• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.48-48
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• 2014

Arbuscular Mycorrhizal Fungi(AMF) is widespread symbiont forming mutualistic relationship with plant root in terrestrial forest in ecosystem. They provide improved absorption of nutrient and water, and enhance the resistance against plant pathogen or polluted soil, therefore AM fungi are important for survival and maintaining of individual or community of plant. For last decade, many studies about the functional variation of AM fungi on host plant growth response were showed that different geographic isolates, even same species, have different effect on host plant. However, little was known about functional variation of AM fungal isolates originated single population, which provide important insight about intraspecific diversity of AMF and their role in forest ecosystem. In this study, four AM fungal isolates of Rhizophagus clarus were cultured in vitro using transformed carrot (Daucus carota) root and they showed the difference between isolates in ontogenic characteristics such as spore density and hyphal length. The plant growth response by mycorrhizas were measured also. After 20 weeks from inoculation of these isolates to host plants, dry weight, Root:Shoot ratio, colonization rates and N, P concentration of host plant showed host plant was affected differently by AM fungal isolates. This results suggest that AM fungi have high diversity in their functionality in intraspecific level, even in same population.

• Research in Plant Disease
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• v.25 no.4
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• pp.188-195
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• 2019

Among 6 fungicides, fluazinam, which had an excellent inhibitory effect on mycelial growth and spore germination, was also effective in controlling jujube anthracnose in the field. While EC₅₀ values of metconazole and tebuconazole ranged from 0.2 to 0.9 ㎍/ml and from 0.4 to 1.1 ㎍/ml against the mycelial growth, respectively, each inhibitory effect on spore germination was low by 7.4% and 11.1% at 50.0 ㎍/ml. In the field test, they showed the control value of 80.5% and 77.0%, respectively. The protective fungicides, as mancozeb and folpet, which had a low inhibitory effect on the mycelial growth, but had a high inhibitory effect of spore germination, showed excellent disease control activities by 87.6% and 92.0% in the field. Showing a result of resistance monitoring conducted with the isolates of Colletotricum gloeosporioides, the resistance against carbendazim was already generated in the field, but it was thought that there was no resistance to pyraclostrobin, fluazinam and tebuconazole. However, if the resistance factor value of the population of C. gloeosporioides isolates to pyraclostrobin was high by 160.4, the diversity of the response to the fungicide in the population was high, so it should be taken more attention to the resistance management.

• The Korean Journal of Mycology
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• v.16 no.1
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• pp.41-48
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• 1988

To investigate germination characteristics of soils on Fusarium species under different soil conditions, this study was carried out to test spore germination of 4 Fusarium species. Among 102 soil samples, spore germinations of Fusarium solani f. sp. pisi, F. oxysporum f. sp. cucumerium, F. oxysporum f. sp. raphani and F. coccophilum were under 50% in 98, 85, 82 and 83 soil samples, respectively. The highest spore germination of F. solani f. sp. pisi, F. oxysporum f. sp. cucumerium and F. coccophilum was obtained in 21 soil samples of pH 5.1-6.0, whereas F. oxysporum f. sp. raphani was in 33 soil samples of pH 4.1-5.0. The highest spore germination of F. solani f. sp. pisi, F. coccophilum and F. oxysporum f. sp. cucumerium was obtained in 4 soil samples holding soil moisture content of 41-60%, while F. oxysporum f. sp. raphani was in 22 soil samples of 21-30%. F. oxysporum f. sp. raphani only showed a direct correlation(r=0.29) between spore germination and soil moisture content. On the basis of each spore germination in cultivated and non-cultivated soils, there was significant difference(p=0.01) in 4 Fusarium species. F. solani f. sp. pisi only indicated significant difference(p=0.0l) between two contrasting-soils, cultivated and non-cultivated soils. The numbers of microbial population were higher in soils suppressive to spore germination than soils conducive to spore germination.

• Research in Plant Disease
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• v.26 no.2
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• pp.61-71
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• 2020

With 32 fungicides, it was examined the inhibitory effects on the mycelial growth of Alternaria dauci KACC42997 causing Alternaria leaf blight of carrot. Showing the results of the agar dilution method, the fungicides belonging to C2, C5, G1, E2, and E3 group were excellent in inhibiting mycelial growth. Protective fungicides belonging to M group, except for iminoctadine tris-albesilate, and pyraclostrobin belonging to C3 group were effective in inhibiting spore germination of pathogens. The fungicides included into C2 group inhibiting succinate dehydrogenase activity and the G1 group inhibiting demethylase activity showed the excellent inhibitory effect on mycelial growth but the inhibitory effect of spore germination was very low. However, fluazinam belonging to C5 group was excellent in inhibiting spore germination as well as mycelial growth. Especially, when 100 ㎍/ml of fluxapyroxad belonging to the C2 group was treated, 47.1% of spore formation was inhibited on the medium. In comparison of the resistance factors of 3 fungicide groups, as G, C, and E group, in populations of A. dauci isolates collected from Gumi, Pyeongchang, and Jeju, resistance factor in the population of Jeju was the lowest. However, two isolates resistant to fludioxonil belonging to E2 group were found in the isolate group of Pyeongchang, and both showed cross-resistance to iprodione and procymidone.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.493-503
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• 2015

This study analyzed how spatial distribution of Himantormia lugubris is affected by the microenvironment in the Antarctic Specially Protected Area (ASPA) No. 171 located in the Barton Peninsula of King George Island that belongs to the maritime Antarctic. In order to determine the population structure of H. lugubris growing in Baekje Hill within ASPA No. 171, we counted the individuals of different size groups after dividing the population into 5 growth stages according to mean diameter as follows: ≤ 1 cm, 1-3 cm, 3-5 cm, 5-10 cm, and ≥ 10 cm. The count of H. lugubris individuals in each growth stage was converted into its percentage with respect to the entire population, which yielded the finding that stages 1 through 5 accounted for 32.8%, 25.3%, 15.9%, 22.5%, and 3.5%, respectively. This suggests that the population of H. lugubris in ASPA No. 171 has a stable reverse J-shaped population structure, with the younger individuals outnumbering mature ones. The mean density of H. lugubris was 17.6/0.25 m², mean canopy cover 13.3%, and the mean dry weight 37.8 g/0.25 m². It began to produce spore in the sizes over 3 cm, and most individuals measuring 5-10 cm were adults with sexually mature apothecia. The spatial distribution of H. lugubris was highly heterogeneous. The major factors influencing its distribution and performance were found to be the period covered by snow, wind direction, moisture, size of the substrate, and canopy cover of Usnea spp. Based on these factors, we constructed a prediction model for estimating the spatial distribution of H. lugubris. Conclusively, the major factors for the spatial distribution of H. lugubris were snow, wind, substrate and the competition with Usnea spp. These results are important for understanding of the distribution in the maritime Antarctic and evolution of H. lugubris that claims a unique life history and ecological niche.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.361-370
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• 1982

The effects of climatic factors on organisms lire variable and complex, and it, however, can be interpreted in terms of those on the distribution and those on the population densities. The distribution of an organism may largely be determined by the temperatures, except some temporal organisms which are depended on the air mass movements. Population density of an organism is determined by various climatic factors, such as previous winter temperature, temperature of growing season and rainfall. The start of growing season of the rice plants has been shifted to earlier since last decade in Korea. This may mean that the overall climatic condition during the growing season might be considerably different from those in past years, and such a difference in climatic conditions might have close relation with the recent status of the diseases and insect pests through direct effects on the physiology and population dynamics of the organisms, as well as through on the biotic associations of the pest organisms. The white back planthopper and brown planthopper have become the key insect pests in Korea in recent years. They are migratory and have high reproductive pontentials and more generations than average residential insects. The synchronization of the migrants and physiological condition of the rice plants seems to be the important factors in relation to the recent outbreaks of these insects; the high reproductive rate can be obtained with the growth stage of rice being 30-50 days after transplanting. The modication of the microclimate associated with high plant density and some other introduced new cultural techniques also have some relation with the outbreak. The key diseases of the rice are the blast disease, sheath blight and the bacterial leaf blight. For the rice blast, the seedling blast and leaf blast during the early growing season and the neck blast, have become more serious, the former may be related to hotbed nursery and the later may be related to the high humidity in early August, and synchronization of the heading time which has been shifted to early part from middle or late part of August. In general, for the rice diseases, the development of the new races have been the most serious which are largely resulted from the introduction of the new varieties, but it also seems to be related with the prolonged periods of the favorable condition associated with the shifted growing seasons. In general, the diseases and insect pest problems have become much more variable and complex, and control measures should be based on the thorough knowledge of the ecology of the pest organisms, that is, effects of various environmental factors on the disease cycle; spore release, spore deposition, infection, colonization and sporulation of the disease organisms, and those on the development, reproductive potentials, dispersal, age specific responses of the insects. The well organized real-time pest management systems, such as alfalfa weevil management system developed at the Purdue University in U.S., is the prime importance for the implementation of the pest management principles.

• Horticultural Science & Technology
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• v.19 no.2
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• pp.170-173
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• 2001

Postharvest diseases developed on harvested products result in a great economic loss. The objective of this research was to develop a chemical treatment to control major postharvest pathogens including Botrytis cinerea and Penicillium expansum in the cold storage room. Acetic acid ($2.4mg{\cdot}L^{-1}$, $4.8mg{\cdot}L^{-1}$) inhibits spore germination and mycelial growth of B. cinerea and P. expansum on PDA at room temperature ($25^{\circ}C$) and low temperature ($2^{\circ}C$). Fumigation of cold storage room with $SO_2$ ($5g{\cdot}m^{-3}$) gas or gaseous acetic acid ($4.8g{\cdot}m^{-3}$) prior to operation greatly reduced population of fungi in the cold storage room.

• The Plant Pathology Journal
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• v.35 no.5
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• pp.437-444
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• 2019

Chlorine dioxide ($ClO_2$) has been widely used as an effective disinfectant to control fungal contamination during postharvest crop storage. In this study, Fusarium oxysporum f. sp. batatas SP-f6 from the black rot symptom of sweetpotato was isolated and identified using phylogenetic analysis of elongation factor 1-${\alpha}$ gene; we further examined the in vitro and in vivo inhibitory activities of $ClO_2$ gas against the fungus. In the in vitro medium tests, fungal population was significantly inhibited upon increasing the concentration and exposure time. In in vivo tests, spore suspensions were drop-inoculated onto sweetpotato slices, followed by treatment using various $ClO_2$ concentrations and treatment times to assess fungus-induced disease development in the slices. Lesion diameters decreased at the tested $ClO_2$ concentrations over time. When sweetpotato roots were dip-inoculated in spore suspensions prior to treatment with 20 and 40 ppm of $ClO_2$ for 0-60 min, fungal populations significantly decreased at the tested concentrations for 30-60 min. Taken together, these results showed that $ClO_2$ gas can effectively inhibit fungal growth and disease development caused by F. oxysporum f. sp. batatas on sweetpotato. Therefore, $ClO_2$ gas may be used as a sanitizer to control this fungus during postharvest storage of sweetpotato.

• Research in Plant Disease
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• v.13 no.1
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• pp.45-49
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• 2007

Single spores were isolated from infected roots of Chinese cabbage with a typical clubroot symptom, collected from different Chinese cabbage cultivation areas in Korea. When the single spore isolates were inoculated on Chinese cabbage, radish, turnip, kale, leaf mustard and Williams' differential varieties, among 321 roots harvested two weeks after inoculation, a visual symptom was observed on only one root and light/uncommon symptoms were done on 70 roots. These 71 individuals were homogenized and used as inocula. These inocula caused generally higher pathogenicity than that of single spore. Finally 15 isolates, with enough growth for conducting further experiment, were selected. These 15 individuals were grouped four, seven, two and two into race 1, race 4, race 9 and race 11, respectively, using Williams' differential set. It was confirmed that race 4 were dominantly present in Korea. These 15 had been obtained from roots of Chinese cabbages, radishes and turnips inoculated with single resting spores and had shown pathogenicity to Laurentian and Wilhelmsburger belong to Rutabaga in Williams' differential variety set. Therefore, we assume that such characteristic pathotypes including race 4, especially, of P. brassicae showing strong pathogenicity to Chinese cabbage, radish and turnip may be dominant in Korea.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.2
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• pp.203-209
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• 1999

This study was conducted to obtain the basic data on agricultural use of arbuscular mycorrhizal fungi(AMF) in salt accumulated plastic film house soil by evaluating the density of AMF spores in plastic film house in Yeong Nam area and surface sterility condition, germination rate of AMF spores, and hyphal growth in vitro. The density of AMF spores in plastic film house soils was highest in the site of water melon, and those of cucumber, melon, hot pepper sites were followed in order. The number of AMF was in the range of 101-207 per 100 g dry soil. With decreasing the ratio of bacteria to fungi(B/F), the population density of AMF was increased, and available $P_2O_5$ content of soil was significantly correlated to the population densities of AMF($r=0.416^*$). The surface sterility rate and spore germination of AMF isolated in plastic film house soil were more than 50% in 2% chloramin T and 2% chloramin T + antibiotic and 0.5% NaOCl treatments. The germination rate of Gigaspora margarita in the range of initial pH 5~9 of the medium was more than 56%. Hyphal growth was increased as pH of the medium increased. However the germination rate of Acaulospora spinosa was highest in the medium of pH 9, and hyphal growth in vitro was poor and not related to pH of the medium.