Lawn Diseases in Australia

Lawn diseases in Australia can quickly turn a vibrant green yard into a patchy brown eyesore. In Gympie and the Sunshine Coast’s warm, humid climate, fungal and bacterial pathogens thrive under weather extremes and turf stress.

Healthy lawns matter in Australian conditions for cooling, erosion control, recreation and home appeal, so it’s crucial to detect problems early. Signs like yellow, orange or straw-coloured spots, rings or thread-like growths often signal disease rather than pest damage.

Regularly inspecting the grass helps you identify trouble early, because diseases (often fungal in origin) can spread rapidly if unchecked.

How to Identify Lawn Diseases

Distinguishing disease from pests or environmental damage is key. Lawn diseases usually appear as irregular patches, rings or spots of discoloured turf. For example, fungal infections often leave powdery, moldy or thread-like growths on grass blades. In contrast, insect or pet damage tends to chew, bite or disturb the soil.

Turf type also matters: warm-season grasses (couch, buffalo, kikuyu) often show different symptoms than cool-season grasses (ryegrass, fescue). A patchy pattern with dead or rusty-coloured spots is a strong sign of disease, not just drought or nutrient deficiency. Identifying the specific lawn disease can be difficult for homeowners, so when in doubt consider professional turf testing or consultation.

Common Lawn Diseases

Dollar Spot

Symptoms: Small, round straw-coloured spots (2–5 cm across) appear on the lawn, resembling silver coins. Grass blades within each spot often have bleached centers and reddish-brown hourglass-shaped lesions. In the early morning dew, fine white fungal threads may connect the patches.

Conditions: Dollar Spot thrives in mild, humid weather (often spring or autumn evenings ~10–20 °C). It attacks turf under drought stress or low nitrogen (especially weak couch or kikuyu lawns) and areas with heavy thatch. Cool, dewy nights and even slight moisture on leaves favor this fungus.

Prevention & Treatment: Mow at a moderate height and remove excess thatch. Fertilise to maintain balanced growth (avoid nitrogen starvation). Water deeply in the morning so leaves dry by evening. If dollar spot spreads, apply a contact fungicide: for example, a granular or spray treatment with Mancozeb can provide broad control of the fungus. Regular feeding and good aeration will help the lawn recover quickly.

Brown Patch (Rhizoctonia solani)

Symptoms: Large circular or irregular brown patches (often 30 cm to over 1 m across) develop suddenly. The centre may recover as green grass later, while the edges remain a dark tan. On bladed grasses like fescue, a “smoke ring” (dark margin) sometimes outlines patches. Individual leaf sheaths and stems show brown, sunken lesions.

Conditions: Brown Patch erupts in hot, humid weather (daytime >27 °C) with long periods of leaf wetness (rain or irrigation). It’s common in summer after heavy rains or when watering at night. Excessive nitrogen fertilizer in warm weather worsens it, as do poor drainage and dense thatch.

Prevention & Treatment: Improve air flow by pruning nearby plants, and thatch by aerating the lawn. Water lawns early in the day only, to allow drying before night. Avoid heavy nitrogen feeds during the summer months. If patches are large or expanding, a mid-summer fungicide spray may be needed. Products containing systemic or multi-site actives can be effective when applied preventively in warm seasons.

Rust

Symptoms: An orange or reddish-brown dusty coating forms on the grass blades, giving the lawn a rust-coloured appearance. Grass often turns a straw-yellow colour before the rust spores become obvious. Rubbing a lawn shoe or a blade of grass typically releases a puff of rusty-orange dust. Patches of rust-affected turf are irregular and usually extensive in nutrient-poor areas.

Conditions: Rust thrives in cool, dry weather (late spring, autumn) on slow-growing grass. It often signals low soil fertility (especially nitrogen). Rust can occur even after a rain has stopped, because the fungal spores remain on leaves until dry conditions prevail.

Prevention & Treatment: Maintain adequate fertiliser levels so grass is vigorous. Water regularly (in moderation) to prevent drought stress and raise the mowing height. Mechanical aeration reduces stress on roots. Fungicide is rarely needed unless rust severely discolours the lawn; in that case a light application of a general fungicide can suppress the spores until the turf recovers.

Powdery Mildew

Symptoms: Leaves in shaded or dense areas develop a white or gray powdery coating that resembles flour. The mold can cover large patches of turf, and affected grass may eventually yellow and thin out. You may also see powdery growth on the undersides of leaves.

Conditions: Powdery mildew occurs in cool, humid conditions, especially in shade or low light (spring or autumn). It favors slow-growing grasses (fine fescues, bentgrass or neglected bluegrass). Lack of air circulation and persistent leaf moisture allow the mildew to flourish.

Prevention & Treatment: Improve sunlight and ventilation by trimming back overhanging foliage. Avoid excessive irrigation or late-evening watering. Increase mowing height slightly to promote air flow. Some turf farmers recommend raising magnesium levels (e.g. a light Epsom salts drench). If powdery mildew covers the lawn heavily, a fungicide spray such as a DMI product or a broad-spectrum fungicide can clear the infection more quickly.

Slime Mould (Fuligo/Physarum)

Symptoms: Irregular white, yellow, orange or black slimy patches or mats appear on the grass surface. These can be a few inches up to several feet wide. The slime is spongy or foamy; when disturbed it often crumbles into a dark dust of spores. Grass beneath the slime may look matted or bleached but is not actually infected or harmed.

Conditions: Slime molds form when decaying organic matter (thatch, leaves, wood chips) is on the soil surface and the weather is warm and wet. Spring rains or overwatering can trigger them. Importantly, slime mold feeds on surface bacteria in thatch – it does not infect living grass tissues.

Prevention & Treatment: These are cosmetic issues, not true turf diseases. Remove them by simply raking or hosing off the slime (the grass underneath will quickly green up once exposed). To prevent recurrence, keep the lawn clean of excess debris, and improve drainage. No fungicide is needed – healthy lawn culture (airing, watering) is sufficient.

Fairy Ring

Symptoms: Circular or arc-shaped rings appear in the lawn. There are three types: 1) A ring of dark green, over-fertile grass; 2) a ring of dead or brown turf, often with mushrooms or puffballs on the fringe; 3) underground mycelium with no visible ring. In the common Type II, a band of lush, dark green grass outlines a central dead zone.

Conditions: Fairy ring fungi (several basidiomycete species) live on buried wood or thatch and decompose organic matter. They become visible in dry summers (after rains trigger growth). The lush-green ring is caused by nitrogen released from decomposing material, while Type I rings occur when the fungus repels water, killing grass.

Prevention & Treatment: Fairy rings are notoriously hard to eliminate. Core-tine aeration and routine watering inside the ring can break the water-repellent layer. Using a wetting agent may help water penetrate. Feeding the lawn with fertiliser often “masks” the ring by making surrounding grass thicker. Fungicides are generally not very effective, but a preventive fungicide application in spring or summer might suppress spore development. Often the best approach is core-aerating and fertilising regularly to make your lawn robust.

Anthracnose

Symptoms: Irregular dead patches with straw-coloured turf appear, often with ragged, blighted edges. Infected grass may turn a dull bronze or red colour. On close inspection, stems and leaf sheaths may be coated with a dark fungus. Severe cases can cause patchy thinning and dead crowns (small root clumps).

Conditions: Anthracnose is most active in summer heat stress and high humidity. It often hits shaded, compacted lawns (or turf under heavy play). Annual bluegrass (on greens) is particularly susceptible, but anthracnose can attack couch or ryegrass stands under stress. Generally, warm weather after a period of slow growth favors this pathogen.

Prevention & Treatment: Relieve stress by aerating compacted soil and ensuring even moisture. Maintain good fertility (moderate N) and avoid overcrowding. Reduce thatch and mow at a slightly higher height if shade is an issue. Well-tended turf often outgrows mild infections. If necessary, apply a fungicide during peak summer heat. Homeowners can use a broad-spectrum turf fungicide as a preventive spray, though severe cases on fine turf sometimes need specialized products (e.g. DMI or QoI fungicides used by golf course superintendents).

Pythium Blight (Grease Spot)

Symptoms: Scattered grass patches turn very dark brown or black and appear greasy or water-soaked. Affected grass blades wilt and collapse rapidly. In early stages (especially at dawn), you may see white, cobweb-like mycelium around the edges of the spots. These greasy lesions can expand quickly and merge, often following irrigation lines or low spots.

Conditions: Pythium thrives in extremely hot, humid weather (days over 30 °C with warm nights and high humidity). Overwatering (especially at night) and poor drainage also trigger it. It often shows up on cool-season lawns suddenly, but can affect any lawn if conditions are right. Overfertilising with nitrogen and phosphorus can worsen it.

Prevention & Treatment: Water only in the early morning and avoid flooding lawns in summer. Improve soil drainage (aerate and fix low spots). Mow wet grass as little as possible. Pythium blight can devastate lawns overnight, so prompt action is needed. If you spot a greasy patch, discontinue watering, improve airflow (use a leaf blower if dew is heavy), and consider a fungicide. A recommended approach is a curative fungicide (e.g. metalaxyl or mefenoxam for Pythium specifically). Mancozeb can help prevent spread of Pythium blight (it’s listed for turf use on grease spot), so apply it early in an outbreak or as a preventive under high-pressure conditions.

Spring Dead Spot

Symptoms: Circular dead patches (10–40 cm across) appear in spring on warm-season grasses. These dead spots are uniformly brown and sunken relative to surrounding grass. The centre of each patch usually remains dormant while thin, spindly shoots regrow around the edge as the weather warms. Repeatedly, the rings deepen each year.

Conditions: Spring Dead Spot is caused by Ophiosphaerella fungi attacking the roots of bermudagrass (couch). Infection occurs in fall/winter, but symptoms only become obvious in spring as grass breaks dormancy. It’s most severe after cool, wet winters. Contributing factors include high thatch, acidic soil and excessive potassium fertiliser before winter.

Prevention & Treatment: Manage soil nutrition carefully: apply only moderate nitrogen and ensure good calcium levels in late summer/early autumn (lime acidic soil if needed). Power-rake or core-aerate the lawn in late summer to reduce thatch. Some turf managers apply a fungicide injection in fall (on golf courses), but for home lawns this isn’t practical. Recovery requires careful spring care: level out low spots, overseed/patch as grass greens up, and use balanced fertiliser. Heavily infected areas may need replacement sod, but good preventative care can greatly reduce the problem.

Take-All Patch (Root Rot)

Symptoms: Patches of grass die in irregular rings or arcs. Affected turf first turns bright yellow or orange, then tan. You may notice green grass surviving in the center of a ring. On cool-season lawns (fescue, bentgrass), the ring outlines become prominent. Infected turf pulls up easily and has blackened roots.

Conditions: Caused by Gaeumannomyces graminis var. avenae, take-all patch occurs in cool, wet springs on bentgrass, fescue and rye lawns. It is favored by soils with low calcium (pH too low) and by overwatering. Often seen on newly established lawns in newly constructed or reclaimed soils.

Prevention & Treatment: Maintain proper soil pH (neutral to slightly alkaline – lime the lawn if it’s acidic). Ensure good calcium and balanced nutrition (avoid excess phosphorus). Core-aeration helps develop strong roots. Once the disease strikes, cure is difficult – most control is preventive. In high-value turf, some managers apply spring-time fungicide drenches, but for home lawns focus on improving lawn vigor and pH.

Fusarium Patch (Microdochium nivale)

Symptoms: Also called pink patch or pink snow mold. Irregular patches (10–20 cm) of turf turn straw-coloured or pinkish. In wet conditions you may see fine white fungal threads (mycelium) at the patch edges. The fungus often creates small pin-sized orange spores on the leaves during wet cold weather.

Conditions: Fusarium patch occurs in cool, wet weather (early spring or late autumn) when day/night temperatures hover ~8–15 °C. It typically strikes fine turfs (like putting greens) and close-mowed lawns. It can happen on all cool-season grasses (annual bluegrass, fescue, etc.) if conditions are right.

Prevention & Treatment: Increase sunlight and reduce moisture: prune overhead tree branches, improve drainage, and minimize irrigation. Avoid high nitrogen late in fall. For severe problems, a preventive fungicide application (just before the expected cool wet period) can protect turf. Many turf fungicides effective against snow mould (triadimefon, iprodione, etc.) also control Fusarium patch. Mancozeb may suppress it if applied beforehand, but dedicated snow-mould fungicides are more reliable for cool-season lawns.

Red Thread

Symptoms: Irregular patches of grass take on a pinkish or reddish tint. Looking closely, you’ll see fine red or pink threadlike strands (1–2 cm) tangled on the leaf tips and sheaths in early morning. Affected areas often have green grass in the center with a ring of pink straw-colour around. The threads can smear onto shoes or tools as a sticky pink web.

Conditions: Red thread thrives in cool, moist weather (spring and autumn) when the grass is slow-growing. It is most common on fine fescue and perennial ryegrass lawns that lack nitrogen. It does not kill the grass but signals poor fertility.
Prevention & Treatment: Red thread is usually cosmetic. Correct the cause by fertilising with a nitrogen-rich lawn food in spring. Water in the morning only to reduce humidity, and mow at the normal height. Improving drainage helps. The fungus often dies back on its own as conditions change; fungicides are generally unnecessary. If the patches are widespread and unsightly, a single treatment with a general fungicide can help the lawn recover faster.

Leaf Spot & Leaf Blights (Bipolaris, Curvularia, etc.)

Symptoms: Individual grass blades show brown to black oval spots or lesions (often with purple margins). As the spots coalesce, whole leaf blades or tufts can die, leading to large patchy areas of thinning turf. You might see linear streaks on blades (especially on kikuyu and couch) that turn yellow. In high humidity you may observe fungal spores on the leaves.

Conditions: These opportunistic fungi strike in warm, humid conditions (late spring through autumn), especially on heat-stressed or poorly nourished turf. Overwatering and high thatch exacerbate the problem by keeping leaves wet. The pathogens (Bipolaris, Curvularia, Dreschlera species) overwinter in dead grass, so spring/summer outbreaks are common.

Prevention & Treatment: Proper lawn care limits damage: remove clippings from diseased areas, mow frequently (don’t mow low when disease is active), and water properly. Aeration reduces stress on roots. Avoid excess nitrogen in summer; a balanced slow-release fertiliser is best. If large patches develop, apply a broad-spectrum fungicide labeled for leaf spot control.

Downy Mildew (Yellow Tuft)

Symptoms: Small, yellowish spots appear across the lawn, often following the patterns of water flow or drainage. Affected grass grows in dense tufts from a single crown (“witches’-broom” appearance). Blades may have a grayish downy coating on their undersides during wet conditions. Patches of downy mildew often look like light, uneven yellow splotches on the grass.

Conditions: Downy mildew (sometimes called yellow tuft in turf) is caused by water mold fungi (e.g. Sclerophthora). It favors cool, very wet weather (early spring or extended rain periods) and poorly drained soils. It attacks many grass species, especially fine turf like bentgrass. Over-irrigation and shade encourage it.

Prevention & Treatment: Improve drainage and airflow in low-lying areas. Water the lawn judiciously, avoiding waterlogged conditions. Mow a bit higher to reduce shade on the grass. Because this is a water mold, systemic fungicides like metalaxyl/mefenoxam work best. If needed on valuable turf, apply a recommended fungicide before expected moist weather.

Prevention Strategies for Australian Lawns

• Proper watering: Water deeply but infrequently, and only in the early morning. Morning watering gives grass time to dry before nightfall and discourages fungal growth.
• Balanced fertilising: Use a complete turf fertiliser to keep grass vigorous. Diseases like red thread and dollar spot often attack nitrogen-deficient lawns. Avoid excessive nitrogen in summer (which fuels brown patch or Pythium).
• Mowing and aeration: Mow at the correct height for your grass species and avoid scalping. Aerate and dethatch annually to improve drainage and air flow. This controls thatch and surface debris where pathogens (or weeds like Bindii or African lovegrass) can harbor.
• Choosing grass varieties: Select disease-resistant turf types suited to coastal Queensland (for example, certain buffalo or couch cultivars). A hardy variety suffers fewer fungal attacks.
• Professional help: If problems persist, consider calling turf services professionals. Experts can diagnose issues, adjust your lawn care program, and apply treatments safely. Roberts Turf provides lawn care support and advice tailored to Queensland conditions.

Treatment Options

• Cultural control: First, improve lawn care. Adjust irrigation (no overnight watering), fertiliser (correct nutrient balance), and eliminate shade where possible. Raise cutting height slightly to reduce stress. Rake or brush out slime molds and thatch to expose turf to sunlight and air.
• Organic methods: Beneficial practices like composting, organic soil conditioners or microbial inoculants strengthen turf health, making disease attacks less likely. However, these generally help prevent disease rather than cure an active infection.
• Chemical control: Save fungicides as a last resort for severe outbreaks. Preventive applications under high risk conditions (hot, humid weather) can stop diseases early. For example, a broad-spectrum fungicide like Mancozeb is labeled for many turf diseases and can be applied following label directions. Always rotate modes of action and use the product sparingly.
• Spot treatment: If you catch an outbreak early, you may be able to spot-treat with water and gentle cleaning (for slime molds, etc.). Large or recurring problems usually require a full lawn treatment schedule.

Quick Reference Table

FAQs

Q: Are lawn diseases seasonal or year-round? Many common lawn diseases in Australia are seasonal. Warm-season turf pathogens like Spring Dead Spot or Take-All Patch become obvious in spring on couch/bermudagrass. Others like brown patch or Pythium blight peak in the hot, humid summer. Cool-season diseases (pink patch/Fusarium, rust, snow mold) occur in cooler, wetter months. Good year-round care (watering, fertilising, aerating) minimizes disease risks.

Q: How do diseases spread, and can they infect my neighbour’s lawn? Yes – fungi and bacteria can spread to nearby lawns. Wind-blown spores, water runoff, lawn mower clippings, or even pet fur can carry disease into other yards. Quickly removing and destroying infected clippings and treating disease spots (for example, by applying fungicide) helps protect both your lawn and your neighbours’.

Q: How can I tell a disease apart from nutrient deficiency or drought stress? Diseases usually create irregular patches, rings or spots (often with visible mold or threadlike growth). Nutrient deficiencies cause more uniform yellowing of the turf. Drought stress typically results in large, evenly browned areas (the grass feels dry underfoot). If you see orange or rust-colored spores, fuzzy molds or slime, suspect a disease. When unsure, consult a turf expert or extension service for diagnosis.

Q: When should I call professional turf services for lawn disease? If disease patches cover large areas or keep recurring, it’s time to call the pros. Lawn care specialists have experience identifying and treating stubborn outbreaks. Roberts Turf offers comprehensive turf services and expert advice to get your lawn healthy again. Acting early and following professional guidance can save your lawn.

Protect your turf by staying vigilant and following best lawn care practices. Check out our shop for quality fungicides, fertilisers and turf care gear to keep your lawn healthy all year.

Got a question? Just call us—help is always at hand.
Call us today on 07 5478 9438

Visit our turf farms at:

Roberts Turf Supplies Sunshine Coast
520, Chevallum Road,
Chevallum, QLD 4555
https://maps.app.goo.gl/yRud5D78NqBZE1fs6

Roberts Turf Supplies Gympie
54 Wide Bay Hwy
Bellsbridge QLD 4570
https://maps.app.goo.gl/7ChiZSGzjoAPoFMh7