Latin Name: Colletotrichum cereale
Other Names: Basal rot

Symptoms: Early attacks are easy to spot by the yellow color of individual plants throughout the lawn. The development of the disease depends on temperature and humidity. In wet weather and temperatures below 20°C, irregular yellowish spots of 1-3 cm appear. The youngest affected leaves are often brick-red in color. Root rot may also appear. Affected plants are then easier to pull out and will show black rot at the base of the leaves. Large yellow to reddish-brown spots are visible in wet weather (>25˚C). When diseased plants degenerate, the lawn becomes less dense with bare patches (bare soil). Anthracnose is often seen when the soil is compacted, lacks fertilizers, or is wet.

Hosts: Can attack all lawn species. Annual meadow grass is particularly sensitive.

Periods: From summer to winter, but possible throughout the year.

Latin Name: Several species of bacteria, including the genus Desulfovibrio, cyanobacteria.

Symptoms: Black layer in the root profile of the turf. In an anaerobic environment, this is a biological process, bacteria are involved in reducing sulfates and sulfur into sulfite ions (SO3 2-) which mainly exist in their gaseous form (H2 S). Metallic cations combine with hydrogen sulfide (H2 S) to form a black precipitate composed of acid and sulfite. This black layer is not directly lethal to the turf, but it increases problems with water flow and gas exchange, and above all, indicates the presence of hydrogen sulfide, which prevents the respiration of the root system cells and is toxic.

Hosts: Waterlogged soils and sanding operations without sufficient aeration can promote the formation of black layers by superimposing layers of thatch and sand, making the soil impermeable. Soil asphyxiation favors the organisms responsible for the creation of the black layer. Excess sulfur and certain metals, including iron. Limit sulfate inputs.

Periods: All year round and especially during periods when the soil is excessively wet.

Latin Name: Laetisaria fuciformis/Corticium fuciforme

Other Names: Corticium disease

Symptoms: The attacks become evident with the appearance of small irregular spots of 2-5 cm in pale brown color evolving to straw color. There are often healthy plants among the affected ones. The spots can cover large areas. The fungus then develops the very typical reddish filaments at the tips of the affected leaves. The affected area appears with a typical red hue.

Hosts: All turfgrass species but especially common on perennial ryegrass and red fescue.

Periods: Often present from March to October but can develop throughout the year if conditions are favorable. Favored by humid weather and temperatures of 16-22˚C. Often an indicator of Low nitrogen in the plant.

Latin Name: Microdochium nivale/Fusarium nivale/Gerlachia nivalis
Other Names: Winter Fusarium

Symptoms: The damage caused by the fungus may appear not
only after snow cover, but also in humid conditions with temperatures just above 0°C: spots of 4-6 cm, gray waterlogged plants visible at the beginning of the attack. The spots grow to merge into larger patches. A dark brown edge is often present on the outer edges where the infection is active. Above the affected area, a pink cottony mycelium forms if the humidity is sufficiently high. Late applications of heavy topdressings can promote the disease. The turf regenerates from the center of the spots.

Hosts: Can attack any species of turfgrass, but bentgrasses, annual meadow grass, and perennial ryegrass are particularly sensitive. Cold fusarium is the most important disease on turf.

Periods: Damage is often present during autumn, winter, and after the snow melts in March. Heavy rains can dislodge the spores: the disease follows the flow of water.

Latin Name: Drechslera spp. and Bipolaris spp.
Other Names: Helminthosporiosis

Symptoms: Dark oval or elliptical leaf spots. Depending on the species, the spots are reticulated or more compact and often eye-shaped, allowing identification of this disease. Humidity promotes the development of the disease especially when the sugar content of the leaves is low – during vigorous growth the disease has less impact.In the shade, plants are more sensitive.

Hosts: Perennial ryegrass, red fescues, and annual meadow grass as well as tall fescue are frequently affected by helminthosporiosis.

Periods: Helminthosporiosis is very common on temperate grass species but also on Cynodon dactylon and zoysia. If conditions are favorable, the disease can develop throughout the year and its presence can often further degrade an already mediocre winter appearance.

Latin Name: Sclerotinia homeocarpa

Symptoms: On closely mown turf, the disease appears as small spots 1-2 cm in diameter. Generally, the spots are circular and very distinct, unless the attack is so severe that the spots merge to form larger affected areas. Inside the spots, the grass is discolored, white or straw-colored. Often, a darker border separates the discolored and sunken center from the healthy turf around it.

Hosts: Bentgrasses, Poa sp., fescues, and Zoysia.

Periods: A lack of nitrogen can make plants sensitive. Dormant mycelia become active when both night and daytime temperatures are above 16°C. If the nights are mild and humid, the disease can progress very quickly from spreading in surface wetness.

Latin Name: Sclerophthora macrospora

Symptoms: This disease appears as small, bright-yellow patches, usually 1–3 cm in diameter, consisting of densely tillered plants. Affected plants have shortened, weakened roots and can be easily pulled from the turf surface. The pathogen disrupts crown and root development, producing a tufted, uneven sward. Under prolonged wet conditions, symptoms may expand or coalesce, giving an irregular mottled appearance on closely mown turf.

Hosts: Most common on intensively maintained fine turf, particularly golf and bowling greens. In the UK it is seen mainly on Poa annua and Agrostis spp., though other fine grasses can be affected where soil saturation or restricted aeration occurs.

Periods: Favoured by cool, wet weather in spring and autumn. Outbreaks may also occur in wet summers, especially after sand topdressing, brushing or dragging when moisture persists at the surface.

Latin Name: Typhula incarnata
Other Names: Typhula Blight

Symptoms: The infection spreads rapidly under the snow, where humidity is high and the temperature is around 0°C. Small grey spots become visible when the snow melts. Individual plants dry out and degenerate to form a dry, paper-like structure. If humidity is high, a grey-white mycelium develops. The affected areas are often about 50 cm in diameter. A typical feature of grey mold is the presence of golden-brown sclerotized structures the size of a pinhead. Symptoms are often observed on dried leaves or at the base of the roots. The affected areas rarely die, but regenerate relatively quickly in spring.

Hosts: All turfgrass species, but bentgrasses, annual bluegrass, and perennial ryegrass are particularly sensitive.

Periods: From October until March after the snow.

Latin Name: Pythium spp.
Other Names: Pythium foliar blight / cottony blight / grease spot / Pythium “melting out” and “damping off” on sprouts/seedlings

Symptoms: Pythium can cause damage both to young seedlings (sprouts) and mature plants. Round patches several tens of centimeters in diameter appear during warm and humid periods. The appearance is reminiscent of turf submerged in water and feels greasy to the touch. With high humidity, the mycelium may appear cottony.

On Seedlings:Pythium spp. are among the fungi capable of causing damping-off (attacks on roots and/or aerial parts). Additionally it can occur in heavy seed application rates.

Hosts: All species are susceptible.

Periods: All year round but especially in warm and umid weather.

Latin Name: Marasmius oreades, Scleroderma spp., Hygrophorus spp. etc.

Symptoms: Fairy rings can vary greatly in size: a few centimeters, but they rarely exceed a diameter of 5-10 meters. They are classified according to their appearance:

• Type 1: Forming rings where the turf withers and dies. The ring is bordered on each side by darker, vigorously growing grass. Fungi may be present. A white mycelium is present under the affected plants. In the soil, there is a typical mushroom odor. This type is the most damaging.
• Type 2: Forms rings with vigorously growing grass.
• Type 3: Apparently does not visibly affect the turf but creates mushrooms on the surface.

Hosts: All turfgrass species.

Periods: Once present, the rings generally remain for years.

Latin Name: Puccinia and Uromyces spp.

Symptoms: The onset of the attack is characterised by small light yellow spots on the leaves. The spots enlarge as the fungus develops in the leaves. Then a large number of yellow, brown, or black spores are produced. Their appearance depends on the type of rust. A fine powder or "dust" is often visible on the surface of the leaves when the spores are released. A severe attack gives the turf a yellowish or brownish appearance. The spores are spread by wind, people, and machines. They can quickly travel to other locations. The attack weakens the plants and the turf may thin out.

Hosts: All turfgrass species.

Periods: Mainly from June to September. Rusts develop mainly above 20°C on stressed plants.

Latin Name: Rhizoctonia solani
Other Names: Rhizoctonia blight

Symptoms: Only the leaves are affected, and the turf usually recovers with proper nutrition & adequate moisture. The affected areas appear discolored, with round spots following a purplish-green appearance. On tall fescue, the disease may be uniform, without visible spots. The English term "brown patch" refers to a brown border sometimes present, giving the turf a dried-out appearance, similar to a lack of water.

Hosts: Mainly a problem on tall fescue, amenity ryegrass & creeping bentgrass, but the number of potential hosts is large. Easy propagation using mycelium or sclerotia.

Periods: Especially in summer/autumn in the presence of continuous humidity – hence the importance of starting any irrigation late at night or early in the morning (avoid watering on hot soils).

To Be Avoided: Excess nitrogen fertilisation at the end of spring beginning of summer – however maintain a balanced fertilisation of P & K. Higher sensitivity in the year of sowing.

This is not a fungal or bacterial disease but a physical phenomenon associated with poor degradation of organic matter.

Other Names: Localised Dry Spot (LDS)

Symptoms: Certain areas of the turf, more or less extensive, are
of an appearance similar to a real lack of water. However, the cause is asphyxiation caused by a substrate that has become insufficiently permeable & hydrophobic & by shallow, & weak, rooting. Certain diseases may be present without being responsible for the problem.

Hosts: All species are affected, but more frequently on golf greens due to excessive thatch accumulation caused by insufficient mechanical maintenance, inadequate fertilisation & poor decomposition of organic matter. The turf weakens and degrades easily, leaving bare soil areas.

Periods: From early summer until autumn – but poor aeration will have consequences throughout the year.

Latin Name: Pyricularia oryzae

Symptoms: The spots on the leaves are initially round or oval, light brown with a dark brown border. In humid weather, they become grey  &produce spores. As they spread, they encircle the leaf, leading to the death of the plant. If the disease progresses, it can seriously damage the lawn.

Hosts: All species are affected, but more frequently on tall fescue (Festuca arundinacea) & ryegrass (Lolium perenne).

Periods: When temperatures are between 28 & 32°C, &  there is continuous humidity in the turf for 9 hours, or when temperatures are between 20 & 23°C, & there is continuous humidity for 21-36 hours. The fungus also requires at least 14 hours of uninterrupted leaf moisture to initiate infection. Any factor that increases leaf moisture promotes the development of pyriculariosis.

Latin Name: Sclerotium rolfsii
Other Names: Southern blight / Rolf’s disease

Symptoms: The disease is favored by warm and humid weather, which causes the sclerotia to germinate. The light beige then brown sclerotia, visible during attacks at the base of the plants, are quite large – 1 to 3 mm in diameter. Pale ring-shaped patches of turf quickly appear, often leading to almost total dieback. The sparse regrowth in the center of the patches gives a characteristic appearance of the disease. Presence of whitish mycelium if humidity is high.

Hosts: The disease mainly affects bentgrasses, bluegrasses & sometimes Cynodon spp. However the host range is very broad. Rare in regions with temperatures below 0°C.

Periods: Warm and humid periods. A lawn in poor condition, too thatchy, poorly balanced on soil where excesses & shortages of water alternate, is more vulnerable.