In the present study, a severe outbreak of Sclerotium rot on Korean melon(Cucumis melo L. var. makuwa Makino) observed in Jinju, Korea in August of 2014 and 2015 is reported. The fruit rot disease on the surface of Korean melon fruit appeared as water soaked lesion followed by the development of large rotten areas with abundant white mycelial growth. Abundant white mycelial mats with globoid and white to brown sclerotia(1-3 mm) were also developed on stems near the soil line, and infected plants withered. The fungal pathogen was isolated on potato dextrose agar(PDA) and formed white colonies with numerous sclerotia on PDA. The sclerotia were globoid in shape, 1-3 mm in size, and white to brown in color. The mycelium formed typical clamp connection. These measurements and taxonomic characteristics were most similar to those of Sclerotium. DNA sequencing and phylogenetic analysis of the complete internal transcribed spacer rRNA gene region confirmed that the fungal isolates were Sclerotium rolfsii Saccardo. Koch’s postulates were supported by pathogenicity tests conducted on fruit. Based on mycological characteristics, pathogenicity tests, and molecular identification, the fungus was identified as Sclerotium rolfsii. To the best of our knowledge, this is the first report of a Sclerotium rot caused by S. rolfsii on Korean melon in Korea.

고추를 비롯한 채소작물에 심각한 피해를 야기하는 흰비단병의 생물학적 방제제를 개발하기 위하여 시설재배 토양에서 분리한 세균 중에서 흰비단병균인 Sclerotium rolfsii의 균사생장을 강하게 억제하는 균주를 선발하였다. 선발된 균주는 형태적, 생리적 분석과 16S rRNA 분석결과를 바탕으로 Bacillus amyloliquefaciens로 동정하였고 최종 선발균주를 Bacillus amyloliquefaciens KBC1009로 명명하였 다. Bacillus amyloliquefaciens KBC1009의 배양특성을 조사한 결과 배양온도 30℃, pH 7의 조건에서 72시간동안 배양했을 때 배양 효율이 가장 우수하였으며, 배양에 적정한 영양원은 탄소원 glucose, 질 소원 yeast extract를 사용했을 때 가장 높은 균수를 나타내었다. 포장에서 고추 흰비단병에 대한 Bacillus amyloliquefaciens KBC1009의 방제효과를 검정하기 위해 흰비단병원균을 토양에 접종하고 B. amyloliquefaciens KBC1009 배양액(5×108 cfu/ml)을 500배로 희석하여 10일 간격으로 3회 관주 처리한 결과 무처리대비 66.7%의 방제효과를 나타내었다.

Background : In previous study, we reported Sclerotium rot caused by Sclerotium rolfsii in Ixeridium dentatum for the first time. This experiment was conducted to select highly effective pesticides against Sclerotium rot caused by S. rolfsii in I. dentatum. Methods and Results : The chemical efficacy and the injury test were carried out. A total of five pesticides were used for the experiment test. For the efficacy test, we investigated spore germination and mycelial growth inhibiting ability by each pesticides in vitro and disease inhibiting ability in the field. For the chemical injury, we investigated appearance of abnormalities on condition of reference amount and fold amount in the field. In vitro, three kinds of chemicals such as Fludioxonil suspension concentrate (SC), Tebuconazole suspension concentrate (SC), and Flutolanil emulsifiable concentrate (EC) showed complete spore germination inhibitory effect, However in two chemicals such as Pyraclostrobin water-dispersible granule (WG) and Pyribencarb suspension concentrate (SC), the mycelial growth inhibitory effect was partially recognized but the spore germination was not inhibited. In the field, we performed an artificial inoculation experiment using sclerotia. As a result four kinds of chemicals such as Fludioxonil SC, Tebuconazole SC, Flutolanil EC, and Pyraclostrobin WG showed control value of above 80% against Sclerotium rot caused by Sclerotium rolfsii except Pyribencarb SC. Also there was no chemical injury in reference amount and in fold amount respectively, compared to non treated control. Conclusion : From the above results, we selected four items of pesticides including Fludioxonil SC, Tebuconazole SC, Flutolanil EC, and Pyraclostrobin WG as effective chemicals against Sclerotium rot caused by Sclerotium rolfsii in Ixeridium dentatum.

본 연구는 전작물 재배에 따른 마늘 흑색썩음균핵병 피해 경감 효과를 평가하기 위해 2년간 수행되었다. 콩 참깨 호박 네마장황, 대파를 전작물로 재배하였으며, 대조구로 휴경처리구와 병원균 무접종구를 두었다. 전적물 재배 후 마을을 파종하고 재배하면서, 흑색썩음균핵병 이병주율과 수량을 조사하였다. 2013년 흑색썩음균핵병은 병원균 무접종구, 콩, 네마장황처리구에서 가장 낮았으며, 호박처리구에서 가장 높았다. 2014년에는 네마장황, 콩, 대파처리구에서 흑색썩음균핵병 이병주율이 낮았으며, 호박처리구에서 가장 높았다. 처리구 별 마늘의 수량은 2013년에는 콩, 네마장황, 대파 처리구에서 가장 높았고 호박처리구에서 가장 적었으며, 2014년에는 콩, 네마장황, 대파처리구에서 높았고, 호박처리구에서 가장 적어 이병주율과 유사한 경향을 보였다. 이상의 결과를 토대로 콩-마늘과 네마장황-마늘재배체계가 흑색썩음균핵병을 억제하기 위한 윤작체계가 될 수 있을 것으로 생각되었다.