Morphological and Molecular Characterization of the Potato Rot Nematode, Ditylenchus destructor, Parasitizing Garlic in Korea

A survey of plant parasitic nematodes was carried out in 650 garlic fields in Korea from 2020 to 2022. Migratory endoparasite nematodes (Ditylenchus sp.) were recovered from 6% of the garlic samples, with an average density of 494 individuals per garlic bulb. The morphological characteristics of males and females from the 2022 survey were very similar to D. destructor, but D. dipsaci was not found. The Korean population traits have a lateral field containing six incisures, and the posterior esophagus part overlaps the intestine dorsally. PCR and DNA sequencing were performed for the D2/D3 region of the ribosomal DNA 28S and the ITS region, and the phylogenetic analysis strongly supports the monophyly of D. destructor. This is the first report of D. destructor parasitizing garlic in the Republic of Korea. In Korea, due to changes in agricultural or environmental conditions, the most damaging potential PPNs changed from D. dipsaci to D. destructor in garlic cultivation.