Identification of Diseases in Sports turf Andrew Wight

Understanding fungal diseases Fungi, diverse groups of either single-celled or multicellular organisms that obtain food by direct absorption of nutrients. Some of these fungi are parasitic (feed on living matter) and cause serious plant diseases. Most fungi reproduce by spores, which are tiny particles of protoplasm. The common mushroom may form 12 billion or more spores on its fruiting body; the giant puffball may produce several trillion. These spores can be spread by the wind, machinery, people’s feet etc. The spores and the fungi themselves can remain inactive in the soil for long periods until conditions are suitable for fungal growth. It is for this reason that fungal attacks can suddenly appear in turf grass swards

Sports turf diseases Diseases come in 3 types Fungi Bacteria Viral But in the UK nearly all grass diseases are caused by fungi

Disease Triangle Host (Grass Plant) Pathogen Environment (Disease that attacks grass) (Where grass lives)

Common UK sports turf diseases 1) Fusarium patch 2) Red thread 3) Anthracnose 4) Take-all patch 5) Leaf spot 6) Rust 7) Fairy rings 8) Grey snow mould

Fusarium Patch Occurs in cool, wet humid conditions Orange/brown spots start at 3cm Grows to 10cm with outer edge dark brown when active Causing factors Too much Nitrogen fertiliser Shade Heavy dew Poor drainage High thatch content Poa annua is very susceptible

Cultural control of fusarium The best defence against Fusarium Patch Disease is to have healthy turf. This means considering the growing environment that the turf is living within throughout the seasons. Provision of light, air, food and water are essential for a healthy sward. Fusarium, like most fungi, relishes damp, enclosed, still, and low light conditions. If it is possible to improve any of these factors this will aid disease resistance in the future. An appropriate maintenance regime should be followed, including correct mowing, scarification, feeding, weeding and aeration.

Red Thread Occurs in mild, damp conditions Causes Low nitrogen levels Symptoms Long thin red needles in patches of bleached straw like turf Crown rarely infected so doesn’t kill grass Control Applications of nitrogen fertiliser if appropriate for time of the year will help control the symptoms

Anthracnose basal rot Symptoms – discolored turf rotting of base of plant Yellowing of youngest leaf Occurs in Cool wet conditions Likes compacted wet root zones that have low fertility Control Improve surface drainage Reduce any shade Reduce annual meadow grass content of sward

Take all Patch Occurs in summer/autumn months in warm, dry weather Symptoms Patches/rings up to 30cm Bent grass mainly affected (often weeds and unaffected fescue can be seen in the affected areas). Small black needles (fruiting bodies of fungus) 1mm long can sometimes be seen on the leaf Control Over-seed areas with fescue grasses that are not affected by the disease.

Dollar Spot The disease shows as 2 to 4 cm diameter bleached spots which do not increase much in size but which do coalesce to form large areas of bleached turf. Dollar spot can develop either during late spring/early summer or late autumn but more severe outbreaks appear to develop in the autumn. Drought-stressed turf is particularly susceptible to infection but high humidity or heavy dew are necessary for disease development. High daytime temperatures and low night time temperatures, when combined with the presence of heavy dew, are ideal conditions for this disease. Turf grass grown under low nitrogen nutrition is more susceptible to dollar spot but root zone pH does not appear to influence susceptibility. Removal of dew is essential to minimise the chance of infection. Adequate nitrogen nutrition is critical both to minimise the onset of the disease and also to aid recovery of an affected sward.

Snow Mould Snow mould damage looks like circular patches (3"-12") of dead and matted grass. Depending on the severity of the outbreak, the circles can coalesce and become a large mass. Snow mould is a fungal disease that appears in the early spring as the snow melts. There are two types of snow mould. Grey snow mould (also known as Typhula blight) and pink snow mould (sometimes referred to as Fusarium patch). Pink snow mould infects the crown of the plant and can cause more severe injury than grey snow mould which only infects the leaf tissue. Prevention Avoid excessive nitrogen fertilizers in the autumn Reduce thatch levels

Type 1 Fairy Ring Symptoms Ring of dead grass sometimes with mushrooms present. Cause- the fungi in the fairy ring produce a waxy substance that coats the soil particles in the affected area reducing the amount of water that can enter the soil. This weakens the grass and the fungi attack and break down the weakened grass. The bright green grass on either side of the dead ring is caused by nutrients been released as the fungi break down organic matter. Control Wetting agents can help reduce the impact but to control the issue an approved fungicide must be used. Attempts can be made to remove affected soil by digging out the ring but this is rarely successful.

Leaf spot Occurs in mild, wet conditions Affects mainly Poa grasses but can affect Bents, Rye and Fescue Leaf tissue has red spots Attacks stressed areas of turf first Causes Nutrient deficiencies Cool / warm temperatures Moist / wet surfaces Over feeding with Nitrogen (creating lush growth) Over watering Close mowing Shade Poor air movement Susceptible grass species High soil pH

Rust Symptoms Orange lesions on leaf Cause – one of the main cause is under nourished turf. Doesn’t necessarily kill grass, but is unsightly and can stain players clothing Rust Disease tends to be present on Rye Grasses and Smooth Stalked Meadow Grass. It can be a problem on football pitches due to Rye grass content. Control is not normally required unless outbreak is severe in which case an approved fungicide should be applied. In addition correct fertiliser applications will help avoid the disease

Conditions that encourage diseases 1) Extremes of temperature 2) Unsuitable pH 3) Shade 4) Nutrient imbalance 5) Moisture (wetness of surface) 6) Soil condition (compaction) 7) Grass susceptibility 8) Humid conditions (dew) 9) Depth of thatch

Methods of controlling diseases 1) Suitable pH in soil 2) Improve light (reduce shade) 3) Improve air circulation 4) Aeration – improve root growth and drainage 5) Control thatch levels 6) Remove surface moisture 7) Discourage Annual Meadow grass 8) Correct level of fertiliser application 9) Reduce grass stress (correct mowing, scarifying etc.) 10) Use a suitable fungicide control