• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1542-1550
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• 2016

This is the first report that paromomycin, an antibiotic derived from Streptomyces sp. AG-P 1441 (AG-P 1441), controlled Phytophthora blight and soft rot diseases caused by Phytophthora capsici and Pectobacterium carotovorum, respectively, in chili pepper (Capsicum annum L.). Chili pepper plants treated with paromomycin by foliar spray or soil drenching 7 days prior to inoculation with P. capsici zoospores showed significant (p < 0.05) reduction in disease severity (%) when compared with untreated control plants. The disease severity of Phytophthora blight was recorded as 8% and 50% for foliar spray and soil drench, respectively, at 1.0 ppm of paromomycin, compared with untreated control, where disease severity was 83% and 100% by foliar spray and soil drench, respectively. A greater reduction of soft rot lesion areas per leaf disk was observed in treated plants using paromomycin (1.0 μg/ml) by infiltration or soil drench in comparison with untreated control plants. Paromomycin treatment did not negatively affect the growth of chili pepper. Furthermore, the treatment slightly promoted growth; this growth was supported by increased chlorophyll content in paromomycin-treated chili pepper plants. Additionally, paromomycin likely induced resistance as confirmed by the expression of pathogenesis-related (PR) genes: PR-1, β-1,3-glucanase, chitinase, PR-4, peroxidase, and PR-10, which enhanced plant defense against P. capsici in chili pepper. This finding indicates that AG-P 1441 plays a role in pathogen resistance upon the activation of defense genes, by secretion of the plant resistance elicitor, paromomycin.

• The Korean Journal of Pesticide Science
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• v.4 no.1
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• pp.64-70
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• 2000

Control effects of phosphorous acid were investigated on three diseases. For Phytophthora blight of red pepper, protective and curative effects of phosphorous acid at the concentration of $1,408{\mu}g$ a. i./mL were 91.0% and 80.0%, respectively. In case of late blight of tomato, caused by Phytophthora infestans, protective and curative effects were 63.4% and 13.0% at the same concentration, respectively. However, the protective and curative effects of phosphorous acid increased by decreasing inoculum density of Phytophthora infestans. The protective effects of phosphorous acid on control of Phytophthora blight of red pepper was persisted for 4 days with high control efficacy (94.0%). The protective and curative effects of phosphorous acid ($1,408{\mu}g$ a. i./mL) on cucumber downy mildew were 82.0% and 62.0% respectively. The foliar application of phosphorous acid also promoted shoot growth and fresh weight of red pepper.

• The Plant Pathology Journal
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• v.15 no.4
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• pp.217-222
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• 1999

Treatment with antagonistic rhizobactera Burkholderia cepacia strain N9523 or an inducer of resistance DL-$\beta$-amino-n-butyric acid (BABA) effectively inhibited Phytophthora capsici infection on pepper plants in artificially infested pots. Treatment with BABA alone at $1,000\mu\textrm{g}$/ml or together with B. cepacia in combination induced a strong protection from the Phytophthora disease in the greenhouse. In artificially infested field, protection of pepper plants against the Phytophthora epidemic by BABA treatment was maintained at a considerable level. In contrast, soil drench with the antagonist B. cepacia alone, or in combination with BABA did not suppress the Phytophthora epidemic in the field. Mortality of pepper plants caused by P. capsici infection was significantly reduced by treatment with the antagonist Pseudomonas aeruginosa strain 950923-29 and BABA (12-29% plants diseased) relative to the untreated control (41-91% plants diseased) in the naturally infested field. Treatment with the antagonist Ps. aeruginosa strain 950923-29 and BABA also resulted in high levels of protection against Phytophthora blight in pepper plants. In the plastic filmhouse test, the average percentage of plants diseased was significantly low relative to the naturally infested field. Treatment with the antagonist Ps. aeruginosa strain 950923-29 and BABA in combination was most effective in suppressing the Phytophthora disease in field and plastic filmhouse.

• Microbiology and Biotechnology Letters
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• v.29 no.3
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• pp.186-193
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• 2001

A powerful antagonistic bacterium against Phytophthora capsici causing phytophthora blight of red pepper was isolated from the cultivated soil in Kyongju Korea, The bilogical control mechanisms of the isolated strain were caused by strong antifungal antibiotic, siderophore and cellulase. The strain was identified as Chryseomonas luteola by the cultural morphological and physiological characteristics. The opti- mal culture medium for the antibiotic production was determined as follows : 0.15%D(+) cellobiose, 0.55% $NH_4$CI, 0.01% KCI 0.7% $K_2$$HPO_4$ 0.2% $KH_2$PO$_4$ and 0.5% sodium citrate at pH 7.0 The optimal incubation time was 84 hours at $30^{\circ}C$ In pot bioassay, the treatment of C luteola 5042 protected red pepper plant against the blight of Phytophthora capsici.

• Journal of Applied Biological Chemistry
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• v.52 no.3
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• pp.116-120
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• 2009

We found out the new method of the consortium for the environmental friendly agriculture by 8 kinds of the selected antagonistic rhizobacteria. This research involved composition of mutual complementary consortium by each antagonistic function such as production of antibiotic, siderophore, antifungal cellulase and insoluble phosphate solubilization. The consortium No.11 among composed consortium candidates showed the most pepper growth promoting activity and Phytophthora blight suppression on the in vivo pot test of red-pepper plant. The consortium No. 11 is combination of PGPR Bacillus subtilis AH18 and Bacillus licheniformis K11. B. subtilis AH18 and B. licheniformis K11 both could produce the auxin, antifungal ${\beta}$-glucannase and siderophore. Also, they had mechanism for solubilization of insoluble phosphate. But, B. licheniformis K11 could produce the antibiotic of iturin which was able to inhibit Phytophthora capsici. We confirmed complementary noncompetitive mutualism between B. subtilis AH18 and B. licheniformis K11 of the consortium No.11. The results came out through treatment of two strains co-culture, treatment of individual culture and co-treatment of two individual cultures for the growth and Phytophthora blight suppression of red-pepper. The treatment of two strains co-culture didn't show a synergic effect in comparing sole treatment on the pepper growth promotion and Phytophthora blight suppression. But, when the pots were treated simultaneously with co-treatment of two individual cultures, an synergic effect was seen in the growth promotion of roots, stem, leaves and suppressed Phytophthora blight on red-pepper in vivo pot test.

• Korean Journal of Environmental Agriculture
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• v.24 no.4
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• pp.409-415
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• 2005

To control Phytophthora blight of red pepper biologically caused by Phytophthora capsici, we developed Trichoderma harzianum DYMC for commercial product. DYMC was storage at room temperature and was investigated their population every 3 months for 1 year. For investigating the dynamic population of T. harzianum in the pot soils, we applied powder and suspension applications with DYMC, and then investigated for 95 days. The efficacy of powder and suspension applications of DYMC for control of Phytophthora blight of red pepper and plant growth were investigated for 50 days in greenhouse experiment. The population of T. harzianum was decreased at the room temperature for 1 year but there was not statistically significance. After soil treated in the pot with DYMC, the population of Trichoderma spp. was the highest when DYMC powder at 5 g was applied to mix with pot soil, and the population was deceased significantly among treatment means as time goes by ($R^2=0.76$, F=10.5960, P=<.0001). Incidence of Phytophthora blight of, red pepper was significantly reduced among treatment means on 50th day after treated with DYMC ($R^2=0.82$, P=16.4758, P=<.0001). Disease control value was the highest at 62.5% when DYMC powder at 5 g was applied to mix with pot soil. No significant difference (P=0.05) of effects of plant and root growth showed by treated with DYMC on 60th day, except stem. Mixing the application of DYMC powder with soil to control Phytophthora blight of red pepper was greater than suspension application to dilute with water. DYMC could be used as an effective biocontrol agent to control Phythophthora blight of red pepper.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.47-51
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• 2000

Phytophthora blight of pepper, which is caused by Phytophthora capsici Leonian, is not only the most destructive disease worldwide, but also difficult to control effectively. It has been needed to have new trials for effective control to the disease. We employed radiation hormesis of gamma ray as the new trial in the control strategy. Two cultivars, Kwangbok and Dabok, were used to analyse whether gamma ray radiation can induce disease resistance. The germination rate of pepper seeds was significantly enhanced by the radiation at all dose levels. Stimulatory effect for resistance induction was found to differ between cultivars. It was confirmed that the remarkable effect was induced in Dabok and depended on radiation dosage. Disease resistance at 4 Gy was much higher than that of control. On the other hand, no detectable induction effect for resistance was observed in Kwangbok which was moderate resistant cultivar to gamma ray radiation. [Hormesis, Gamma ray, Pepper, Phytophthora blight, Resistance induction].

• Horticultural Science & Technology
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• v.30 no.2
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• pp.185-191
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• 2012

For initiation of resistance breeding program of the red pepper, 21 PR ($Phytophthora$ resistance) cultivars, 36 cultivars collected from USA and 'Supermanitta' which is a susceptible cultivar against phytophthora blight were assayed against phytophthora blight, powdery mildew, and anthracnose. For seedling assay of phytophthora blight, three different mating type strains of $Phytophthora$ $capsici$ were used (A1, A2, Sterile). The result showed that most of the pepper of PR cultivars were resistance or moderately resistance at each mating type. 'Yeokganghongjanggun' was resistant to all three $P.$ $capsici$ strains and 'PR-Datta' and 'PR-Manitta' were resistant or moderately resistant at each type. In case of the collected cultivars, 'NuMex J.E.Parker', 'Omni Color', and 'SCM334' were resistant to all the three types and some cultivars including 'Sweet Banana' and 'Tabasco' were moderately resistant to each type fungi. 'Orange Habanero' and 'Black Cuban' were resistant to powdery mildew and 'Supermanitta' and 'PR Keumdong' were moderately resistant, while 'Santa Fe Grande', 'NuMex Pinata' and 'Puya' were very susceptible. In the case of anthracnose, 'Aji Limon' and 'Capsicum baccatum var. pendulum 3-4' were resistant and 'Pobalno', 'Omni Color', 'Negro', 'Mesilla', 'Mulato', 'Bhut Jolokia', 'Big Dipper', 'Black Cuban', 'NuMex Pinata', and 'NuMex Big Jim' were moderately resistant. The most PR cultivars except 'Taesan' were susceptible or very susceptible. These resistant individuals identified through this experiment can be used as sources of resistance to pepper pathogens in the future breeding programs.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.340-345
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• 2010

Two similar microbial fungicides (termed as MA and MB) developed in a Korean biopesticide company were analyzed and compared each other in their biocontrol activities against the phytophthora blight of chili pepper caused by Phytophthora capsici. MA and MB contained the microbe Paenibacillus polymyxa and Bacillus subtilis, respectively, with concentrations over those posted on the microbial products. In comparison of the isolated microbes (termed as MAP from MA and MBB from MB) in the antagonistic activities against P. capsici was effective, prominently against zoospore germination, while MBB only significantly inhibited the mycelia growth of the pathogen. Some effectiveness of MAP and MBB was noted in the inhibition of zoosporangium formation and zoospore release from zoosporangia; however, no such large difference between MAP and MBB was noted. In a pot experiment, MA reduced the severity of the phytophthora blight more than MB, suggesting that the disease control efficacy would be more attributable to the inhibition of zoospore germination than mycelia growth of P. capsici. These results also suggest that the similar microbes MA and MB targeting different points in the life cycle of the pathogen differ in the disease control efficacies. Therefore, to develop microbial fungicides it is required to examine the targeting points in the pathogen's life cycle as well as the action mode of antagonistic microorganisms.

• The Korean Journal of Pesticide Science
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• v.12 no.3
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• pp.270-276
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• 2008

Through the agar dilution method on V-8 juice agar, sensitivity of Phytophthora capsici causing pepper Phytophthora blight to metalaxyl was investigated by using isolates obtained from infected pepper plants during 3 years from 2005 to 2007. By the lapse of time, $EC_{50}$ value to metalaxyl was decreased, showing 1.45, 0.83, and $0.32{\mu}g\;mL^{-1}$ in 2005, 2006, and 2007. None of 2007 isolates was found to be resistant to metalaxyl. Compared the sensitivity of P. capsici isolates to metalaxyl with those to mandipropamid and dimethomorph, there is not a cross resistance response between metalaxyl and mandipropamid/dimethomorph. The resistance to metalaxyl in pepper Phytophthora blight pathogen was not related with the mycelial growth on V-8 agar medium and the pathogenicity on pepper plants.