The bermudagrass mite (Eriophyes cynodoniensis), also called bermudagrass stunt mite, is a very small, elongate, creamy white or translucent-colored mite that requires a magnification of 15x to 20x to see. This eriophyid mite is very host specific, as it only feeds on bermudagrass. Additional generations (from eggs to adults) of mites can occur every 7 to 10 days, meaning that populations can increase rapidly. This turfgrass pest is present throughout the Southern US.
Damage to lawns affected by bermudagrass mite becomes noticeable in late spring, as some areas may be yellow with low vigor or fail to become green out of winter dormancy. Bermudagrass leaves die back to the stems as mites feed under the bermudagrass leaf sheaths, where they suck plant sap from the stems. This damage causes a witch’s broom effect (see Figure 1) on bermudagrass stems as the mite feeding reduces the elongation of grass stems and causes a swelling of leaf sheaths.
All bermudagrass cultivars are susceptible to bermudagrass mites. However, some popular cultivars, such as ‘Tifway’, might produce fewer witch’s brooms. Nevertheless, all varieties will be thinned by a mite infestation.
Because bermudagrass mites are so small, the presence of witch’s brooms is often the best symptom to diagnose a mite infestation. During heavy infestations, turfgrass stems and stolons may die, resulting in dead areas in the lawn during the summer. Witch’s broom symptoms are most noticeable around the perimeter of these dead areas.
Cultural Controls: Keep turfgrass as healthy as possible to avoid infestations. Apply lime and fertilizer according to soil test recommendations. Dolomitic limestone provides calcium and magnesium needed for good turfgrass growth and reduces soil acidity, thus improving the availability of trace elements to the plants. High nitrogen levels are associated with increased damage by bermudagrass mite. Always follow a soil test’s recommendations to avoid applying excessive nitrogen to the lawn. For more information, see HGIC 1652, Soil Testing.
Mow bermudagrass lawns at 1 inch tall. Mowing heights above 1 inch favor the mite infestation making damage more noticeable. If mites are present, bag and dispose of the clippings when mowing to avoid spreading mites to other areas of the lawn. Water the lawn with 1 inch of irrigation water after mowing. If needed, dethatch the lawn in May to aid in removal of grass tissue infested with mites. Dethatch uninfested areas first, and then the areas with the mite infestation. Avoid accidentally spreading infested thatch onto uninfested lawn areas. Core aerate the lawn as needed to improve drainage and reduce soil compaction. For more information, see HGIC 1200, Aerating Lawns.
Water the lawn to reduce drought stress. In heavier clay soils, irrigate turfgrass one time per week with 1 inch of water during periods of insufficient rainfall. In sandy soils, the lawn may need irrigation two times per week. Deep, infrequent watering can help improve the appearance of lawns stressed by a mite infestation. In addition, this helps reduce the occurrence of weeds and turfgrass diseases. For more information, see HGIC 1207, Watering Lawns.
Chemical Control: Pesticide products labeled for use on home lawns are not effective against bermudagrass mites. The cultural controls discussed above are important in helping the turfgrass to avoid, as well as to recover and tolerate, mite infestation in turfgrass.
Pest Diagnosis: For a positive identification of the bermudagrass mite infestation, put samples of the witch’s brooms into a gallon-sized, re-sealable storage bag and take them to the local county Clemson Extension office. For a nominal fee, the turfgrass samples can be sent to the Clemson Plant & Pest Diagnostic Clinic for positive identification.