• Mycobiology
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• v.39 no.4
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• pp.321-323
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• 2011

Severe violet root rot occurred in a field of membranous milk vetch in Bonghwa, Korea, in October 2010. Two fungal isolates from the diseased plants were identified as Helicobasidium mompa based on their morphological, cultural, and molecular characteristics. This is the first report that H. mompa causes violet root rot on membranous milk vetch in Korea.

• The Plant Pathology Journal
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• v.38 no.5
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• pp.513-521
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• 2022

Our study was carried out to determine the control efficacy of sodium hypochlorite (NaOCl) for violet root rot caused by Helicobasidium mompa in apple. The experiment was conducted in the farm located at Chungbuk province in South Korea from 2014 to 2016. When infected apple trees were treated at least two or three times with 31.25 and 62.5 ml/l available chlorine content in NaOCl, it greatly increased the rooting of rootstock, and restored the tree crown density by 44.4-60.5%. In addition, the number of commercial fruit setting was increased by 54.3-64.5%, and the total starch content in shoots was significantly higher than other non-treated apple trees. However, the untreated disease control and thiophanate-methyl WP treated trees showed the symptom of dieback. Therefore, our results indicate that the drenching treatment of NaOCl with 31.25-62.5 ml/l available chlorine content more than two times from late fall to early spring could effectively control the violet root rot and recover tree vigor up to 60%.

• Research in Plant Disease
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• v.26 no.2
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• pp.88-94
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• 2020

Recently, the severe dieback of apple trees resulting from soil-borne diseases has occurred in South Korea. The casual agents of dieback were surveyed on 74 apple orchards that had been damaged nationwide in 2016-2019. The number of apple orchards affected alone by Phytophthora rot, violet root rot, and white root rot was 31, 34, and 3, respectively. Also, the total number of mixed infection orchards was 6. Out of 9,112 apple trees affected by dieback, the trees damaged by Phytophthora rot, violet root rot, and white root rot were 3,332, 3,831, and 44, respectively. Moreover, the total number of mixed infection apple trees was 1,905. The provinces mainly affected were Gyeongnam, Gyeongbuk, Chungbuk, and Jeonbuk. The survey on these infected apple orchards will be available to form management strategy for the dieback that had been increased by soil-borne fungal pathogens.

• Plant Disease and Agriculture
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• v.1 no.1
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• pp.37-44
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• 1995

This study was carried out to select effective fungicides against white and violet root rot caused by Rosellinia necatrix and Helicobasidium mompa with nine fungicides including thiophanate-methyl from 1993 to 1994. Through laboratory, greenhouse and field trials on inhibitory effect of mycelial growth and disease incidence against the two fungal pathogens, 5 fungicides have been selected finally. Thiopanate-methyl, benomyl, iminoctadine-triacetate and isoprothiolane were proven to have high control effect against R. necatrix. In addition to thiopanate-methyl and benomyl, tolclofos-methyl has been selected for effective control of H. mompa, since it showed prominent control effect in field trial than in laboratory or green house test.

• Research in Plant Disease
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• v.23 no.1
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• pp.49-55
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• 2017

The previous study showed that die-back of apple trees caused by soil-borne diseases was significantly high in the apple orchards in Chungbuk province. The correlation between dieback ratio and cultivation environment in apple orchards infected by soil-borne diseases was investigated in this study. The dieback ratio of five orchards diseased by violet root rot and five places infected by white root rot showed significantly positive correlation with Ca content and available $P_2O_5$ content in soil, respectively. Whereas, the dieback ratio of fourteen orchards diseased by Phytophthora root rot was not significant. Subgrouping of cultivation environment analysis showed that the slope degree of orchard and the number of fruit setting also affected the dieback ratio caused by violet root rot and Ca content in soil also affected the dieback ratio caused by white root rot. It showed that the slope degree, soil texture, Mg and Ca content affected the dieback ratio caused by Phytophthora root rot. These results can be applied to reduce die-back ratio by the modification cultivation environment for each soil-borne disease.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.19-20
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• 2003

Helicobasidium mompa Tanaka and Resellinia necatrix Prillieux cause violet root rot and white root rot of various crops, respectively. Intensive cultural practices, such as the use of dwarf stock, glasshouse cultivation, etc., predispose plants to the diseases. The diseases can be controlled only by biennial drench of 50100L of chemicals for each tree. Biocontrol with soil microorganisms proved ineffective under field conditions. Long-term control may be hampered by the perennial growth of hosts and by the difficulty in the establishment of antagonists in soil. Crop rotation or soil amendment is not applicable, either. Fungal viruses with dsRNA genome (Buck 1986) are promising against root diseases of fruit trees since they exist within the cytoplasm of fungal hyphae and need no effort to help them persist in the field. The viruses are considered to spread though the network of fungal mycelia in the soil once they enter the fungal cytoplasm. Here, we present preliminary results from a project to control the root diseases of fruit trees with dsRNA.(중략)

• The Plant Pathology Journal
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• v.35 no.2
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• pp.156-163
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• 2019

Our study investigated the available chlorine content, contact time and difference among strains of each pathogen for sodium hypochlorite (NaOCl) to control chemically against soil-borne fungal pathogens, such as Phytophthora rot by Phytophthora cactorum, violet root rot by Helicobasidium mompa, and white root rot by Rosellinia necatrix, causing die-back symptom on apple trees. As a result, the colony growth of Phytophthora cactorum was inhibited completely by soaking over 5 s in 31.25 ml/l available chlorine content of NaOCl. Those of H. mompa and R. necatrix were inhibited entirely by soaking over 160 s in 62.5 and 125 ml/l available chlorine content in NaOCl, respectively. Also, inhibition effect on available chlorine in NaOCl among strains of each soil-borne pathogen showed no significant difference and was similar to or better than that of fungicides.

• Research in Plant Disease
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• v.22 no.3
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• pp.198-201
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• 2016

Recently, severe dieback of apple tree has occurred in the apple orchards of Chungbuk province. Dieback rate and its casual agents have been investigated on the Chungbuk province apple orchards in 2013-2015. Out of 29,265 apple trees in the 27 orchards throughout Chungbuk province, 4,000 apple trees (13.7%) showed dieback symptoms. The causes of dieback were Phytophthora rot (50.4%), violet root rot by Helicobasidium sp. (27.1%), rodents (10%), white root rot by Rosellinia sp. (6.3%), and freezing injury (6.3%). Compared to previous reports published in 1995 and 2006, Phytophthora rot was the most dominant disease, which is thought to be due to high temperature during growing season and the increase of lowland cultivation. Results of this study will be useful to establish of the management strategy of apple tree dieback that has been increased recently.

• Journal of Ginseng Research
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• v.39 no.2
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• pp.94-104
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• 2015

Background: Ginseng (Panax ginseng Meyer) is an important medicinal herbs in Asia. However, ginseng varieties are less developed. Method: To developed ginseng varieties, a pure line selection method was applied in this study. Results: Gumpoong was testing of 4-yr-old specimens in 2002, the proportions of the below-ground roots that were rusty colored for Gumpoong was 1.29 in Daejeon and 1.45 in Eumseong, whereas the proportions for its yellow berry variant were 2.60 and 2.45 in the two regions, respectively. Thus the Gumpoong was resistant to root rust. Sunpoong has a high yielding property. Its average root weight is 70.6 g for 6-yr-old roots. Its yield is 2.9 kg/$1.62m^2$ and the rate of heaven- and earth-grade product is 20.9%, which is very high compared to 9.4% for Yunpoong. Sunone is resistance to root rot and the survival rate of 4-yr-old roots was 44.4% in 1997, whereas that of the violet-stem variant landrace was 21.7%. Sunhyang has content of arginyl-fructosyl-glucose (AFG), which produces the unique scent of red ginseng, is $95.1{\mu}mol/g$ and greater than the $30.8{\mu}mol/g$ of Chunpoong in 6-yr-old plants. Sunun and Cheongsun are being nurtured to protect genetic resources. Conclusion: Developed ginsneg varieties will be used as the basis for the protection of genetic resources and breeding.