• Korean Journal of Medicinal Crop Science
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• v.28 no.2
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• pp.142-151
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• 2020

Background: Suppressive soil inhibits soil-borne diseases if pathogens are present, and ginseng does not show injury even if replanted in the same field. Methods and Results: Soil chemical properties and microbial community of soil were investigated in soil suppressive and conducive to ginseng root rot. Root rot disease in 2-year-old ginseng was tested by mixing conducive soil, with suppressive or sterilized suppressive soil. The root rot ratio in suppressive soil was 43.3% compared to 96.7% in conducive soil. Biological factors acted to inhibit the root rot because disease ratio was increased in the sterilized suppressive soil compared to that in non-suppressive soil. The suppressive soil had lower pH, nitrate nitrogen and sodium than the conducive soil. Dominat bacteria and fungi (more than 1.0%) were 3 and 17 species in conducive soil and 7 and 23 species in suppressive soil, respectively. The most predominant fungi were Pseudaleuria sp. HG936843 (28.70%) in conducive soil and Pseudogymnoascus roseus (7.52%) in suppressive soil. Conclusion: Microbial diversity was more abundant in the suppressive soil than in the conducive soil, and the proportion of pathogens (Nectriaceae sp.) causing root rot was significantly lower in the suppressive soil than in the conducive soil.

• The Korean Journal of Mycology
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• v.18 no.3
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• pp.164-177
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• 1990

This study was carried out to obtain some useful data for increasing an effective ginseng production. There was a direct relationship (r=0.2645) between spore germination of Fusarium solani and soil pH, and (r=0.315) between Cylindrocarpon destructans and soil pH. On the other hand, there was a direct relationship (r=0.19) between relative hyphal growth of Rhizoctonia solani and soil pH. There was a direct relationship (r=0.21) between number of total bacteria and F. solani, (r=0.37) between actinomycetes and F. solani and (r=0.20) between celluloytic bacteria and F. solani. However, there was an inverse relationship (r=-0.20) between number of total fungi and F. solani. There was a direct relationship (r=0.24) between number of actinomycetes and R. solani. Each ginseng pathogen-suppressive soil screened was 40 in F. solani, 20 in C. destructans and 9 soil samples in R. solani among 146 soil samples, respectively. The mean contents of K, Ca and Mg were fairly lower in each ginseng pathogen-suppressive soil than conducive soil, whereas Na were somewhat lower. The mean contents of organic matter were over 2 times higher in each ginseng pathogen-suppressive soil than conducive soil. The mean contents of phosphate were fairly lower in F. solani and R. solani-suppressive soil than conducive soil and, on the other hand, were somewhat higher in C. destructans-suppressive soil than conducive soil. The mean soil pH was somewhat lower in each ginseng pathogen-suppressive soil than conducive soil. The mean contents of sand were about 2 times higher in each ginseng pathogen­suppressive soil than conducive soil, whereas silt and clay were somewhat lower. The microbial numbers of total bacteria, total fungi and celluloytic fungi were higher in F. solani-suppressive soil than conducive soil, whereas actinomycetes and celluloytic bacteria were lower. Each microbial number of total bacteria or total fungi indicated a significant difference (p=0.05) between F. solani­suppressive and conducive soil, and the microbial number of actinomycetes was a highly significant difference (p=0.01) between F. solani-suppressive and conducive soil. The microbial numbers of total bacteria, total fungi, actinomycetes and celluloytic fungi were higher in C. destructans-suppressive soil than conducive soil, whereas celluloytic bacteria were about 2 times lower. On the other hand, the microbial numbers of total fungi were higher in R. solani-suppressive soil than conducive soil, whereas total bacteria, actinomycetes, celluloytic bacteria and celluloytic fungi were lower. Fourteen of 16 F. solani-suppressive soils tested were suppressive to ginseng root rot, whereas fifteen of 16 C. destructans-suppressive soils were suppressive. Ginseng root rots of ginseng disease-suppressive soils were in the range of 1.0-17.4% in F. solani-suppressive soil and 0.2-20.4% in C. destructans-suppressive soil, respectively.

• Korean journal of applied entomology
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• v.23 no.3 s.60
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• pp.142-146
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• 1984

Soils suppressive and conducive to ginseng root rot were studied by examining the mycelial growth of Fusarium solani, Phytophthora cactorum, and Sclerotinia sp. on extracts of each type soil. Rhizosphere environments of the two soils were also compared. Mycelial growth of all root rot fungi used was more severely restrained on the suppressive soil extract agar than that of conducive one. However, when heated at 100C for 30 minutes, mycelial growth of F. solani and Sclerotinia sp. was not affected, regardless of type soil used, whereas R. solani and P. cactorum grew better on conducive soil extract. Mycelial growth of all fungi used was stimulated as the treated temperature became higher. No significant differences between the two types of the soil were found in propagules of F. solani. The numbers of total fungi and total bacteria and the ratioes of total fungi to Fusarium and total bacteria to Fusarium were higher in the suppressive soils than in the conducive ones. Higher amount of clay existed in the suppressive soils, Mg and Na contents were lower in those soils than the conducive ones.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.2
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• pp.79-83
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• 2005

Rice and weed interference in the paddy field caused by resource competition and allelopathy. Evaluation method of active weed suppressive behavior of rice to weed was developed by eliminating light competition at soil condition. Twenty eight days old rice seedlings (6-7 leaf stage) which was grown at saturated, no drainage pot were clipped above $3\~4cm$ from the soil surface. Weeds seeded around clipped rice stem, named ratoon seeding screening method, showed varietal suppressive difference to Echinochloa crus-galli, Echinochloa crusgalli var. praticola and Monochoria vaginalis. Potential allelopathic rice varieties, Sathi, AC1423 and PI312777 showed better suppressive activity to weed seedling growth than Nonganbyeo and Keumobyeo. Weed suppression of one plant of rice cultivars could be evaluated by the cell size of $2.5\times2.5cm$ at rice clipping of seedling 29 days after rice seeding.

• 한국균학회소식:학술대회논문집
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• 2015.05a
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• pp.54-54
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• 2015

Crops lack genetic resistance to most necrotrophic soil-borne pathogens and parasitic nematodes that are ubiquitous in agroecosystems worldwide. To overcome this disadvantage, plants recruit and nurture specific group of antagonistic microorganisms from the soil microbiome to defend their roots against pathogens and other pests. The best example of this microbe-based defense of roots is observed in disease-suppressive soils in which the suppressiveness is induced by continuously growing crops that are susceptible to a pathogen. Suppressive soils occur globally yet the microbial basis of most is still poorly described. Fusarium wilt, caused by Fusarium oxysporum f. sp. fragariae is a major disease of strawberry and is naturally suppressed in Korean fields that have undergone continuous strawberry monoculture. Here we show that members of the genus Streptomyces are the specific bacterial components of the microbiome responsible for the suppressiveness that controls Fusarium wilt of strawberry. Furthermore, genome sequencing revealed that Streptomyces griseus, which produces a novel thiopetide antibiotic, is the principal species involved in the suppressiveness. Finally, chemical-genetic studies demonstrated that S. griseus antagonizes F. oxysporum by interfering with fungal cell wall synthesis. An attack by F. oxysporum initiates a defensive "cry for help" by strawberry root and the mustering of microbial defenses led by Streptomyces. These results provide a model for future studies to elucidate the basis of microbially-based defense systems and soil suppressiveness from the field to the molecular level.

• Korean Journal Plant Pathology
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• v.14 no.3
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• pp.268-277
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• 1998

The production of Korean ginseng, one of the most important medicinal root crops, is limited by many factors including soil sickness, root rots in fields as well as during storage prior to consumption. Although much research has been conducted on the diseases in field condition, little information is available on the control of postharvest roots rots. To obtain better management strategy of postharvest root rots in ginseng, biological control using antagonistic bacteria was attempted. Of 208 bacteria obtained form suppressive soil samples, 4 were selected based on the inhibitory effect on mycelial growth of two major causal fungi for postharvest root rots in ginseng, Botrytis cinerea and Fusarium solani. The culture filtrates of these bacterial antagonists greatly inhibited the conidial germination of both pathogenic fungi and produced abnormal morphology such as swollen germ tubes in F. solani and vacuolation of nongerminated conidia in B. cinerea. The population levels of bacterial antagonists on the ginseng roots were gradually increased up to 8 days of incubation. Postharvest root rots of ginseng caused by f. solani and B. cinerea were controlled in dipping tests in the ranges of 60∼80% by antagonistic Bacillus spp. obtained from suppressive soil. These results suggest that biological control using these antagonistic bacteria would be an alternative strategy to control postharvest root rots in ginseng.

• Korean journal of applied entomology
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• v.24 no.2 s.63
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• pp.85-95
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• 1985

It has been tried to find effective biological control measures involved in nature of soil suppressiveness to fusarium wilt of cncumber caused by Fusarium oxysporum f. sp. cucumerinum Owen. Total 28 soil samples were obtained from Jinju, Haman, Namji, Milyang and Suncheon vinyl house area. The disease response of test soil was quantified in terms of DI50 value which caculated from log-probit transformation of diseases response curves. Soils designated 5 from Jinju, 7 from Suncheon, 22 from Namji were recognized as suppressive to fusarium wilt of cucumber. This suppressiveness was completely nullified after autoclave. The disease suppressiveness of tested soil did not indicate any consistency according to either chemical property or texture of soil. Conidial germination, induction and germination of chlamydospore were markedly inhibited in supprerssive soil compared to those in intermediate or conducive soils, however, mycelial lysis did not appear to have direct relationship with disease suppressiveness of given soil. Population density of fluorescent Pseudomonads and Bacillus spp. in the soil originated from different degree of suppressiveness were not different significantly but the number of lytic bacterial plaques measured by triple layer agar method was remarkably higher in suppressive soil than that in intermediate or conducive soil.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.1
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• pp.104-109
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• 1994

For Selection of powerful antagonistic bacteria for biological control of soil borne Erwinia rhapontici causing rot of the vegetables and fruit, excellent straints (S43, S62) were selected from rhizopere in vegetables root rot suppressive soil. Selected strains were identified to be Pseudomonas sp. with Apl 20NE kit tests. Optimum culture condition for the maximum production of antagonistic substance was determined , when isolate was cultured in 523 synthetic broth media at pH 7.0 and 30 during 3 days. Antagonistic substance productivity of isolated Pseudomonas sp. (S43, S62) in the fertilizer soil were increased to about 40-50% compared to that in the non fertilizer soil.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.91-97
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• 1995

The 543 microbial strains were isolated from the rhizosphere in ginseng root rot-suppressive soil. From these, isolate KGM-100 was finally selected for the screening of powerful antagonistic bacterium for the soil-born Fusarium solani causing root rot of many important crops. The isolate KGM-100 was identified as Pseudomonas aeruginosa. Antibiotics produced by the P. aeruginosa KGM-100 were partially characterized as heat-stable and low-molecular weight antibiotics. The strain also produced siderophore, which was assumed to be pseudobactin. Pot test showed approximately 30-50% biological control effects when Fusarium solani-infected soil was treated with the P. aeruginosa KGM-100.

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.354-361
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• 2014

This study was conducted to investigate whether several composted liquid manures (CLMs) are useful for biological control of large patch on zoysiagrass and investigate the chemical and biological factors to suppress large patch in soil treated with CLMs. The CLMs were produced at 4 different facilities for livestock excretion treatments located in Korea. Field experiments were carried out at 5 golf courses located near each facility. CLM and Chemical fertilizer (CF: water soluble fertilizer, 20-20-20) were applied four and three times with N at $12g\;m^{-2}$ per year, respectively. There was significant increase of concentration of K, Na, and Cu of soil treated with CLM compared to CF treatment. Among experimental plots, CN and GG2 plot sites were shown significant higher effect of biological control 80% and 50% respectively against large patch disease. The number of bacteria, Actinomycetes, and fungi in soil at these sites significantly increased and fluorescein diacetate hydrolytic activity was enhanced, while the soil was treated with CLM. The results of this study demonstrated that CLM application has effect on soil to suppress large patch and reduce the use of fungicide in environment-friendly turf management.