• Korean journal of applied entomology
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• v.58 no.1
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• pp.49-54
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• 2019

Clover cyst nematode, Heterodera trifolii are one of the major pests that damage Chinese cabbage in high land cultivation area and have recently been distributed in Korea. This study was conducted to investigate the effect of temperature and inoculation density on the proliferation of clover cyst nematode. The clover cyst nematode was proliferated at $15-30^{\circ}C$ and the egg, female adult and cyst number was the highest at $20^{\circ}C$. As the inoculation density increased, the number of female cyst nematodes increased with the inoculation density and when 16 eggs were inoculated per gram of soil, the amount of growth, number of egg and cyst was the highest. Number of females and eggs were formed more in cabbage than in kale regardless of inoculation density. Chinese cabbage was a favorable host for clover cyst nematode growth than kale.

• Research in Plant Disease
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• v.26 no.2
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• pp.72-78
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• 2020

Clover cyst nematode, Heterodera trifolii, is one of the most important plant-parasitic nematode on Kimchi-cabbage in highland in Korea. Recently, a demand of soil disinfection machine for fumigants is increasing. This study was conducted to assess the control effects of a newly developed prototype soil disinfection machine to the cyst nematode. Two fumigants, dimethyl disulfide (DMDS) and metam sodium (MNa), were treated using the machine in a field, which was infected with the cyst nematode. After 4 weeks, control effects of fumigants were assessed as eggs hatching rates inside of cysts extracted from the soil, and as a number of females reproduced in roots of Kimchi-cabbage. DMDS (39 l/10 a) suppressed over 99.0% of the eggs hatching rate and the number of females reproduced. On the other hand, MNa (29 l/10 a) controlled the egg hatching rates from minimum 78.3% to maximum 99.4%, and the number of females from 34.7% to 49.3%. The control effects of two fumigants to clover cyst nematode by treated depth were no significant differences statistically. These results showed that DMDS treatment using the soil disinfection machine was expected to have the control effects for the clover cyst nematode.

• Korean Journal of Environmental Biology
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• v.39 no.3
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• pp.329-335
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• 2021

Chinese cabbage fields have been damaged by cyst nematodes in highland of Gangwon province in Korea since the year 2011, and clover cyst nematode (CCN) is one of the most problematic cyst nematodes in the crop. To investigate the plant resources for breeding new Chinese cabbage cultivar, which is resistant to CCN, screening for resistance of fifty-seven Brassicaceae plant resources to CCN was conducted. Among the plant resources, fifty-four plant resources (Brassica rapa subsp. pekinensis, B. rapa, Brassica sp., B. juncea, B. carinata, B. rapa subsp. nipposinica, B. rapa subsp. narinosa, B. rapa var. perviridis, B. rapa var. perviridis, B. napus var. napobrassica, and Eruca sativa) were very susceptible to CCN and the number of females on roots was more than 300. Two plant resources (B. carinata and B. tournefortii) with more than 100 females on roots were susceptible to CCN. However, African mustard (B. tournefortii, Korean Genebank accession no. IT218058) was resistant to CCN because of the small number of females (4±1.8) on roots. This study showed that African mustard (IT218058) was valuable as a breeding material for Chinese cabbage, which is resistant to CCN.

• Korean Journal of Environmental Biology
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• v.39 no.1
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• pp.1-5
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• 2021

Radish is one of the major vegetable crops and has been damaged economically by the causal agent of Fusarium wilt disease, Fusarium oxysporum f. sp. raphani (FO) in the highlands of Gangwon province, Korea. Recently, clover cyst nematode, Heterodera trifolii(HT), occurred in highland of Jeongseon area and poses a threat to radish plants. The nematodes, besides causing direct damage to radish plants, possess the capability to synergize with other plant pathogens, leading to the development of a disease complex. The aim of this study was to investigate the interaction between FO and HT in radish plants. The length of plants co-infected with both FO and HT was shorter than that of plants infected with FO alone, but there was no statistically significant difference. However, the disease severity was much higher in the plants co-infected with both FO and HT(1.60±0.97) compared to FO alone(0.20±0.42)(df=3, F=10.17, p<0.001). Disease incidence was also about two-fold higher in plants co-infected with both FO and HT (80%) compared to FO alone (44%). These results suggested that the clover cyst nematode should be considered in the management of Fusarium wilt disease in the highlands of Gangwon province.

• Korean journal of applied entomology
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• v.57 no.4
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• pp.339-345
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• 2018

The sugar beet cyst nematode (SBCN), Heterodera schachtii first detected in Taebaek, Gangwon-do in 2011, is one of the major plant parasitic nematodes that cause economic damage to the Chinese cabbage in highland regions. In addition, the distribution of clover cyst nematode (CCN), H. trifolii was confirmed in the highland Chinese cabbage cultivated regions in 2017. In order to investigate the spread of cyst nematodes, this study has been conducted since 2013 in the highland Chinese cabbage cultivation area. In addition, in 2017, the Real-Time PCR technique with the species-specific primer was used to investigate those two cyst nematodes and the soybean cyst nematode (SCN), H. glycines which is known for its distribution in Korea, focusing on the main production regions of highland Chinese cabbage cultivation. The number of infected fields in the Chinese cabbage plantation in highland increased every year to confirm distribution in Taebaek, Samcheok, Jeongseon and Gangneung in 2017, and the cumulative number of infection fields reached 245 by 2017. Of the 41 possible cyst nematode samples for PCR analysis, 61% were CCN, only 9.8% of the SBCN and 29.3% of the SCN were identified. Therefore, some of the previously known SBCN or CCN discoveries are likely to have been infected with SCN. It is believed that the CCN needs to be controlled in the future as CCN have been found to be dominant species in the highland Chinese cabbage plantation regions.

• Research in Plant Disease
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• v.26 no.2
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• pp.116-119
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• 2020

To investigate the effects of Brassicaceae cover crops on clover cyst nematode, Heterodera trifolii, 10 cultivars consisting of six of oil radish and four of white mustard were planted in the nematode infected field at Jeongseon city. Two months after planting, the cover crops were plow down and incorporated into the soil using rotavator, decomposed for 1 month, then transplanted kimchi-cabbages. After 70 days, the density of eggs inside of the cyst and the number of females in the soil were examined. As a result, the reproduction rates of eggs in each plots of Adios and Anaconda cultivars, which were 0.04 and 0.02, respectively, were greatly reduced. The number of females in the plots of above two cultivars showed means at 2.5 and 3.5 per 300 ㎤ soil, which were lower than those of other plots. In addition, fresh weights of three plants in the two plots, which were 7.67 and 7.35 kg, were significantly higher than that of the control plot. Collectively, these results suggest that the two cultivars of Brassicaceae cover crops, Adios and Anaconda, could be used for reducing the cyst nematode density.

• Korean journal of applied entomology
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• v.59 no.4
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• pp.361-369
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• 2020

This study aimed to investigate the differences in the effects of nematicidal materials (Burkholderia rinojensis, fluazaindolizine, fluopyram, fosthiazate, hydrogen peroxide, and imicyafos) on eggs and larvae of the sugar beet cyst nematode, Heterodera schachtii and clover cyst nematode, H. trifolii, which have recently become problematic in highland Chinese cabbage cultivation areas in Korea. Comparison of the hatching rates according to the test materials showed differences between treatments. In the treatment with fluopyram, fosthiazate, and imicyafos, a very high hatching inhibitory effect of 99% was observed in both nematodes, and there was no difference in the efficacy of treatments between nematode species except for that with hydrogen peroxide. Regarding the nematocidal activity of treatments against hatched larvae, only the fluazaindolizine treatment, despite showing a high hatching inhibitory effect, showed a low nematicidal effect of less than 30% against both nematodes, whereas a mortality rate of more than 90% was observed in the other treatments. There was no difference between nematode species in the reactions of the 2nd instar juveniles to all nematicidal test materials after 24 and 48 h of treatment. Although there are limitations to the laboratory experiment, the reaction to the nematicidal materials of the two cyst nematodes that damage the same host was similar, and simultaneous control is suggested in the areas where the two nematodes occur together.