• The Plant Pathology Journal
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• v.26 no.4
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• pp.394-401
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• 2010

Resin flow, symptom development, and lignin biosynthesis in response to wounding and fungal inoculation were investigated in Pinus rigida and Pinus densiflora. The two-year-old seedling stems were subjected to three types of treatments: (i) wounding without inoculation, (ii) wound-inoculation with a conidial suspension of Fusarium circinatum, and (iii) pre-wounding woundinoculation with the fungus 20 days after the initial wounding. Resin flow from wounding sites was more evident in P. rigida than P. densiflora in all treatments. The wound-inoculation with the fungus induced almost two-fold higher levels of resin flow than the other treatments in both species. The pre-wounding woundinoculation appeared to result in a decrease in pitch canker development in the two pine species. Some reductions in disease severity were observed in the prewounding wound-inoculated P. rigida, showing a mean disease severity of less than 85%, compared with approximately 100% in the wound-inoculated stems. Disease severity was approximately 50% in the woundinoculated P. densiflora, whereas 10% in the pre-wounding wound-inoculated stems. Higher amounts of lignin were found from bark (ca. 40%) than from xylem (ca. 30%). The wound-inoculated bark and the pre-wounding wound-inoculated bark exhibited higher amounts of lignin among the other treatments. These results suggest that the wound-inoculation apparently prompt the increase in resin flow and lignin biosynthesis from the two pine species, and the prior wounding may be involved in decreased disease severity against the further invasion of F. circinatum.

• Journal of Microbiology and Biotechnology
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• v.32 no.2
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• pp.160-169
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• 2022

In the present study we evaluated the efficacy of a bioformulation of Streptomyces cameroonensis for control of black pod disease in cocoa and enhancement of seedling growth. The formulation developed using talc powder and cassava starch as carriers showed high shelf-life of 1.07 × 10⁶ CFU/g after six months storage at 4℃. The formulation was tested for inhibition of spore germination in Phytophthora megakarya and showed 100% inhibition at 10% (w/v) of formulation. To determine the efficacy of the formulation, we performed an in planta assay in the greenhouse on two hybrids of cocoa seedlings, the tolerant SNK413 × (♂) T79/467 and the susceptible UPA 134× (♂) SCA 12. Detached leaf assay showed a significant reduction in the disease severity index of about 67% for the tolerant hybrid and 55% for the susceptible hybrid compared to non-treated plants. A significant enhancement in stem length, leaf surface area and root weight was observed. Analysis of biochemical markers of defense showed a significant increase in total polyphenol, flavonoid, and total protein contents. There was also significant upregulation of PR-proteins such as chitinases, peroxidases and β-1, 3-glucanases following treatment of both tolerant and susceptible hybrids, though with a higher level of synthesis in the tolerant hybrids. A significant increase was also observed in polyphenol oxidase activities in plants treated with the formulation. This work demonstrated the stability and effectiveness of the S. cameroonensis powder formulation in suppressing black pod disease in cocoa and subsequently enhancing the growth of seedlings.

• Journal of Microbiology and Biotechnology
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• v.4 no.1
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• pp.68-74
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• 1994

A bacterial strain YB-70 which has powerful biocontrol activity against Fusarium solani causing plant root-rot resulting in considerable losses of many economical crops was isolated and selected from over 500 isolates from a ginseng rhizosphere in suppressive soil, and identified as a strain of Bacillus subtilis. In several biochemical and in vitro antibiosis tests on F. solani with culture filterates from B. subtilis YB-70, our data strongly indicated metabolites which mediated inhibition of the fungal growth were presumed to be heat-stable, micromolecular, and ethyl alcohol solutable antifungal substances. Suppression of root-rot by B. subtilis YB-70 was demonstrated in pot trials with eggplant (Solanum melongena L) seedlings. Treatment of the seedling with the bacterial suspension (1.7~1.9$\times$$10^5$ CFU/g) in F. solani-infested soil significantly reduced disease incidences by 68 to 76% after 25 to 30 days. The results supported that B. subtilis YB-70 have excellent potentials as a biocontrol agent.

• Korean Journal Plant Pathology
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• v.14 no.5
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• pp.418-424
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• 1998

The production of 8-ketotrichothecenes, deoxynivalenol (DON), nivalenol (NIV), and their monoacetyl derivatives was studied in rice and corn cultures using 8 isolates of Fusarium graminearum which were obtained from corn and barley samples. Higher concentrations of trichothecenes were produced on rice than corn, and production of the toxins on rice was enhanced by growing the fungi at $25^{\circ}C$. The isolates were used for evaluation of toxin production and pathogenicity after artificial inoculation to 5 corn and 3 barley cultivars. The kinds and the relative amounts of trichothecenes produced in cultures were consistent with those in infected kernels of corn and barley with some exceptions. As for DON chemotypes, the ratios of 15-acetyl-DON to 3-acetyl-DON were varied among the pathogen-cultivar interactions. The corn and barley cultivars showed the significant differences of resistance to the Fusarium isolates in disease severity and seedling blight, and resistance ranking to the different isolates was varied. However, significant correlations were observed between the total concentrations of trichothecenes in infected kernels of corn and barley and pathogenicities of the Fusarium isolates to the hosts.

• Animal cells and systems
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• v.10 no.1
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• pp.21-25
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• 2006

In the present study, Dravya-an organic compound used for seed treatment along with the common fungicides to test its compatibility in the management of Alternaria padwickii in paddy. Dravya (a sea weed extract) was found highly compatible with fungicides like Bavistin and Dithane M-45. Incidence of Alternaria padwickii and Bipolaris oryzae was also reduced to a greater extent in the paddy seed samples of Dravya treatment. On the other hand, it also enhanced the seed germination and seedling vigour. Seedlings of treated samples also showed enhanced activity of peroxidase upon challenge inoculation with Alternaria padwickii. The enzyme activity in the seedlings challenged with the pathogen was two fold more over control. The suppression in disease incidence in growing plants indicated the promising effect of Dravya and Dithane M-45 under green- house conditions.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.89.1-89
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• 2003

Disease suppression by ectomycorrhizal(ECM) fungi has been demonstrated on red pine seedlings. Culturing of pathogenic fungi on petri plates containing culture filtrates of ECM fungi showed that culture filtrates of the ECM fungus Hebeloma cylindrosporum may inhibit the mycelial growth of all tested soil-borne plant pathogenic(SBPP) fungi upto 60％, In order to examine the effects of ECM fungi on SBPP fungi and on red pine seedlings, both symbiotic and pathogenic fungi were inoculated into the soil with red pine seedlings by three inoculation methods; pre-inoculation of SBPP fungi 10 days before inoculation of ECM fungi, simultaneous inoculation of both fungi, post-inoculation of SBPP fungi 60 days after inoculation of ECM fungi. Seedling mortality, seedling growth, and ectomycorrhizal formation by the combined treatments were examined and compared. Pine seedlings were dead by the pre-inoculation of pathogenic fungi, except Rhizina undulate which required 9-12 days, within 6 days after inoculation. Among pathogenic fungi tested, Fusarium oxysporum was the most pathogenic with the mortality of 44％. However, no dead seedlings were shown by simultaneous inoculation of both fungi or pre-inoculation of ECM fungi. In addition, pine seedlings treated by simultaneous or post-inoculation of SBPP fungi were relatively higher than those treated by pre-inoculation in diameter at root crown and the number of ectomycorrhizal roots. There were no significant differences among inoculation methods in root length and dry weight of treated seedlings. It means that ECM fungi somehow play a role in protecting primary roots of red pine seedlings against invasion by the SBPP fungi.

• Research in Plant Disease
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• v.16 no.3
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• pp.331-335
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• 2010

The purpose of this study was to develop a method to effectively control mosses that are generated in container. To meet the goals, 6 kinds of chemical agents at different concentrations were applied to the container containing seedlings of Pinus densiflora with growing liverwort (Marchantia polymorpha) and Chamaecyparis obtusa with growing haircap moss (Polytrichum commune). It was found that quinoclamine was the most effective chemical agent to control mosses. Quinoclamine was effective in controlling liverwort (100% controlled) and haircap moss (95.5% controlled) at its concentration of 0.9 g/l. Next to quinoclamine, it was found that haircap moss and liverwort was effectively controlled by pyroligneous liquid which was followed by flumioxazin and oxyfluorfen. Seedling damages were observed in both two species treated with higher concentration of flumioxazin and oxyfluorfen.

• The Plant Pathology Journal
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• v.34 no.5
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• pp.393-402
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• 2018

Rice world production is affected due to the growing impact of diseases such as bacterial panicle blight, produced by Burkholderia glumae. The pathogen-induced symptoms include seedling rot, grain rot and leafsheath browning in rice plants. It is currently recognized the entrance of this pathogen to the plant, from infected seeds and from environmental sources of the microorganism. However, it is still not fully elucidated the dynamics and permanence of the pathogen in the plant, from its entry until the development of disease symptoms in seedlings or panicles. In this work it was evaluated the infection of B. glumae rice plants, starting from inoculated seeds and substrates, and its subsequent monitoring after infection. Various organs of the plant during the vegetative stage and until the beginning of the reproductive stage, were evaluated. In both inoculation models, the bacteria was maintained in the plant as an endophyte between $1{\times}10^1$ and $1{\times}10^5cfu$ of B. $glumae.g^{-1}$ of plant throughout the vegetative stage. An increase of bacterial population towards initiation of the panicle was observed, and in the maturity of the grain, an endophyte population was identified in the flag leaf at $1{\times}10^6cfu$ of B. $glumae.g^{-1}$ fresh weight of rice plant, conducting towards the symptoms of bacterial panicle blight. The results found, suggest that B. glumae in rice plants developed from infected seeds or from the substrate, can colonize seedlings, establishing and maintaining a bacterial population over time, using rice plants as habitat to survive endophyticly until formation of bacterial panicle blight symptoms.

• Research in Plant Disease
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• v.10 no.1
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• pp.69-72
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• 2004

The control activity of isoprothiolane and tricyclazole mixed with carbosulfan, and probenazole by the nursery treatment was performed against rice leaf and neck blast caused by Magnaporthe grisea. In the paddy field, three fungicides showed good activities against leaf blast 3 months after nursery treatment. Especially the activity of tricyclazole against leaf blast gradually increased by the laps of time to 85.5％, which was assessed at 6 September,2003. Although the control value of isoprotholane and tricyclazole mixed with carbosulfan against neck blast was 47.5％ and 61.1％, respectively, probenazole showed a very high activity against not only leaf blast but also neck blast, of which that was 91.2％. No phytotoxicity was observed in all the treatments after transplanting rice seedling in the paddy field. Based on these results, three systemic fungicides tested in this study showed such a good potential that they might be used to formulate the nursery treating granule.

• Research in Plant Disease
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• v.19 no.2
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• pp.118-120
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• 2013

During the early spring of 2007 to 2009, stem rot of sweet potato (Ipomoea batatas L.) caused by Sclerotium rolfsii occurred in seedling stage grown in plastic film house at Iksan. In seedling stage of sweet potato, symptoms were initially appeared in yellowing and then the seedlings were eventually wilted. The fungus produced abundant white silky mycelium on infected tissues and soil line. Seedlings were very susceptible and died quickly once they were infected. The whole area of a petridish was rapidly covered with white mycelium on agar medium. Sclerotia began to produce after 7 days of mycelial growth and white sclerotia quickly melanized to a dark brown coloration. The causal agent isolated from the diseased plants was identified as Sclerotium rolfsii Saccardo on the basis of the morphological and cultural characteristics. All isolates of S. rolfsii caused similar symptoms on the host petioles by artificial inoculation.