Diversity, Pathogenicity, and Biological Characteristics of Root Rot Pathogens from Lycium barbarum L. in Qinghai Province, China

Lycium barbarum L. is an important economic crop in Qinghai province, China. Howev-er, root rot seriously reduces the economic results of L. barbarum. Here, we collected the diseased L. barbarum roots from Nuomuhong Farm of Haixi Mongolian and Tibetan Autonomous Prefecture, Qinghai Province, China, to clarify the diversity, pathogenic-ity, and biological characteristics of its root rot pathogens. A total of 125 isolates were collected, and based on morphological characteristics and rDNA-ITS, TEF-1α, and RPB2 gene sequence analysis, they were identified as Fusarium equiseti, F. avenaceum, F. solani, F. citri, F. acuminatum, F. culmorum, F. sambucinum, F. incarnatum, F. oxysporum, F. tricinctum, Microdochium bolleyi, and Clonostachys rosea. These fungi were used to inocu-late the roots of 1-year-old L. barbarum seedlings using scratching and root-irrigation inoculation methods, and all isolates caused root rot. The lethal temperatures were 50°C for F. acuminatum, F. sambucinum, and F. culmorum; 55°C for F. equiseti, C. rosea, M. bolleyi, F. avenaceum, F. citri, F. incarnatum, and F. tricinctum; and 65°C for F. solani, and F. oxysporum. The best media for the 12 pathogen species were potato dextrose agar, mung bean soup culture, and carnation leaf piece agar. The optimum carbon sources were sucrose, dextrin, and soluble starch, and the optimum nitrogen sources were beef extract, peptone, and yeast extract. This is the first report that M. bolleyi, F. avenaceum, and F. citri cause root rot in L. barbarum. Moreover, our findings provide a theoretical foundation for root rot management in the future.