Turf Yellowing Disease in Paspalum vaginatum (Turf Grass): Identification of Causative pathogen and Chemical Control

Symptoms of an unknown foliar yellowing have been observed in Paspalum vaginatum in Kandy District of Sri Lanka since 2013. Affected leaves initially exhibit yellowing of leaves followed by browning downwards from the leaf tip. Since there is no previous record of the disease in Sri Lanka, no control measures have been established. Thus, the aim of this study was to isolate and identify the causal agent of turf yellowing disease in commercial turfs in Mawanella, Peradeniya and Kandy area Sri Lanka and to evaluate the efficacy of available fungicides against pathogen. Pathogens were isolated from infected P. vaginatum and identified using macroscopic and microscopic features and concluded that the disease found in P. vaginatum was caused by Curvularia trifolii. Effect of synthetic fungicide Captan, Chlorothalonil and Sulphur against the isolates was tested both in-vitro and in-vivo conditions. The isolates was consistently reisolated from diseased grasses, but not from health controls, demonstrating that the isolates was pathogenic to turf grass. The effects of all concentrations of all the fungicides used (except Sulphur in recommend dose) with regards to mycelia growth were significantly (p=0.05) different from the control. The highest concentration of Captan (40 mg/10 ml) and recommend dose of Chlorothalonil (30μl/10ml) was the most efficient fungicide against C. trifolii. In-vitro and in-vivo respectively. The present study concludes and Chlorothalonil was the most effective among the tested fungicides for the control of C. trifolii causing the turf yellowing disease in field condition.