Bermudagrass Mites Information
Species & Identification
Bermudagrass mites, or bermudagrass stunt mites, are increasingly problematic pests of bermudagrass. They attack both common and hybrid bermudagrass cultivars. The mites are extremely small (about 0.2 mm in length) and, therefore, will require high magnification to see. They have translucent to creamy white, banana-shaped bodies with two pairs of short legs.
Damage & Symptoms
Bermudagrass mite can be damaging anywhere bermudagrass is grown. Infestation causes shortened internodes, stunted leaves, swollen stems, and excessive tiller production at the infested nodes. These symptoms are collectively referred to as witches’ brooms. Infested terminals often appear lighter in color. Damage can appear as quickly as 13 days after infestation. Stolon and root development are also affected, which can lead to thinned and dead turf. Severe infestations can result in large bare areas. Weeds can invade these thinned turf or bare ground. Damage is most noticeable in late spring and summer in South Carolina, though the exact timing varies from year to year.
Life Cycle
Researchers are still working to fully understand the life history and biology of bermudagrass mites. It only takes 7-10 days for a bermudagrass mite to develop from egg to adult. Hundreds of individuals of all life stages live under a single leaf sheath where they suck sap from plant stems. Mites spread through movement of infested plants, clippings, wind, and machinery. It is not known in which life stage or where bermudagrass mites overwinter.
Scouting
Presence of witches’ brooms indicates mite infestation. Witches’ brooms persist even after mites are killed; therefore, careful examination of witches’ brooms is necessary to confirm mite presence. To look for the mites, peel back the leaf sheaths and examine the exposed stems with microscopes or a hand lens at 16 to 20 times magnification. Severity of infestation is indicated by the prevalence of witches’ brooms and the quality of the turf, including turf coverage and color. There is currently no treatment threshold for bermudagrass mite.
Cultural Control
Mite infestations are commonly associated with stressed turf. Preventing drought stress, i.e., achieving at least 100% evapotranspiration rate, can reduce witches’ broom numbers. Low mowing height or scalping can remove bermudagrass mites from the infested turf, but clippings must be collected and disposed. Overfertilization can worsen bermudagrass mite infestations. Some bermudagrass cultivars are more tolerant to mite infestations than others. In research settings, ‘Midlawn’, ‘Tifsport’, and ‘GN-1’ tend to be more resistant while ‘Patriot’ and ‘Celebration’ have been moderately susceptible. However, no cultivar has shown consistent resistance to bermudagrass mites.
Chemical Control
Miticides can control bermudagrass mite infestations, but with their rapid life cycle, bermudagrass mites often re-infest a treated area quite quickly. Thus, repeated applications are often needed to sufficiently control bermudagrass mites. Adding a penetrating surfactant (such as Dyne-Amic or Penetrant Plus) can help the penetration of miticide beneath leaf sheaths where mites are located. While several insecticides are registered for management of mites (in general) in turf, few have been shown to be effective in managing bermudagrass mite. Currently, abamectin and spirotetramat are the most effective miticides available for bermudagrass mite management and they are only available for use on golf courses.
| Active Ingredient(s) | Trade Name(s) | Rate (per 1000 ft²) | Use Site(s) | IRAC Code(s) |
|---|---|---|---|---|
| Abamectin | Todal, Divanem | 0.3673-0.5510 fl oz, 0.0717-0.1435 fl oz | G, G | 6 |
| Azadirachtin | Azatrol EC | 1.3 fl oz | A C G L R S | UN |
| Bifenthrin | Bifen 7.9F, UP-Star Gold, Talstar P, Broadside GC, Wisdom, UP-Star SC, Bifenture, Capture, Sniper LFC/LFR, Bifen 2 AG, OnyxPro, Reveal, Baseline, Bifen XTS, UP-Star EC, Bifenture EC, Brigade 2EC | 0.25-0.5 fl oz, 0.1-0.4 fl oz, 0.08-0.16 fl oz, 0.07-0.15 fl oz, 0.08-0.16 fl oz | A C L R, A C G L R S, S, A C G L R S, A C L R, S | 3A |
| Deltamethrin | DeltaGard G, D-Fense SC | 2-3 lb, 0.6-0.9 fl oz | L, A L R | 3A |
| Lambda-cyhalothrin | Demand G, Avesta, Demand, Scimitar CS, Scimitar GC, Lambda GC-O, Lambda Select | 2-3 lb, 3.4-7 ml, 2.9-6 ml | A C L R, A C G L, A C G L R S, A C G L R S | 3A |
| Lambda-cyhalothrin + novaluron + pyriproxyfen | Proflex | 6.4-12.8 ml | A C G L R | 3A + 15 + 7C |
| Spiromesifen | Forbid 4F | 1.4-4 fl oz per 100 gal | A C G L R | 23 |
| Spirotetramat | Kontos | G [24(c)] | 23 | |
| Zeta-cypermethrin + bifenthrin + imidacloprid | Triple Crown Golf, Triple Crown T&O | 0.23-0.46 fl oz, 0.23-0.46 fl oz | A C G L R S, A C L R | 3A + 3A + 4A |
