• Research in Plant Disease
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• v.18 no.2
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• pp.101-108
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• 2012

In 2006, pinewood nematode, Bursaphelenchus xylophilus, was isolated from about 50 years old trees of Pinus densiflora and P. koraiensis showing leaf-wilt and -drying symptoms in Gwangju, Gyeonggi-do and Chuncheon, Gangwon-do. Isolation of pinewood nematodes from sapwood of infected pine trees showed no difference in population density between tree species and among the sampling heights on the main stem. Migration of pinewood nematodes in the host tree were investigated by inoculation of red pine (P. densiflora, 3 years old) seedlings with B. xylophilus. The nematodes seemed to move in red pine seedlings prior to multiplication and it might have taken about 20 days to start multiplication and expression of symptoms including wilt and dieback. In initial time after inoculation, nematodes started migration through the cortical resin canal from inoculated site and further showed upward and downward movements. More nematodes were observed in cortical resin canal during early period of inoculation and later in resin canal of xylem and tracheid also while, the pith still remained free from nematode. The density of B. xylophilus was higher in seedlings of low-vigor with poor root growth than in seedlings of normal root growth. Seedlings showing high density of B. xylophilus exhibited stem discoloration and secondary infection by fungus at the inoculation site.

• Korean journal of applied entomology
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• v.53 no.2
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• pp.141-147
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• 2014

Pinewood nematode (PWN: Bursaphelenchus xylophilus) is known to kill pine tree species that are indigenous to countries where the pest was inadvertently imported, but some cultures from the extraction of dead pines do not damage trees. Experiments were conducted to examine the effect of pre-inoculation of these low-pathogenic pinewood nematode on resistance of pine trees against the pest species. The pre-inoculated pine saplings showed induced resistance which lasted for a year, and repeated inoculation of these low-pathogenic nematodes enhanced tree resistance. All nematode samples extracted from dying or dead pines that had been killed not more than three months before the extraction were pathogenic, and most of those extracted from pines that had been killed 2-3 years before were low-pathogenic. When inoculated in pine saplings, number of low-pathogenic nematodes settled, as studied two days after inoculation, was not different from that of pathogenic ones. However, as studied after 30 days of inoculation, rate of reproduction in low-pathogenic nematodes was far lower than that of pathogenic nematodes. The rate of reproduction of several nematode isolates growing on fungal mat media of Botrytis cinerea varied, but three of four low-pathogenic isolates showed same level of reproduction rates as pathogenic ones.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.527-533
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• 2009

This study was performed to investigate the escape of pine wood nematode (PWN), Bursaphelenchus xylophilus, from two vector species (Monochamus alternatus and M. saltuarius) through oviposition and feeding behavior. First, we checked number of PWNs escaped from M. alternatus emerged from three different cases of pine logs. In case A, healthy pine trees were cut into logs and left in pine forest infected with PWN. In case B, healthy pine trees were cut into logs, left in large screen cage, and let them oviposited by M. alternatus emerged from pine trees infested with PWN. In case C, pine trees which were harboring M. alternatus were cut into logs, and PWN was inoculated artificially. The M. alternatus adults emerged from the above three cases of pine logs were checked in the next year to know how many PWN they were harboring in their bodies. The percentages of M. alternatus harboring PWN (18.3 and 15.6%, respectively) and number of nematodes per vector ($5,713.1{\pm}9,248.3$ and $2,034.1{\pm}4,746.8$ PWNs, respectively) in case A and B logs are similar to each other. However, the percentage and the number in case C (38.3% and $20,083.1{\pm}32,188.3$ PWNs) were higher than those of case A and B. Among 52 M. alternatus adults harboring PWN from all the three cases, 20 adults (38.5%) were harboring more than 5,000 PWNs per beetle. And these 20 adults were harboring 97.9% of the total PWNs in 52 adults. Second, we checked the daily escape of PWNs from M. alternatus and M. saltuarius collected at pine forest infested with PWN. The PWN escaped from their vector body for $34.9{\pm}12.4$ days for M. alternatus, and for $23.9{\pm}16.2$ days for M. saltuarius, reaching at peak escape during the 2nd week of emergence of the two vector species. A 44.5 and 47.2% to the total PWNs escaped from vector body within 2 weeks of vector emergence for M. alternatus and M. saltuarius, respectively. The number of PWNs escaped from each vector was $3,570.6{\pm}5,189.2$ and $1,556.2{\pm}1,710.3$ for M. alternatus and M. saltuarius, respectively.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.337-343
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• 2010

The purpose of this study was to understand water stress development in pine seedlings inoculated with Bursaphelenchus xylophilus. Leaf water potentials of four years old Pinus densiflora seedlings inoculated with the nematode were measured with a plant moisture system at predawn and midday. The midday leaf water potentials on the 35th day after the inoculation were -1.04 MPa in the infected seedlings, while -0.94 MPa in the non-infected seedlings. The predawn water potentials on the 56th day were -0.71 MPa in the infected, while -0.26 MPa in the non-infected. At this time the leaves of the infected seedlings became yellow and resin did not exude on the cut basal stem. Density of the nematode was maximum on the 28th day, but dropped sharply on the 68th day. The phloem and pith tissues became brown and the resin exudation reduced in the infected seedlings. In conclusion, pinewood nematode inoculation developed water stress in pine seedlings in a month.

• The Korean Journal of Pesticide Science
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• v.14 no.2
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• pp.138-147
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• 2010

Nematicidal activity against pine wood nematode, Bursaphelenchus xylophilus, was tested in the pot and field by the treatment of microbial formulation after media optimization. The optimized media composition was glycerol 10 g, soybean meal 10 g, NaCl 1 g, $CaCO_3$ 2 g, $K_2HPO_4$ 0.125 g per liter and microbial complex formulation was made with liquid and powder type. Most effective antibiotics against symbiotic microorganism with nematode, kanamycin, was added to the formulation. The control effects against pine wood nematodes were checked by pot test and field test. In the result of treatment by trunk injection, five times treatment was more effective than one time and the treatment with the formulation of concentrated culture supernatant was the most effective in the nematicidal activity showing below 10% mortality in pine tree.

• The Korean Journal of Pesticide Science
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• v.20 no.1
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• pp.56-65
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• 2016

Pine wood nematode, Bursaphlenchus xylophilus is a fatal damaging pest, infecting pinewood trees and is one of the serious forest pest in Korea. Trunk injection is one of the most effective method to protect the live pine trees from nematode infection. The aim of this research was to reveal the efficacy of the nematicidal materials from 46 Kyrgyzstan, 88 Vietnam plant materials and 21 active materials (${\alpha}$-terpinene, ${\alpha}$-pinene, ${\beta}$-thujaplicin, cinnamaldehyde, eugenol, emodin, geraniol, limonone, methyl palmitate, matrine, myrcene, methyl gallate, nicotine, quassin, resveratrol, rotenone, thymol, thujaplicin, terthiophene, tuberstemonine, ${\gamma}$-terpinene) isolated from plants for using as trunk injection agents. Eclipta prostrata extract was highly effective against pine wood nematode in plant extracts and terthiophene has the best nematicidal activity from active materials isolated from plants. Foliar spray of terthiophene on Japanese black pine (Pinus thunbergii) tree reduced proliferation of inoculated pine wood nematode at 22 days after treatment, however no efficacy was found over 22 days. Eclipta prostrata extract and terthiophene can be used as nematicide for further nematicidal efficacy test against any other plant parasitic nematodes and trunk injection efficacy against pine wood nematode.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.97-101
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• 2008

For the isolation of Actinomycetes showing nematocidal activity against Pine wood nematode, Bursaphelenchus xylophilus, about 2000 culture broth of Actinomycetes were tested and their activity were compared with that of Streptomyces avermitilis resulting a selected strain AW050027. The cultural, morphological and physiological analysis was performed for the identification of a selected strain. Phylogenetic analyses based on 165 rDNA gene sequences showed that the selected strain AW050027 belonged to the genus Micromonospora and M. corioriae $NAR01^T$ was the closest neighbors, sharing 98.9% 165 rDNA gene sequence similarity.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.512-518
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• 2015

Pine wilt disease (PWD) caused by pine wood nematode, Bursaphelenchus xylophilus, has become the most serious threat to pine trees in Korea. This study was subjected to investigate effective biological control agent against PWD. To select nematocidal bacteria against PWD, Bacillus licheniformis MH48 was selected among five bacteria due to its high nematocidal potential. B. licheniformis MH48 was tested for cell growth and protease activity to evaluate its nematicidal potential. In the B. licheniformis MH48, cell numbers were highest three days after incubation, while protease activity was highest after seven days. In the effect of different concentrations of B. licheniformis MH48 culture broth against B. xylophilus, 20% concentration of culture broth showed approximately 80% of pine wood nematode mortality compared to the control. Especially, pine wood nematode's cuticle layers were degraded two days after treatment of B. licheniformis MH48 culture broth. The present study suggests that B. licheniformis MH48 can be one of the potential biocontrol candidates against pine wood nematode due to its ability to produce protease.

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.570-575
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• 2008

This study was carried out to provide basic information on physiological changes of 4-year-old seedlings of Pinus thunbergii inoculated with pine wood nematodes by analyzing changes of symptom development, stem and needle water content and nematode populations in stem. Twenty days after inoculation, needles were discolored as an external symptom, and xylem drying and pith browning occurred at the above and below of the inoculation sites as an internal symptom. However, xylem drying began to occur 10 days after inoculation, which was determined by the difference in drying status of xylem and cortex between control and inoculated seedlings. Although population of pine wood nematode increased from 5 to 10 days after inoculation, it has increased dramatically from 10 to 20 days after inoculation when both internal and external symptoms appeared. As the time passed by after inoculation with pine wood nematodes, water content of stem and relative water content in current needles and branch gradually decreased. As the number of nematodes increases, water content of stem and relative water content of current needles and branches decreased significantly. There was a positive relationship between the number of nematodes and xylem drying and/or disease development, but the number of nematodes rapidly decreased as seedlings become severely diseased.

• The Korean Journal of Pesticide Science
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• v.19 no.4
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• pp.440-449
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• 2015

Pine wood nematode (PWN), Bursaphelenchus xylophilus is one of the most serious pests of pine tree. Trunk injection of some nematicides in tree is well known as an effective control method. However there are some limitating factors which hindering the efficacy of trunk injection in field or potted tree. In this study we suggested easy and useful alternative screening methods of nematicides against PWN. Reproduction of PWN was influenced by tree twig moisture (high reproduction in high moisture trig) and paraffin coating was 78.6% reduced moisture loss in tested twig. There were no reproduction different in up and down site from infection site of twig at 1 month after inoculation of PWN and also distance (5 and 10 cm) from inoculation site of PWN did not influence the reproduction of PWN. Numbers of reproduced PWN were higher with decreasing diameter of twig. Numbers of reproduced PWN were similar to P. thunbergii and P. densiflora. However reproduction was increased depending on high inoculation density and longer propagation period. When inoculation of PWN on cut twig injected with emamectin benzoate 2.15% EC and morantel tartrate 8% SL in trunk of Pinus thunbergii in the field, PWN number were significantly reduced than untreated control. We suggest this screening method for PWN control agents.