Microdochium nivale
Skip to: What is Winter Fusarium? Key Identifying Features of Winter Fusarium, When Does Winter Fusarium Occur? How Can I Help Prevent Winter Fusarium? How Can I Treat Winter Fusarium in My Lawn?
What is Winter Fusarium?
Winter Fusarium is a lawn disease that affects the leaf and stem of the grass. It will first appear as small, orange to dark brown, water-soaked patches on the lawn. Then, once the disease grows, the patches will increase in size and change to a light grey colour.
Winter Fusarium is commonly found on cool-season grasses, such as rye and fescue; however, it can also be observed on warm-season grasses, including couch and kikuyu. This disease affects not only lawns but also other plants, including vegetables, as well as wheat, barley, and oats.
Key Identifying Features of Winter Fusarium
When this disease is first present, it will appear in small patches that look like they are soaked in water. As the disease continues to spread, the colour will change from orange/brown to light grey. When the turf is cut low, the patch can also have a smoke-like ring that occurs on the outer edge.
When condition are wet and cool, you may experience fluffy white mycelium on the edge of the patches. If the affected area receives more direct light, the mycelium can induce spore production. This will create a pink colour along the edge of the diseased patch.
- Appears as orange/brown patches
- Usually 5cm in diameter but can continue to grow to 20cm if left untreated
- Smoke-like rings can appear on the outer edge when grass is cut short
- Patch can look like it is soaked in water
- Mycelium may be present when conditions are wet
When Does Winter Fusarium Occur?
This lawn disease will commonly grow in the cooler months, typically between May to September. This disease can occur when day temperatures are between 7-20 degrees Celsius when the weather is wet and overcast. This disease will also grow when heavy thatch is present, and the soil has high levels of nitrogen and low levels of phosphorus and potassium.
How Can I Help Prevent Winter Fusarium?
There are cultural practices that you can follow to help prevent and control the impact of Winter Fusarium on your lawn. Increasing air circulation within the soil and profile of the grass will assist. You can achieve this by aerating your lawn with either a garden fork or tyne aerator. If the profile of your lawn has a bit of thatch buildup, consider dethatching it in the spring (dethatching should be avoided in winter).
If shade is heavy, pruning back any surrounding trees and shrubs that cast shade on the lawn will assist. This disease prefers Alkaline soils, so ensuring you are maintaining a low soil pH can assist.
How Can I Treat Winter Fusarium in My Lawn?
If this disease has become widespread or is developing and spreading rapidly, you may want to consider using a fungicide. Fungicide options for Winter Fusarium include Tombstone Fungicide, Mancozeb and Heritage Maxx.
When treating this disease, it is important to note that as this disease affects the leaf and stem of the grass and mainly occurs in winter, you may not see recovery straight away after treatment. Often, you will need to wait till spring when active growth resumes so that the disease can fully grow out. Once the grass has been able to fully grow out of the disease, the appearance of the grass will improve.
For more lawn care tips and advice, make sure you check out our other lawn care blogs here.
