• The Plant Pathology Journal
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• 제16권3호
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• pp.147-150
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• 2000

Sporulation patterns of rice blast fungus were studied at relatively later stages of leaf blast and neck blast seasons in Icheon, Korea. This experiment was done by detaching lesion-bearing leaves and panicle bases. The number of conidia remaining on the leaf blast lesions of different cultivars from Jul 20 to Jul 23 ranged from 3,640 to 82,740 spores. More conidia were observed on the adaxial surface because they were released from abaxial surface. After heading, sporulation was observed from the lesions on the flag leaves but the number of spores was less than in the late July. Detached panicle bases or uppermost internodes infected by Pyricularia grisea produced abundant amount of conidia. Among these panicle bases, 30.1 mm size lesion recorded the highest count of 244,560 spores. When we compared the sporulation amount using the KY-type spore trap, more conidia were recorded from intact lesions than from the lesions which removed conidia and conidiophore The ratio of conidia release against total sporulation ranged from 20.5%-25.0% for leaf blast and 8.2%-25.3% in the neck blast. Effective inoculum potential was also discussed.

• The Plant Pathology Journal
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• 제27권4호
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• pp.333-341
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• 2011

Two antifungal bacteria were selected from forest soils during the screening of microorganisms antagonistic to Cylindrocarpon destructans, a cause of ginseng root rot. The antifungal bacteria were identified as Bacillus subtilis (I4) and B. amyloliquefaciens (yD16) based on physiological and cultural characteristics, the Biolog program, and 16S rRNA gene sequencing analyses. Antagonistic activity of both bacterial isolates to C. destructans increased with increasing temperature. More rapid starch hydrolytic activity of the bacteria was seen on starch agar at higher temperatures than at lower temperatures, and in the higher density inoculum treatment than in the lower density inoculum treatment. The bacterial isolates failed to colonize ginseng root the root tissues inoculated with the bacteria alone at an inoculum density of $1{\times}10^6$ cfu/ml, but succeeded in colonizing the root tissues co-inoculated with the bacteria and C. destructans. Scanning electron microscopy showed that the pathogen was damaged by the low-density inoculum treatment with the bacterial isolates as much as by the high-density inoculum treatment. Both bacterial isolates were more effective in reducing root rot when they were treated at a concentration of $1{\times}10^6$ cfu/ml than at $1{\times}10^8$ cfu/ml. Also, only the former treatment induced prominent wound periderm formation, related to structural defense against pathogen infection. The results suggest that the bacterial antagonists may have high potential as biocontrol agents against ginseng root rot at relatively low-inoculum concentrations.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2018년도 춘계학술대회 및 임시총회
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• pp.41-41
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• 2018

There has been an impetus in the development of biocontrol agents (BCAs) with the removal of a number of chemical compounds in the market, especially in the European Union. This has been a major driver in the development of Integrated Pest Management systems (IPM) for both pest and disease control. For control of mycotoxigenic fungi, there is interest in both control of colonization and more importantly toxin contamination of staple food commodities. Thus the relative inoculum potential of biocontrol agent vs the toxigenic specie sis important. The major bottlenecks in the production and development of formulations of biocontrol agents are the resilience of the strains, inoculum quality and formulation with effective field efficacy. It was recently been shown for mycotoxigenic fungi such as Aspergillus flavus, under extreme climate change conditions, growth is not affected although there may be a stimulation of aflatoxin production. Thus, the development of resilient biocontrol strains which can may have conserved control efficacy but have the necessary resilience becomes critical form a food security point of view. Indeed, under predicted climate change scenarios the diversity of pests and fungal diseases are expected to have profound impacts on food security. Thus, when examining the identification of potential biocontrol strains, production and formulation it is critical that the resilience to CC environmental factors are included and quantified. The problems in relation to the physiological competence and the relative humidity range over which efficacy can occur, especially pre-harvest may be increase under climate change conditions. We have examined the efficacy of atoxigenic strains of A. flavus and Clanostachys rosea and other candidates for control of A. flavus and aflatoxin contamination of maize, and for Fusarium verticillioides and fumonisin toxin control. We have also examined the potential use of fluidized-bed drying, nanoparticles/nanospheres and encapsulation approaches to enhance the potential for the production of resilient biocontrol formulations. The objective being the delivery of biocontrol efficacy under extreme interacting climatic conditions. The potential impact of climate change factors on the efficacy of biocontrol of fungal diseases and mycotoxins are discussed.

• The Plant Pathology Journal
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• 제40권3호
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• pp.290-298
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• 2024

K-Maryblyt has been developed for the effective control of secondary fire blight infections on blossoms and the elimination of primary inoculum sources from cankers and newly emerged shoots early in the season for both apple and pear trees. This model facilitates the precise determination of the blossom infection timing and identification of primary inoculum sources, akin to Maryblyt, predicting flower infections and the appearance of symptoms on various plant parts, including cankers, blossoms, and shoots. Nevertheless, K-Maryblyt has undergone significant improvements: Integration of Phenology Models for both apple and pear trees, Adoption of observed or predicted hourly temperatures for Epiphytic Infection Potential (EIP) calculation, incorporation of adjusted equations resulting in reduced mean error with 10.08 degree-hours (DH) for apple and 9.28 DH for pear, introduction of a relative humidity variable for pear EIP calculation, and adaptation of modified degree-day calculation methods for expected symptoms. Since the transition to a model-based control policy in 2022, the system has disseminated 158,440 messages related to blossom control and symptom prediction to farmers and professional managers in its inaugural year. Furthermore, the system has been refined to include control messages that account for the mechanism of action of pesticides distributed to farmers in specific counties, considering flower opening conditions and weather suitability for spraying. Operating as a pivotal module within the Fire Blight Forecasting Information System (FBcastS), K-Maryblyt plays a crucial role in providing essential fire blight information to farmers, professional managers, and policymakers.

• 한국연초학회지
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• 제30권1호
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• pp.1-7
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• 2008

Bacterial wilt caused by Ralstonia solanacearum has become a severe problem on tobacco in Korea. No effective single control measure is available at present time. One of the most potential way for controlling the bacterial wilt on tobacco is growing tobacco cultivars resistant to the bacterial wilt. In this study, optimal conditions for screening tobacco cultivars resistant to the bacterial wilt were examined to provide reproducible and efficient methods in growth chamber testing and field experiments for evaluating plant disease resistance. For this, already-known inoculation methods, inoculum densities, and incubation temperature, and plant growth stages at the time of inoculation were compared using tobacco cultivars resistant (Nicotiana tabacum cv, NC95), moderately resistant (N. tabacum cv. SPG70), and susceptible (N. tabacum BY4) to the bacterial disease. It was determined that root-dipping of tobacco seedlings at six true leaf stage into the bacterial suspension with inoculum level of $10^8$ colony-forming units (CFU)/ml for 20 min before transplanting was simple and most efficient in testing for resistance to the bacterial wilt of tobacco caused by R. solanacearum, for which disease incidences and severities were examined at 2 weeks of plant growth after inoculation at $20{\sim}25^{\circ}C$ in a growth chamber. These experimental conditions could discriminate one tobacco cultivar from the others by disease severity better than any other experimental conditions. In field testing, the optimum time for examining the disease occurrence was late June through early July. These results can be applied to establishing a technical manual for the screening of resistant tobacco cultivars against the bacterial wilt caused by R. solanacearum.

• 한국식물병리학회지
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• 제13권3호
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• pp.167-171
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• 1997

올방개 지문무늬병균(E. mematosporus)의 접종농도, 처리회수, 올방개의 모령이 제초효과에 미치는 영향을 온실에서 검정하였다. 포자현택액의 농도를 $10^{5}$ conidia/ml로 조정하여 분무접종하였을 때 15~20일 이내에 올방개 지상부 줄기의 82.6%~92.1% 정도가 고사하였으나, 그 이하의 농도에서는 제초효과가 53.7%이하로 급격히 감소하였다. 또한 지상부 줄기의 고사는 지하부 괴경형성에서도 영향을 미쳐, $10^{5}$ conidia/ml의 농도에서는 무처리나 $10^[3},\;10^{4}$ 농도의 처리에 비해 약 6~21배의 괴격형성 억제력을 나타내었다. 올방개 지문무늬평균 분생포자현탁액($6.3\;{\times}\;10^{5}$ conidia/ml)은 여러번 처리할수록 제초효과가 높았는데 2회 이상 처리했을 때 지상부 줄기의 고사율(93.8%)이 급격히 증가하였고 고사하기까지의 시간도 단축되었으며 신초의 발생율은 1회 처리에 비해 2.5배 무처리에 비해 12배 감소시켰고 지하부 괴경형성도 1회처리에 비해 6배, 무처리에 비해 35배 억제하였다. 올방개의 모령에 따라서도 제초효율에 차이가 있었는데 신초 형성후 20일 되었을 때 처리하는 것이 줄기 고사율이 가장 높았고, 신초의 발생율이 현저히 감소하였으며 또한 지하부 괴경형성 억제력도 높게 나타났다. 이상의 결과로 보아 올방개 지문무늬병균의 최적처리의 포자량은 $10^[5}$ conidia/ml 이상, 1주일 간격으로 2~3회 처리하며 신초형성 20일 후 처리하는 것이 가장 효과적이라 생각된다.

• 식물병연구
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• 제15권3호
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• pp.217-221
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• 2009

Fludioxonil은 미국 EPA에 의해 저독성(reduced-risk) 살균제로 분류되었으며, 이 살균제는 Pseudomonas pyrrocinia가 생산하는 항균 물질인 pyrrolnitrin을 선도 물질로 하여 합성하였다. 본 연구에서는 상추 품종, 기주 식물의 생육 시기, Botrytis cinerea 포자농도, 접종원의 영양분 농도 등의 발병 조건에 따른 fludioxonil의 상추 잿빛곰팡이병에 대한 방제효과를 온실에서 실험하였다. 상추의 생육시기에 따른 fludioxonil 방제효과를 실험한 결과, 2 ${\mu}g$/ml 처리구는 어린 유묘에서 잿빛곰팡이병 방제효과가 더 높았으나, 10 ${\mu}g$/ml 이상 농도에서는 생육 시기에 따른 방제효과의 차이는 거의 없었다. 또한 fludioxonil 10 ${\mu}g$/ml 이상 농도 처리구는 B. cinerea의 포자 농도(2.5$\times$10개/ml 부터 $2{\times}10^6$ 개/ml까지)에 관계없이 모두 우수한 방제효과를 나타냈다. 반면에 fludioxonil 2 ${\mu}g$/ml은 접종원의 포자농도가 높을수록 낮은 방제효과를 보였다. 그리고 영양분농도에 따른 fludioxonil의 잿빛곰팡이병 방제효과를 실험한 결과, potato dextrose broth의 농도가 낮을수록 fludioxonil은 상추 잿빛곰팡이병에 대한 높은 방제효과를 나타냈다. 이상의 결과로부터 살균제 fludioxonil은 상추 잿빛곰팡이병에 대한 효과적인 살균제임을 알 수 있었으며, 다만 낮은 농도에서는 발병 조건에 따라 다소 낮은 방제효과를 나타낼 수 있을 것이다.

• 한국산림과학회지
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• 제65권1호
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• pp.43-47
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• 1984

한국산(韓國産)과 미국산(美國産) 모래밭버섯 균근균(菌根菌)(Pisolithus tinctorius : Pt)의 포자접종효과(胞子接種効果)를 비교(比較)하기 위하여 리기테다 소나무 파종상(播種床)에 접종(接種)을 하였다. methyl bromide로 훈증(薰蒸)된 묘포장(苗圃場)에 $1m^2$당(當)의 1g의 Pt포자(胞子)를 접종(接種)하고 파종(播種)하여 당년(當年) 가을에 묘고생장(苗高生長)을 조사(調査)하였는데 미국(美國) Pt로 접종(接種)된 묘목(苗木)은 한국(韓國) Pt로 접종(接種)된 것보다 묘고(苗高)에서 15% 더 컸으며, 훈증(薰蒸)만 하고 접종처리(接種處理)되지 않은 묘목(苗木)을 중간정도의 생장(生長)을 보였다. 따라서 한국(韓國) Pt의 묘목(苗木)는 별로 없는 것으로 추측된다. 그 다음해 실시한 볕도의 실험(實驗)에서, 토양훈증(土壤薰蒸) 후 미국(美國) Pt 혹은 韓國 Pt로 접종(接種)한 묘목(苗木)은 훈증(薰蒸)없이 자생균근균(自生菌根菌)으로 감양(感梁)된 묘목(苗木)보다 당년(當年)에 묘고(苗高)에서 각각 66%와 60% 더 컸다. 이것은 Pt 접종효과(接種効果)와 토양훈증효과(土壤薰蒸効果)가 함께 나타난 것으로 생각된다. 본 실험(實驗)은 균근균(菌根菌) 포자(胞子)를 접종원(接種原)으로 사용할 수 있는 가능성을 보여주는 것이며, 미국(美國) Pt와 같이 어떤 지역(地域)에 적응한 Pt 균(菌)의 선발(選拔)이 중요하다는 것과 한국(韓國)에서도 우수한 균근균(菌根菌)을 선발(選拔)할 필요가 있다는 것을 나타내고 있다.

• 한국미생물·생명공학회지
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• 제36권2호
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• pp.115-120
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• 2008

근권 미생물을 대상으로 뿌리에서의 집락 형성 실험, 풋마름병 방제 효과 그리고 화학 농약에 대한 내성을 검정하여 SKU48-2 균주를 선발하였다. SKU48-2균주는 균체 현탁액$(10^8CFU/ml)$을 처리하였을 때 60%이상의 풋마름병 방제 효과를 나타내었으며, 형태적, 생화학적 특성과 16S rDNA sequence 분석 결과 Bacillus subtilis SKU48-2로 동정되었다. 선발 균주 SKU48-2는 화학 농약에 대해 강한 내성을 가져 토양 내 잔류 농약에 의해 영향을 받지 않을 뿐만 아니라, 화학 농약과의 혼용에 의해서 저농약 사용이 가능하고 미생물제제 단독 사용 시 보다 높은 방제 효과를 기대할 수 있다. SKU 48-2균주가 액상의 배양액 상태에서는 4주 만에 생균밀도가 급격히 감소한 반면, talc, vermiculite와 peat등의 담체 사용 시는 생균밀도가 6개월 간 유지됨이 확인되어 고형 제제화의 기초를 마련하였다.

• Animal Bioscience
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• 제35권7호
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• pp.999-1009
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• 2022

Objective: To improve the feeding value of rice straw (RS), this study evaluated the potential of rice straw fermented with Pleurotus sajor-caju (FRS) as dairy goat feed. Methods: Spent Pleurotus sajor-caju mushroom substrate was used as fungi inoculum to break the lignocellulose linkage of rice straw, which was solid-fermented at 25℃ to 30℃ for 8 weeks. The ruminal degradation of pangolagrass hay (PG), FRS, and RS were measured in situ for 96 hours in three dry Holstein cows, respectively. Effect of fungi fermented RS on milking performance was studied in feeding trials. A total of 21 Alpine goats a trial were divided into 3 groups: a control group in which PG accounted for 15% of the diet dry matter, and FRS or RS was used to replace the PG in the control group. Goats were fed twice a day under two 28-day trial in individual pens. Meanwhile, a 3×3 Latin square trial (14 days/period) was conducted to study the rumen digestion of three diets by using three fistulated dry goats. Rumen contents were collected for metabolite analyses every one to three hours on the last two days. Results: In situ study showed that fermentation could elevate the rumen degradable fraction and effective degradability of RS (p<0.05). Effective degradability of FRS dry matter was significantly increased from 29.5% of RS to 41.7%. Lactating trial results showed that dry matter intake and milk yield in the PG group and FRS group were similar and higher than those in RS group (p<0.05). The concentration of propionic acid and total volatile fatty acid in the RS group tended to be lower than those in PG group (p<0.10). There were no differences in rumen pH value and ammonia nitrogen level among the groups tested. Conclusion: Fermentation of rice straw by spent Pleurotus sajor-caju mushroom substrate could substantially enhance its feeding value to be equivalent to PG as an effective fiber source for dairy goat. The fermented rice straw is recommended to account for 15% in diet dry matter.