<i>Leptosphaerulina</i> species isolated from golf turfgrass in China, with description of <i>L. macrospora</i>, sp. nov.

Leptosphaerulina leaf blight occurs on most turfgrasses. Hitherto, <i>Leptosphaerulina</i> species associated with this disease include <i>L. americana, L. argentinensis, L. australis</i>, and <i>L. trifolii</i>. However, following Koch’s postulates, <i>L. australis</i> was confirmed as saprobes but not pathogens, and the other three species have not been tested. The pathogenicity of <i>Leptosphaerulina</i> spp. is still questionable. In this study, we isolated 19 <i>Leptosphaerulina</i> strains from diseased golf turfgrasses in China, and they were identified as <i>L. gaeumannii, L. saccharicola</i>, and a new species, <i>L. macrospora</i>, through multilocus (ITS, 28S, <i>rpb2</i>, and <i>tub2</i>) phylogenetic analyses and morphological observations. Pathogenicity test revealed that the three <i>Leptosphaerulina</i> species identified in this study cannot infect live/healthy turfgrass tissues of <i>Poa pratensis</i> and <i>Agrostis stolonifera</i> and only produced pseudothecia on the dead leaves of stressed seedlings. Considering the results of pathogenicity tests in this and previous studies, we speculate that most <i>Leptosphaerulina</i> species isolated from diseased turfgrass are not pathogens but saprobes. Applying proper management practices to prevent severe turfgrass stress is a key measure to reduce or eliminate the effects of <i>Leptosphaerulina</i> on golf turfgrass.