• Title/Summary/Keyword: plant pathogens.

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Anti-microbial Activities of Ten Lauraceae Species against Propionibacterium acnes (여드름 유발균 Propionibacterium acnes에 대한 녹나무과 10종의 항균활성)

  • Cho, Ju Sung;Chi, Lai Won;Jang, Bo Kook;Jeong, Heon Sang;Lee, Cheol Hee
    • Korean Journal of Plant Resources
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    • v.31 no.5
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    • pp.423-432
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    • 2018
  • This study was performed to develop a new natural antimicrobial materials by analyzing the effect of extracts obtained from Ten Lauraceae Species on the inhibitory activity against Propionibacterium acnes. The plant materials were collected from Wando and Jeju islands, and the antimicrobial activity of the crude extracts was examined by the agar diffusion method with different part (i.e., leaf and branch), solvents (i.e., distilled water, 80% ethanol, and 100% methanol) and at different ultrasonic extracting times (i.e., 15, 30, and 45 minutes). The control agents used were synthetic antimicrobials, methylparaben and phenoxyethanol, at concentrations of 0.4, 1, 2, and 4 mg/disc. Altogether, extracts of 10 species used in the study showed inhibitory activity, which confirmed their antimicrobial action against acnes. Among these, leaves of Laurus nobilis L. which was extracted in 80% ethanol for 45 min showed the largest clear zone (19.8 mm). Leaves of L. nobilis L., showing highest antimicrobial activities among 10 species, were successively reextracted with n-hexane, chloroform, ethylacetate and n-butanol. As a results, in all fractions except butanol, clear zone above 10 mm were formed. The ethyl acetate fraction showed the highest inhibitory activity (13.3 mm) and the inhibitory activity was significantly higher than that of crude extract (10.2 mm) and phenoxyethanol as a control (12.5 mm).

Alternaria mycotoxins and its incidence in fruits and vegetables

  • Patriarca, Andrea
    • 한국균학회소식:학술대회논문집
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    • 2018.05a
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    • pp.13-13
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    • 2018
  • Alternaria is a ubiquitous fungal genus, widely distributed in the environment and a range of different habitats. It includes both plant pathogenic and saprophytic species, which can affect crops in the field or cause post-harvest spoilage of plant fruits and kernels. Numerous Alternaria species cause damage to agricultural products including cereal grains, fruits and vegetables, and are responsible for severe economic losses worldwide. Most Alternaria species have the ability to produce a variety of secondary metabolites, which may play important roles in plant pathology as well as food quality and safety. Alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA), tentoxin (TEN) and altenuene (ALT) are considered the main Alternaria compounds thought to pose a risk to human health. However, food-borne Alternaria species are able to produce many additional metabolites, whose toxicity has been tested incompletely or not tested at all. Both alternariols are mutagenic and their presence in cereal grain has been associated with high levels of human esophageal cancer in China. TeA exerts cytotoxic and phytotoxic properties, and is acutely toxic in different animal species, causing hemorrhages in several organs. The possible involvement of TA in the etiology of onyalai, a human hematological disorder occurring in Africa, has been suggested. Altertoxins (ALXs) have been found to be more potent mutagens and acutely toxic to mice than AOH and AME. Other metabolites, such as TEN, are reported to be phytotoxins, and their toxicity on animals has not been demonstrated up to now. Vegetable foods infected by Alternaria rot are obviously not suitable for consumption. Thus, whole fresh fruits are not believed to contribute significantly with Alternaria toxins to human exposure. However, processed vegetable products may introduce considerable amounts of these toxins to the human diet if decayed or moldy fruit is not removed before processing. The taxonomy of the genus is not well defined yet, which makes it difficult to establish an accurate relationship between the contaminant species and their associated mycotoxins. Great efforts have been made to organize taxa into subgeneric taxonomic levels, especially for the small-spored, food associated species, which are closely related and constitute the most relevant food pathogens from this genus. Several crops of agricultural value are susceptible to infection by different Alternaria species and can contribute to the entry of Alternaria mycotoxins in the food chain. The distribution of Alternaria species was studied in different commodities grown in Argentina. These food populations were characterized through a polyphasic approach, with special interest in their secondary metabolite profiles, to understand their full chemical potential. Alternaria species associated with tomato, bell pepper, blueberry, apples and wheat cultivated in Argentina showed a surprisingly high metabolomic and mycotoxigenic potential. The natural occurrence of Alternaria toxins in these foods was also investigated. The results here presented will provide background for discussion on regulations for Alternaria toxins in foods.

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vfr, A Global Regulatory Gene, is Required for Pyrrolnitrin but not for Phenazine-1-carboxylic Acid Biosynthesis in Pseudomonas chlororaphis G05

  • Wu, Xia;Chi, Xiaoyan;Wang, Yanhua;Zhang, Kailu;Kai, Le;He, Qiuning;Tang, Jinxiu;Wang, Kewen;Sun, Longshuo;Hao, Xiuying;Xie, Weihai;Ge, Yihe
    • The Plant Pathology Journal
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    • v.35 no.4
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    • pp.351-361
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    • 2019
  • In our previous study, pyrrolnitrin produced in Pseudomonas chlororaphis G05 plays more critical role in suppression of mycelial growth of some fungal pathogens that cause plant diseases in agriculture. Although some regulators for pyrrolnitrin biosynthesis were identified, the pyrrolnitrin regulation pathway was not fully constructed. During our screening novel regulator candidates, we obtained a white conjugant G05W02 while transposon mutagenesis was carried out between a fusion mutant $G05{\Delta}phz{\Delta}prn::lacZ$ and E. coli S17-1 (pUT/mini-Tn5Kan). By cloning and sequencing of the transposon-flanking DNA fragment, we found that a vfr gene in the conjugant G05W02 was disrupted with mini-Tn5Kan. In one other previous study on P. fluorescens, however, it was reported that the deletion of the vfr caused increased production of pyrrolnitrin and other antifungal metabolites. To confirm its regulatory function, we constructed the vfr-knockout mutant $G05{\Delta}vfr$ and $G05{\Delta}phz{\Delta}prn::lacZ{\Delta}vfr$. By quantifying ${\beta}-galactosidase$ activities, we found that deletion of the vfr decreased the prn operon expression dramatically. Meanwhile, by quantifying pyrrolnitrin production in the mutant $G05{\Delta}vfr$, we found that deficiency of the Vfr caused decreased pyrrolnitrin production. However, production of phenazine-1-carboxylic acid was same to that in the wild-type strain G05. Taken together, Vfr is required for pyrrolnitrin but not for phenazine-1-carboxylic acid biosynthesis in P. chlororaphis G05.

Effect of Soluble-silicate or Chitosan Foliar Spray on Ginseng Cultivated in Blue-white Plastic Film House

  • Seo, Sang Young;Cho, Jong hyeon;Kim, Chang Su;Kim, Hyo Jin;Kim, Dong Won;An, Min Sil;Jang, In Bae
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2019.10a
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    • pp.46-46
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    • 2019
  • The experiments were performed in the Jinan (elevation: 300 meters above sea level), Jeollabuk-do. Seedlings (n = 63 per $3.3m^2$) of ginseng cultivar (Cheonpung, Yeonpung) were planted on April 10, 2015. Shading material of plastic film house was blue-white film. Before the Planting seedling, silicate (3 kg/10 a) or chitosan (40 kg/10 a) was fertilized and foliar sprayed on the leaves 1000 times dilution solution once a month from May to September every year. The growth results of 5-year old ginseng surveyed in 2018 are as follows. The average air temperature in the plastic film house was the highest at $26.6^{\circ}C$ and $26.5^{\circ}C$ in July and August, respectively, and the highest temperature was $40.5^{\circ}C$ in July. The maximum daily temperature of $35^{\circ}C$ or more was 30 days, with the average soil temperature being $24.9^{\circ}C$ in August. The chemical properties of the test soil are as follows. pH was 6.4~6.9 level and EC was 0.35~0.46 dS/m. The organic matter content was 33.5~41.4 g/kg, and available-P content was 251.9~306.8 mg/kg. Exchangeable cations contents, such as K, Ca and Mg were all the appropriate ranges. The soil microbial density surveyed by the dilution plate method was 10~50 times higher than that of control (Non-treatment) and actinomycete density was 3~6 times higher. Pathogens of the genus Fusarium by Metagenome analysis decreased 91.3% and 68.2% respectively in the foliar sprayed of chitosan and soluble-silicate. The light intensity (PAR) in the blue-white film plastic film house gradually increased until July and then decereased, with the average of light intensity in March-October was $120.3umol/m^2/s$. The growth of aerial parts such as plant height and stem length was better than non-sprayed group in silicate or chitosan treatments and Yeonpung cultivar was superior to the Cheonpung cultivar. The SPAD value was higher in Yeonpung cultivar foliar sprayed with soluble-silicate. The growth of underground parts such as root length and taproot length were better in chitosan and soluble-silicate treatment than control, especially in Yeonpung cultivar foliar sprayed with chitosan was good in taproot length and taproot diameter, and fresh weight of root was 60.1 g. Ginsenoside contents were 24.9 mg/g and 22.4 mg/g, in the Cheonpung cultivar foliar sprayed with soluble-silicate or chitosan respectively, 28% and 15% higher than control (19.5 mg/g). The incidence of disease by Alteraria panax and Botrytis cinerea was 3~9% and 4~9%, respectively. High temperature damage rate was 3~5%.

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Soil Microbial Community Analysis using Soil Enzyme Activities in Red Pepper Field Treated Microbial Agents (토양효소활성을 이용한 미생물제제 처리 고추경작지의 토양미생물군집 분석)

  • Kim, Yo-Hwan;Lim, Jong-Hui;An, Chang-Hwan;Jung, Byung-Kwon;Kim, Sang-Dal
    • Journal of Applied Biological Chemistry
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    • v.55 no.1
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    • pp.47-53
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    • 2012
  • Increasing concerns over green farming technology, plant growth promoting rhizobacterium (PGRP) having growth promoting as well as plant disease suppressing properties was recently preferred to use for biological control of plant pathogens infecting plant. We measured the influence of the selected microbial consortium agents-a mixture of PGPR strains-, commercial bio-fungicide, and chemical pesticides on soil microbial community in red pepper field. The activities of soil enzyme such as dehydrogenase, urease, phosphatase, ${\beta}$-glucosidase, and cellulase were analyzed to investigate that of soil microbial community. We also measured plant length, main stem, stem diameter, number of branches and yields of red-pepper in order to observe the red pepper growth promotion. The results of measuring enzyme activities were dehydrogenase 3.5584 ${\mu}g$ TPF $g^{-1}h^{-1}$, urease 15.8689 ${\mu}g$ $NH_4{^-}N$ $g^{-1}h^{-1}$, phosphatase 0.5692 ${\mu}g$ PNP $g^{-1}h^{-1}$, ${\beta}$-glucosidase 2.4785 ${\mu}g$ PNP $g^{-1}h^{-1}$, and cellulase 86.1597 ${\mu}g$ glucose $g^{-1}h^{-1}$ in the soil treated with the microbial consortium agents, so it came out to be very active in the soil. Observing the growth of red-peppers, the main-stem length and the stem diameter were 6.1% and 8.1% higher in the soil treated with the selected microbial consortium agent than the chemical pesticides. After harvesting, yields were 7.3% higher in the soil treated with selected microbial consortium agents than the chemical pesticides. These results showed that microbial consortium agents contribute to increasing soil microbial diversity, growth promoting, and yield of red pepper.

Analysis of Foodborne Pathogenic Contamination of Cooked Hams and Sausages in Korean Processing Facilities (가열 햄 및 소시지류 제조공장에서 식중독 세균에 대한 오염 분석)

  • Park, Hyun-Jung;Go, Eun-Kyung;Wee, Sung-Hwan;Yoon, Ha-Chung;Heo, Eun-Jeong;Kim, Young-Jo;Lee, Hee-Soo;Moon, Jin-San
    • Food Science of Animal Resources
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    • v.32 no.1
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    • pp.103-111
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    • 2012
  • This study was carried out to examine foodborne pathogenic contamination from 1,080 samples of cooked hams and sausages at 10 Korean processing facilities in 2010. The samples were collected from the six primary and additional sterilization products in same lot. To detect Salmonella spp., Staphylococcus aureus, Listeria monocytogenes and Clostridium perfringens in those products (n=1,080), the domestic standard method for Processing and Ingredients Specification of Livestock Products was used. As a result, Salmonella spp. was not detected in all 636 ham and 444 sausage samples. However, L. monocytogenes was detected in four (0.6%) ham and eight (1.8%) sausage samples from five manufactures. S. aureus was also only detected in 4 (0.6%) ham samples from two manufacturers, and C. perfringens was detected in 3 (0.5%) ham samples from three manufacturers, the contamination levels of these pathogens were less than 100 CFU/g. In conclusion, the results of this study indicate that the additional sterilization step of processing manufacturers could not assist to control the foodborne pathogenic bacteria.

The Anti-Bacterial Effect of Witch Hazel(Hamamelis virginiana) on Oral Pathogens (Witch hazel(Hamamelis virginiana)의 구강병원균에 대한 항균 효과)

  • Ryu, Seong-Yong;Ahn, Hyung-Joon;Kwon, Jeong-Seung;Park, Ju-Hyun;Kim, Jae-Young;Choi, Jong-Hoon
    • Journal of Oral Medicine and Pain
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    • v.33 no.2
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    • pp.159-166
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    • 2008
  • An ideal anti-bacterial medication for oral infection requires selective effect on pathogens causing dental caries and periodontal disease but not on normal flora. In addition, it should be less toxic for human and even for environment. This study was to seek such a natural anti-bacterial medication and thus anti-bacterial effect of Hamamelis virginiana was evaluated. Many recent researches on the anti-bacterial effect of natural plant extract and essential oil have reported that natural products can be used as medication for prevention and restrainment of dental caries, halitosis and periodontitis. It has been also reported that Hamamelis virginiana has anti-bacterial effect on Porphyromonas gingivalis, Fusobacterium nucleatum, Capnocytophaga gingivalis, Veilonella parvula, Eikenella corrodens, Peprostreptococcus micros, and Actinomyces odontolyticus. This study evaluated anti-bacterial effect of Hamamelis virginiana on Streptoccoccus mutans, Haemophylus actinomycetemcomitans, and Klebsiella pneumoniae to expand its anti-bacterial effect on other important oral pathogens and eventually to develop its oral care products or apply to clinical purpose. In this study, anti-bacterial tests for antibiotic disk susceptibility, minimal inhibitory concentration and minimal bactericidal concentration were performed to evaluate anti-bacterial effect of Hamamelis virginiana against Streptoccoccus mutans, Haemophylus actinomycetemcomitans, and Klebsiella pneumoniae. The results showed that Hamamelis virginiana has anti-bacterial effect on all pathogen strains tested in this study and furthermore Hamamelis virginiana possesses bactericidal effect other than bacteriostatic effect on Streptoccoccus mutans, Haemophylus actinomycetemcomitans, Klebsiella pneumoniae. This study indicates that a natural anti-bacterial medication for oral diseases can be developed using Hamamelis virginiana.

Biological Control of Anthracnose (Colletotrichum gloeosporioides) in Red Pepper by Bacillus sp. CS-52 (Bacillus sp. CS-52를 이용한 고추 탄저병 (Colletotrichum gloeosporioides) 방제 특성)

  • Kwon, Joung-Ja;Lee, Jung-Bok;Kim, Beam-Soo;Lee, Eun-Ho;Kang, Kyeong-Muk;Shim, Jang-Sub;Joo, Woo-Hong;Jeon, Chun-Pyo;Kwon, Gi-Seok
    • Korean Journal of Microbiology
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    • v.50 no.3
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    • pp.201-209
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    • 2014
  • This study was carried out in order to develop a biological control of anthracnose of red pepper caused by fungal pathogens. In particular, this study focuses on the Colletotrichum species, which includes important fungal pathogens causing a great deal of damage to red pepper. Antagonistic bacteria were isolated from the soil of pepper fields, which were then tested for biocontrol activity against the Colletotrichum gloeosporioides anthracnose pathogen of pepper. Based on the 16S rRNA sequence analysis, the isolated bacterial strain CS-52 was identical to Bacillus sp. The culture broth of Bacillus sp. CS-52 had antifungal activity toward the hyphae and spores of C. gloeosporioides. Moreover, the substances with antifungal activity were optimized when Bacillus sp. CS-52 was grown aerobically in a medium composed of 0.5% glucose, 0.7% $K_2HPO_4$, 0.2% $KH_2PO_4$, 0.3% $NH_4NO_3$, 0.01% $MnSO_4{\cdot}7H_2O$, and 0.15% yeast extract at $30^{\circ}C$. The inhibition of spore formation resulting from cellulase, siderophores, and indole-3-acetic acid (IAA), were produced at 24 h, 48 h, and 72 h, respectively. Bacillus sp. CS-52 also exhibited its potent fungicidal activity against anthracnose in an in vivo test, at a level of 70% when compared to chemical fungicides. These results identified substances with antifungal activity produced by Bacillus sp. CS-52 for the biological control of major plant pathogens in red pepper. Further studies will investigate the synergistic effect promoting better growth and antifungal activity by the formulation of substances with antifungal activity.

Potential Contamination Sources on Fresh Produce Associated with Food Safety

  • Choi, Jungmin;Lee, Sang In;Rackerby, Bryna;Moppert, Ian;McGorrin, Robert;Ha, Sang-Do;Park, Si Hong
    • Journal of Food Hygiene and Safety
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    • v.34 no.1
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    • pp.1-12
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    • 2019
  • The health benefits associated with consumption of fresh produce have been clearly demonstrated and encouraged by international nutrition and health authorities. However, since fresh produce is usually minimally processed, increased consumption of fresh fruits and vegetables has also led to a simultaneous escalation of foodborne illness cases. According to the report by the World Health Organization (WHO), 1 in 10 people suffer from foodborne diseases and 420,000 die every year globally. In comparison to other processed foods, fresh produce can be easily contaminated by various routes at different points in the supply chain from farm to fork. This review is focused on the identification and characterization of possible sources of foodborne illnesses from chemical, biological, and physical hazards and the applicable methodologies to detect potential contaminants. Agro-chemicals (pesticides, fungicides and herbicides), natural toxins (mycotoxins and plant toxins), and heavy metals (mercury and cadmium) are the main sources of chemical hazards, which can be detected by several methods including chromatography and nano-techniques based on nanostructured materials such as noble metal nanoparticles (NMPs), quantum dots (QDs) and magnetic nanoparticles or nanotube. However, the diversity of chemical structures complicates the establishment of one standard method to differentiate the variety of chemical compounds. In addition, fresh fruits and vegetables contain high nutrient contents and moisture, which promote the growth of unwanted microorganisms including bacterial pathogens (Salmonella, E. coli O157: H7, Shigella, Listeria monocytogenes, and Bacillus cereus) and non-bacterial pathogens (norovirus and parasites). In order to detect specific pathogens in fresh produce, methods based on molecular biology such as PCR and immunology are commonly used. Finally, physical hazards including contamination by glass, metal, and gravel in food can cause serious injuries to customers. In order to decrease physical hazards, vision systems such as X-ray inspection have been adopted to detect physical contaminants in food, while exceptional handling skills by food production employees are required to prevent additional contamination.

History of Plant Protection Science since 1900 in Korea (한국(韓國)에 있어서의 식물보호(植物保護) 연구사(硏究史) -1900년대(年代)를 중심(中心)으로-)

  • Park, Jong-Seong
    • Korean Journal of Agricultural Science
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    • v.6 no.1
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    • pp.69-95
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    • 1979
  • The study was conducted to search developmental process of plant protection science from review of forty-three hundreds literatures presented since 1900 in Korea and to forecast future statues of the science to be done. About 80 percent of literatures related to plant protection science such as plant pathology, applied entomology, weed science and agricultural pharmacology were collected from publications of agricultural and forestry reseach organizations attached to Office of Rural Development and Office of Forestry. The rest of literatures were mainly collected from Korean Journal of Plant Protection Society and small number of literatures were also collected from publications of the other journals of crop science and thesis collection of agricultural colleges. In Korea, research organizations of plant protection science are divided into two main groups such as exclusive agricultural research organizations and agricultural colleges. It is pointed out that the former contributions to plant protection science are very great compared to those of the latter since 1900. From periodical consideration of developmental process of the science since 1900, the history or the science are divided into three eras such as introduction and sprout of modern plant protection science during the first forty years, distress of the science during the following twenty years including the Second World War and the Korean War and rapid growth of the science after 1961. In spite of long time distress of the science during the Second World War and the Korean War, the researches on plant protection science in post-war have been done twice as many as pre-war. From consideration of the subject plants in researches of plant protection, it is shown that a great many researches on protection of rice plant have been done and occupy 37 percent of plant protection researches since 1900. And also researches on protection of fruit-trees and cash-crops are not so many as those of rice plant but have been done in noticeable numbers. In fact, researches on protection of fruit-trees and cashcrops were the most important subjects of plant protection researches in pre-war while those of rice plant were the most important subjects after 1930, particulary in post-war. From consideration of contents of plant protection researches, it is said that more fundamental researches than applied ones such as practical control methods of diseases, insect pests and weeds were done in pre-war while more applied researches than fundamental ones were done in post-war, Among applied researches, those of chemical control were the most important subjects. Researches on disease and insect-pest resistance have been done in both pre-war and post-war while researches on forecasting of disease and insect-pest and race of plant pathogens have been done in post-war. And also researches on weed control mainly have been done after 1960. Researches on agricultural chemicals for control of diseases, insect pests and weeds still belong to a new field which must be expected in future, and there is nothing to notice with the exception of practical application of agricultural chemicals introduced from foreign countries. Some of important researches on diseases and insect pests were discussed in relation to developmental process of plant protection science in Korea since 1900. In future, researches on plant protection will be develop to the direction supporting importance of integrated control for plant protection. Therefore, it is pointed out that security of highly educated and trained scientists with enlargement of reseach fields of plant protection science are necessary and role of agricultural colleges for future development of the science must be emphasized.

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