Brown Patch Disease
This disease is not common in the UK or in Ireland but it may be seen regularly across the rest of Europe.
It is caused by the fungus Rhizoctonia solani.
This soil-borne fungus may be found in most rootzones and may, along with other Rhizoctonia spp., commonly cause disease on seedling turf.
Symptoms of this disease will vary depending on the weather conditions and the sward composition as well as the condition of the turf. Generally, close-mown turf will show patches of watersoaked* plants which rapidly increase in diameter from a few centimetres dia. to around 0.5m. Under warm, humid conditions, the affected patches will have what is called a 'smoke ring' around the edge of the affected turf. As the height of the sward increases, the symptoms will appear more like watersoaked*, straw-coloured patches in which the plants are collapsed on top of one another.
Under warm, humid conditions, this disease will progress rapidly across a susceptible sward. Dead plants may well show small (about 1mm dia.) dark brown sclerotia* within the decaying leaf tissues.
*Watersoaked This is a term generally used to describe the appearance of leaf tissue that has become wet-looking, generally darkened and translucent as a result of fungal infection breaking down the internal structure of the leaf.
*Sclerotia These are masses of fungal hyphae which are bound together in hard structures which allow the fungus to survive periods of adverse environmental conditions.