• The Korean Journal of Ecology
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• v.27 no.5
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• pp.307-310
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• 2004

It was found that seed germination and seedling growth of selected species were inhibited by phytotoxic substance released from fir trees. The aqueous extracts of leaves caused significant inhibition in the seed germination of the receptor plants, Whereas seed germination of some species was not inhibited in extracts of leaves, but seedling elongation of the receptor plants was also decreased by the aqueous extract. Dry weight growth was slightly increased in lower concentration of the extract, while that was proportionally inhibited by higher concentration of the extracts. Chemical substances of fir trees were shown the biological toxicity. The GC method was employed for analysis of phytotoxic chemicals and sixteen chemical substances were identified such as benzoic, phenylacetic, etc. Also 33 volatile substances were identified from the fir tree. These chemical compounds are assumed the substances related to allelopathic potential of Abies holophylla plant species.

• The Korean Journal of Ecology
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• v.12 no.1
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• pp.21-35
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• 1989

It was found that seed germination and seedling growth of selected species were inhibited by phytotoxic substance released from black pine. The longer was the aqueous extraction time of black pine needles, the smaller was the relative germination and growth of the species were inhibited in aqueous leachate and rain leachate as well as in soil underneath the black pine trees. In addition, the growth of lettuce was suppressed in volatile substances from black pine needles. To detect phytotoxic substances of black pine needles, paper chromatography and high performance liquid chromatography were used and fourteen kinds of KDICical compounds were isolated and identified as phenolic acids including benzoic acids. The growth of lettuce was inhibited in the experiment using reagents identical to these KDICical substances and a great inhibition was observed in the concentration of less than 5$\times$ M.

• The Korean Journal of Ecology
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• v.20 no.3
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• pp.181-189
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• 1997

Phenolic compounds from 7 species of naturalized invader species and Korean wild plants were analyzed by high performance liquid chromatography. Eleven phenolic compounds including benzoic acid were identified. The extract of naturalized plants was significantly more inhibitory to seed germination and seedling growth of the both naturalized and Korean wild plants. The content of total phenolic compounds in each extract were 43.5 mg/l in Ailanthus altissima as the maximum amount and 25.5 mg/l in Phytolacca americana as the minimum. Phytotoxic substances of ethanol extracts was investigated for antifungal activity against 23 selected fungus species. The antifungal activity of Phytolacca americana showed the greatest clear zone of 23 mm in Aspergillus awamori and its activity had an effect against 6 fungus species. Ailanthus altissima formed the greatest clear zone of 26 mm in Erwinia carotovora sub. sp. carotovora and had an effect agsinst 2 fungus species.

• The Plant Pathology Journal
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• v.20 no.1
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• pp.52-57
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• 2004

Sclerotinia sp. (isolate BWC98-105) causes stem blight and root rot in Leghum sp., and is presently being evaluated as a potential mycoherbicide for the control of Trifoliorium repens. Bioassays have shown that Sclerotinia sp. produces phytotoxic substance which is biologically active against T. repens. Two biologically active compounds, designated as compoundsI and II, were produced in vitro from the culture filtrate of BWC98-105 isolate Sclerotium sp. Compounds I and II were purified by means of liquid-liquid extraction and $C_{18}$ open column chromatography (300 ${\times}$ 30 mm, i.d). To determine the purity, the purified compounds were analyzed by RP-HPLC. The analytical RP-HPLC column was a TOSOH ODS-120T (150 ${\times}$ 4.6 mm i.d, Japan), of which the flow rate was set at 0.7 mL/min using the linear gradient solvent system initiated with 15 % methanol to 85 % methanol for 50 min with monitoring at 254 nm. Under these RP-HPLC conditions, compounds I and II eluted at 3.49 and 4.13 min, respectively. Compound II was found to be most potent and host specific. However, compound I had a unique antibiotic activity against phytopathogenic bacteria like bacterial leaf blight (Xanthomonas oryzae) on rice, where it played a less important role in producing toxicity on T. repens. No toxin activity was detected in the water fraction after partitioning with several organic solvents. However, toxin activity was detected in the ethyl acetate and butanol fractions. In the leaf bioassay using compound II, the disease first appeared within 4-5 h as water soaked rot, which subsequently developed into well-defined blight affecting the whole plant.

• Korean Journal Plant Pathology
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• v.13 no.2
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• pp.132-137
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• 1997

Phytotoxicity of the culture filtrate and culture conditions for the production of the phytotoxin by Exserohilum monoceras 92-044 were examined. The necrotic lesions were developed on the leaves of Echinochloa crus-galli within 48 hrs after inoculation of the culture filtrate, and the leaves were completely blighted within 5∼7 days. Maximum toxicity was found in the culture broth containing 20% V-8 juice. Phytotoxin accumulation and fungal growth reached their highest peak at around 11 days. Typical symptom appeared on the leaf of E. crus-galli within 48 hrs. Only a weak chlorosis appeared on rice, Arundinella hirta (THUNB) and henry crabgrass (Digitaria sanguinalis SCOP.), but no further symptom developed.

• Horticultural Science & Technology
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• v.31 no.5
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• pp.626-632
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• 2013

In the course of a developing screening method for resistant radish to Fusarium oxysporum f. sp. raphani, we found that the fungus produces phytotoxic compound against Raphanus sativus. The culture filtrate of F. oxysporum f. sp. raphani KR1 represented the strongest phytotoxicity when the fungus was incubated in the malt extract broth with 150 rpm at $25^{\circ}C$ for 14 days. Under bioassay-guided purification, we isolated a substance from liquid culture of F. oxysporum f. sp. raphani KR1, with phytotoxic effect against R. sativus. The compound was identified as fusaric acid by mass and nuclear magnetic resonance spectral analyses. Phytotoxicity of the compound against cruciferous vegetable crops, including radish, cabbage, and broccoli, was investigated. Fusaric acid represented phytotoxicity on radish seedlings by concentration dependant manner. And the phytotoxin demonstrated strong phytotoxicity on the resistant cultivars as well as susceptible cultivars of radish to F. oxysporum f. sp. raphani. In addition, fusaric acid isolated from the fungus also showed a potent phytotoxic efficacy against non-host Brassicaceae crops of the fungus such as cabbage and broccoli. The results demonstrate that fusaric acid produced by F. oxysporum f. sp. raphani is non-host-specific toxin and for screening of resistant radish to the fungal pathogen, spore suspension of the fungus without the phytotoxin has to be used.

• The Korean Journal of Pesticide Science
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• v.11 no.1
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• pp.38-45
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• 2007

Laboratory and greenhouse experiments were conducted to determine the herbicidal effect of two types of ${\delta}$-aminolevulinic acid (ALA), microbiologically-produced ALA (Bio-ALA) and synthetically produced ALA (Synthetic-ALA), on plant growth and chlorophyll content of Chinese cabbage. ALA effect on early plant growth was greatly concentration dependant, showing significant inhibition at higher concentrations. Both pre- and post-emergence application of ALA exhibited significant degree of photodynamic phytotoxicity. Older plants with many leaves were more tolerant to ALA than younger plants, showing less injury. No significant difference in herbicidal activity of two types of ALA, Bio-ALA and Synthetic-ALA, on plant height and chlorophyll content of Chinese cabbage was observed. However, residual biological activity and physico-chemical properties of Synthetic-ALA were more stable than those of Bio-ALA. Our results suggest that ALA had herbicidal potential with both pre- and post-emergence application, and that the chemical may be a valuable mean of eco-friendly weed control based on natural microbial substance.

• Journal of Korean Society of Forest Science
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• v.84 no.3
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• pp.394-405
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• 1995

Certain ericaceous understory plants of temperate forests proliferate following forest clearcutting and fire. Rapid vegetative growth of these plants may affect conifer regeneration due to their strong competitive abilities and allelopathic properties. Planted conifers in these shrub-dominated habitats experience "growth check" which may result in a loss of productivity or in extreme cases total failure of forest regeneration. This growth check phenomenon is exemplified in Calluna Sitca spruce Scots pine ecosystems of western Europe, Kalmia black spruce ecosystem of eastern Canada and Gaultheria-cedar/hemlock ecosystem of the Pacific Northwest of the United States. Dynamics of Kalmia black spruce ecosystem following disturbance was used to explain the mechanism of conifer growth inhibition and their regeneration failure. It is argued that in addition to competition for nutrients, Kalmia allelopathy plays a major role in growth inhibition of black spruce. This conclusion is supported by the results of various field, laboratory and greenhouse experiments. Eight phenolic compounds were isolated and identified from the leaves of Kalmia angustifolia, four of which are known to be highly phyotoxic to black spruce. Methods of overcoming the allelopathic effects of Kalmia in order to enhance black spruce regeneration in Kalmia-dominated sites are discussed.

• The Korean Journal of Pesticide Science
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• v.6 no.3
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• pp.202-208
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• 2002

A phytotoxin was purified by repeated chromatography from liquid cultures of Fusarium oxysporum BG isolated from barnyardgrass. Its chemical structure was determined to be dehydrofusaric acid by mass and NMR spectral analyses. The substance showed a potent phytotoxic activity against growth of duckweed with a $EC_{50}$ value of $1.5{\mu}g/ml$. It also inhibited the root growth of barnyard millet, cress, barnyard grass, and rice cultivar 'Dongjin'. However, it had no inhibitory activity against seed germination of barnyard millet and cress, and the shoot growth of the four plant species.