The root-lesion nematode, Pratylenchus subpenetrans, on ginseng (Panax ginseng) in Korea

Abstract

Nematology , 2006, Vol. 8(4), 637-639 Short communication The root-lesion nematode, Pratylenchus subpenetrans , on ginseng (Panax ginseng) in Korea Jeong Ho K I M 1 , 2 , Yong Ho J EON 1 , 3 , Hoon P ARK 4 , Byung-Dae L EE 5 , Dae-Hui C HO 3 , Byung-Yong P ARK 6 , Zakaullah K HAN 1 and Young Ho K I M 1 , ∗ Korean ginseng (Panax ginseng C.A. Meyer), is a deciduous perennial plant belonging to the Araliaceae family and is cultivated mostly in Korea and China. Ginseng root is highly prized for its medicinal properties and, in addition to the root itself, is made into many different kinds of products, including powder, extracts, tablets, capsules, tea, tonic drinks and cosmetics. Ginseng is cultivated under shade for 4-6 years for commercial use, growing for about 1 year in the nursery and the remainder in the field. Initially, ginseng cultivation in Korea was exclusively confined to some mountainous areas where summer temperatures were cooler. However, cultivation has now been extended to lowland areas with the aid of improved cultural techniques such as growing the crop in raised beds. Today, ginseng is grown throughout Korea, the total area of ginseng production in South Korea being ca 13 000 ha (Ministry of Agriculture and Forestry, 2006). Contamination of soil with nematodes and other pests, together with physical and chemical properties of the land, need to be considered for proper site selection. In Korea there is limited information available regarding the nature and extent of nematode disease problems in ginseng. Root-knot nematode Meloidogyne hapla Chitwood, 1949 and potato rot nematode Ditylenchus destructor Thorne, 1945 have been found occurring commonly in ginseng fields (Choi, 1976), the latter being responsible for the root-rot disease of ginseng (Ohh et al ., 1983). Although the root-lesion nematode, Pratylenchus penetrans (Cobb, 1 Department of Agricultural Biotechnology and Center for Plant Molecular Genetics and Breeding Research, Seoul National University, Seoul 151-921, Korea 2 Korea Turfgrass Institute, Subsidiary of Korea Golf Course Business Association, Sungnam 463-840, Korea 3 Agro-tech Research Group, KTG revised: 22 May 2006 Accepted for publication: 23 May 2006 Keywords: histopathology, host record, plant-parasitic nematode, symptomatology. 1917) Filipjev & Schuurmans Stekhoven, 1941, has been found in Korean ginseng fields (Chung et al ., 2004), P. subpenetrans Taylor & Jenkins, 1957 has not previously been isolated from ginseng root and this species is reported herein for the first time from Korea. Severe root damage caused by P. subpenetrans was found on ginseng seedlings in beds (1-year-old ginseng fields) at Anseong and Punggi in Gyeonggi and Gyeong- buk provinces, respectively, the major ginseng cultivation areas of Korea. The disease incidence varied from field to field with from 50-100% plants infested by P. subpene- trans . The typical symptoms observed took the form of le- sions on the main root of 1-year-old seedlings, the lesions being sunken and the roots constricted in places (Fig. 1C, D). Sometimes, severe constrictions occurred at several sites on a single root, producing a bead-like appearance. The lower portion of severely rotted roots was sometimes missing. Initially, above-ground symptoms were not dis- tinct, but leaf discoloration was noticed around late June in fields with damaged plants (Fig. 1A, B). Slight wilting occurred in severely damaged plots. Pratylenchus subpenetrans was found in all the dis- eased root tissues (Fig. 2A, B). Sunken or constricted le- sions usually contained no nematodes, inner root tissues being necrotic but surrounded by the natural periderm layer (Fig. 2C, D). This suggests that secondary (lateral) growth had been inhibited by the nematode infection. In late autumn or early winter, hundreds of nematodes were © Koninklijke Brill NV, Leiden, 2006 637 Also available online - www.brill.nl/nemy