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Fungal pathogens associated with red-skin root disease of Panax ginseng in Northeast China

Wei Gao: Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences

<div>Red-skin root disease of Asian ginseng (<em>Panax ginseng</em>) is a major problem that significantly reduces the ginseng quality and yield in Northeast China. The disease has been considered as physiological disorders in most of reports but infectious disease in very few studies. In Jun. 2012 and Sep. 2013, a total of 230 fungal isolates were obtained from 206 red-skin root samples collected from 13 commercial fields in 9 counties of 7 cities, in Jilin and Heilongjiang provinces, representing the main ginseng growing areas in China. 151 isolates with <em>Cylindrocarpon</em>-anamorph were identified into 7 species in 2 genera, by using a muti-gene analysis along with morphological characters. The seven species included <em>Dactylonectria </em>sp., <em>D. hordeicola</em>, <em>Ilyonectria mors-panacis</em> <em>I. robusta</em> and 3 unclassified <em>Ilyonectria</em> species. 74 <em>Fusarium</em> isolates were identified into <em>F. acuminatum</em>,<em> F. avenaceum</em>, <em>F. solani </em>and <em>F. torulosum</em>. The rest 5 isolates were <em>Rhexocercosporidium panacis</em>. Among these species, <em>Ilyonectria </em>sp. 1,<em> I. robusta </em>and<em> F. solani </em>were the three commonest species with isolation frequency of 36.1%, 20.9% and 23.9%, respectively, but all of them were weakly aggressive by pathogenicity test on detached 3-year-old ginseng roots using at least 3 isolates for each species. All other species isolated showed pathogenicity on ginseng. The identification of fungal pathogen complex causing red-skin root disease in<em> P. ginseng </em>would help to devise disease control strategies.</div>