Characterization of Three Spp. Causing Wilt Disease of L. in Korea

In July 2021, wilting symptoms were observed in adult and seedling hemp ( L. cv. Cherry Blossom) plants grown in a greenhouse. As the disease progressed, yellowing and wilting symptoms on the leaves developed, resulting in whole plant death. In seedling plants, typical damping-off symptoms were observed. To identify the pathogen, the roots of diseased plants were sampled, surface sterilized, and cultured on potato dextrose agar (PDA) media. From the culture, 4 different fungal isolates were recovered and purely cultured. Each fungal isolate showed distinct growth shapes and color development on malt extract agar, oatmeal agar, sabouraud dextrose agar, and PDA media. Microscopic observation and molecular identification using ribosomal DNA internal transcribed spacer sequencing identified them as 3 spp. and 1 . Additional sequencing of elongation factor 1-alpha and β-tubulin regions of 3 spp. revealed that 2 of them are , and the other one is . To examine which isolate can act as a causal agent of wilt disease of hemp, each isolate was tested for their pathogenicity. In the pathogenicity test, AMCF1 and AMCF2, and AMCF3, but not AMCF4, were able to cause wilting disease in hemp seedlings. Therefore, we report that AMCF1 and AMCF2, and AMCF3 as causal agents of Fusarium wilt of hemp plants. To our knowledge, this is the first report of the wilt disease of L. caused by spp. in Korea.