Powdery Mildew

A fungal disease caused by Erysiphe graminis. It should not cause much concern, being more of a superficial disease which produces a white to light grey dusting of spores on infected grass leaves. These can turn yellowish where the dusting is dense as the disease obtains nutrients from the leaves, and the sward density can also be thinned, although it is more prevalent on longer rather than shorter turf. It can often appear during dry periods, especially high humidity presence amongst the leaves, during the main growing season. It is more prevalent on grass under shaded conditions and where

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  Pre-emergence Damping Off

A grass seed which has germinated but no leaf has emerged, and the seed then rots. Common fungal pathogens are Fusarium spp, Pythium spp, Dreschlera spp, and Rhizoctonia spp. This condition is sometimes just called Seed Rot although there is a technical difference as to whether the seed has germinated and not emerged or just not germinated at all (which is the formal definition of Seed Rot), but for practical purposes pre-emergence damping off can be called seed rot. An increased likelihood of this damping off occurring is due to sowing seed at the wrong time of year, especially when it

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  Pustule

A raised spot on a plant, often due to fungal infection in turfgrasses, which can burst producing spores to spread the disease further.

  Pythium Diseases

A range of fungal Pythium species causing severe damage to cool season (including Annual and Perennial Ryegrass, Browntop Bent, Creeping Bent, Annual Meadow Grass, and more) and warm season turfgrasses (especially Manila Zoysia Grass). Infected turf can be susceptible to the following types of attack: • Pythium Seed Rot (non-germinating seed rotting away); • Pythium Blight (most common for new seedlings; also called damping off); • Pythium Root Rot (wet soil conditions, with roots rotting away). Pythium is a common cause of damping off and seed rot, so can be particularly prevalent at seeding and germination times.

  Red Thread

An easily recognised disease of turfgrass, due to its distinct red needles which are present on infected leaves. It is a common disease of Slender and Strong Creeping Red fescues and Perennial ryegrass, although it is a cosmetic disease and turf will readily recover with physical and cultural controls. It is prone to attack turf that is lacking in vigour, is stressed and nutritionally poor, especially where Nitrogen is lacking, typically attacking in mid to late summer, through to early autumn.

  Rhizoctonia Diseases

A range of fungal diseases which affect warm season, as well as cool season turfgrasses. The main cool season disease is Brown Patch; whilst for warm season turfgrasses, especially Zoysia Grasses, and besides R. solani (which can have the common name of Large Patch for some warm season attacks), other Rhizoctonia species can be a problem: Leaf Spot (R. zeae); Sheath Spot (R. oryzae) and Yellow Patch (R. cerealis).

  Rust

A term used to describe a range of fungal organisms which cause this disease, although it should not be cause for major concern in the UK as good turfcultural practices should be adequate to prevent or at least limit any damage from rusts. Puccinia species are the main cause of a yellowing of a leaf along with a subsequent orange-brown rusty colour on the leaf, with an irregular arrangement of small bumps (pustules) on the leaf consisting of dusty-powdery spores.

  Seed Rot

Sown grass seed has failed to germinate and the seed decays and rots. This is often termed Pre-emergence Damping Off, although for that definition the distinction is that germination has occurred, but the leaf has failed to emerge. An increased likelihood of seed rot is due to poor seed bed preparation, using old grass seed, sowing seed at the wrong time of year, especially when it is wet and cold, and when surface drainage is poor or rainfall continuous. the soil retains a lot of moisture keeping the soil surface wet. To reduce the chance of seed rot aim to produce a well-prepared seed

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  Seedling Diseases

A general term that relates to disease attacking a grass seed at different stages. 1. Seed rot, when the seed has not germinated and has rotted away. 2. Pre-emergence damping off, where internal germination has begun, but is not it has then been attacked by disease and dies off. 3. Post-emergence damping off, where young leaves have appeared but are then attacked and killed by a disease. High humidity, surface moisture, lack of air flow, shade, high seeding rates and a poorly prepared seed bed all contribute to increasing the likelihood of an attack by a seedling disease.

  Take-All Patch

A name for a destructive disease of bent grass species, killing the grass roots and crown. Its scientific name is Gaumannomyces graminis. This disease might, but not often, also be referred to by its older common name of Ophiobolus patch disease, or just Ophiobolus. Its former scientific name was Ophiobolus graminis.