• Research in Plant Disease
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• v.8 no.4
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• pp.228-233
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• 2002

This experiment was carried out to investigate the primary inoculum of strawberry anthracnose in nursery field. The pathogen, Colletotrichum gloeosporioides was not detected in soil and weeds of nursery field but symptom of anthracnose was developed in mother plants collected from market after incubation in humid chamber, The symptom of anthracnose was expressed in the strawberry plant that reserved for 17 days in field after inoculation by spore suspension but was not observed there after. When inoculated leaves were observed by SEM, only appressoria were observed 7 days after inoculation. So, it is guessed that dissemination of Colletotrichum sp. into nursery held will be by contamination of mother plants, and diagnosis by naked eyes may be impossible because symptom will be not developed if environment is to be adequate to penetration and in case of imperfect penetration after germination, the pathogen remains appressorium to achieve penetration.

• Korean Journal Plant Pathology
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• v.13 no.3
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• pp.184-190
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• 1997

Lesion enlargement of ginger rhizome rot was most rapid at 35~40 C, but delayed greatly as temperature decreased. Time needed for a killing a ginger plant, 22~25 cm long, was about 5 days at 35~40 C, but was 15 days at 15 C in a growth chamber test. Higher RH above 90%, higher soil moisture level above 80% of maximum soil moisture capacity, and deeper planting below 4cm enhanced the lesion development on ginger stems and rhizomes. Pythium myriotylum existed in field soil as forms of hyphal portion, hyphal swelling body, or oospore- or zoospore-like bodies, and served as the origin of its colonization. Inocula of P. myriotylum was randomly distributed in soil surface around ginger plants, but its density was decreased as increasing soil depth with the highest density at 0~10 cm soil depth. Population density of P. myriotylum did not vary significantly between the rhizoplane and the rhizosphere soil of a ginger plant, but differed greatly between the disessed and healthy plants with several to several hundreds times higher population in the diseased plants. A positive curvilinear relationship was found between P. myriotylum density and ginger rhizome rot severity.

• Korean journal of applied entomology
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• v.23 no.1 s.58
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• pp.22-27
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• 1984

The effects of solarization on the suppression of soilborne plant pathogen and the growth promotion of cucumber plants were examined in artificially infested soil by vinyl mulching and not mulching from July 25 to August 25, 1983. During the solarization period, the highest temperatures were $58^{\circ}C,\;45^{\circ}C,\;and\;42^{\circ}C$, at 5cm, 15cm, and 25cm of soil depth respectively. The inoculum of cucumber wilt pathogen, Fusarium oxysporum f. sp. cucumerinum, was mixed with soil 30cm deep and saturated with water. The pathogen was completely killed after 30dys of solarization in 5cm soil depth and 98 percent of inoculum was eliminated in 15cm soil depth. But the survival rate of the fungi in 25cm soil depth of solarized plot did not show significant differences compared with those in nontreated plot in 5cm and 15cm depth. Although some of the pathogenic fungi might survive from solarized soil in 15cm and 25cm depth, the ability of microconidia production was reduced significantly The number of microconidia grown on Komada's medium in isolates the primary colonies from solarized soil was less than that in isolates from nontreated soil approximately by one fourth. The first subcultured solates from the solarized soil grown on potato dextrose agar also produced a small amount of microc. onidia compare with that of subcultured isolates from nontreated soil. Cucumber seedlings planted in the soil collected from solarized plot grew much better than that in the soil from nontreated plot at any of soil loved, especially in 5cm of soil depth. And the fruits harvested from cucumber plants grown in the solarized plot were more in number and leavier in weight than that from nontreated plot. Besides the typical symptom development, significant growth suppression wvas recognized with increase of inoculum density of F. oxysporum f. sp. cucumerinum at early stage of cucumber seedlings in steam sterilized soil.

• Applied Biological Chemistry
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• v.35 no.5
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• pp.361-366
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• 1992

The antagonistic bacteria, showing distinguished effect against Fusarium oxysporum and Rhizoctonia solani were isolated from the rhizosphares of horticultural plants and identified as Bacillus subtilis. The strains were studied for their chracteristics of biochemistry, physiology, antagonistic effect against plant pathogenic fungi, and growth promoting effect on horticultural plants. The Bacillus thuringiensis(BT) HD-1 toxin gene was introduced into these B. subtilis. The BT toxin genes on chromosome of the bacteria were identified by southern blotting, but its proteins were not detected by SDS-PAGE. These transformed bacteria showed growth promoting effect and showed also insecticidal and antagonistic effects against Bombix mori and fungi F. oxysporum and R. solani but not against nematode Bursaphelenchus xylophilus.

• Research in Plant Disease
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• v.10 no.4
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• pp.290-296
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• 2004

Bacterial blossom blight is one of the most important diseases of kiwifruit (Actinidia deliciosa). The disease occurs during flowering in the late May and disease outbreaks associated with rainfall during the flowering season have resulted in a severe reduction in kiwifruit production. The causal organism isolated from diseased blossoms of kiwifruits was identified as Pseudomonas syringae pv, syringae based on the physiological and biochemical characteristics and pathogenicity test. Dead fruit stalks, dead pruned twigs, fallen leaves and soils mainly provided R syringae pv. syringae with overwintering places in the kiwifruit orchards, and the inocula also overwintered on buds, trunks, branches, and twigs on the kiwifruit trees. Among the overwintering places, the incula were detected in the highest frequencies from dead fruit stalks. The population density of P. syringae pv. syringae was speculated to be over $1{\times}10^4$cfu/ml for the bacterial infection, and the optimum temperature for the bacterial growth ranged 20 to $25^{\circ}C$. The highest population density of P. syringae pv. syringae on the overwintering places was detected in May and June when the daily average temperature coincided with the optimum temperature for bacterial growth of P. syringae pv. syringae.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.11-17
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• 2007

Previously developed transgenic watermelon rootstocks (gongdae) inserted by CGMMV-CP were examined to test the virus tolerance levels. In the restricted plastic house, the $T_{3}$ watermelon rootstock showed tolerance to CGMMV until 70 days after inoculation on the leaves while the non-transformed watermelon rootstock became susceptible at 20 days after inoculation. In the field, tolerance efficiency of transgenic rootstocks maintained up to 40% at 71 days after contamination with CGMMV in the soil while all of the non-transformed rootstocks became susceptible at 37 days with the same condition. In the same field, transgenic rootstocks showed more tolerance to CGMMV than the non-transformed rootstocks as those were inoculated on the leaves, but it showed only 10 days delay before being susceptible. Therefore, transgenic rootstocks have a characteristic of delay effect against CGMMV susceptibility, rather than resistance character. From $T_{3}$ rootstocks homozygous for the CGMMV-CP horticulturally favorable individuals were selected for further breeding and a transgenic line was finally obtained at the $BC_{1}T_{5}$. A material transfer experiment was conducted to find out if the DNA, RNA or expressed protein in the transgenic rootstocks could move to the grafted scion (non-transformed watermelon, Super-Kumcheon). PCR, northern, and western blot analysis were performed and no evidence of transferring of those materials from rootstock to scion was ever found.

• Horticultural Science & Technology
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• v.32 no.6
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• pp.879-886
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• 2014

This study was conducted to test in vitro the antagonistic effect of composted liquid manure (CLM) against soil-borne turfgrass pathogenic fungi, Rhizoctonia solani AG-2-2 (IIIB) (brown patch), R. solani AG-2-2 (IV) (large patch), and Sclerotinia homoeocarpa (dollar spot) for environmentally friendly turfgrass management. CLMs were collected from 9 livestock excretion treatment facilities around the country including Gunwi (GW), Hapcheon (HC), Hoengseong (HS), Icheon (IC), Iksan (IS), Muan (MA), Nonsan (NS), and Yeoju (YJ). CLMs of IC, GW, and IS showed s ignificant (p < 0.05) mycelium growth inhibition that was 17.8%, 20.4%, and 48.0% against R. solani AG-2-2 (IIIB), R. solani AG-2-2 (IV), and S. homoeocarpa, respectively. A t otal of 110 bacterial isolates were obtained from the CLMs that showed antagonistic effects. Among them, 5, 4, and 10 microbe isolates showed promising antifungal activity against mycelium growth of R. solani AG-2-2 (IIIB), R. solani AG-2-2 (IV), and S. homoeocarpa, respectively. The bacterial isolates ICIIIB60, GWIV70, and ISSH20 effectively inhibited the mycelial growth of three soil-borne turfgrass pathogens. Selected bacterial isolates were identified as Alcaligenes sp., Bacillus licheniformis Ab2, and B. subtilis C7-3 through 16s rDNA gene sequence analysis. Among 5 fungicides, the most compatible fungicide with ICIIIB60, GWIV70, and ISSH20 was tebuconazol, toclofos-methyl and toclofos-methyl, respectively. These findings suggested that CLMs could be effectively used not only as organic liquid fertilizer sources but also as biological control agents for soil-borne turfgrass diseases such as brown patch, large patch, and dollar spot.

• Korean journal of applied entomology
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• v.22 no.3 s.56
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• pp.186-192
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• 1983

The growth of germ tube of Fusarium oxysporum f. sp. cucumerinum was remarkably inhibited on the water agar treated with 100ppm of Fe-EDDHA, a synthetic iron chelating agent, whereas germination rate of microconidia did not show much differences compare with that of non treated water agar. Both of the germination and the germ tube elongation of microconidia were suppressed significantly in King's B agar by the bacterial siderophores produced by Pseudomonas putida. The highest germination of the chlamydospores was obtained in the soil added with $0.25\%$ of glucose plus $0.05\%$ of asparagine. The chlamydospores of cucumber wil fungus germinated about $14\%$ in rhizosphere soil of 2 day-old cucumber seedlings within 48 hours, and the germination was enhanced notably in rhizosphere soil of 10 day-old seedling. But the rates of germination was not increased according to cucumber growth age after 10 day-old seedling. The effect of P. putida and Fe-EDDHA on the germination on chlamydospores in conducive soil was not pronounced in the non-rhizosphere soil added with nutrient. However, the germination was suppressed significantly both in rhizosphere soil and in rhizosphere soil added with nutrient. The suppression of chlamydospore germination was greater in the bacteria inoculated soil than that in Fe-EDDHA treated soil.

• Research in Plant Disease
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• v.16 no.3
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• pp.299-305
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• 2010

Objective of this study is to examine whether pine wood nematode (PWN: Bursaphelenchus xylophilus) in the sawdust discharged from infected trees cause pine wood disease or not. For this, survival time of PWN in soil was examined in which soil moisture was controlled as 15%, 22.5%, and 30% in volume ratio, respectively. The pathogenicity tests were conducted under greenhouse and field conditions. Survival time of PWN in soil was about three days in the saturated (about soil moisture of 23% in volume ratio) and dark condition between 25 and $28^{\circ}C$ of room temperature. None of potted seedlings with non-wounded roots was infected by PWN in sawdust. In field, pine wood disease was not occur in any pine trees. These results indicated that PWN discharged on soil when the infected trees were cut by chain saw can not cause pine wood disease.

• Journal of Bio-Environment Control
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• v.18 no.2
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• pp.171-176
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• 2009

Hydroponic culture has been developed to control soilborn diseases, to increase yield and to enhance the quality of vegetable, The pathogen could be detected from infected plant materials, hydroponic tanks, culture solution and solid media of the severely infected greenhouse, The density of pathogen population was coincided with the severity of disease incidence, For example, 1,900cfu m$L^{-1}$ pf pathogens were counted from tomato plants sampled in a 20% diseased greenhouse. The pathogens may be introduced in the greenhouse through the contaminated soil surrounding the house and/or through the infected young seedlings grown on the nursery soil. Also, not detected to Ralstonia solanacearum from tomato seeds (House Momotaro, Bbaebbae, Ggoggo, and Minicarol cultivar) selling at a market.