Brown patch disease of Zoysia turfgrass (Zoysia matrella (L.) Merr.) caused by Rhizoctonia solani Kuhn.
Smaller, yellowish brown areas of diseased grass [Zoysia matrella (L) Merr.] were observed scattered in a home garden lawn in Kandy District (Central Province) of Sri Lanka. There was also a ring of brown grass and whitish aerial mycelium grown in between foliage and runners, boarding a greenish area. The ring, referred to as 'smoky ring', could be recognized from a distance during early morning hours of certain dry days. The upper half of the affected leaves was reddish brown and necrotic and separated from the greenish lower portion by a thin, dark brown and wavy band. From the symptoms, the pattern of symptom development in the field and the identity of the pathogen, the disease was diagnosed as the brown patch. The causal organism, isolated on PDA, was identified as Rhizoctonia solani Kuhn. A similar condition was also observed later in a turf in Digana area in the same District. Whitish sporophores of an epiphytic slime mould (Order Physarales) were observed on the surface of grass leaves which did not appear to have a role in the disease. Though the brown patch caused by R. solani is a common disease in turfgrass all over the world, this appears to be the first report in Sri Lanka.