Anthracnose Disease of Carpetgrass (Axonopus compressus) Caused by Colletotrichum hainanense sp. nov.

Abstract

Carpetgrass (Axonopus compressus) is a creeping, stoloniferous, perennial warm-season grass that is adapted to humid tropical and subtropical climates. Recently, outbreaks of anthracnose disease of A. compressus caused by an unidentified Colletotrichum sp. were observed in the Hainan and Guangdong provinces in southern China. In late winter and early spring, the disease incidence reached 100% in some badly infected lawns. Under high-moisture conditions, the crowns and oldest leaf sheaths of the majority of the plants became necrotic, which led to whole lawns turning reddish brown. Pathogenicity was confirmed by inoculating uninfected A. compressus plants with a conidial suspension of the Colletotrichum sp. isolated from diseased Axonopus plants. Phylogenetic analyses of the combined internal transcribed spacer, Sod2, Apn2, and Apn2/Mat1 sequences revealed the pathogen to be a novel species of the Colletotrichum graminicola species complex. Microscopic examination showed that the species was also morphologically distinct from related Colletotrichum species. As a result of the phylogenetic, morphological, and pathogenicity analyses, we propose the name Colletotrichum hainanense for this pathogen of A. compressus in southern China.