Disease Chart
Here is a list of diseases that trouble South Australian lawns, grass and turf. If you require further help or cannot find the problem troubling you, feel free to bring in a sample to Munns Instant Lawn and we will be happy to assist you.
With over 40 years of experience, we guarantee we can help you out.
You may also be interested to read other articles in our Lawn Care Help section or look at our Lawn Care Products.
Dollar Spot (Sclerotinia homeocarpa)
Diagnosis
Small, straw-coloured patches of turf 2-7cm in diameter.
Management
- Disease is more severe under low nitrogen fertility
- Limit thatch thickness
- Avoid irrigation in late evening and prior to midnight
- Spray with Mancozeb fungicide
Fairy Ring
Diagnosis
Circles or arcs of mushrooms or wilted, dead, or dark green turf. White fungal "mycelium" may be found in the thatch and soil around the circles and arcs.
Management
- There is no fungicide available to kill fairy ring. The fairy ring will eventually grow out.
- Maintain affected area with liquid wetting agent to prevent soil from becoming oily.
Fusarium Patch
Diagnosis
Yellow to brown, irregular shaped patches of turf.
Leaf legions yellow with black centres.
Occurs in warm and wet conditions.
Management
- Disease is more severe under low nitrogen fertility
- Avoid irrigation in late afternoon and prior to midnight
- Reduce irrigation frequency to minimise the time the leaf blades are wet
- Reduce thatch levels
- Apply Greenkeeper fertiliser
- Control fungicides include: TMDG (Thiram) and Mancozeb
Leaf Spot (Helminthosporium)
Diagnosis
Round to oval chocolate-brown spots on leaves.
Spots may have tan centres.
Management
- Avoid irrigation in late afternoon and prior to midnight
- Limit thatch thickness
- Maintain a balanced fertiliser program
- Decrease shade and increase air circulation to enhance drying turf
- Control fungicides include: Mancozeb
Powdery Mildew
Diagnosis
White powdery masses of fungal spores scattered over the surface of lawn blades.
Management
- Disease is more severe under excess nitrogen conditions
- Maintain a balanced fertiliser program
- Control fungicides include: Mancozeb
Brown Patch (Rhyzoctonia Blight)
Diagnosis
Circular patches of brown turf from 25mm to a metre in diameter.
Blades at the margins of the patches have yellow irregular shaped legions with thin brown borders.
Patches are surrounded by smokey coloured ring of mycelium.
Management
- Avoid irrigation in late afternoon and in evening prior to midnight
- Apply sulphate of potash - disease more severe in soils low in potassium
- Limit thatch thickness
- Maintain a balanced fertiliser program
- Control fungicides inc: Mancozeb
Pythium Blight
Diagnosis
Greasy brown patches or turf ranging from 25mm to 100mm.
A distinguishing feature is the grey-white cottony mycelium that can be observed.
Management
- Avoid irrigation in late afternoon and in evening prior to midnight
- Disease is more severe under excess nitrogen conditions
- Improve surface drainage
- Do not mow infected areas when they are wet
- Control fungicides include TMDG (Thiram) liquid
Slime Mould
Diagnosis
Large amounts of these organisms may suddenly appear on grass blades and stems in circular to irregular patches 2-60cm in diameter. The sporangia are typically white, grey or purplish brown but other colours are also possible.
The affected patches of grass do not normally die or turn yellow and the sporangia usually disappears within 1-2 weeks.
Management
Control methods are usually unnecessary because these organisms are more unsightly than harmful. Some fungicides can be used to control slime moulds when they are abundant and become unsightly, simple removal is usually most appropriate:
- Wash the leaves with a stream of water
- Rake or brush slime moulds from leaves