Winter lawn diseases

Author: Stefan Palm   Date Posted: 7 August 2023 

While most lawn diseases are not common 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 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. 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 it 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 with little experience in doing so. Having said that, most have tell-tale characteristics that give them away. If you suspect you 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 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 factors are common to disease?

  • Disease usually becomes apparent quite quickly in your lawn - typically over the course of a day or two. 
  • When present in warm-season lawns such as couch, kikuyu and buffalo, common diseases rarely kill your lawn. In most cases, your lawn will recover. 
  • Disease can occur in combination with other problems, such as poor drainage. Sometimes, it's hard to determine which is doing more damage. 

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 your automatic irrigation is 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 disease-free is by keeping it in tip-top shape. This type of preventative approach includes:

  • Fertilising three 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 are 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, systemic fungicides such as Tombstone Duo are available, once again depending on what type of disease you have. 

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


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