PEST
 
   NAME
     Couchgrass Mite
     Various Mite Species
 
   ORDER
     Acarina

Description of the Pest
There is a range of mites that cause ‘Witches Broom’ in couch such as (Dolichotetranychus australianus). The microscopic mites have eight-legs. 
They have rasping mouth parts and the mites have a gradual metamorphosis.

Appearance of the Pest
They initially appear in the sheaved base of the leaves but are no normally noticed until the grass forms untidy thickets.

Period of Activity
Most active during hot dry periods, from the tropical to temperate regions, where it may remain active throughout the year.

Susceptible Plants
Turf Grasses are susceptible to several species of Mite such as the Couch Grass Mite (Oolicteranychus austrianusa), Grass Webbing Mites (Oligonychus species) and the microscopic size Eriophyid Mites (Eriophyes species), which forms no web.
Generally the insects attacks the growing tip of the grass causing the plant to be stunted or forming ‘Bunchy Top’ with a proliferation of leaves and yellowing of the foliage. This damage can be severe and the lawn recovers slowly. Infestations are most damaging during summer and the Couch Grass Mite infests Cynodon dactylon (Couch) and Digitaria didactyla (Blue Couch).
 
 Grass Webbing Mites
Image by B. Sonsie

Grass Webbing Mites attacks Cynodon dactylon (Couch), Digitaria didactyla (Blue Couch) and Stenotaphrum secundatum (Buffalo).

Eriophyid Mites (Eriophyes species) attacks Pennisetum clandestinum (Kikuyu) and Agrostis palustris (Bent)

Damage Caused
The insects reduce the internodal spacing and the emerging leaves are closely packed, giving a broom-like appearance. The leaves become mottled then turn brown and die. Runners fail to develop reducing coverage and the infected areas are predominantly along the margins of the lawn, against or over walls.

   Damage on turf

Control
Heavy rain will reduce numbers significantly, as will frequent overhead watering. Cut off and destroy infected areas and promote growth with fertilising and regular watering. 

Chemical Control
Areas may be sprayed with wettable sulphur or dicofol. The mites are well protected and difficult to kill.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.