• Journal of Ginseng Research
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• v.9 no.2
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• pp.163-169
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• 1985

The efficacy of fungicides was compared for control of root rot as well as leaf blight caused by Phytophthora cactorum on ginseng plants. Growth of P. cactorum in rlitro was completely or highly inhibited by metalaxyl, tetracyclin, captafol, carbendazim, and thiophanate + thiram. In field trials, the disease was significantly reduced not only in the root rot but also in the leaf blight when metalaxyl was applied at 4.17 mg a.i. per plant for soil drenching and 1.25 mg a.i. for foliage application. Also captafol was effective on control of the leaf blight but its effect was inferior to that of metalaxyl. Metalaxyl lost its effectiveness in vivo between the 5th and 7th week after soil wren ching. Phytotoxicity was, however, observed on 2 years old ginseng plants when metalaxyl was drenched at 8 mg a.i. while no phytotoxic symptom was developed on 2 years old ginseng plants at 4k mg a.i. and 3 years old at 16 mg a.i. per plant, respectively.

• Journal of Microbiology and Biotechnology
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• v.26 no.3
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• pp.488-492
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• 2016

Rhodococcus species have become increasingly important owing to their ability to degrade a wide range of toxic chemicals and produce bioactive compounds. Here, we report isolation of the Rhodococcus sp. KB6, which is a new leaf-inhabiting endophytic bacterium that suppresses black rot disease in sweet potato leaves. We determined the 7.0 Mb draft genome sequence of KB6 and have predicted 19 biosynthetic gene clusters for secondary metabolites, including heterobactins, which are a new class of siderophores. Notably, we showed the first internal colonization of host plants with Rhodococcus sp. KB6 and discuss its potential as a biocontrol agent for sustainable agriculture.

• Korean Journal of Plant Resources
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• v.10 no.2
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• pp.128-134
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• 1997

This study was conducted to test on the resistance of varieties bred by crossing with Asominori to bacterial leaf blight. Nakdongbyeo and Dongjinbyeo which were susceptible to HB 9011, 8 resistant varieties including Ilmibyeo derived from Asominori and Asominori, Hwangok, 13 varieties including Chukoku 45 which were resistance to HB 9011, HB 9022 and HB 9033 were used to screen their res ponce depending on the various screening methods such as the true resistance, the secondary infection resistance and the disease common field test methods, and the results are as follows: Among 13 varieties tested, 11 varieties including llmibyeo showed tme resistance to HB 9011. Less than 1.0cm of disease lesion were developed on these varieties. Disease lesion was not developed on most of the Asominori lines including Daechongbyeo against IIB9011 and 1lmibyeo was also resistance to HB 9011, on this variety disease lesion area rate was 1.2%, and 7 varieties including Hwajinbyeo showed field resistance to HB 9022. Disease lesion area rate were 19.6% on Nakdongbyeo. 15.6% on Dongjinbyeo, from 3.0% to 2.4% on Asominori lines, and 0.5% on the Asominori when screened at disease common area. Disease was not developed on Keumnambyeo. Significant correlation coefficiences were found between the results from the test methods of the true resistance, the field resistance ancl the field resistance at disease common field tests on Asominori lines, but in some cases, even the varieties on which disease lesions developed, showed field resistance to HB 9022 and HB 9033.

• Research in Plant Disease
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• v.21 no.2
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• pp.103-106
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• 2015

Isolates of the rice blast fungus show a range of tissue-specificities infecting leaves, nodes, neck and panicles. Although neck and panicle blast cause significantly greater yield losses than the leaf blast, virulence tests of the blast isolates have been performed only rice leaves instead of neck and panicles. In this study, we have developed a virulence test method for neck and panicle blast. We selected three representative isolates from each of leaf, neck, and panicle blast. We observed that severe disease lesions developed on the neck and the panicles when the infected rice plants were incubated in a dew chamber for 48 h instead of 24 h when tested on leaves. Unlike the leaf blast, a typical lesion on the neck and panicles appeared after 14 days post-infection as opposed to 7 days with leaf blast. This method will be applied to examine tissue-specificity of the rice blast fungus isolates.

• The Plant Pathology Journal
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• v.27 no.4
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• pp.360-366
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• 2011

Bacterial leaf spot of Euphorbia pulcherrima has been reported in many countries. Characterization by polyphasic approaches indicated that the isolates from India, USA and New Zealand could be distinguished based on rep-PCR profiles and gyrB phylogenies, while the Chinese isolates should be ascribed to Xanthomonas axonopodis pv. poinsettiicola.

• Mycobiology
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• v.51 no.5
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• pp.313-319
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• 2023

During disease surveys of Angelica acutiloba plants in Korea, leaf spot symptoms were observed in a field in Andong in July 2019, and stem rot symptoms in vinyl greenhouses in Yangpyeong in April 2020. Incidence of leaf spot and stem rot of the plants ranged from 10 to 20% and 5 to 30%, respectively. Morphological and cultural characteristics of fungal isolates from the leaf spot and stem rot symptoms fitted into those of the genus Phoma. Molecular phylogenetic analyses of two single-spore isolates from the symptoms using concatenated sequences of LSU, ITS, TUB2, and RPB2 genes authenticated an independent cluster from other Didymella (anamorph: Phoma) species. Moreover, the isolates showed different morphological and cultural characteristics in comparison to closely related Didymella species. These discoveries confirmed the novelty of the isolates. Pathogenicity of the novel Didymella species isolates was substantiated on leaves and stems of A. acutiloba through artificial inoculation. Thus, this study reveals that Didymella acutilobae sp. nov. causes leaf spot and stem rot in Angelica acutiloba.

• The Plant Pathology Journal
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• v.18 no.4
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• pp.179-186
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• 2002

Four newly developed cotton mutants (M-111, M-7662, M-358 and M-218) were compared for their resistance against Cotton leaf curl virus(CLCuV) together with commercial resistant (CIM-443, CIM-482, CIM-473, FH-900 and FH-901) and susceptible (5-12) varieties by artificial inoculation through grafting and under natural field conditions. Infectivity and success of grafting were 100% in all cases. None of the grafted plants were found immune or asymptomatic. All the grafted mutants and most of their single plant progeny rows (SPPRs) showed highly resistant responses as the symptoms displayed by these mutants were milder than the commercial cultivars. Grafted mutants also had delayed disease reactions as they took more time (25-30 days) to produce disease symptoms, as compared with resistant commercial varieties that produced disease 18-22 days after inoculation. Growth of the grafted SPPRs of tested mutants was normal, which is an indication that there will be no production losses. Observations under natural infestation of whitefly showed that two SPPRs of M-ll/CE and M-7662-1/2 and one resistant variety CIM-443 exhibited slight incidence of disease, while one SPPR of M-l1/59 and S-12 were moderately susceptible and highly susceptible with 21％ and 97.l％ disease incidence, respectively. This study also showed that plants displaying more disease symptoms through grafting were easily infected under natural conditions. These results suggest that preference should be given to those plants that exhibited highly resistant responses after artificial inoculation.

• The Plant Pathology Journal
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• v.16 no.5
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• pp.280-282
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• 2000

A leaf spot disease occurred on Allium tuberosum Roth. (Chinese chive) in Korea. All the isolates of Stemphylium sp. from the lesions of the diseased plant parts were identified as S. vesicarium (Waller.) Simmons, based on the morphological characteristics of conidia and conidiophores. Pathogenicity of the fungus was proved by artificial inoculation on Chinese chive plants. This is the first record of leaf blight on Chinese chive caused by S. vesicarium in Korea.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.47-53
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• 1994

Incidences of blast caused by Pyricularia grisea Sacc. on 24 leading cultivars and elite lines of rice were investigated in the fields at Icheon, chuncheon, Jecheon, Naju from 1990 to 1992. In the blast nursery, disease index of leaf blast on Jinmibyeo and Ilpumbyeo were very low as 1 to 3 at Naju, but as high as 6 to 9 at Icheon and other Chuncheon in 1990, but the disease did not occur in other locations and years. The most variable incidence of temporal and spatial leaf blast was observed on Nagdongbyeo, which was 30.6% at Icheon and 2.1% at Chuncheon on 1990, but the disease did not occur at Naju during the investigation. Percentages of diseased panicles on Chucheongbyeo were 11.6% in 1990 and 4.3% in 1992 at Icheon. Odaebyeo and Sobaekbyeo revealed more severe blast occurrences at Chuncheon and Sangju where the elevation was higher than the other places. Regional race distributions of rice blast fungus were more variable at Icheon and Chuncheon than the others.

• Research in Plant Disease
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• v.22 no.2
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• pp.81-93
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• 2016

Out of plant-associated bacteria, certain plant growth-promoting bacteria (PGPB) have been reported to increase plant growth and productivity and to elicit induced resistance against plant pathogens. In this study, our objective was to broaden the range of applications of leaf-colonizing PGPB for foliar parts of road tress and pepper. Total 1,056 isolates of endospore-forming bacteria from tree phylloplanes were collected and evaluated for the enzymatic activities including protease, lipase, and chitinase and antifungal capacities against two fungal pathogens, Colletotrichum graminicola and Botrytis cinerea. Fourteen isolates classified as members of the bacilli group displayed the capacity to colonize pepper leaves after spraying inoculation. Three strains, 5B6, 8D4, and 8G12, and the mixtures were employed to evaluate growth promotion, yield increase and defence responses under field condition. Additionally, foliar application of bacterial preparation was applied to the road tress in Yuseong, Daejeon, South Korea, resulted in increase of chlorophyll contents and leaf thickness, compared with non-treated control. The foliar application of microbial preparation reduced brown shot-hole disease of Prunus serrulata L. and advanced leaf abscission in Ginkgo biloba L. Collectively, our results suggest that leaf-colonizing bacteria provide potential microbial agents to increase the performance of woody plants such as tree and pepper through spray application.