• Korean Journal of Agricultural and Forest Meteorology
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• v.5 no.3
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• pp.191-199
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• 2003

Optimum transplanting time for extremely early rice cultivation as an after-crop of fruit and vegetables under greenhouse conditions in the southern area was determined. Rice was transplanted on March 10, March 20, March 30, April 10 and April 20 far three years from 1998 to 2000. Meteorological computations for rice production were high for heading between early May and early July, but they were too low for heading between late July and early August. Especially the expected yield predicted with 35,000 spikelets, the average spikelets per $m^2$ for extremely early transplanting. Computation for heading between late July and early August was low by 106 kg/10a compared with that yield at heading during the same period in the field. As the transplanting date in extremely early rice cultivation was earlier) rice growth at early stages was more retarded by low temperature. Rice growth at heading stage recovered with high temperature, showing less difference for the transplanting date. Abnormal tillers occurred by 15.5∼22.2%. The contribution of 1,000 grain weight${\times}$ripened grain ratio to yield of the extremely early rice cultivation in the greenhouse was 50.6%, indicating 16% hi일or than the degree of panicle per $m^2$ on yield. The estimated optimum transplanting time on the basis of yield for the extremely early greenhouse rice cultivation ranged from March 19 to April 28, and the estimated critical transplanting date on the basis of accumulated effective temperature was March 12. Rice reduced the amount of NO$_3$-N by 97.1% and EC by 90.5% in greenhouse soil with continuous fruit/vegetables fer more than a 10-year period, and completely removed the root-knot nematodes.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.700-707
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• 2020

The root-knot nematode (Meloidogyne incognita) is an important pathogen in crop cultivation, however, few methods are available to control this parasitic roundworm. In this study, the nematicidal effects of approximately 30 Streptomyces strains isolated from soil samples of Mt. Naejang (Korea) were tested against Meloidogyne incognita, and the culture broth of the strains KRA-24 and KRA-28 exhibited approximately 75% and 85% insecticidal activity, respectively, in in vitro assays. In in vivo pot experiments, these strains reduced the number of nematodes in the soil and the number of egg masses in the roots of red peppers. The two strains also survived in the presence of insecticidal agents (0.1 to 3.0%) such as fosthiazate, ethoprophos and terbufos when they were used in parallel. The mixture of KRA-24 or KRA-28 culture broth and fosthiazate exhibited nematicidal effects that were similar to those observed when KRA-24 or KRA-28 were used alone. Our results clearly suggest that the Streptomyces strains KRA-24 and KRA-28 should be promoted as a biocontrol agent against Meloidogyne incognita.

• Korean Journal of Plant Resources
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• v.28 no.1
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• pp.93-100
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• 2015

The objective of this study was to determine the effectiveness of rapeseed meal in controlling soil nematode. Two different rapeseed meals (Jeju local rape varieties and 'Sunmang' variety) were mixed with the soil to control nematodes environmentally. When soil physical properties in the rapeseed meal-mixed soils were analyzed, OM (organic matter), $P_2O_5$, Ca, Mg, CEC (Cation Exchange Capacity) value increased. Especially, the level of OM was 3-fold higher than control soil. Glucosinolate content of rapeseed meal was higher in Jeju local rape varieties than 'Sunmang' variety. The major components of glucosinolates were consisted of progoitrin, gluconapin, glucobrassiaca napin, and sinigrin. These components were likely to be involved in reducing nematode density.

• Mycobiology
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• v.49 no.5
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• pp.491-497
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• 2021

An endolichenic fungus Xylaria grammica EL000614 produces grammicin, a potent nematicidal pyrone derivative that can serve as a new control option for root-knot nematodes. We optimized an Agrobacterium tumefaciens-mediated transformation (ATMT) protocol for X. grammica to support genetic studies. Transformants were successfully generated after co-cultivation of homogenized young mycelia of X. grammica with A. tumefaciens strain AGL-1 carrying a binary vector that contains the bacterial hygromycin B phosphotransferase (hph) gene and the eGFP gene in T-DNA. The resulting transformants were mitotically stable, and PCR analysis showed the integratin of both genes in the genome of transformants. Expression of eGFP was confirmed via fluorescence microscopy. Southern analysis showed that 131 (78.9%) out of 166 transformants contained a single T-DNA insertion. Crucial factors for producing predominantly single T-DNA transformants include 48 h of co-cultivation, pretreatment of A. tumefaciens cells with acetosyringone before co-cultivation, and using freshly prepared mycelia. The established ATMT protocol offers an efficient tool for random insertional mutagenesis and gene transfer in studying the biology and ecology of X. grammica.

• Research in Plant Disease
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• v.22 no.4
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• pp.227-235
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• 2016

Plant disease caused by root-knot nematode is a major problem in crop production. Using of chemical pesticides, one of the most efficient methods to control nematodes, have raised issues in toxicity to humans and animals and environmental pollution. In this study, to select actinomycete strains that have potential to serve as a microbial agent for control of nematodes, we investigated nematicidal activity of culture broth from 670 Streptomyces isolates. A culture filtrate of KRA15-528 isolate that was identified as S. flavogriseus on the basis of 16S rRNA sequence analysis, showed strong nematicidal activity against second stage of juveniles of Meloidogyne incognita and inhibited egg hatching; exposure to 10% of culture filtrate resulted in 71% juvenile mortality at 48 hours afters treatment and suppressed egg hatching by 54% at 9 days after treatment. When the KRA15-528 culture filtrate was partitioned with ethyl acetate and butanol, ethyl acetate layer exclusively showed strong activity; 91%, 53%, 30% of mortality at 1,000, 500, $250{\mu}g/ml$, respectively. Additionally, the culture filtrate suppressed gall formation on cucumber plant by M. incognita with no phytotoxicity. These results suggest that S. flavogriseus KRA15-528 has potential to serve as a microbial nematicide for the control of root-knot nematode disease.

• Korean journal of applied entomology
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• v.52 no.4
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• pp.327-333
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• 2013

Plant parasitic nematodes were isolated from 274 soil samples collected from soybean fields in Korea. Nematode importance rating in soybean is proposed based on this study and by reviewing other reports. Soybean cyst nematode, Heterodera glycines is the most important nematode species and rated as $1^{st}$ because it detected from 38%(range 25-51%) of soil samples with high density except Jeju province. Root-knot nematode, Meloidogyne spp. is rated $2^{nd}$ and is more widely distributed in southern provinces, Gyeongnam, Jeonnam, and Jeju province (detection rate ranged 16-44%). Pratylenchus is rated $3^{rd}$ and is more frequently detected from northern provinces such as Gyeonggi and Gangwon (detection rate ranged 10-13%). Helicotylenchus is rated $4^{th}$ and is particularly important in Jeju province (detection rate is 62% and numbers averaged 571 nematodes/$300cm^3$ soil), which is the main production area for sprouting soybean in Korea. Tylenchorhynchus, Paratylenchus, Criconema, Criconemoide, Mesocriconema, Ogma, Xiphinema, Paratrichodorus, and Trichodorus occur in low frequency and density, thus they are rated to $5^{th}$. We propose to delete following nematode genus from the list of soybean parasitic nematode in Korea because their parasitism on soybean is unconfirmed or negligible; Tylenchus, Aphelenchus, Aphelenchoides, Ditylenchus, Hirschmanniella immamuri, Basiria graminophila, Psilenchus, and Pseudhalenchus. Therefore, we revised 30 species in 16 genera as soybean parasitic nematodes in Korea. Importance rating is $1^{st}$ Heterodera glycines, $2^{nd}$ Meloidogyne spp., $3^{rd}$ Pratylenchus spp. and $4^{th}$ Helicotylenchus spp. especially in Jeju province.

• The Korean Journal of Pesticide Science
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• v.12 no.2
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• pp.155-161
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• 2008

The inhibitory effect of herbal extracts using methanol and hexane collected from Sudan and Korea was evaluated on egg hatching of Meloidogyne incognita. The concentration of herbal extracts were 10,000, 1,000 and 100 ppm, respectively. They were treated to Meloidogyne incognita eggs after 3, 7, and 21 days of hatching. All herbal extracts inhibited egg hatching significantly compared to the control. The degree of inhibition was directly related to the concentration of the extracts. At 10,000 ppm, very fewer individuals were hatched at all the periods of exposure with the exception of the extract of fruits of Quisqalis indica which gave 84.4 and 54.5% at 7 and 21 days, respectively. Egg hatching was completely ceased, especially after 7 days for most of the extracts. While at 1,000 ppm relatively high numbers of eggs were hatched compared to the higher concentration, as well the extracts Q. indica reported many number of hatched eggs compared to others, especially at 21 days. On the other hand, the extract from pods of Cucumis mello var agrestis gave the least hatching number of eggs at all periods of exposure which gave 2, 8, and 3% at 3, 7, and 21 days, respectively in comparison to the control. Whereas at 100 ppm, inhibition increased with exposure time. However, the extract leaf of Desmodium caudatum represented the fewer hatching eggs at 3 and 7 days.

• Korean journal of applied entomology
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• v.27 no.3
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• pp.149-158
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• 1988

Nematophagous fungi were successfully isolated by baited plating, centrifugation technique of soil, and direct isolation from naturally ingested nematodes. Predominant seven fungi isolated were identified as Artheobotrys arthroboteyides, A.conoides, A. oligospora, Dactylella lobata, Fusatium oxysporum, Monacrosporium ellopsoporum and Harposporium anguillu-lae. Of these, six fungi were tested for cultural characteristics except. H, anguillulae, extre-mely fastidious fungus in artificial media. Among 14 media tested in this experiment, Corn-meal Agar (CMA) and Oatmeal Agar (OMA) were the most suitable media for growing all six nematophagous fungi. Weakly saprophytic M. ellipsospoyum also grew vigoroualy on these two media. The radial growth, dry weight and sporulation of the fungi tested were quite diverse depending on the culture media. D. lobata revealed good growth and abundantly sporulated on Glucoes Peptone Agar (GPA). Although over-all growth of F, oxysporum was not satisfactory on Sucrose Nitrate Agar (SNA), the sporulation was best on this medium. Optimum conditious for mycelial growth and sporulation of nematophagous fungi ranged pH 5-8 and 20-$30^{\circ}C$ on SNA. D. lobata and F, oxysporum grew vigorously and most profusely sporulated on all media tested. They turned out an most promising biocontrol agents for their aggressive growth and sporulation over the ranges of temperature and pH ranges.

• Korean Journal of Organic Agriculture
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• v.19 no.2
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• pp.215-228
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• 2011

To establish the organic cultivation of pepper using green manure crops, this work studied the growth characteristics and yield of green manure crops, mineral composition of green manure crops, mineral uptake in shoots of green manure crops, chemical composition in soil of green manure crops, and the growth characteristics and yield of pepper in vinyl house. Shoot dry weight of green manure crops was higher level in Sorghum bicolor and Sorghum than in Crotalaria juncea and Glycine max. Also, the roots were spread deeply into soil in Sorghum bicolor and Sorghum. Density of root-knot nematodes in rhizosphere of green manure crops was significantly more decrease in Crotalaria juncea and Sorghum than in Glycine max and Sorghum bicolor. Total nitrogen and CaO content of green manure crops was significantly higher in Crotalaria juncea and Glycine max than in Sorghum bicolor and Sorghum. $K_2O$ content was significantly higher in Sorghum bicolor and Sorghum than in Crotalaria juncea and Glycine max. MgO content was not significant difference at all green manure crops. Cations content ratio of $K_2O$ : CaO : MgO was 3.4 : 1.4 : 1. Total nitrogen uptake in shoots of green manure crops was high level in Glycine max, Sorghum bicolor and Sorghum compared with in Crotalaria juncea. $K_2O$ and MgO uptake was significantly higher in Sorghum bicolor and Sorghum than in Crotalaria juncea and Glycine max. Value of pH in soil of green manure crops was more increase in Crotalaria juncea and Glycine max than in Sorghum bicolor, Sorghum and control, but after cultivation of pepper pH in soil was recovered with initial soil pH before seeding of green manure crops. EC value in control, green manure crops, and pepper cultivation decreased by 44%, 15~18%, and 38~61% level, respectively, compared with initial soil of green manure crops treatment. K content in soil of control, Crotalaria juncea and Glycine max cultivation was increased by 14%, but the K content in soil of Sorghum bicolor and Sorghum decreased by 24~38%. Cation exchange capacity (CEC) in soil of Crotalaria juncea and Sorghum bicolor decreased by 11%, but CEC in soil of Glycine max, Sorghum and control increased by 11%. Harvest fruit yield was higher in Crotalaria juncea, Glycine max, and Sorghum bicolor cultivation than in control and Sorghum.

• Analytical Science and Technology
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• v.27 no.5
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• pp.234-242
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• 2014

Imicyafos which is a nematicide for controlling root-knot nematodes has been registered in the Republic of Korea in 2012, and the maximum residue limits of imicyafos are set to watermelon and korean melon as each 0.05 mg/kg. Extremely reliable and sensitive analytical method is required for ensuring food safety on imicyafos residues in agricultural commodities. Imicyafos residues in samples were extracted with acetone, partitioned with hexane and dichloromethane, and then purified with florisil. The purified samples were analyzed by HPLC-UVD and confirmed with LC-MS. Linear range was between 0.1~5 mg/kg with the correlation coefficient ($r^2$) 0.99997. Average recoveries of imicyafos ranged from 77.0 to 115.4% at the spiked levels of 0.02 and 0.05 mg/kg with the relative standard deviations of 2.2~9.6%. Limit of detection and quantification were 0.005 and 0.02 mg/kg, respectively. An inter-laboratory study was conducted to validate the determination method in depth, and the results were satisfactory. All of the validation results revealed that the developed analytical method in this study is relevant for imicyafos determination in agricultural commodities and will be used as an official analytical method.