• Mycobiology
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• v.28 no.3
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• pp.115-118
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• 2000

To determine the degree of variability among the host plant species in their abilities to become colonized by arbuscular mycorrhizal fungi (AMF), the inoculum for AMF was collected from the various sites in Korea and was inoculated to the three horticultural plants; Tagetes patula, Torenia fournieri, and Salvia splendens. After 4-month growth under greenhouse, mycorrhizal root colonization rates and spore density were measured. The roots of T. patula showed higher colonization rate than both plants of T. fournieri and Salvia splendens. The mycorrhizal root colonization was influenced by both of the AM fungal inoculum and the host species or their interactions. The combination of the host and fungal species was suggested to be important for the application of AMF to horticultural crops.

• Korean Journal Plant Pathology
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• v.14 no.2
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• pp.145-149
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• 1998

Four nonpathogenic isolates of Fusarium oxysporum isolated from spinach showed suppressive effect on the occurrence of the Fusarium wilt of spinach caused by F. oxysporum f. sp. sprinaciae, among which NF01 controlled the disease most effectively. And NF01 was not pathogenic to tomato, cucumber, radish and spinach. This isolate was further tested for the biological control of the disease. The isolate was not inhibitory to the growth of the pathogen on potato sucrose agar medium, however the Fusarium wilt disease occurred less by drenching spore suspension of the nonpathogenic isolate. The control effect of the isolate was higher at lower inoculum level of the pathogen than at the higher inoculum level, and in the pretreatments than the simultaneous treatment of the isolate with the pathogen inoculation. The nit mutants of the isolate were easily formed on chlorate containing media, and was reisolated selectively as nit mutant from infected soil and plants. The reisolation rate of the isolate as opposed to pathogen was high at preinoculated soil and plants relative to the simultaneous inoculation of the isolate with the pathogen.

• Research in Plant Disease
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• v.10 no.4
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• pp.209-216
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• 2004

The circular leaf spot of persimmon is occurred almost every place where persimmon is cultivated, especially the disease outbreak severely in southern part of Korea. The disease reveals unusually long incubation period after pathogen invade into leaf tissue and no practical control measure is available once the symptom has appeared. Most of the farmers just follow the suggested spray schedules calculated on the basis of weather condition of ordinary years. Therefore the damages due to circular leaf spot greatly differ year after year. In this article, we tried to describe and summarized the investigation on the circular leaf spot pathogen, Mycosphaerella nawae, related to disease outbreak such as overwintering of pathogen, inoculum formation and spread, incubation period after infection, and secondary inoculum. With the summary of these results, we suggest the disease cycle of circular leaf spot of persimmon. The pathogen overwinters in diseased leaves as mycelial form or pseudoperithecial premodium. The pseudoperitheria become matured in spring as the temperature raise and forms asci and ascospores. The maturation of pseudoperithecia are closely related to the temperatures during March and early April. The ascospores completely mature in early May and the ascospores released when the pseudoperithecia absorbed enough moisture after rainfall. The release of ascospores are diverse greatly with the variation of maturity of pseudoperithecia. Generally the spore start to release from middle of May to early of July. Duration of ascospore release is depend on the weather condition of particular year, especially amount and number of precipitation. The ascospores produced from pseudoperithecia is known to the only inoculum for circular leaf spot disease. But according to the results obtained from our investigations, the conidia formed on the lesions which incited by natural infection. This conidia are infectious to persimmon leaves and formed identical symptom as natural infection. The time of producing secondary inoculum of circular leaf spot of persimmon is considered too late to develop new disease. Generally the importance of secondary inoculum is low but the conidia produced in early September are competent to develop new disease and new infection also significantly affect to harvest of persimmon. The importance of circular leaf spot disease is recognized well to farmers. The approaches to control of the disease should be initiated on the basis of the knowledges of inoculum dynamics and ecology of disease development. The forecasting system for circular leaf spot is need to be developed.

• Korean Journal Plant Pathology
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• v.14 no.4
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• pp.325-330
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• 1998

On the basis of the fact that the pycnidiospore of Botryosphaeria dothidea, the causal fungus of apple white rot is a typical water borne spore, a method for quantitative analysis of pycnidiospore dispersal from the warts produced on the diseased apple tree stem was developed. The warts on which cracks developed either on or around them were cut off at the base, and shaked in the water for 4hours at 2$0^{\circ}C$, in which condition the maximum number of spores were released. The volume of shaking solution was calculated as 1 ml per one wart. At the end of shaking, Trio, a household detergent was added to the shaking solution to the concentration of 0.1%, and shaked for additional 10 minutes at 35$^{\circ}C$ to take off the spores attached on the glass ware. One milliliter of the spore suspension thus prepared were passed through transparent membrane filter (pore size : 3.0 ${\mu}{\textrm}{m}$), and the spores attached on the filter were counted under a microscope ($\times$200) after staining them with lactophenol supplemented with aniline blue. The results thus obtained were statistically consistent when at least 30 warts were used simultaneously in single shaking. This method can be applicable in the elucidation of ecology of sporulation and spore dispersal, and also in the screening of the sporulation inhibitor which can be used in the control of the disease by reducing the inoculum density.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.529-532
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• 2001

Korean food waste, one of the abundantly available but environmentally problematic organic wastes in Korea, was utilized as solid-substrate by fungal strain Aspergillus niger ATcC 6275 for the production of enzymemixture containing amylase, cellulase and xylanase. The enzyme mixture can be used as high value-added animal feed. Solid-state fermentation method yielded a 84-fold enhancement in xylanase activity compared with submerged fermentation method. The effect of incubation period, incubation temperature, pH of medium, moisture content, inoculum size and enrichment of the medium with nitrogen and carbon sources were observed for optimal production of these enzymes The optimal amylase activity of 33.10 U/g, cellulase activity of 24.41 U/g, xylanase activity of 328.84 U/g were obtained at 8 days incubation with 50%(w/w) soy bean flake, with incubation temperature of $25^{\circ}C$, pH of 6.38, optimal moisture content of 55% and with inoculum size of $3.8{\times}10^6$spore/g. Enzyme activities were enhanced when ImM $CaSO_4$, 2% Malt extract and 2% galactose were added as mineral, nitrogen and carbon enrichment respectively.

• Journal of Sericultural and Entomological Science
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• v.4
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• pp.69-78
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• 1965

1. In younger larval stages, the incubation period of Spicaria pracina was showed to generally last for 8 days after the inoculation of 1st instar, for 11 days after that of 2nd instar, and for 12 days after that of 3rd instar. 2. The more the inoculum of spore is, the more silkworm jundices appear severely throughout all stage except 1st instar. 3. Especially in matured larval stages, more death rate due to silkworm jundice was showed to appear than that due to green muscardine and the more the larvae became mature, the more the loss due to jundice were severe. 4. Among other inoculum, the control by 5 per cent cerisan lime resulted in getting the best economical effect while this chemicals did harm to the silkworms, being of 20.1 per cent death rate.

• The Plant Pathology Journal
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• v.16 no.3
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• pp.147-150
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• 2000

Sporulation patterns of rice blast fungus were studied at relatively later stages of leaf blast and neck blast seasons in Icheon, Korea. This experiment was done by detaching lesion-bearing leaves and panicle bases. The number of conidia remaining on the leaf blast lesions of different cultivars from Jul 20 to Jul 23 ranged from 3,640 to 82,740 spores. More conidia were observed on the adaxial surface because they were released from abaxial surface. After heading, sporulation was observed from the lesions on the flag leaves but the number of spores was less than in the late July. Detached panicle bases or uppermost internodes infected by Pyricularia grisea produced abundant amount of conidia. Among these panicle bases, 30.1 mm size lesion recorded the highest count of 244,560 spores. When we compared the sporulation amount using the KY-type spore trap, more conidia were recorded from intact lesions than from the lesions which removed conidia and conidiophore The ratio of conidia release against total sporulation ranged from 20.5%-25.0% for leaf blast and 8.2%-25.3% in the neck blast. Effective inoculum potential was also discussed.

• Microbiology and Biotechnology Letters
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• v.20 no.5
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• pp.527-533
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• 1992

The optimal conditions for cellulase and xylanase production by Trichoderma reesei 28217 were studied for enzymatic deinking of old newspaper. The amounts of cellulase and xylanase from the strain was varied by initial medium pH, Tween 80, inoculum size of spore suspension, and carbon and nitrogen sources. The optimal conditions for cellulase production were pH 5.0-6.5, 0.02% of Tween 80, 0.5-1.0% of inoculum size of spore suspension ($1{\times}10^{7}$/ml). cottonseed meal as nitrogen source, and corn flour as carbon source. On the other hand, the optimal conditions for xylanase production were pH 6.5, 0.01% of Tween 80, corn steep liquor as nitrogen source, and disintegrated old newspaper as carbon source. The inoculum size for xylanase production was the same as for cellulase production. The concomitant production of cellulase and xylanase in shake flask culture was efficiently induced in the medium containing 0.5% cottonseed meal as nitrogen source and 1.0% old newspaper and 2.0% corn flour as carbon sources. In this case the activities of cellulase and xylanase produced were 6.11-7.22 IU/mJ and 97.7 IU/ml. respectively. However, the cellulase production in $5{\ell}$ fermentor scale was slightly decreased compared with that in flask scale. Moreover, xylanase production was severely reduced in a fermentor scale. The study for the reason of decreased enzyme production in fermentor is further needed.

• Microbiology and Biotechnology Letters
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• v.8 no.2
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• pp.87-92
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• 1980

These experiments were conducted to manage more safe the selected strains and improve their characteristics. The results obtained were as follows: Preservation on soil at the range of 0 to 5 C was suitable and there were no remarkable changes on their abilities to produce citric acid until 10 months preservation. The successive transfer of spore slightly stimulated the selected strain, M-315 to produce citric acid and the spore precultured on sporulation medium for 7-10 days was desirable as inoculum. Under UV-irradiation from the selected strains, 109 mutants whose morphological characteristics were changed were isolated. Among them, the mutant M-80-12 was shown 3.2％ increase on acid producing ability than that of its parent.

• 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.