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Couch mites – a turf pest profile

Damage from Couch MiteCausal Agent
Aceria cynodontis (Eriophyes cynodoniensis )

Susceptible turfgrasses  
Common couch, the “Tif” hybrids more resistant

Symptoms
This pest is also in the USA and South Africa where it referred to as Bermudagrass Mite.  Typical symptoms could include:

      – First indication is turf not growing as vigorously as it should in spring, despite adequate irrigation and fertility
      – Leaf tips firstly appear yellow and start rolling
      – Symptoms will progress to shortened internodes with the development of  “witches broom”
      – Will further progress to affected turf areas having clumped appearance, resembling miniature cabbage heads
      – Leaves may die back to stems
      – If not controlled, stems and stolons may die back

Close up of couch miteConditions favouring couch mite
        –  Dry warm weather during spring & summer
        – Turf under stress from irrigation, fertility and heat will recover slower from damage

Life cycle
          1. Over winter in green leaf sheaths
          2. Females start laying eggs in spring
          3. Multiple life cycles per season of only 7-10 days depending on temperature
          4. Can survive temperatures of up to 50ºC
          5. Nymphs and adults will feed under leaf sheaths with mixed populations up to 200 individuals per leaf sheath
          6. All stage primarily spread by clippings

Cultural control
         1. Maintain adequate fertility levels
         2. Counter possible factors contributing to slow turf growth
         3. Reduce mowing height and collect clippings in affected areas

Microscopic photograph of a couch mite (0.2mm)

Chemical control
General – pyrethroids, diazinon
Apply to wet turf or add surfactants to aide with penetration, re-apply 7-10 days later

What to look for
        – Climate – warm and dry (20 – 40ºC)
        – Eye – Retarded turf growth
        – Yellowing, “witches broom” tufty uneven growth patches
        – Lens – Small wormlike mites (0.2 mm) under leaf sheaths of affected plants
        – Management –   Recent history of increased mowing height or no clipping removal

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