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

<i>Lycium barbarum</i> L. is an important economic crop in Qinghai province, China. However, root rot seriously reduces the economic results of <i>L. barbarum</i>. Here, we collected the diseased <i>L. barbarum</i> roots from Nuomuhong Farm of Haixi Mongolian and Tibetan Autonomous Prefecture, Qinghai Province, China, to clarify the diversity, pathogenicity, and biological characteristics of its root rot pathogens. A total of 125 isolates were collected, and based on morphological characteristics and rDNA ITS, <i>TEF</i>-<i>1α</i>, and <i>RPB2</i> genes sequence analysis, they were identified as <i>Fusarium equiseti</i>, <i>F. avenaceum</i>, <i>F. solani</i>, <i>F. citri</i>, <i>F. acuminatum</i>, <i>F. culmorum</i>, <i>F. sambucinum</i>, <i>F. incarnatum</i>, <i>F. oxysporum</i>, <i>F. tricinctum</i>, <i>Microdochium bolleyi</i>, and <i>Clonostachys rosea</i>. These fungi were used to inoculate the roots of 1-year-old <i>L. barbarum</i> seedlings using scratching and root-irrigation inoculation methods, and all isolates caused root rot. This is the first report that <i>M. bolleyi</i>, <i>F. avenaceum</i>, and <i>F. citri</i> caused root rot in <i>L. barbarum</i>. And the best media, the lethal temperatures, and the optimum carbon sources and nitrogen sources of the 12 pathogen species were determined in this study. Moreover, our findings provide a theoretical foundation for root rot management in the future.