Dead spots caused by turf mites

Author: Stefan Palm   Date Posted: 6 February 2016 

It is a daily occurrence for customers to come into our shop with some photos and, or a sample of sick looking turf and ask, “why has my grass got these dead patches”.

There are many reasons for dead or dying patches in lawn and one of them is turf mites. While turf mite infestation is not super common in domestic lawns, I have seen it more this year than any other. Experts say that this is due to the drought conditions we have experienced over the past few years.

Turf Mites are microscopic organisms and come from the arachnid class (the same class as spiders and scorpions). They breed quickly, have a short life span and occur in their millions. Mite damage is most common in couch and kikuyu lawns and can have a number of effects on your lawn.

The first noticeable damage often happens in spring when the lawn fails to begin its normal growth in spite of plenty of water and fertiliser. Further from that (and in an effort not to get too technical) the mites sit at the base of the blades of the grass where they attach to the runner (called the stolon) and suck the life from the grass. This results in a stunting effect. The turf noticeably loses its colour in patches and takes on what’s called a “witches broom” effect (see the photo below where you can see the yellow stunted shoots of lawn that resemble witches brooms) and all this can happen in a matter of days. For those who are technically minded, “mites cause a shortening of the internodes and the apparent stimulation of abnormally excessive plant growth. The mites remain hidden under the leaf sheaths and vary in number from a few to a hundred or more under a single sheath. With heavy infestations the grass will turn brown and die.” Eventually the grass, in infested lawns, thins out leaving the lawn susceptible to weed and diseases attack.

Conditions that favour mites are dry warm weather during spring & summer. Turf under stress from irrigation, fertility and heat will recover slower from damage.

So…. “How do I control Turf Mites” I hear you say. One of the best ways is to create an environment that they don’t like. This includes:

  • Making sure your grass is adequately fertilised (ideally 3 times per year)
  • Making sure your grass is adequately watered
  • Making sure you don’t leave clippings on your lawn where mites are a problem

If you are doing all this and still manage to get an outbreak, then chemical control is your only option. Off the shelf chemicals that contain pyrethroids or diazinon are O.K at best at controlling mites. If you don’t have success with these, then the best control method is with products containing abamectin (Thumper). This will need to be sprayed by a professional pest control company.

If you think you have a mite problem or any other problem resulting in your lawn dying, then cut out a core sample and take it down to your lawn specialist for correct identification.

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