Bermudagrass Scale

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Mature bermudagrass scales on stolon.
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Bermudagrass scale damage can look like drought, disease or other maladies!
  • Scientific Name: Odonaspis ruthae Kotinsky. [Phylum Arthropoda: Class Insecta: Order Homoptera: Family Diaspididae]


  • Common Names: bermudagrass scale


  • Climatic Zone: topical and subtropical


  • Geographic Distribution: Worldwide, where its hosts, mainly Cynodon is cultivated. In the United States, this scale attacks bermudagrass from California to Florida. It is also known from Hawaii.


  • Damaging Stage: nymphs and adults


  • Hosts: This scale is most frequently reported on bermudagrass, Cynodon dactylon (L.), though it has been found on centipedegrass, Eremochloa ophiuroides (Munro.) Hack, bahiagrass Paspalum notatum Flugge, St. Augustinegrass, Stenotaphrum secundatum (Walt.) Kuntz, and tall fescue Festuca arundinacea Schreb.


  • Damage Symptoms: Bermudagrass first appears to grow slowly and has a yellow color. This often looks like drought stress. Heavy infestations may dramatically thin and kill patches of bermudagrass. This type of damage is more evident during periods of hot, dry weather. Where bermudagrass enters winter dormancy, this scale can cause a delay in the spring green up.


  • Description of Stages: This is a typical armored scale which lays eggs and has winged male stages.

Eggs: The elongate oval eggs are pink to light burgundy-colored and are located within the female shell.

Crawlers: The eggs hatch into a first instar nymph called a crawler. This stage is pink and the body is very flat and oval. They have short legs, antennae and eye spots.

Settled Nymphs: Settled crawlers begin to produce an oval, waxy test (shell) which is first straw yellow and then covered with white waxy secretions.

Adults: Adult females have shells, or tests, which are egg-shaped or oval in outline and 3/64 to 1/16-inch (1.0-1.75mm) long. Often, there is a straw yellow area, the exuvium, near the larger end. The actual female body, inside the test, is oval and pinkish in color. Male scale tests are about one-half the size of females. The males are able to emerge from their test and are small gnat-like insects with one pair of wings. Their yellowish-pink bodies are about 1/50-inch (0.5mm) long and have two or three long white waxy threads arising from the tip of the abdomen.


  • Life Cycle and Habits:

Little is known about the actual time periods needed for development of this scale. Most studies have attempted to assess development by counting the numbers of different stages at various times of the year. From these studies, it appears that the bermudagrass scale may have two overlapping generations per year in the southern states. In Georgia and Florida, eggs are laid and crawlers are most active in the spring rainy season. Settled crawlers and adults can be found during much of the season, though little growth occurs during winter dormancy or during summer drought periods. It is suspected that this scale has continuous generations in warmer climates where the bermudagrass does not go dormant. The eggs are laid and retained inside the female scale test. As the eggs hatch over several weeks, the tiny crawlers move along the stolons and lower grass stems. They prefer to settle under old leaf sheaths at the bases of crowns, but they may be found anywhere on the stolons and lower stems. Often, large numbers of settled crawlers and young adults can be found on stems and stolons in the soil or thatch layer. Rarely are the scales exposed on upper plant parts. As the settled scales grow, they begin to cover the body with loose waxy filaments which eventually give way to the formation of a solid, waxy shell-like test. At maturity, the scales often extend slightly from under the old leaf sheaths which originally hid the body. Populations can be so large at nodes and crowns that the scales seem to be stacked on top of each other.


  • Control Approaches: At present, no biological controls are known for this pest. Undoubtedly, small predators take their toll on the crawlers but this has not been confirmed. Insecticide treatments have not been very successful in controlling this pest and none are currently registered for this purpose. Since eggs and crawlers may be present over extended periods, timed applications for crawlers are difficult to make. Damage assessment and control thresholds are not developed for this pest. However, when 30-40% of the turf shows yellowing from this pest, control procedures are probably warranted.

Cultural Control - Water and Fertilize Turf - Bermudagrass that is well fertilized and watered, generally can outgrow this pest. However, damage can begin to appear if irrigation must be discontinued in the summer.

Chemical Control - Traditional Insecticides - No insecticides are specifically registered for this pest, but systemic insecticides known to control armored scales may be effective against this scale.

Monitoring

When yellowed turf is encountered, the scale should be sampled for by digging out several affected stolons with attached above ground stems. Inspect the nodes and bases of the stems for the oval, white scales. If the scale is confirmed, a sampling program should be followed. 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 cut into three foot long segments and two are cut into 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 monofiliment 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 yellowing from scale activity. Each ft2 with yellowed turf is counted as one. Fairways and roughs should be sampled every 50 yards and four hoop samples should be taken for each green and apron. Tees should have two hoop samples. When presence of the scale activity is noted, samples should be taken every two months. If the activity is increasing and exceeds four ft2 grids per 10 sampled, chemical controls are probably warranted. Below four ft2 grids per 10 sampled, cultural controls should be used.