts, mites consume plant fluids after making shallow cuts using their stylets (needles like mouthparts). The bermudagrass mite feeding triggers the production of witch’s broom (Figs. 3 and 4) as the growth of bermudagrass terminals becomes abnormal (Fig. 3). The space between nodes becomes short, and they produce small, narrow, and pointy leaves. More tillers are produced at every node. All these symptoms cause severe stunting of turfgrass. General yellowing of grass blades (chlorosis) is also observed. With excessive witch’s broom and stunting of terminals, bermudagrass becomes thinned in many areas (Fig. 5).
In the spring, the affected turfgrass shows a delay in breaking dormancy and slowing the greening-up process. The affected turfgrass appears as if it is affected by drought. The feeding damage is more apparent when the bermudagrass green-up in the spring.
Management
Stress is the single most important factor that drives bermudagrass mite infestation. Excessive water deprivation and foot traffic on the turfgrass lead to stress. Proper irrigation and fertilizer applications will help the turfgrass relieve stress. Fertilization can increase the mite population as more nitrogen becomes available. Because the aesthetic appearance of turfgrass is the front and center for the clientele in most cases, fertilization can help improve the overall appearance of turfgrass.
Scalping turfgrass by mowing turfgrass at a low height (~1 inch ) can help remove bermudagrass mites and witch’s broom-affected bermudagrass terminals. Removing the bermudagrass clipping away from the lawn or field after mowing is a critical management tactic, regardless of whether or not any other tactics are administered. The mites effectively move from the infested clippings within 2 hours to healthy, non-infested bermudagrass. Thus, removing bermudagrass clippings is critical for mite management, as it can reduce witch’s broom symptoms by at least 65%. Disposal of the removed clippings away from the non-infested bermudagrass to avoid infestation in new areas is also an important practice to consider. Bermudagrass mites can live in grass clippings that do not show any symptoms witch’s broom. Thus, removing grass clippings and properly disposing of the turfgrass is still a healthy practice, especially if you notice any signs of bermudagrass mite infestation on the grass.
Pyrethroid insecticides, such as bifenthrin or lambda-cyhalothrin, and combination products that have pyrethroid, such as bifenthrin + imidacloprid + zeta – cypermethrin, can effectively reduce mite population. Abamectin products, especially registered for site use, could be used if necessary. Abamectin is registered for nematode control and is proven to reduce bermudagrass mites and symptoms in grass. Make sure to carefully read the label instructions before using any insecticide. Spirotetramat is an effective insecticide that has good efficacy on bermudagrass mite management; however, it is not registered for use on turfgrass in Georgia. Please check the Kontos label registration status at the Envu webpage (https://www.us.envu.com/turf-and-ornamentals-management/production-ornamentals/products/kontos).
Regardless of the product, applications must start in the spring to target early mite populations and be repeated regularly (every 2 weeks) when mite infestations are severe. It is recommended that a proper surfactant, such as Harrell’s activator + SA (salicylic acid) or non-Ionic penetrant, be added to miticide solution in every application to improve penetration of miticide through gaps between stems and leaf sheathes where the mites feed.
References
Boeri PA, Benda ND, Unruh JB, Dale A 2018. Biology and the management of the bermudagrass mite, Eriophyes cynodoniensis. https://edis.ifas.ufl.edu/publication/IN1217
Brown MS, Blubaugh CK, Chong JH. 2021. Biology and management of eriophyid mites in turfgrass. J Integr Pest Manag 12:25. https://doi.org/10.1093/jipm/pmab020
Brown MS, Chong JH. 2024. Removing grass clippings reduces bermudagrass mite (Acari: Eriophyidae) infestation during turfgrass regrowth. Exp Appl Acarol. 93(1):133-140. doi: 10.1007/s10493-024-00911-w
Reinert JA, Dudeck AE, Snyder GH. 1978. Resistance in bermudagrass to the bermudagrass mite. Environ. Entomol. 7(6):885–888. https://doi.org/10.1093/ee/7.6.885
Tuttle DM. 1984. Evaluation of pesticides on bermudagrass.Insecticide and Acaricide Tests 9(1):349–350. https://doi.org/10.1093/iat/9.1.349
