Winter lawn diseases

Author: Stefan Palm   Date Posted: 5 July 2022 

While most lawn diseases are not prevalent during Winter, if you have brown, irregular patches in your lawn that you can't explain, you may have a fungal problem.

Lawn diseases are often caused by fungal strains and can cause significant amounts of damage to your lawn.  Most present themselves as dead and dying patches. The problem with diagnosing with those symptoms alone is that most lawn problems present as dead and dying patches making it difficult for home gardeners to tell if disease is a problem or not. Fungal diseases are uncommon in domestic lawns, and even more uncommon in winter. It isn't unusual to see dead and dying patches in lawns during winter, however it's far more likely that they are caused by other factors such as:

  • Poor drainage
  • Untreated beetle problems from Autumn
  • Thatchy lawns that have been scalped
  • Pet damage
  • Overuse

While it's easy to attribute patchiness to disease and treat accordingly, in doing so, you may overlook a more likely problem and then be surprised when the problem persists. It can be difficult to diagnose disease in turf, especially for home gardeners who have little experience in doing so. Having said that, most have tell-tale characteristics that give them away. If you suspect that you do have a winter fungal disease,  it's best to get the problem diagnosed by a lawn specialist.

Types of fungal diseases you may see during winter.

One type of disease you could see is winter fusarium (pictured here). It can be found in both warm and cool season grasses such as rye, fescue, bluegrass and kikuyu. It usually starts as a small patch about 5cm in diameter and can enlarge into patches 20cm in size or even larger at times. They start out in colour as orange-brown and then decline into a grey colour. This disease favours cool, wet environments where the soil is soaked for long periods of time. A smoke-coloured ring may be present around the outside of the patch. Another disease is root decline. This disease exists as a root pathogen and can be found in most warm season varieties, especially couch. It results in patches of thinning turf up to 1m in diameter that can take on a straw-like appearance. There are other less likely types too. Look for irregular patches in your lawn that appear and spread quickly. Sometimes you'll see powdery substances on the surface in the thatch of the lawn, other times if you look closely you may see coloured rings around the outside of the patches and brown legions or spots on the blades of the lawn. 

What conditions promote disease?

To see disease during winter, you may have some drainage issues. Check to see that water is draining freely away from your lawn and that you have all of your automatic irrigation turned off. Other adverse conditions include soil compaction,  excessive shade, over fertilising and incorrect pH.  

How do you treat disease?

The best way to ensure your lawn stays free from disease is by keeping it in tip-top shape. This type of preventative approach includes:

  • Fertilising 3 times per year (spring, summer and autumn)
  • Managing water properly. For example, watering properly in the warm seasons and ensuring that your soil drains freely in the winter.
  • Ensuring your soil is pH neutral or as close to this as possible.  
  • Managing soil compaction. If your soil is prone to compaction, consider coring and top dressing. The best time to do this is early Spring
  • Managing thatch levels. Fungal disease thrives in lawns that are kept very short and when there is excessive thatch. For warm season grasses such as couch, kikuyu and buffalo, maintain a healthy layer of thatch

In doing this, you'll maintain a healthy lawn that will resist attack and an environment that funguses don't really like growing in! If you're doing all of this and still manage to get some disease, there are chemical treatments available. As I mentioned earlier, if you suspect you have some disease issues, have them diagnosed by a lawn specialist so that the right chemical treatment can be recommended. When you know that your lawn areas are susceptible to fungal disease or is even in the early stages of an outbreak, you can use products such as Mancozeb DF as a protectant. It helps stop the disease from spreading. For more serious issues, there are systemic fungicides available such as Tombstone Duo, once again depending on what type of disease you have. I'd recommend you have these applied for you though by an expert rather than attempting this yourself.

As always, if you have a problem you can't solve, reach out to me at or give our team a call on 8298 0555. We're always happy to help. 


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