Couch Mite Control in Your Lawn

Until recently there was a bit of confusion around which species of mite the Couch Mite was. There was also little data about how widespread the Couch Mite was in Australia. A scientific study about a decade ago solved all that. The conclusion was that the Couch Mite (Aceria cynodoniensis) is widespread in Australia and it is found in all mainland states.

The Couch Mite is of concern because it is microscopic and hidden away inside the sheaths of couch grass, and therefore, its presence is only made obvious by the damage it causes. That means by the time you see the damage a severe infestation is well under way. Therefore, prevention is key to managing this turf pest. Couch Mite is favoured by hot, dry conditions so make sure your lawn is watered appropriately during those conditions to prevent your lawn becoming stressed.

There is evidence that Couch Mite is spread on grass clippings. Ensure you mow with a catcher and that you compost those clippings. If you don’t, the mites will just walk off the drying lawn clippings and on to the nearest healthy blade of couch grass.

If Couch Mite infestations are common in your area and the preventative measures don’t work, you may need to use a registered pesticide. Try Yates Baythroid Advanced Insect Killer for Lawns. To treat Couch Mites, mix as directed in a garden sprayer or watering can and evenly apply over the lawn. Do not water lawn for at least 24 hours after product application, watering is not essential for product to work for Couch Mite control. Repeat treatment, if necessary. Please see label for full instructions prior to application.

Mites are not insects but are arachnids, related to spiders. Couch Mite is a member of the family Eriophyidae, which are particularly small mites that are difficult to see without high magnification. Couch Mite is widely spread in Australia, as well as many other countries where it is usually known as ‘Bermudagrass Mite’. The origin of Couch Mite is still the subject of debate.

The mouthparts of Couch Mites are so small that they cause very little direct damage while feeding. However, Couch Mites inject plant growth regulators within their saliva into couch grass tissues that inhibits cell growth and leads to distorted new growth.

Another mite that may occur on couch grass, sometimes at the same time as Couch Mite, is the ‘Flat Mite’ or ‘False Spider Mite’ (Dolichotetranychus australianus) of the mite family Tenuipalpidae.

Couch Mite is a tiny eriophyid mite with adult mites measuring between 0.15 mm and 0.2 mm in length.  Nymphs are even smaller, with first stage nymphs being one-third the size of an adult and the second stage nymph being two-thirds the size of an adult.

Adult Couch Mites are torpedo-shaped, translucent whitish-cream in colour, and they only have two pairs of legs at the front end of their bodies (i.e., four legs in total). The adult mites may be visible under a USB digital microscope, but a dissecting microscope with magnification of at least 30x would be a better option.

Couch Mite eggs are spherical, translucent and about 0.06 mm in diameter.

Adults of the Flat Mite Dolichotetranychus australianus are slightly larger than Couch Mites being 0.25 mm to 0.275 mm long. D. australianus mites are flattened elongated mites, reddish-orange coloured, with four pairs of legs at each end of the body (i.e., eight legs in total). D.australianus appears to be as widely distributed in Australia as the Couch Mite.

Couch Mites develop through a life cycle of egg to first instar nymph (protonymph) to second instar nymph (deutonymph) to adult. The life cycle takes from 7 to 14 days depending on the temperature. All stages of the life cycle may be found together between stems and leaf sheaths.

Couch Mites are at their most active and cause most damage during spring and early summer.

Couch Mites may spread on grass clippings, other turf insects, birds and wind.

• Common Couch grass (Cynodon dactylon) and hybrid couch grass (C. dactylon × C. transvaalensis)

• Yellowing of tips, tufted growth (i.e., “witches’ broom” rosetting at runner nodes) and stunting of terminals.
• Stunted terminals fail to grow and recover from the damage, and often die in winter. Damaged stems and stolons do not produce new shoots. Research shows that turf takes a long time to recover from an infestation of Couch Mites.
• Infested turf becomes thin, and bare patches appear.
• Bare patches expand, and join to form large bare patches.
• Weeds may invade bare patches.
• Couch Mite infested turf may be more susceptible turf diseases.
• Damage is usually most severe during hot, dry conditions.
• Damage caused by the Flat Mite Dolichotetranychus australianus is typically seen as compressed “pine tree” like shoot growths off runner nodes rather than the rosetting (i.e., “witches’ broom”) of Couch Mites.

• Look for symptoms such as “witches’ broom”.
• Check areas of thinning turf for further symptoms.

• Ensure your lawn is appropriately watered and fertilised. To grow a healthy, strong lawn, apply Yates Dynamic Lifter Organic Lawn Food. It's a slow release organic based fertiliser with the ingredients of composted manure, Blood and Bone, fishmeal and seaweed that improves the soil and fertilises the lawn. Suitable for use on all lawns, including Buffalo lawns.
• Couch mite may be spread by lawn clippings. If Couch Mite is prevalent in your area try to always mow with a catcher and put your lawn clippings in the compost.
• Use a registered lawn pesticide. Try Yates Baythroid Advanced Insect Killer for Lawns. Follow label directions.

• The natural enemies of Couch Mite in Australia are unknown.