First report of Rhizoctonia solani AG-4 HG-I causing leaf blight disease on Cattleya x hybrid in Taiwan

Leaves of a Cattleya x hybrid registered in Taichung, Taiwan developed dark-brown necrotic lesions with a yellow halo. Two isolates (CaRh1 and CaRh2) were collected and identified as Rhizoctonia solani AG-4 HG-I based on morphology and molecular characteristics. Leaves of this Cattleya and other orchids (Dendrobium sp., Oncidium sp. and Phalaenopsis sp.) that were wound-inoculated with the two isolates developed dark-brown, slightly sunken necrotic lesions. This is the first report of R. solani AG-4 HG-I causing symptoms on leaves of Cattleya x hybrid in Taiwan.