Dong-Geun Kim

Soil Nematode Fauna in Dokdo Island of Korea

Nematode fauna in Dokdo island was investigated for two years between 2008 and 2009. Population density and biomass were 239,500 m 2 (26,000�836,000) and 103.9 mg/m 2 (3.0�388.6), respectively. Total of 31 species of nematodes were identified : Acrobeloides is the most important genus with prominence value (PV) of 117.8, followed by Rhabditidae (PV = 81.9), Prismatolaimus (PV = 39.0), and Aphelenchoides (PV = 31.4). Among feeding group, bacteriovorus nematode composed 77% of density and 62% of biomass followed by plantparasitic and fungivorus nematodes. A species of Pratylenchus having distinctive tail terminus is under study as a new species. Biological indices, Shannon and Wiener index (2.46), Simpson’s diversity index (0.86), Species evenness (0.73), Species richness (1.30) indicate that nematode fauna in Dokdo island is diverse and unique. This study may give a general idea of nematode fauna at the Dokdo island.

Occurrence of Root-knot Nematode on Dendranthema x grandiflorum and Influences on Plant Growth

Over 98％ of Dendranthema x grandiflorum plants growing under a glasshouse in Gumi, Korea were infested with Meloidogyne hapla. Dendranthema x grandiflorum cv, `Ardilo` had fewer eggmass (3.3/g root), followed by cv. `Euro` (6.5), and cv. `Monarisa` had the most eggmasses(17). The coefficient correlation between plant growth and nematode reproduction(number of eggmass per plant) indicated that nematode reduced chlorophyll content in leaf (r

Resistance of Newly Introduced Vegetables to Meloidogyne arenaria and M. incognita in Korea

To select resistant vegetables against two species of root-knot nematodes, M. incognita and M. arenaria, 39 vegetables belongs to 7 families, 13 genera, 25 species were screened in greenhouse pot test. Susceptible vegetables to both nematodes were amarath and leaf beet in Amaranthaceae, Malabar spinach in Basellaceae, Moroheiya in Tiliaceae, and Water-convolvulus in Convolvulaceae, Pak-choi in Brassica campestris var. chinensis, Tah tasai in B. campestris var. narinosa, B. campestris var. chinensis x narinosa, Leaf mustard, Mustard green in B. juncea, Kyona in B. juncea var. laciniate, Choy sum in B. rapa subsp. arachinenesis, Kairan in B. oleracea var. alboglabra, Arugula in Eruca sativa, Garland chrysanthemum in Chrysanthemum coronarium, Endive in Cichorium endivia, Artichoke in Cynara cardunculus var. scolymus, Lettuce in Lactuca sativa. Resistant to M. arenaria but susceptible to M. incognita were B. oleracea cv. Matjjang kale, B. oleracea var. gongyloides cv. Jeok kohlrabi, and C. intybus cv. Radicchio. Resistant vegetables to both nematodes were C. intybus cv. Sugar loaf, Grumoro, Radichio treviso, B. oleracea cv. Manchu collard, Super matjjang, B. oleracea italica, B. oleracea var. botrytis italiana, and Perilla in Lamiaceae. Vegetables resistant to both species of root-knot nematodes could be used as high-valued rotation crops in greenhouses where root-knot nematodes are problem.

Resistance of Commercial Pepper Cultivars to Root-knot Nematodes

Ninety two pepper (Capsicum annuum L.) cultivars were screened for resistance to two common species of root-knot nematodes, Meloidogyne incognita and M. arenaria. All 92 pepper cultivars were resistant to M. arenaria (0-3 eggmass/plant) but were susceptible to M. incognita (76-678 eggmass/plant). Susceptibility to M. incognita were slightly differed; `Geomok` and `Shintaepung` had relatively less eggmass (300 eggmass/plant). Therefore, pepper is highly recommended as a high-valued rotation crop to only those greenhouses infested with M. arenaria, but should restrict for M. incognita.

Primary Inoculum of Strawberry Anthracnose in Nursing Field

This experiment was carried out to investigate the primary inoculum of strawberry anthracnose in nursery field. The pathogen, Colletotrichum gloeosporioides was not detected in soil and weeds of nursery field but symptom of anthracnose was developed in mother plants collected from market after incubation in humid chamber, The symptom of anthracnose was expressed in the strawberry plant that reserved for 17 days in field after inoculation by spore suspension but was not observed there after. When inoculated leaves were observed by SEM, only appressoria were observed 7 days after inoculation. So, it is guessed that dissemination of Colletotrichum sp. into nursery held will be by contamination of mother plants, and diagnosis by naked eyes may be impossible because symptom will be not developed if environment is to be adequate to penetration and in case of imperfect penetration after germination, the pathogen remains appressorium to achieve penetration.

First Report of an Unrecorded Nematode-Trapping Fungus Species Monacrosporium phymatopagum in Korea

A fungus that can capture nematodes by means of sessile adhesive knobs was isolated from rotten wood in Uiseong, Korea. It was found to produce single, spindle-shaped, 3-4 septate (commonly 4-septate) conidia, (range, ) long and (range, ) wide. Conidiophores were found to be hyaline, erect, straight, and high. On the basis of these morphological features, the fungus was identified as Monacrosporium phymatopagum. This is the first report of M. phymatopagum in Korea which can be a potential biological control resource of plant parasitic nematode.

An Unrecorded Species of Nematode-trapping Fungus, Dactylella pseudoclavata in Korea

Dactylella pseudoclavata that captures nematodes in adhesive networks was isolated from nematode-infested strawberry plants from Andong, Korea. It produces obclavate, 0-1 septate conidia, long and wide, with round distal ends and bases shaped like bottle-necks. The conidiophores were simple, occasionally branched, long, producing 1-4 conidia at the apex. Chlamydospores were abundant, intercalary or catenulate, yellowish to brown, globate or subglobate, wart on the surface, in size. This is the first report of Dactylella pseudoclavata in Korea.

Observation of Root-knot Nematodes in the Root Gall Formed on Oriental Melon

Oriental melon, Cucumis melo L. cv. Geumssaragieuncheon, grafted on Shintozoa (Cucurbit maxima Cu. moschata) was planted in a greenhouse infested with Meloidogyne arenaria and root galls were examined five months after planting. A gram of root gall was volumed at ca. 10 cm3 and contained in an average of 363 females (170 developing and 193 matured females), 2,120 secondstage juveniles (J2), and 13,074 eggs. In addition, there was 56 J2 per soil around the infested plant. An oriental melon had an average of 134.6 g of root gall (70% of total root weight) per 0.72 area. In a conservative estimation, an oriental melon plant could accommodate ca. 1.2 eggs and J2 per 0.72 . The eggs contained in root tissues could be an important inoculum source to the next crop and the fate of these eggs are well worth further investigation.

Epidemiology of the Crown Gall (Agrobacterium tumefaciens) of Persimmon Tree

Occurrence and epidemiology of crown gall caused by A. tumefaciens in persimmon tree was investigated. Persimmon tree was more sensitive to crown gall disease than peach and jujube tree. Over 80% persimmon trees were infected to crown gall in all investigated region with no relation to planted years. Yield of infected tree was severely decreased to 54%. Incidence of crown gall in nursery field of persimmon tree was also severe and the infection rate of persimmon seedlings collected from market was 34%. It was guessed that the primary inoculum of crown gall caused by A. tumefaciens is infected persimmon seedlings.

Canker of Pomegranate (Punica granatum) Caused by Botryosphaeria dothidea

Canker farmed on a pomegranate tree(Punica granatum) with yellowing leaves and death of some twigs was founded at a garden of Gyungbuk Agricultural Technology Administration. Botryosphaeria dothidea was isolated from the canker and pathogenisity of the isolate was confirmed by artificial inoculation to the pome-granate twig, which showed the same symptom with naturally infected twig. This is the first report of a natural infection of pomegranate tree by Botryosphaeria dothidea in Korea.