• Korean Journal of Agricultural and Forest Meteorology
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• v.2 no.4
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• pp.148-155
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• 2000

The typhoon and flooding injury in rice were investigated both the region of downpour at the middle of August and the region of typhoon 'Yanni' at the late of September, 1998 in Kyongbuk provincial of Korea. More than 10% of rice stem were buried by soil inundation, the heading was delayed and the high node tiller was brought out. Yield components were deteriorated and yield was reduced. As the clay in the muddy water was attached on grains of rice, the yield was greatly reduced by reason of low grain filling ratio and polished rice ratio. The injury of muddy water was less at yellow ripening stage than at early ripening stage. On the other hand, the muddy water injury was reduced by the fungicide 'Benomyl' and 'Daconil' treatments. The degree of lodging according to varieties and ripening stages was not made a great difference, while the lodging was mainly occurred in the early transplanting time. In a week after lodging, viviparous spikes were occurred in almost all varieties, the degree of viviparity was shown highly in order of early maturing, middle maturing and late maturing varieties in the field as well as in laboratory test. The viviperous spikes were greatly occurred in the lodging toward hill space within row than row space because the more grains were touched on the ground.

• Mycobiology
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• v.47 no.3
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• pp.308-318
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• 2019

Bio-sulfur can be produced in the process of desulfurization from a landfill and collected by some microorganism such as Thiobacillus sp. as a sulfur element. In order to investigate practical use of bio-sulfur as an agent for controlling plant disease, in vitro antifungal activity of bio-sulfur was tested against Colletotrichum orbiculare known to cause cucumber anthracnose. Efficacy of bio-sulfur for suppressing anthracnose disease was also evaluated in vivo using cucumber leaves. Mycelial growth of C. orbiculare on medium containing bio-sulfur was inhibited. Disease severity of cucumber leaves pre-treated with bio-sulfur was significantly decreased compared to that of untreated ones. To illustrate how bio-sulfur could suppress anthracnose disease, structures of cucumber leaves infected with C. orbiculare were observed under a fluorescent microscope and a scanning electron microscope (SEM). Cucumber leaves pre-treated with bio-sulfur showed a low rate of appressorium formation whereas untreated ones showed abundant appressoria. Shrunk fungal hyphae were mostly observed on bio-sulfur-pretreated leaves by SEM. Similar results were observed on leaves pre-treated with a commercial fungicide Benomyl(R). These results suggest that inhibition of appressorium formation of C. orbiculare by bio-sulfur may contribute to its suppression of cucumber anthracnose.

• Journal of Practical Agriculture & Fisheries Research
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• v.24 no.3
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• pp.5-14
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• 2022

Trichoderma is known as pathogen caused serious green mold disease on commercial production. T. pleuroti and T. pleuroticola were common species in various mushroom media. Many strains of T. pleuroti, known as aggressive species causing major economic losses in Korea, showed benomyl resistance. Accurate identification and detection of Trichoderma species associated with oyster mushrooms is very important for disease control. We developed species-specific primers for T. pleuroticola, T. pleuroti, T. harzianum, and T. atroviride based on species-specific fragments isolated from amplified fragment length polymorphism analysis. PCR products corresponding to the predicted fragment of 500bp, 230bp, 180bp, and 410bp were amplified from T. pleuroticola, T. pleuroti, T. harzianum, and T. atroviride, respectively. Multiplex PCR assay using species-specific primers quickly and accurately identified and detected T. pleuroti from mushroom media in which various species co-exist. Our results can be useful for the effective control of mushroom disease.

• Research in Plant Disease
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• v.18 no.3
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• pp.194-200
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• 2012

The objective of this research was to select effective fungicides for the control of Fusarium head bight (FHB) of wheat. We tested fourteen commercial fungicides against FHB in the laboratory and under field. Fludioxonil FS, Fludioxonil SC, and Benomyl + Thiram WP highly inhibited the mycelial growth of Fusarium graminearum on the medium while Oxine-copper WP, Thiophanate-methyl WP, and Copper hydroxide WP were not effective against FHB. To verify the disease control in field condition, we selected four fungicides such as Fludioxonil SC, Captan WP, Difenoconazole + propiconazole EC, and Metconazole SC. Their control efficacy on FHB disease severity of wheat was examined after the fungicide treatment twice (30th April and 10th May, 2012) in the two field locations (Iksan and Gimje). With no treatment, FHB severity was 45% and 33.7% in Gimje and Iksan, respectively. FHB disease incidence after fungicide treatment was between 0.3% and 2.2% in Gimje, showing over 95% FHB disease control. FHB disease incidence of fungicide-treated sector in Iksan showed slightly higher than Gimje but the control value of fungicides exhibited 87-90%. No side effect of the chemicals was observed in fungicide treatment. These results showed that four fungicides were effective in the FHB disease control in wheat.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.40-47
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• 2000

The comparative toxicity of ten acaricides, seven insecticides and five fungicides to the two-spotted spider mite, Tetranychus urticae and its predators, Amblyseius womersleyi and A. eharai was evaluated by a leaf spray bioassay. Five of the acaricides tested, bifenazate, etoxazole, acequinocyl, flufenoxuron and chlorfenapyr were much less toxic to adult females of A. womersleyi and A. eharai than to T. urticae adult females. A. womersleyi adult females treated with five acaricides produced $52{\sim}93%$ as many eggs as untreated adult females. And A. eharai adult females treated with five acaricides laid $54{\sim}73%$ as many eggs as untreated adult females. The remaining acaricides showed high toxicity to adult females of A. womersleyi and A. eharai. All the insecticides tested were less toxic to T. urticae adult females than to adult females of A. womersleyi and A. eharai. However, tebufenozide and diflubenzuron did not significantly affect the survival and reproduction of adult females of A. womersleyi and A. eharai. All the fungicides tested showed low mortality (${\leq}24%$) to adult females of predatory mites. However, benomyl had significant effect on the reproduction of adult females of A. womersleyi and A. eharai. Four acaricides (bifenazate, acequinocyl, flufelloxuron and chlorfenapyr) were much less toxic to eggs of A. womersleyi and A. eharai than to T. urticae eggs. However, etoxazole caused relatively low hatchability ($58{\sim}62%$) of eggs of A. womersleyi and A. eharai. All the insecticides and fungicides tested did not significantly affect the hatch of eggs of predatory mites. It may be suggested from these results that four acaricides, two insecticides and four fungicides described could be Incorporated into the integrated mite management system with A. womersleyi and A. eharai in pear orchard.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.34-40
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• 2018

BACKGROUND: In order to select a fungicide that can effectively control anthracnose disease in Japanese plum fruit, mycelial growth inhibition effect and spore germination inhibition effect of six fungicides were tested in vitro against six isolates of Colletotrichum acutatum and five isolates of C. gloeosporioides that were isolated from diseased Japanese plum fruit. METHODS AND RESULTS: Inhibitory effects of fungicides on mycelial growth were investigated after inoculating each isolate on potato dextrose agar amended with four discriminatory concentrations of each fungicide for 7 days at $25^{\circ}C$. For spore germination inhibitory effect, each isolate of the Colletotrichum spp. was cultured in potato dextrose agar for 7-14 days at $25^{\circ}C$. After adjusting the concentration of spores of each isolate to $1{\times}10^6mL^{-1}$ by diluting with 0.025% PDB, the spore suspension was mixed with each fungicide (1:4, v/v), and $60{\mu}L$ aliquots were dispensed to sterile hole slide glass. Hole slide glasses were placed in a humidified box and incubated for 15 hours at $25^{\circ}C$. Then, spore germination was observed under an optical microscope. At recommended concentration of fungicide prochloraz manganese showed the highest mycelial growth inhibitory effect and dithianon showed the lowest mycelial growth inhibition. The $EC_{50}$ values for the inhibition of spore germination by dithianon and pyraclostrobin were $0.069-0.126{\mu}g/mL$ and $0.37-1.59{\mu}g/mL$, respectively. Although benomyl, prochloraz manganese, azoxystrobin, and tebuconazole did not inhibit the spore germination, they appeared to restrain mycelial growth by abnormal growth of germ tube and mycelium after germination. CONCLUSION: Dithianon seemed to have preventive effect. Prochloraz manganese, azoxystrobin, and tebuconazole were likely to have control effect. Pyraclostrobin is considered to have both preventive and control effect against anthracnose disease of Japanese plum fruit.

• Research in Plant Disease
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• v.30 no.1
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• pp.66-77
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• 2024

Black wood ear mushroom (Auricularia auricula-judae) is one of the most economically important mushrooms in China, Japan, and Korea. The cultivation of wood ear mushrooms on artificial substrates is more efficient in terms of time and cost compared with their natural growth on trees. However, if the substrate cultivation is infected by fast-growing fungi, the relatively slow-growing ear mushroom will be outcompeted, leading to economic losses. In this study, we investigated the competitive fungal isolates from substrates infected with fast-growing fungi for the cultivation of ear mushrooms in Jangheung and Sunchon, Korea. We collected 54 isolates and identified them by sequencing their internal transcribed spacer region with morphological identification. Among the isolates, the dominant isolates were Trichoderma spp. (92.6%), Penicillium spp. (5.6%), and Talaromyces sp. (1.8%). To find an appropriate eco-friendly biocontrol agent, we used five Streptomyces spp. and Benomyl, as controls against Trichoderma spp. and Penicillium spp. Among the six Streptomyces spp., Streptomyces sp. JC203-3 effectively controlled the fungi Trichoderma spp. and Penicillium spp., which pose a significant problem for the substrates of black wood ear mushrooms. This result indicated that this Streptomyces sp. JC203-3 can be used as biocontrol agents to protect against Trichoderma and Penicillium spp.

• Research in Plant Disease
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• v.9 no.2
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• pp.79-84
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• 2003

A wilt disease of commercial cyclamen (Cyclamen persicum) which grown in greenhouse was found in Gyeo-nggi province of Korea during the period from August, 2001 to July, 2002. The disease incidence was up to 42.7% in Kimpo, Gyeonggi province. The disease was more severe in ebb and flow irrigation system than con-ventional overhead flooding\'s. The wilted cyclamen plants showed the chlorosis of leaves and followed by the death. The vascular tissues of the infected basal stem and bulb were discolored with black streaks. The casual fungus was identified to be Fusarium oxysporum f. sp. cyclaminis on the basis of mycological characteristics. Effect of infected soil showed 100% infection rate when the cyclamen plants were grown in potting with infested soil. Examine resistant cultivar showed ‘Matis red’, ‘Schubert’, ‘Victoria’ and ‘Chopin’ were the resistant cultivars but most of cultivars were susceptible to Fusarium wilt. The control effect of chemicals for cyclamen wilt was not much efficient to curative effects even though. Benomyl WP and Fludioxonil SC on the Fusarium wilt had only preventive effects by soil drenching in the pot before inoculation of F. oxysporum. This is the first report on the fusarium wilt of cyclamen caused by F. oxysporum f. sp. cyclaminis in Korea.

• Research in Plant Disease
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• v.8 no.3
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• pp.184-188
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• 2002

An antagonistic bacteria, Bacillus licheniformis Nl strain which effectively inhibited mycelial growth of gray mold rot pathogen, Botrytis cinerea was isolated from the rhizosphere of perilla crop. Powder soy formulation by B. lichentfomis Nl strain as a biocontrol agent was developed far the first time and estimated its control effect on perilla leaves in this study. First of all, far the mass production of antifungal metabolites of B. lichentfomis Nl strain in flask liquid culture, the most effective carbon and nitrogen source were selected as glucose and tryp-tone, respectively, For the formulation, vegetative biomass of B. licheniformis Nl strain from 5-day-old liquid culture in nutrient broth added glucose and tryptone was mixed with soy flour, rice flour glucose, FeSo$_4$~7$H_2O$, and MnCl$_2$. 4$H_2O$, and dried and pulverized. In plastic house test, powder soy formulation effectually controlled gray mold rot as the control value of 93.1 %, was more effective than chemical fungicide, benomyl showing the control value of 86.1%. Thus, development of powder soy formulation of B. lichentfomis Nl will aid large-scale application of biological control in field trials.

• Research in Plant Disease
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• v.10 no.4
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• pp.331-336
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• 2004

The fungus genus Sclerotinia contains a number of important plant pathogens. Vegetable growers in our country are probably most familiar with Sclerotinia sclerotiorum, the causes of sclerotinia rot on crisphead lettuce. S. sclerotiorum has a wide host range which can include lettuce as well as crops such as broccoli, cabbage, carrots, celery, beans, peppers, potatoes, stocks, and tomato. Some fungicides, including benomyl, are effective in some crops, but not all. So, we isolated a antagonistic bacteria that are active on sclerotinia rot caused by S. sclerotiorum and that can be used to control it. About 702 strains had been isolated from soil around plant roots in the field. Ten strains showed strong antifungal activity against S. sclerotiorum. In pot test for antagonistic activity, A-7 strain showed high control value against the pathogen when compared with others. The strain was, therefore, selected as a biocontrol candidate against sclerotinia rot and its biochemical properties and 16S rDNA sequence was analyzed. The A-7 strain was highly related to Bacillus subtilis and B. amyloliquefaciens. To confirm precise identification, we had performed gyr A gene sequences analysis. Its sequence had 96% similarity with B. amyloliquefaciens. Consequently, the isolate was identified as B. amyloliquefaciens A-7.