• Research in Plant Disease
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• v.16 no.2
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• pp.170-175
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• 2010

A monoterpenoid benzylideneacetone (BZA) is a bacterial metabolite isolated from culture broth of an entomopathogenic bacterium, Xenorhabdus nematophila K1. It was tested in this study the control efficacy of the metabolite against two major fungal diseases occurring in red-pepper plants. BZA exhibited significant antifungal activities against Phytophthora capsici and Colletotrichum acutatum. Under natural light conditions, the antifungal activity of BZA was maintained for more than sixty days. The antifungal activity of BZA was not lost even in soil because the incidence of Phytophthora blight against red-pepper plants was significantly reduced when the suspensions of P. capsici were poured to the rhizosphere soils mixed with BZA. Application of the BZA suspension spray to the fruit surface infected with C. acutatum significantly suppressed the disease occurrence of anthracnose on the red-pepper plants. These results suggest that BZA can be used to develop a promising agrochemical to control phytophthora blight and anthracnose of redpepper plants.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.93.2-94
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• 2003

In our previous studies, we selected three antagonistic bacteria, KJ1R5, KJ2C12, and KJ9C8 against Phytophthora capsici, the casual agent of Phytophthora blight of pepper. For elucidating production, root colonization, and total microbial activity were investigated. The dual culture assay was accomplished to elucidate existence of antibiotics. In this assay, any antagonistic bacteria did not inhibit growth of six important fungal plant pathogens, suggesting that these antagonists do not produce antibiotics. root surface or rhizosphere soil colonizations were examined with spontaneous rifampicin-resistant mutants equal to antagonistic ability of wild types. KJ2C12 colonized consistently rhizosphere soil while yellowish colonies of KJ1R5 and KJ9C8 well colonized root surfaces and rhizosphere soil. Total microbial activity in pots treated with the antagonistic bacteria was measured using fluorescein diacetate hydrolysis. total microbial activity of three antagonistic bacteria treatments was significantly higher than that of buffer-treated control until 4days after treatment. However, total microbial activity of treatment of three antagonistic bacteria decreased after 7 days. These results indicate that the antagonistic bacteria, KJ1R5 and KJ9C8 colonized and protected roots well against Phytophthora blight of pepper through competition of infection courts, especially competitions.

• The Plant Pathology Journal
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• v.20 no.4
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• pp.277-282
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• 2004

Amendments of a recirculating nutrient solution with potassium silicate were evaluated as a means to control Phytophthora capsici infections on pepper plant(Capsicum annuum L.). Supplying the solutions with 100 or 200 ppm of silicate significantly reduced motility, root decay, and yield losses attributed to infection of P. capsici. Treating inoculated plants with potassium silicate increased root dry weights and number of fruit, especially high-grade fruit. Results were slightly superior to non-inoculated controls. The two varieties, PBC 137 and PBC 602, responded similarly to the treatments. No significant differences were observed between the 100- and 200 ppm silicate treatments. Results were better when greenhouse conditions favored the spread of P. capsici. Silicon alone did not increase pepper yield, suggesting that it acts as a disease suppression agent rather than as a fertilizer, The phenomena by which silicon confers protection against P. capsici infection and disease development are not fully understood, but our results indicate that mechanisms other than a mechanical barrier to fungal penetration are involved.

• Current Research on Agriculture and Life Sciences
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• v.23
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• pp.33-41
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• 2005

Above 130 accessions of pepper consisting of 50 introductions from Mexico and Nepal, and resistant and susceptible controls were tested for resistance to bacterial wilt and to Phytophthora root rot at seedling stage by artificial inoculation. Aa the results, KC897, KC939, KC936 were newly found resistant to bacterial wilt in addition to already known resistance sources such as KC126, KC350, KC351, KC353. No new sources of resistance to Phytophthora root rot were found among the introductions from Mexico and Nepal.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1994.06a
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• pp.50-61
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• 1994

Biological control of important fungal diseases such as Phytophthora blight of red pepper, gary mold rot of vegetables, and powdery mildew of many crops was attempted using an antagonistic bacterium, Bacillus sp. AC-1 in greenhouses and fields. The antagonistic bacterium isolated from the rhizosphere soils of healthy red pepper plant was very effective in the inhibition of mycelial growth of plant pathogenic fungi in vitro including Phytophthora capsici, Rhizoctonia solani, Pyricularia oryzae, Botrytis cinerea, Valsa mali, Fusarium oxysporum, Pythium ultimum, Alternari mali, Helminthosporium oryzae, and Colletotrichum gloeosporioides. Culture filtrate of antagonistic Bacillus sp. AC-1 applied to pot soils infested with Phytophthora capsici suppressed the disease occurrence better than metalaxyl application did until 37 days after treatment in greenhouse tests. Treatments of the bacterial suspension on red pepper plants also reduced the incidence of Phytophthora blight in greenhouse tests. In farmers' commercial production fields, however, the controlling efficacy of the antagonistic bacteria was variable depending on field locations. Gray mold rot of chinese chives and lettuce caused by Botrytis cinerea was also controlled effectively in field tests by the application of Bacillus sp. AC-1 with control values of 79.7% and 72.8%, respectively. Spraying of the bacterial suspension inhibited development of powdery mildew of many crops such as cucumber, tobacco, melon, and rose effectively in greenhouse and field tests. The control efficacy of the bacterial suspension was almost same as that of Fenarimol used as a chemical standard. Further experiments for developing a commercial product from the antagonistic bacteria and for elucidating antagonistic mechanism against plant pathogenic fungi are in progress.

• 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.

• Research in Plant Disease
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• v.18 no.1
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• pp.17-23
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• 2012

Indole compound is a bacterial metabolite synthesized and released by an entomopathogenic bacterium, Xenorhabdus nematophila K1. The antibiotic activity was evaluated against plant pathogens, such as Phytophthora blight and anthracnose of red pepper. Indole significantly suppressed mycelial growth of Phytophthora blight and anthracnose pathogens. Under natural sunlight conditions, indole maintained the antifungal activity for at least sixty days. The activity was not affected under the condition of soil-water. When the indole suspension was applied to surface soil before transplanting of red pepper seedlings and was then regularly sprayed to the foliage of the plants with ten days interval, it resulted in significant reduction of the disease occurrences (Phytophthora blight, anthracnose, soft rot, and black mold) by about 30%. These results suggest that indole can be used to control Phytophthora blight and anthracnose of red pepper.

• Research in Plant Disease
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• v.16 no.2
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• pp.141-147
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• 2010

Resistance to Phytophthora blight (Phytophthora capsici Leonian) of commercial cultivars of Capsicum pepper in Korea were evaluated from 2008 to 2010. In 2008 and 2009, the cultivars were tested for resistance to the Pc003 isolate collected in Youngyang, Gyeongbuk province. In 2010, the selected cultivars in the previous years were tested by inoculating with 3 isolates obtained from the pepper plants in Miryang in Gyeongnam province, Youngyang in Gyeongbuk province, and Goesan in Chungbuk province. A continuous variation in resistance from highly resistant to susceptible was observed among the commercial pepper cultivars. It was also noted that some cultivars, although their names were initiating with 'Yeokgang' or 'PR' meaning Phytophthora resistance, were very low in resistance or susceptible. When the resistant cultivars selected in 2008 and 2009 experiment were inoculated with the 3 isolates, all the commercial cultivars except a rootstock, 'Tantan', succumbed to the exceptionally virulent Pc005 (Miryang) isolate. Pc002 (Goesan) was a little more virulent than Pc003 (Youngyang). A few cultivars resistant to Pc003 (Youngyang) were severely infected by Pc002 (Goesan). Significant interaction in analysis of variance suggested the differential interactions between cultivars and pathogen isolates. Strategies to breed cultivars having high level of resistance to the highly variable pathogenic fungus, Phytophthora capsici, were discussed.

• 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.2
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• pp.178-184
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• 2010

Four major diseases of chili pepper including two fungal diseases, anthracnose (Colletotrichum acutatum) and Phytophthora blight (Phytophthora capsici), and two bacterial diseases, bacterial wilt (Ralstonia solanacearum) and bacterial spot (Xanthomonas campestris pv. vesicatoria), were investigated under future climate-change condition treatments in growth chambers. Treatments with elevated $CO_2$ and temperature were maintained at $720ppm{\pm}20ppm$ $CO_2$ and $30^{\circ}C{\pm}0.5^{\circ}C$, whereas ambient conditions were maintained at $420ppm{\pm}20ppm$ $CO_2$ and $25^{\circ}C{\pm}0.5^{\circ}C$. Pepper seedlings or fruits were infected with each pathogen, and then the disease progress was evaluated in the growth chambers. According to paired t-test analyses, bacterial wilt and spot diseases significantly increased by 24% (p=0.008) and 25% (p=0.016), respectively, with elevated $CO_2$ and temperature conditions. On the other hand, neither Phytophthora blight (p=0.906) nor anthracnose (p=0.125) was statistically significant. The elevated $CO_2$ and temperature accelerated the progress of bacterial wilt by two days and bacterial spot by one day compared to the ambient treatment. Temperature regime studies of the diseases without changes in $CO_2$ confirmed that the accelerated bacterial disease progress was mainly due to the increased temperature rather than the elevated $CO_2$ conditions.