• The Plant Pathology Journal
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• 제17권3호
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• pp.154-158
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• 2001

A severe root rot of kiwifruit caused by a species of Phytophthora occurred in 1-to 5-year-old vines at the south coast region of Korea in 1997. Infected vines exhibited leaf chlorosis, scorch and defoliation, root and stem rot, and eventual death. The disease was relatively severe in poorly drained lowlands, of which 19 out of 23 fields were damaged by the disease. Meanwhile, only one among 58 upland fields was infected by the disease. Incidence of infected vines reached over 80% in heavily damaged fields and a species of Phytophthora was isolated from inner tissues of roots, stems, and rhizosphere soils of the plants. The causal pathogen was identified as P. drechsleri based on its mycological characteristics. Pathogenicity of the fungus was confirmed by artificial inoculation to seedlings of kiwifruit 'Hayward'. The pathogen was re-isolated from the inoculated plants showing symptoms similar to those observed in the fields. Root rot of kiwifruit caused by P. drechsleri has not been reported previously in Korea.

• The Plant Pathology Journal
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• 제35권3호
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• pp.219-233
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• 2019

Soybean cultivars susceptible to Phytophthora root and stem rot are vulnerable to seed rot and damping-off of seedlings and young plants following an infection by Phytophthora sojae. In this study, the disease responses of Japanese soybean cultivars including currently grown main cultivars during the early growth stages were investigated following infections by multiple P. sojae isolates from Japanese fields. The extent of the resistance to 17 P. sojae isolates after inoculations at 14, 21, and 28 days after seeding varied significantly among 18 Japanese and two US soybean cultivars. Moreover, the disease responses of each cultivar differed significantly depending on the P. sojae isolate and the plant age at inoculation. Additionally, the treatment of 'Nattosyo-ryu' seeds with three fungicidal agrochemicals provided significant protection from P. sojae when plants were inoculated at 14-28 days after seeding. These results indicate that none of the Japanese soybean cultivars are completely resistant to all tested P. sojae isolates during the first month after sowing. However, the severity of the disease was limited when plants were inoculated during the later growth stages. Furthermore, the protective effects of the tested agrochemicals were maintained for at least 28 days after the seed treatment. Japanese soybean cultivars susceptible to Phytophthora root and stem rot that are grown under environmental conditions favorable for P. sojae infections require the implementation of certain practices, such as seed treatments with appropriate agrochemicals, to ensure they are protected from P. sojae during the early part of the soybean growing season.

• 식물병연구
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• 제7권1호
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• pp.8-10
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• 2001

1998년 경기도 고양시의 분화용 칼랑코에(Kalanchoe sp.)재배농가에서 줄기 하부가 검게 썩으며 급격히 시드는 증상으로부터 병원균을 분리.동정한 결과 Phytophthora nicotianae로 동정되었다. 병원균의 형태적 특성은 뚜렷한 유두돌기를 가진 유주자낭을 형성하였고, 원형~rPfis형이며 크기는 20~48$\times$24~64$\mu\textrm{m}$였고, 구형의 후막포자를 다량 형성하였다. 배양적 특성은 V8 juice agar와 corn-meal agar에서는 풍부한 균사를 형성하였으며, PDA에서는 전형적인 거미집 형태로 자라는 특성을 보였다. 생육온도범위는 최저 1$0^{\circ}C$, 최고 37$^{\circ}C$, 최적온도는 3$0^{\circ}C$였다. \\\"Florus\\\"를 비롯한 14개 칼랑코에 주요 재배품종에 대한 병원성검정을 실시한 결과 품종에 따라 저항성의 차이가 있었다.의 차이가 있었다.

• 식물병연구
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• 제13권3호
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• pp.207-210
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• 2007

2007년 5월 전북 전주의 식물원에서 판매중인 아이비에서 줄기 하부가 검게 썩으며 급격히 말라죽는 증상으로부터 병원균을 분리 동정한 결과 Phytophthora cinnamomi로 동정되었다. 병원균의 형태적 특성은 비 돌출형의 탈락성이 없는 계란형, 장타원형 혹은 서양배형의 유주자낭을 형성하였고, 크기는 평균 $33.8{\times}16{\mu}m$였고, 구형의 후막포자를 다량 형성하였으며, 크기는 평균 직경이 $19.7{\mu}m$였다. 유성생식형은 자웅이주로 A1 mating type이 관찰되었고 난포자의 크기는 직경이 $26.2{\mu}m$였다. 균사의 생육적온은 $25{\sim}30^{\circ}C$였다. 이상과 같이 국내 최초의 P. cinnamomi에 의한 아이비줄기썩음병의 발생을 보고하는 바이다.

• 한국자원식물학회지
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• 제12권4호
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• pp.260-268
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• 1999

황련(Coptis japonica)의 추출액을 공시하여 Phytophthora capsici, Fusarium oxysporum, Colletotrichum dematium, C. truncatum, Botrytis cinerea, Botryosphaeria dothidea과 Alternaria porri에 대해 항균 활성 검정, 몇가지 작물에 대한 병해 방제 효과를 조사하고 항균 활성 물질을 동정하였다. 황련 추출액은 P. capsici, F. oxysporum, C. dematium, B. cinerea, B. dothidea 및 A. porri에 대해서 항균력이 우수하였다. Methanol을 용매로 추출하여 분리된 물질과 berberine-Cl 표준품의 항균활성을 비교할 때, 황련추출액으로부터 분리된 물질은 표준품 berberine-Cl과 비슷하게 항균력을 나타내었다. 황련 추출액은 고추 역병(83.3%), 참깨 모잘록병 (92.0%) 및 파 검은무늬병(87.5%)에 대해서 방제효과가 인정되었다. 고추 잎과 과실, 파 잎 및 딸기 과실에는 약해가 나타나지 않았으나 고농도에서는 고추 및 참깨의 발아를 억제하거나 유근의 신장을 억제하는 것으로 나타났다. Methanol로 추출한 황련 추출액으로부터 황색 분말 4.24g/100g을 얻을 수 있었다. 이들 물질을 HPLC로 분석한 결과 항균성을 나타내는 물질은 berberine-Cl로 동정되었다.

• 한국작물학회지
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• 제57권4호
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• pp.389-396
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• 2012

Melon (Cucumis melo) is an annual herbaceous plant of the family Cucurbitaceae. Phytophthora rot, caused by Phytophthora capsici is a serious threat to cucurbits crops production as it directly infects the host plant, and it is difficult to control because of variable pathogenicity. This study investigated the resistance of 450 accessions of melon germplasm against Phytophthora rot by inoculating the seedlings with sporangial suspension ($10^{5\;or\;6}$ zoosporangia/ml) of P. capsici. Disease incidence of Phytophthora rot was observed on the melon germplasm at 7-day intervals for 35 days after inoculation. Susceptible melon germplasm showed either severe symptoms of stem and root rot or death of the whole plant. Twenty out of 450 tested accessions showed less than 20% disease incidence, of which five accessions showed a high level of resistance against Phytopthtora rot. Five resistant accessions, namely IT119813, IT138016, IT174911, IT174927, and IT906998, scored 0% disease incidence under high inoculum density of P. capsici ($10^6$ zoosporangia/mL). We recommend that these candidate melon germplasm may be used as genetic resources in the breeding of melon varieties resistant to Phytophthora rot.

• 한국균학회지
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• 제52권2호
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• pp.73-96
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• 2024

Root and stem rot caused by Phytophthora palmivora is one of the most serious diseases affecting durian production in Thailand where metalaxyl, an effective fungicide against oomycetes, has been used extensively for a long period to control this disease. Although field isolates of P. palmivora resistant to metalaxyl exist in Thailand, a molecular basis for P. palmivora has not yet been elucidated regarding metalaxyl resistance. The current study tested whether P. palmivora RPA1 (the DNA-directed RNA polymerase I subunit gene), a homolog gene of RPA190 associated with metalaxyl resistance in some isolates of Phytophthora infestans, had a role in the resistance mechanism toward metalaxyl. In total, 40 durian-derived isolates of P. palmivora were assessed for metalaxyl sensitivity using a mycelial growth inhibition assay. The effective concentrations for 50% mycelial growth inhibition values for all isolates tested were in the range 0.01-872.88 mg/L. The isolates were clustered into three groups: sensitive (n=23), moderately resistant (n=11), and resistant (n=6) groups. No polymorphism was revealed based on multiple alignment analysis of the amino acid sequences translated from the corresponding DNA sequences in the region of RPA1 of the metalaxyl-sensitive (n=5), moderately resistant (n=2), and resistant isolates (n=6). Furthermore, investigation of the RPA1 expression among these representative isolates (n=3, each group) indicated that RPA1 expression may not be involved in the regulation of P. palmivora resistance to metalaxyl. Based on this line of evidence, there was no detected relationship regarding metalaxyl resistance and P. palmivora RPA1.

• The Plant Pathology Journal
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• 제35권6호
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• pp.698-704
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• 2019

Phytophthora root and stem rot (PRSR) caused by Phytophthora sojae is one of the most destructive diseases of soybean. PRSR recently became an issue as soybean cultivation in paddy fields increased in South Korea. The management of PRSR mainly involves R-gene-mediated resistance, however, little is known about the resistance in Korean cultivars. Major Korean soybean cultivars were investigated for the presence or absence of R-gene-mediated resistance to four P. sojae isolates, two of which were new isolates. Isolate-specific reactions were observed following P. sojae inoculation. Of 21 cultivars, 15-20 cultivars (71.4-95.2%) showed susceptible reaction for each isolate. Ten cultivars were susceptible to all the isolates, and six cultivars were identified to have R-gene-mediated resistance to one or two isolates. The results of this study would provide a framework for the discovery of resistant cultivars, development of new cultivars resistant to P. sojae, and investigation of pathogenic diversity of P. sojae population in South Korea.

• The Plant Pathology Journal
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• 제17권3호
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• pp.184-188
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• 2001

Phytophthora-induced diseases on citrus in Jeju island have been considered of minor importance because of the use as root stock of trifoliate orange, which is immune to Phytophthora. However, brown rot on fruit, which severely occurred in 1998 and 1999, has become a great threat to citrus production in the island. About one-half of the surveyed orchards were infected in 1998 and 4 out of 19 infected fields showed over 20% fruit infection rate. The disease was less severe in 1999, with an estimated infected area and total fruit reduction of 3,155 ha and 15,300 tons, respectively. Typical gummosis was also occasionally observed on cv. Shiranugi, which is mostly cultivated under plastic film houses. Two types of Phytophthora were consistently isolated from various plant parts, identified as P. citrophthora and P. nicotianae. The former was isolated from the aerial parts of the fruit, young leaf, and shoot in the fields. Meanwhile, the latter was only isolated from the basal stem showing gummosis in plastic film houses.

• 농약과학회지
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• 제13권4호
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• pp.275-282
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• 2009

선발된 PGPR 균주인 Bacillus subtilis C4와 Bacillus cereus D8 균주의 유채에 대한 생육촉진 및 무름병균인 Erwinia carotovora와 균핵병균인 Sclerotinia sclerotiorum에 대한 방제효과를 검정하기 위하여 실내검정과 온실검정을 실시하였다. 실내검정 결과, C4와 D8균주처리에 의하여 유채의 생육이 40.3%~74% 증가하였으며 무름병이 대조구에 비하여 80% 감소하였다. 실내검정에서 C4와 D8균주를 종자에 처리하였을 때 뿌리가 크게 신장되었다. 주요 식물병원균 Sclerotinia sclerotiorum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici, Colletotrichum acutatum에 대하여 항균활성시험을 수행한 결과 두 균주 중 C4균주는 모든 병원성 곰팡이에 대하여 항균활성을 나타내었다. 온실검정에서 C4와D8균주처리는 대조구에 비하여 유채의 초장, 엽폭 및 엽장을 19.5%~24.9%, 11.3%~15.3%, 14.1%~20.7% 각각 증가시켰으며 균핵병균인 Sclerotinia sclerotiorum에 대한 억제효과가 우수하였다. 이와 같은 결과를 볼 때 C4, D8 균주 처리는 유채의 생육을 촉진시키며 유채에 저항성을 유도하므로 친환경생물방제에 적용할 수 있을 것으로 생각된다.