• Research in Plant Disease
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• v.29 no.3
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• pp.251-257
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• 2023

In order to examine the pathogenicity of Alternaria dauci, the causal agent of carrot leaf blight, it is necessary to standardize sporulation conditions to ensure the optimal quantity and quality of spore inoculum. Therefore, in this study, the effects of the growth medium, aeration treatment, and UV treatment with 12-hr photoperiod on the sporulation of A. dauci KACC42997 were investigated. A. dauci KACC42997 was pre-cultured for 7 days in a potato dextrose agar medium at 25℃ in the dark condition. When the pre-culture, after removing aerial mycelia, was re-incubated for 5 days, with simultaneous aeration treatment and 12-hr cycle UV treatment at 20℃, the largest number of spores was produced. One hundred seventy isolates of A. dauci were isolated from major carrot growing regions such as Pyeongchang, Gumi and Jeju and tested for sporulation under the conditions established in this study. Except for 20 strains, all strains produced spores. Statistically significant differences in the extent of sporulation were found among local populations of A. dauci isolates, but no difference was observed in their pathogenicity on carrots.

• The Plant Pathology Journal
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• v.22 no.1
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• pp.11-15
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• 2006

Five seed samples of carrot were tested to detect Alternaria spp. by blotter method. A. alternata and A. radicina were detected from all the seed samples as high as $25.8-70.5\%$ and $37.5-63.5\%$, respectively. A. dauci was detected from four seed samples as low as $0.5-7.5\%$. The three Alternaria spp. were detected from the pericarp and the seed coat and endosperm of the carrot seeds but not from the embryo by component plating test. A. alternata and A. radicina were much more detected from the pericarp than the seed coat and endosperm. A. dauci was detected from the pericarp and the seed coat and endosperm at similar rate. The seed sample which was most severely infected with A. radicina showed the lowest rate of germination in the test on top of paper (TP). In the TP test, differences in total infection rate of A. radicina and A. dauci of the seed samples were very closely correlated with those in incidence of seedling rot on the seed samples. However, there was no correlation between infection rate of A. alternata and rate of germination or seedling rot of the seed samples. Soil test for seedling growth revealed that there was no correlation between differences in total infection rate of A. radicina and A. dauci and those in rate of normal seedlings of the seed samples.

• Research in Plant Disease
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• v.17 no.3
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• pp.381-385
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• 2011

Effects of temperatures, relative humidity, pH, and dry periods on conidial germination of Alternaria dauci were evaluated under in vitro conditions. Conidial germination was accelerated at over 95% relative humidity in $15^{\circ}C$ to $25^{\circ}C$ condition. Conidial germination was rapidly reduced at 5 regardless of relative humidity conditions. More than 50% of the conidial germination were initiated within 2 h at $25^{\circ}C$ through pH 5 to 7. The highest conidial germination of A. dauci was on 0.2% of carrot leaf extract. Conidia could survive longer than 12 h, even though its germination decreased. After a 12 h dry period, around 10% of conidia revived and germinated when conidia were hydrated again. These results could be used as the useful information on conidial germination of A. dauci and ecology of Alternaria leaf blight.

• 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.

• The Korean Journal of Mycology
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• v.6 no.1
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• pp.15-20
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• 1978

The purpose of the present study is to describe growth characteristics of seven species of Alternaria occur on naturally infected seeds, and to set up a guide line for quick identification of the species in connection with routine seed health testing. Host range and economic importance of each species are discussed and described with phototographs. The species studied are Alternaria tenuis, A. brassicicola, A. brassicae, A. raphani, A. dauci Alternaria radicina and A. sesami. Other resembling species are discussed in this paper.

• Research in Plant Disease
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• v.17 no.2
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• pp.148-154
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• 2011

This study was conducted to control the seed borne pathogens (Alternaria spp.) of carrot and to examine the seed germination rate by using 13 environment friendly agricultural materials instead of conventional chemicals for organic cultivation. The growth inhibiting effects on pathogens showed the different responses according to each agricultural material and effective 7 materials against seed borne pathogens were selected. Among 7 materials, the carrot seeds sterilized with plant extracts, Tanger Stop and Land Saver were not germinated at all. The germination rate of seeds sterilized with other materials showed the similar levels with reference chemical (Benlate-T) and non-treated seeds. Infection rates of seeds sterilized with seaweed extract, Bellopper for controlling A. radicina and plant extract, Ssial-100 for A. dauci were similar or low infection rate compared with reference chemical. The germination rate and root length of seeds sterilized with Bellopper and Ssial-100 was similar or superior to those of chemical sterilized seeds. The optimal condition seemed to be a little bit different depending on the concentration of materials. As a result, the sterilization of carrot seeds by using the environment friendly materials could be effectively utilized as a technology to inhibit the infection of seed-borne pathogens.

• Korean Journal Plant Pathology
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• v.11 no.2
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• pp.151-157
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• 1995

국내에서 분리한 20종의 Alternaria 277개 균주를 사용하여 Alternaria 진균소독인 altenuene(ALT), altertoxin-I(ATX-I) 및 tenuazonic acid(TA)의 in vitro에서의 생성능과 그 분포를 조사하였다. 각 사용균주를 200g의 살균된 쌀배지에 접종하여 $25^{\circ}C$에서 3주간 배양하였다. Alternaria 배양체들을 methanol로 추출하고 용매분획과 TLC 및 HPLC분석을 통하여 순화하였다. A. alternata와 그와 형태적으로 유사한 A. kikuchiana, A. longipes 및 A. mail는 비록 종간 및 종내의 균주간에 생성량의 차이는 매우 다양하였지만 TA를 비롯한 5종의 진균독소를 모두 생성하였다. A sesami와 A. sesamicola는 4종의 진균독소(AOH, AME, ALT, ATX-I)를 생성하였고 A. cucumerina, A. dauci, A. macrospora, A. porri, A. solani, A. tagetica와 A. zinniae와 같은 대형분생포자와 긴 beak를 형성하는 7종의 Alternaria균들은 AOH와 AME만을 생성하였다. A. brassicicola, A. helianthi, A. panax, A. radicina 및 A. raphani등 5종의 Alternaria는 5종의 진균 독소를 모두 생성하지 않았다.

• Mycobiology
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• v.29 no.1
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• pp.27-42
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• 2001

The taxonomy of the Alternaria spp. has been a subject, of controversy because of their high variability in conidial morphology and polymorphism displayed even in pure cultures. The published Korean literature on the genus Alternaria is scattered and fragmentary, and pertains to about 25 species with special emphasis on occurrence and pathogenicity, but mycological studies on this group of fungi are insufficient. This is the first series of detailed and consolidated account of Korean species of Alternaria, which includes 11 species; viz., Alternaria brassicae, A. brassicicola, A. cinerariae, A. dauci, A. dianthi, A. dianthicola, A. helianthi, A. helianthinffciens, A. iridicola, A. japonica and A. protenta. Detailed diagnostic descriptions, specific characterizations, taxonomic discussions and illustrations for each species are presented.