BERMUDAGRASS MITE

Species:

Eriophyes cynodoniensis Sayed used to be called the bermudagrass stunt mite, but just bermudagrass mite is now the accepted common name.

[Phylum Arthropoda: Class Arachnida: Order Acarina: Family Eriophyidae]

Distribution:

The bermudagrass mite occurs in Australia, New Zealand, and probably wherever bermudagrass is grown. In the United States, it is found in the southern states where bermudagrass, its only host, is normally grown.

Hosts:

Bermudagrass is the only host known to be attacked by this mite though some cultivars are resistant.

Damage Symptoms:

Damage is first noticed when bermudagrass does not have vigorous growth in the spring and is often yellowed. The turf appears stunted and close inspection reveals that the stem length between nodes is greatly reduced. Leaves and buds at the nodes become bushy, forming a rosette or tuft which is called "witchesbrooming." Heavy infestations produce an open, "tufted" appearance with irregular sections eventually turning brown and dying. Damage is most severe during hot dry weather.

Description of Stages:

This mite has stages typical of the eriophyid mite group. These are extremely small mites with worm-like soft bodies and only two pairs of legs facing forward.

Eggs:

Round, translucent white eggs are about 1/3 the length of the adult.

Nymphs:

The first nymph has the tapered worm-like shape of the adult but is almost clear. These mites have only two pairs of short legs rather than the four pairs of legs found on most mites. The abdomen has minute rings which look like segments. The second nymph is about 2/3 the length of the adult and more white in color.

Adults:

Only females are known, as in most eriophyids. These look like the nymphs and are only 1/128 inch (0.2 mm) long when fully grown but have a whitish cream color.

Life Cycle and Habits:

Because of their small size, these mites are very difficult to study, and little is understood about their life cycles and habits. Most eriophyids lay less than a dozen eggs during their adult span and these usually hatch in two to three days. At 75 F it is estimated that adulthood is reached in seven to ten days and eggs are laid for two to five days. Thus, a cycle can be completed in 10 to 14 days. This short time period allows for a rapid build up of a population during summer temperatures. The bermudagrass mite seems to be quite tolerant of high temperatures, having moderate mortality at 120 F. Cold temperatures tend to stop development though survival during the winter can take place where bermudagrass remains green at the soil surface. This mite can apparently spread by the wind or by being carried on the legs of other insects. However, the most common method of spreading is by transportation with infested turf. The mites cannot survive on bermudagrass seed.

Control Approaches:

Eriophyid mites usually are not always killed by normal miticides but may be killed by many insecticides. With the use of fine textured bermudagrasses on golf courses, this mite seems less abundant

Sampling

A three by four foot plastic rectangle should be strung on one ft² grids (12 ft² total). The sampling hoop consists of four sections of 1-inch PVC pipe. Two are three foot long segments and two are four foot long segments. The segments are joined with right angle connecters and glued. Holes are drilled through the sides at one, two and three (on the four foot segments only) feet from each corner. A monofilament string is then threaded, in a grid pattern, through the holes. This hoop is tossed onto the turf and ten of the ft² grids are rated for mite activity. Each tuft of turf with a witchesbroom is counted. Fairways and roughs should be sampled every 50 yards and four hoop samples should be taken for each green apron. Tee banks should have two hoop samples. When presence of the mite activity is noted, samples should be taken every month. If the activity is increasing and exceeds four to eight tufts per ft², chemical controls are probably warranted. Below four tufts per ft², cultural controls should be used.

Cultural Control - Use Resistant Varieties -

Common bermudagrass is often attacked but improved, fine textured varieties such as Tifgreen (238) and Tifway (419) have shown considerable resistance.

Cultural Control - Turf Maintenance -

The bermudagrass mite does not do well in short cut turf. This is why the pest is rare on green or tee surfaces. In other areas, however, mowing too short may scalp the turf. Good fertilization and water will help reduce stress and mask mite populations. Mite attacks are seldom damaging during wet periods when bermudagrass is rapidly growing.

Chemical Control - Soft Pesticides -

Though not specifically registered for this pest, some of the insecticidal soaps can be used on turf. Industry reports indicate that these soaps, when used with sufficient water to thoroughly wet the turf grass blades and stems, are effective in controlling turf attacking mites.

Chemical Control - Traditional Pesticides -

Proper identification is needed because water stress can look like early mite damage. A microscope with at least 30 power magnification will be needed to adequately see the mites. Short residual pesticides may have to be reapplied in seven to 10 days to kill mites hatching from eggs.

©1999 - D.Shetlar & H.D. Niemczyk, all rights reserved, do not copy or reproduce by print or electronic means without permission!

For more information contact:

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Wooster, OH 44691

Bermudagrass mite damage - witches-brooming of stems.

Bermudagrass mite damage from a distance may look like patches of irregular growth with turfted stems.

Drawing of bermudagrass mite adult.

Bermudagrass mites and eggs under leaf sheath.