• Research in Plant Disease
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• v.20 no.3
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• pp.201-205
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• 2014

Damping-off, caused by Rhizoctonia solani and Pythium ultimum, is a very important plant disease and affects seeds and seedlings of many plant species worldwide. To investigate control efficacy of Serenade formulation (1.34%, SC) against Rhizoctonia and Pythium damping-off diseases, seeds of chili pepper and cucumber were sown in soils inoculated with R. solani and P. ultimum and Serenade formulation was applied by soil-drenching with 9-, 19-, and 39-fold dilutions. Control values of Serenade formulation on Rhizoctonia damping-off of chili pepper was 58% and 29% for 9- and 19-fold dilutions, respectively. In the case of cucumber Rhizoctonia damping-off, Serenade treatments showed similar control efficacy with damping-off of chili pepper. On the other hand, control efficacy of Serenade formulation on Pythium damping-off of cucumber was less than control effects on Rhizoctonia damping-off. Only Pythium damping-off of chili pepper treated with 9-fold dilution Serenade was statistically different with untreated control. This result suggest that Serenade formulation could be effectively used for controlling Rhizoctonia and Pythium damping-off diseases.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.8-17
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• 2007

Three-dimensional quantitative structure-activity relationships (3D-QSARs) on the fungicidal activity against damping-off (Pythium ultimum) with N-phenylbenzenesulfonamide and N-phenyl-2-thienylsulfonamide analogues (1-34) were studied quantitatively using CoMFA (comparative molecular field analysis) and CoMSIA (comparative molecular similarity indeces analysis) methodologies. On the whole, the statistical qualities of CoMSIA models with field fit alignment (FF1-FF5) were slightly higher than that of atom based fit alignment (AF1-AF5) but, the deviations of statistical quality between two alignments in case of CoMFA models were slightly lower. The statistical results of CoMFA and CoMSIA model showed that the optimized CoMSIA model (FF1: $r_{cv.}^2\;(q^2)=0.674$ & $r_{ncv.}^2=0.964$) for damping-off is better predictability and fitness for fungicidal activities than CoMFA model (AF5: $r_{cv.}^2\;(q^2)=0.616$ & $r_{ncv.}^2=0.930$). The fungicidal activities according to the information of the CoMSIA (FF1) model were dependence upon the electrostatic and hydrophobic field of the N-phenylbenzene sulfonamide analogues. Therefore, from the results of graphical analyses on the contour maps with CoMSIA (FF3) model, it is expected that the characters of R4-substituent on the N-phenyl ring as hydrophobic and hydrogen bond acceptor will be contributed to the fungicidal activity against damping-off.

• Korean journal of applied entomology
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• v.16 no.4 s.33
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• pp.193-197
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• 1977

Seeds of pea cultivars susceptible to damping-off caused by Pythium ultimum produced sugars intheir exudates in half the time required for resistant cultivars. Also, the amount of reducing sugars was much greater in seed exudates of susceptible than resistant cultivars. Raffinose, melibiose, sucrose, glucose, and fructose (but not maltose, xylose or ribose) were identified in both resistant and susceptible cultivars; however, more glucose and sucrose were detected in seeds from susceptible than from resistant cultivars. Pythium ultimum grew more profusely around seeds from, and in exudates of, susceptible than resistant cultivars.

• The Korean Journal of Mycology
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• v.18 no.2
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• pp.102-108
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• 1990

In order to find out the effect of medicinal plant extracts on germination of zoosporan-gium and mycelium growth of Pythium ultimum, this study was carried out. Among 28 species in 16 families of plants tested, plant extracts from 9 species were strongly inhibitory to zoosporan-gium germination of P. ultimum. Plant extracts from 3 species were strongly inhibitory to mycellium growth of P. ultimum. Especially, Paeonia suffruticosa was strongly inhibitory. P. suffruticosa was shown a strong control effect on damping-off of sesame by P. ultimum sesame, but no effect on cucumber. Seed germination of sesame and cucumber was shown phyto-alexin by extract of Phytolacca esculenta.

• The Korean Journal of Mycology
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• v.31 no.1
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• pp.44-49
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• 2003

Several microbial biocontrol products (Greenbiotech Co., Paju, Korea), Green-all T (Trichoderma harzianum), Green-all S(Bacillus sp.) and Green-all G (Streptomyces sp.) were supplemented with organic amendments such as sawdusts and rice hulls to study on efficacy of biological control of seeding damping-off of cucumber caused by Pythium ultimum. Sawdusts amended into potato dextrose agar alone could inhibit in vitro mycelial growth of P. ultimum. All there microbial products of Green-all T, Green-all G and Green-all S significantly reduced seeding damping-off (LSD, P=0.05). However, several amendments such as sawdusts and rice hulls into Green-all T and Green-all S products did not increase efficacy of biological control compared to non-amended treatment. In contrast, supplements of aminodoctor containing several amino acids (Greenbiotech Co., Korea) into Green-all G product significantly increased efficacy of biological control of seeding damping-off, resulting in from 42% to 2% disease incidence in relation to seedling emergence (LSD, P=0.05). Also, amendment of sawdusts into Tricoderma product significantly increased efficacy of biological control as disease index of 5.0 compared to non-amended control of 56.0 in Green-all T product alone. This indicates that organic amendments could increase efficacy of biological control of cucumber seedling damping-off.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.364.1-364
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• 2001

• The Korean Journal of Mycology
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• v.11 no.1
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• pp.27-32
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• 1983

Five species of the genus Pythium were identified from 91 isolates which were collected from rice seedlings in machine transplanting nursery boxes and paddy fields in Korea. They included P. graminicola complex, P. monospermum complex, P. rostratum complex, and P. ultimum complex. The most frequently found species of the genus Pythium was P. graminicola complex followed by P. monospermum complex. Rice seed germinability was greatly decreased by being infested with P. graminicola complex at nursery box. P. graminicola complex was the most virulent in terms of prohibiting germinations and stunting plants in nursery boxes.

• Journal of Life Science
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• v.12 no.2
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• pp.200-207
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• 2002

This study was carried out to isolate of antagonistic bacterium against Pythium ultimum and Rhizoctonia solani AG-4, causal pathogens of vegetables damping-off. Total of 600 strains were isolated from soil and plait roots. The isolates were screened for antagonism against Pythium ultimum and Rhizoctonia solani AG-4. One strain, named YJ-37, was sellected for detained study among those microoganisms screened. It was identified as Bacillus ehimensis based on morphological and physiological characterisitics according to the Bergey's mannual of systematic bacteriology, Sherlock system of Microbial ID Inc. and 16S rDNA sequences methods. Furthermore Bacillus ehimensis YJ-37 showed antifungal activities against Alternaria altrata, Collectotrichum gloeosporioides, Didymella bryoniae, Fusarium moniliforme, Fusarium oxysporum, F. oxysporum cucumerinum, F. oxysporum niveum, Gloeosporium sp., Glomerella sp., G. cingulata, G. lagenaria, Penicillium digitatum, P. italicum, Phytophthora capsici, Sclerotinia sclerotiorum, and Stemprhylium solani.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1998.11a
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• pp.135-135
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• 1998

To find an antagonist of Pythium ultimum, the causal agent of damping-off, numerous actinomycete strains were screened for in vitro inhibiting mycelial growth of the target fungus and producing bioactive metabolites. A strain identified as Streptomyces sp. G60655 was isolated and used for further antagonistic efficacy. The degree of antagonism between the fungus and G60655 was affected by the medium used. Furthermore, the preinoculation of the antagonist was found to be necessary to exhibit the maximum efficacy of antagonsim against the fungus. From the culture broth, a bioactive metabolite was detected and purified by solvent extraction, silica gel chromatography and preparative HPLC. The FAB-MS spectrum of the active compound showed a molecular ion peak at m/z 1101 (M + H)$\^$+/, suggesting the molecular weight of 1100. The UV absorptions at 242 and 323 nm indicated the presence of aromatic functions. The structure of this compound was identified as echinomycin, a depsipeptide antibiotic by spectroscopic studies including various NMR measurements. Echinomycin was inactive against several soil born fungi, but inhibited the mycelial growth of P. ultimum and its related oomycetous fungi.

• Journal of Life Science
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• v.12 no.4
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• pp.416-422
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• 2002

Bacillus ehimensis YJ-37 was observed as a potential biological agent to control the occurrence of diseases and plant growth.promoting rhizobacteria (PGPR). Population density of B. ehimensis YJ-37 were higher 1.2~2 times in main roots and lateral roots than from nonrhizosphere soil and persisted around 10$^4$g root on the watermelon and radish root system upto 30 days after growing in pot condition. As a PGPR, B. ehimensis YJ-37 enhanced plant growth of watermelon and radish by soil treatment. The leaf area, hypocotyl length, root length and dry weight of radish were about 85, 33, 23 and 89% more than that of untreated plant, respectively. In case of watermelon were about 63, 27, 25 and 69% more than that of untreated plant, respectively. Biocontrol of damping-off in watermelon and radish caused by Rhizoctonia solani AG-4 and Pythium ultimum were carried out in pots using 3. ehimensis YJ-37. The results showed that might contribute to it's suppression of damping-off disease in field plants.