• The Plant Pathology Journal
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• v.23 no.2
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• pp.109-112
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• 2007

This study was to examine the efficacy of a root-dipping application of antagonistic bacterial strains for the control of Phytophthora blight of pepper caused by P. capcisi, and to evaluate their plant growth-promoting effects in the field in 2005 and 2006. The candidate antagonistic rhizobacterial strains CCR04, CCR80, GSE09, ISE13, and ISE14 were treated by dipping plant roots with bacterial suspensions prior to transplanting. The candidate rhizobacterial strains CCR04, CCR80, GSE09, and ISE14 significantly (P=0.05) reduced the disease incidence and the area under the disease progress curves when compared to buffer-treated controls in at least a year test. The metalaxy l(fungicide-treated control) resulted in one of the lowest disease incidences among the treatments in both years. Moreover, the strains CCR04, CCR80, GSE09, and ISE13 significantly (P=0.05) increased the fruit weights and/or numbers of peppers in at least a year test compared to the buffer-treated controls. These results suggest that the antagonistic rhizobacterial strains CCR04, CCR80, and GSE09 could be efficient biocontrol agents by controlling Phytophthora blight of pepper and promoting the plant growth when treated with root-dipping at transplanting.

• The Plant Pathology Journal
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• v.21 no.1
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• pp.64-67
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• 2005

The biocontrol agent Serratia plymuthica A21-4 readily colonized on the root of pepper plant and the bacterium moves to newly emerging roots continuously. The colonization of A21-4 on the pepper root was influenced by the presence ofPhytophthora capsici in the soil. When P. capsici was introduced in advance, the population density of A21-4 on the root of pepper plant was sustained more than $10^6$ cfu/g root until 3 weeks after transplanting. On the other hand, in the absence of P. capsici, the population density of A21-4 was reduced continuously and less than $10^5$ cfu/g root at 21 days after transplanting. S. plymuthica A21-4 inhibited successfully the P. capsici population in pepper root and rhizosphere soil. In the rhizosphere soil, the population density of P. capsici was not increased more than original inoculum density when A21-4 was treated, but it increased rapidly in non-treated control. Similarly, the population density of P. capsici sharply increased in the non-treated control, however the population of P. capsici in A21-4 treated plant was not increased in pepper roots. The incidence of Phytophthora blight on pepper treated with A21-4 was 12.6%, while that of non-treated pepper was 74.5% in GSNU experimental farm experiment. And in farmer's vinyl house experiment, the incidence of the disease treated with the fungicide was 27.3%, but treatment of A21-4 resulted in only 4.7% of the disease incidence, showing above 80% disease control efficacy.

• The Plant Pathology Journal
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• v.18 no.4
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• pp.221-224
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• 2002

In vitro and in vivo activities of a biocontrol agent, Serratia plymuthica strain A2l-4, was evaluated for the control of Phytophthora blight of pepper, Strain A2l-4 inhibited mycelial growth, germination of zoosporangia and cystospores, and formation of zoospore and zoosporangia of Phytophthora capsici in vitro. In the pot experiment, incidence of Phytophthora blight of pepper in non-treated control was 100% at 14 days after inoculation, while no disease was observed in the plot treated with S. plymuthica A2l-4. In the greenhouse test, infection rate of pepper in the non-treated plots was 74.5%, while it was only 12.6％ in the plots treated with A2l-4. Results indicate that S. plymuthica A2l-4 is a potential biocontrol agent for Phytophthora blight of pepper.

• 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.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.110.1-110
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• 2003

Control effect of grafting with rootstocks on Phythophthora blight of pepper was evaluated. The 40∼45 day old seedlings of five pepper cultivars, Wangdaeback, Jinmi, Boosa, Samsungcho and Pochunngchun, as a scion were grafted with ten species of root stocks. There wasn't graft incompatibility in all scion-root stock combinations. After 21 days from inoculation with Phytopkhora capsici, incidence of Phythophthora blight of plant grafted with Kataguruma, R-Safe, R-16, YCM 334 and SCM 334 of rootstocks tested was decreased by 64.6∼100％ compared to non-grafted plant whose disease severity was 3.7. However, plant grafted with Umsung native and Yeongdong native pepper was more sensitive to Phythophthora blight than non-grafed plant. Control effect by grafting was inversely proportional to virulence of inoculum and not significantly different among scion cultivars used. And resistant reaction of scion against Phytophthora blight was not affect that of scion-root stock plant in this study.

• The Plant Pathology Journal
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• v.26 no.4
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• pp.367-371
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• 2010

In this study, we evaluated the efficacy of fluopicolide to inhibit Phytophthora capsici in vitro, and to control pepper Phytophthora blight in a greenhouse and pepper fields. Fluopicolide was tested on various developmental stages of P. capsici 06-143 (a sensitive isolate to metalaxyl) and JHAW1-2 (a resistant isolate to metalaxyl). Mycelial growth and zoosporangium germination of both isolates were completely inhibited at $4.0\;{\mu}g/ml$ of the fungicide in vitro. The $EC_{50}$ (effective concentrations reducing 50%) of P. capsici 06-143 against zoospore were $0.219\;{\mu}g/ml$, while those of JHAW1-2 were $3.829\;{\mu}g/ml$. When fluopicolide was applied at 100 and $1,000\;{\mu}g/ml$ 7 days before inoculation with P. capsici 06-143 in the greenhouse test, the disease was controlled completely until 6 days after inoculation. However, the curative effect of fluopicolide was not as much as the protective effect. When fluopicolide was applied by both soil drenching and foliar spraying, the treatments strongly protected pepper against the Phytophthora blight disease. Based on these results, fluopicolide can be a promising candidate for a fungicide to control P. capsici in the pepper fields.

• Research in Plant Disease
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• v.17 no.2
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• pp.205-210
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• 2011

The disease occurrence on red-pepper plants in relation to cultivation methods of the farmers and to the precipitation was investigated in northern Kyungbuk Province. The major diseases were mosaic, anthracnose and Phytophthora blight in 2007 and 2008. In 2008, mosaic was more severe than that in 2007, but the other diseases were milder than those in 2007. A negative correlation between the mosaic incidence in the harvesting season and the precipitation during May was recognized. On the other hand, there was a positive correlation between the severity of Phytophthora blight in September and the precipitation during August. The occurrence of anthracnose, Phytophthora blight and mosaic in the surveyed pepper plants grown in plastic houses were milder than those in fields, although the farmers cultivating red-pepper plants in the plastic houses were less than 5% in the northern Kyungbuk Province.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.86-86
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• 2003

Phytophthora capsici is a pathogen on several economically important crops including pepper. In pepper growing areas in Korea, Phytophthora blight caused by p. capsici has been considered as the most serious problem in pepper production. The Oomycete attacks the roots, stems, leaves and fruits of the plant. To understand the molecular mechanisms involved in the disease development, the genes expressed doting pepper p. capsici interaction were explored by analyzing expressed sequence tags (ESTs). A complementary DNA (cDNA) library was constructed from total RNA extracted from pepper leaves challenged with p. capsici for 3 days resulting in early stage of symptom development. The comprehensive analysis on the single pass sequencing of over 4000 randomly selected cDNA clones with contig assembly, unique gene extraction, sequence comparison, and functional categorizing will be presented with an emphasis on the genes involved in plant defense and pathogenicity during disease development of the pepper Phytophthora blight.

• The Plant Pathology Journal
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• v.22 no.4
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• pp.364-368
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• 2006

Survival of biocontrol agents and their effective colonization of rhizhosphere are the essential components for successful disease suppression. The effects of hydrogel supplement on bacterial survival and disease control were evaluated in pot and in the field. Addition of 2% hydrogel material to potting soil resulted in significant enhancement of colonization of biocontrol agent Serratia plymuthica A21-4 both in soil and rhizosphere of pepper plants. Rhizosphere colonization of S. plymuthica A21-4 retrieved from 40 days old pepper seedlings indicated 100 times higher bacterial population in hydrogel treated soil than in ordinary pot soil. The pepper plants sown in hydrogelated potting soil showed higher seed germination rate and the better growth of pepper plant than those in ordinary commercial pot soil. Although the suppression of Phytophthora capsid density in the potting soil by treatment of biocontrol agent A21-4 was not significantly different between in hydrogelated soil and ordinary potting soil, the suppression of Phytophthora blight between two treatments was significantly different. A21-4 treatment in hydrogelated potting soil was completely disease-free while same treatment in ordinary potting soil revealed 36% disease incidence. Our field study under natural disease occurrence also showed significantly less disease incidence(12.3%) in the A21-4 treatment in the hydrogelated soil compared to other treatments. Yield promotion of pepper by the A21-4 treatment in the hydrogelated potting soil was also recognized. Our results indicated that hydrogel amendment with biocontrol agent in pot soil would be a good alternative to protect pepper seedlings and increase plant yield.

• Korean Journal of Agricultural Science
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• v.41 no.1
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• pp.29-34
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• 2014

Phytophthora blight occurrence is caused by various environmental factors, and the progress can be regularly predicted so that several predictive models have been developed. The models predict the timing of the disease occurrence, but they do not include the methods of the disease control. Effective fungicide control, control threshold, prediction models were investigated in the study to reflect on customized control modules for the model forecasting the occurrence of Phytophthora blight on hot pepper.