• Research in Plant Disease
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• v.25 no.3
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• pp.124-130
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• 2019

The study was conducted to investigate the infestation and distribution of plant-parasitic nematodes on Chinese yam (Dioscorea batatas) in Andong, Korea. Root-knot nematodes, Meloidogyne incognita was the most prevalent nematode species which is found from 43 yam fields (81.1%) with high population densities (average of 450 juveniles/$300cm^3$). Other nematodes, root-lesion nematode (Pratylenchus spp.) and pin nematode (Paratylenchus spp.) were less problematic. Density of juveniles (J2) of M. incognita was $10\;J2/300cm^3$ by August, then increased to 274 in September and 624 in October. The highest J2 density was found at the soil depth between 40 and 50 cm ($1,840\;J2/300cm^3$). M. incognita was able to infest yam tuber down to a depth of 70 cm and developed galls outside and brown spots inside. The highest number of females were found at 40-50 cm (79 females/10 cm piece) tuber from the top.

• The Korean Journal of Pesticide Science
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• v.20 no.4
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• pp.375-379
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• 2016

This study investigated the decomposing activities on gelatin and egg sac of root-knot nematode (Meloidogyne incognita). Ten Bacillus isolates (KRB-1~10) isolated from the soils of Mt. Naejang. Among them, KRB-5, 9, and 10 showed decomposing activities, and identified as Bacillus subtilis KRB-5, Bacillus amyloliquefaciens KRB-9, and KRB-10 by 16S rRNA sequence analysis, respectively. Under pot experiments using pepper, 100-fold diluted culture broth of three isolates reduced the number of egg sac on roots collected 60 days and 90 days and increased the growth of aerial part compared with the group only treated with Meloidogyne incognita. Especially, the group treated B. subtilis KRB-5 was superior in the growth of pepper. These results suggest that the B. subtilis KRB-5 can be used to control the root-knot nematode on pepper.

• The Plant Pathology Journal
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• v.33 no.4
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• pp.410-423
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• 2017

Pathological interrelations of two soil-borne diseases in cucurbits (watermelon, oriental melon, shintosa and cucumber) caused by Fusarium isolates (FI) and the root-knot nematode (RKN), Meloidogyne incognita were characterized by the fusarium disease severity index (DI), RKN gall index (GI) and eggmass index (EI) in inoculation tests using FI and RKN. Virulence of FI as determined by DI at 4 weeks after inoculation was mostly in the higher order of Fusarium proliferatum F6, F5 and Fusarium oxysporum f. sp. melonis or Fusarium oxysporum f. sp. niveum with no significant differential interactions among the cucurbits and RKN co-infection. Significant increases of DI due to RKN coinfection were noticed in watermelon and oriental melon infected with F. proliferatum isolates, suggesting the DI increase due to RKN coinfection may depend upon the virulence of FI relative to aggressiveness of RKN on the cucurbits. For the coinfection of FI and RKN, GI and EI were mostly reduced logarithmically with the increase of DI, largely more in EI than GI, in all cucurbits except for shintosa. Microscopic examination of the root tissues showed histopathological features characteristic to infection types; formation of fungal hyphae and/or spores and plant defense structures (tyloses and mucilage) in variable degrees and formation of giant cells at variable developmental stages and with variable cytoplasmic depletion or degeneration which were visualized in relations with the values of DI, GI and EI. These findings will be helpful to develop control strategies of the soil-borne disease complex based on their pathological characteristics.

• The Plant Pathology Journal
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• v.31 no.4
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• pp.441-445
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• 2015

Carrot (Dacus carota var. sativus) is one of the top-ten most economically important vegetable crops produced worldwide, and the root-knot nematodes, Meloidogyne spp., are one of the most important pests in the carrot. In Korea, M. hapla and M. incognita are presumed to be the major root-knot nematodes distributing mostly in open carrot fields and greenhouses, respectively. In our study, currently-developed and commercial carrot cultivars and the parental lines were examined for their pathological responses to M. incognita and M. hapla 7 weeks after inoculation with about 1,000 second-stage juveniles (J2) of the nematodes. All the carrot cultivars and lines showed susceptible responses to both nematodes with the gall index (GI) of 2.4-4.4, which were always higher on the carrot plants infected with M. incognita than M. hapla. Gall sizes were remarkably larger with more serious reduction of the root growths in the plants infected with M. incognita than M. hapla, suggesting the carrot lines examined in our study were more susceptible to the former than the latter. In the infection sites of the root tissues, giant cells were more extensively formed, occupying larger stellar regions with the prominent destruction of adjacent xylem vessels by M. incognita than M. hapla. All of these results suggest M. incognita affect more seriously on the carrot plants that are grown in greenhouses, compared to M. hapla that has a major distribution in open carrot fields, which would be used for determining cropping systems based on target nematode species, their damage and pathological characteristics.

• Proceedings of the Korean Society of Soil Zoology Conference
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• 2003.06a
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• pp.11-11
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• 2003

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.32-39
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• 1999

The following is experimental result of selecting soil bacteria showing toxicity against Root-knot nematode (Meloidogyne hapla). Out of 286 strains isolated from soil, one(NC67) showing toxicity against M.hapla is selected The selected strain(NC67) is identified of B. thuringiensis subsp. indiana. It proved out that the toxic maerial against M. hapla produce by NC67 strain is an exotoxin. The result of examining the existence of the extercellular toxicity product by the toxic strain(NC67) by usign activated carbon column chromatography, Dowex 50W column chromatography and TLC of silical gel etc. proved out that it is a single material.

• Korean journal of applied entomology
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• v.39 no.2
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• pp.111-115
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• 2000

Fifty-two nematode predatory fungi were isolated from 37 soil samples collected from eight provinces in Korea. Isolated fungi were tested their predacity against Rhabditis sp. and Meloidogyne incognita in petri dish, and against M. incognita in greenhouse pot experiments. Fifty isolates had trapping organ of adhesive networks and two isolates had adhesive column or adhesive knob. In petri dish experiments, 5 1 isolates against Rhubditis sp. and 26 isolates against M. incognita showed over 91 % of predacity; in greenhouse experiments, however, only three isolates showed over 81% of predacity. These results imply that the results from the laboratory experiments are not consistent with those from the greenhouse experiments. Therefore, to select a promising biocontrol predatory fungi for plant-parasitic nematodes, the screening experiment should be conducted in conditions close to nature.

• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.865-871
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• 2002

A bacterium having strong chitinolytic activity on $0.2\%$ colloidal chitin-containing agar medium was isolated from coastal soil in Korea. Based on the nucleotide sequence of conserved segment of a 165 rRNA gene, the bacterium was identified as Paenibacillus illinoisensis KJA-424. The population of P. illinoisensis KJA-424 and chitinase activity significantly increased for the first 2 days of incubation. On SDS-PACE analysis with $0.01\%$ glycol chitin, three protein bands (63, 54, and 38 kDa) with chitinolytic activity were detected tooted. The effect of P illinoisensis KJA-424 on the egg hatch of root-knot nematode (Meloidogyne incognita) was investigated. After 7 days of incubation with the chitinase-producing P. illinoisensis KJA-424, none of the eggs hatched, whereas a $39.8\%$ egg hatching rate was observed in the water control. Inverted and scanning electron microscopic observations demonstrated that P. illinoisensis KJA-424 deformed and destroyed the eggshell of M. incognita. In conclusion, chitinase-produced by p. illinoisensis KJA-424 caused the lysis of M. incognita eggshell and resulted in the inhibition of egg hatching in vitro.

• Korean journal of applied entomology
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• v.21 no.1 s.50
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• pp.34-37
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• 1982

Two species of root-knot nematode, Meloidogyne incognita and M. hapla, were used in tests of soybean cultivars for resistance. Sixteen soybean cultivars were planted in the 20-cm clay pot and inoculated with each of M. incognita and M. hapla. Four soybean cultivars, Eundaedu, Baegcheon, Dongbugtae and Danyeobkong were resistant; Kwangdu, Hwanggeumkong, and Buseog were moderate, and the rest nine cultivars were susceptible to M. incognita. Jangyeobkong only was resistant, Danyeobkong, Hill, Dongbutae, Hamandaerip and Chungbugbaeg were moderate, and the rest ten cultivars were susceptible to M. hapla. There were no cultivars resistant to both nematodes although Dongbugtae and Danyeobkong were resistant to M. incognita and moderately resistant to M. hapla.

• Research in Plant Disease
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• v.22 no.3
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• pp.184-189
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• 2016

To select resistant oil seed crops against two species of root-knot nematodes, Meloidogyne incognita and M. arenaria, 10 cultivars of sesame (Sesamum indicum L.) and 10 cultivars of perilla (Perilla frutescens var. japonica) were screened in greenhouse pot test. All sesame cultivars tested were resistant to M. incognita but susceptible to M. arenaria. While, perilla was resistant to both Meloidogyne species. Therefore, perilla cultivars could be used as rotation crop in greenhouse infested with both M. incognita and M. arenaria. But, sesame cultivars only can be used as a rotation crop in greenhouse infested with M. incognita but not for M. arenaria.