Rhizoctoniaspp. causing damping-off, root rot and web blight on coriander in Brazil

Fourteen Rhizoctoniaisolates obtained from coriander plants with symptoms of damping-off and web blight were collected in vegetable production areas between the years 2015 and 2017 in five geographical regions of Brazil. Identification was performed using phylogenetic analysis of the internal transcribed spacer region of ribosomal DNA, evaluation of morphological characteristics and pathogenicity test. Phylogenetic analysis revealed seven isolates belonging to the AG4-HGI group and two isolates to the AG2-2LP group; two isolates of the genus Rhizoctoniadid not group with any anastomosis group, representing a new lineage, and two Waiteasp. isolates and one binucleate isolate grouped with Ceratobasidium ramicola. Based on nuclear staining, thirteen isolates were multinucleated, while one isolate was binucleated. The isolates of Rhizoctoniaproduced irregularly shaped and brown sclerotia, while the Waiteaisolate produced orange sclerotia. In plants the formation of hymenia with the presence of unicellular basidiospores was observed. The basidiospore-producing fungus is represented by the new phylogenetic lineage of Rhizoctonia. All isolates were pathogenic in coriander seedlings, causing damping-off. This is the first report of Rhizoctonia solani(AG4-HGI and AG2-2LP), Waiteasp and C. ramicolain coriander in Brazil.