Journal of the Japanese Forest Society
Online ISSN : 1882-398X
Print ISSN : 1349-8509
ISSN-L : 1349-8509
Volume 101, Issue 1
Displaying 1-8 of 8 articles from this issue
Articles
  • Tomoko Fukuzawa, Ryosuke Arai, Hiroshi Kitajima, Masahiko Tokoro, Mine ...
    2019 Volume 101 Issue 1 Pages 1-6
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    Japanese oak wilt usually occurs at altitudes under 300 m. However, it is reported to occur above 1,000 m in Toyama Prefecture, Japan, suggesting that this disease could expand to higher elevations. Ecological knowledge of the occurrence of Platypus quercivorus, which is an ambrosia beetle vector of Japanese oak wilt, at high elevations is important for the prediction and prevention of the expansion of this disease. Therefore, this study investigated the seasonal occurrence and flight behavior of P. quercivorus adults along an altitudinal gradient in the Tanigawa Mountains, which lie on the boundary between Gunma and Niigata Prefectures. To capture P. quercivorus adults emerging from bore holes, emergence traps were set on host oak trees (Quercus crispula) that had died in the last year at every 100 m altitude along a gradient of increasing altitudes (600–1,000 m). Additionally, flight interception traps were set in the same manner to capture flying P. quercivorus adults. Our results showed significant decreases in the number of emerging adults per bore and flying adults at higher altitudes. In conclusion, the reproductive success of P. quercivorus at higher altitudes above 600 m was considerably more reduced than that of lower ones; such a decrease at altitudes over 900 m might be caused by a decrease in the number of Q. crispula trees as a result of change in tree species composition.

    Download PDF (1469K)
  • Kenichirou Kimura
    2019 Volume 101 Issue 1 Pages 7-13
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    The study aimed to clarify the influence of the nuclear disaster on the wood supply and demand and the present situation of forestry and wood industry in Fukushima. Reconstructing the facilities damaged by tsunami and earthquake was partly completed, however, the aftermath of it remains yet. After the disaster, the wood demand rate greatly increased, nevertheless the amount of material production stagnated, so that the imported wood ratio from other prefectures exceeded. The timber price slightly differed from the country's trend, the increase rate was low, and price of roundwood and stumpage price and gross forestry output production decreased than before. In comparative analysis across the areas, the timber demand declined in Soso area in which Fukushima Daiichi Nuclear Power Plant was, and the supply and demand balance was also altered in other areas. The restriction of forestry management owing to the nuclear disaster and the wood price fall stalled the material production and changed the balance of wood production and distribution in Fukushima. Whereas the reconstruction has been progressing in midstream and downstream, the deterioration of management in upstream is getting worse. To reconstruct forestry, measures are needed to improve the upstream process with consideration of situation in Soso area.

    Download PDF (1005K)
Special Issue: Latent Carrier Tree as a Blind Spot of Current Pine Wilt Control Strategies
Preface
Review
  • Application Possibility to Symptomless Infection
    Yuko Takeuchi-Kaneko
    2019 Volume 101 Issue 1 Pages 17-25
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    Assume that there is a pine tree/log in front of you. How do you know whether it is healthy or infected with pine wilt disease? There are several cases requiring diagnosis of pine wilt disease, for example screening of pine trees for eradication and at the port of entry of pine logs and/or packing materials. As symptoms of tree diseases including pine wilt disease often resemble each other, it is necessary for accurate diagnosis to detect and identify the pathogen from the suspicious subject. Thus a lot of morphological or molecular biological techniques have been developed to detect and identify the pathogenic agent, the pine wood nematode (Bursaphelenchus xylophilus) with or without isolation from the subject since it was identified as pathogen in 1971 by Kiyohara and Tokushige. This paper reviews the history of detection and identification methods of the pine wood nematode, namely, diagnosis of pine wilt disease, and discusses their applicability to trees without obvious symptoms, so called latent carriers or asymptomatic trees with case examples.

    Download PDF (1055K)
Short Communication
  • Yong-gi Cho, Kyu-won Jung
    2019 Volume 101 Issue 1 Pages 26-29
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    The damage caused by pine wilt disease in Korea began in 1988, about 30 years ago, and it was not a major problem till around 2000; then the damage increased markedly but declined after the establishment of enhanced countermeasures in 2005 under the special law on pine wilt disease control. Based on the premature judgment that the outbreak of the pine wilt disease had been successfully prevented, the control strategy, including the clear-cutting method which had made it possible to eliminate the asymptomatic carriers was interrupted. As a result, since 2012 pine wilt disease has spread to the whole country again and killed more than 2 million trees in 2014. Recently, the concept of asymptomatic carriers has been introduced into the control guidelines, and thereby it becomes possible to cut down the pine trees surrounding the damaged dead tree when selected by the resin exudation survey, and it becomes also possible to clear-cut some of the target areas. In this paper, we will show the actual status of pine wilt damage and the countermeasures against asymptomatic carriers in Korea.

    Download PDF (1915K)
Articles
  • Fugo Takasu
    2019 Volume 101 Issue 1 Pages 30-34
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    Pine wilt disease has been a serious threat to pine trees. Extensive efforts have been carried out to elucidate the disease mechanisms and to control the disease from a variety of research disciplines such as plant pathology, entomology, forest ecology, and mathematical modeling approaches. It has been known that some pine trees infected by the pine wood nematode do not exhibit the disease symptom and these asymptomatic carrier trees could be a source of new beetles that contribute to spread the disease to new susceptible trees. In this study, I define asymptomatic carrier tree as those that exhibit the disease symptom in the next year after the nematode infection. Mathematical analysis shows that 1) The delay in time to exhibit the disease itself does not contribute much to the disease spread, but 2) The effect of asymptomatic carrier trees to attract beetles in early summer is crucial for the disease spread by increasing contacts of beetles with susceptible tress. Empirical measurement and test of the effect of asymptomatic carrier trees to attract beetles is worth to challenge.

    Download PDF (941K)
  • Toshiyuki Koiwa
    2019 Volume 101 Issue 1 Pages 35-45
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    To reveal the reason why the damage of pine trees caused by pine wood nematode (Bursaphelenchus xylophilus) continues at the same stand after eradication of damaged trees, symptoms (shown in the crown coloration) and amount of oleoresin exudation from the trunk was monitored from the time before eradication in October 1997 to 21 months after eradication in Iwate Prefecture. The trees remained asymptomatic, presenting no oleoresin exudation for more than 14 months, and then these trees receiving egg laying by the Japanese pine sawyer Monochamus alternatus. It suggests that the recurrence of newly-dying trees near previously-killed tree must be related to such asymptomatic carrier trees because the asymptomatic carrier trees were found within a 10 m radius of newly dead trees in 2 of the 3 pine stands examined in the pine wilt disease-damaged forefront area. To eradicate asymptomatic carrier trees, trees that had stopped exuding oleoresin were removed from the damaged pine stand. After this treatment, only a few tree deaths have occurred. When the nematicides were injected into asymptomatic carrier trees, few nematodes were detected from the treated trees, and all of them survived more than 3 years after the treatment. It suggests that asymptomatic carrier trees may play the role of infection source in the process of pine wilting in northeastern Japan. Monitoring of the oleoresin exudation ability of pine trees to detect asymptomatic carrier trees, and nematicides injection for such trees seemed to be effective for suppression of pine wilt disease.

    Download PDF (2074K)
Short Communication
  • Toru Kato, Akira Kenmochi, Yukiko Yamada, Kazuyoshi Futai
    2019 Volume 101 Issue 1 Pages 46-51
    Published: February 01, 2019
    Released on J-STAGE: April 01, 2019
    JOURNAL FREE ACCESS

    This study was conducted to clarify whether asymptomatic carrier trees are killed by pine wilt disease after intensive control of vector beetles (Monochamus alternatus). The effect of trunk injection of nematicide to suppress disease development in asymptomatic carriers was also examined. The test pine forest was located at the tip of the Miho Peninsula in Shizuoka Prefecture. The positions of Pinus thunbergii standing trees and stumps were recorded, and wood samples were collected from each standing tree at three heights to detect Bursaphelenchus xylophilus DNA. Test stands were divided into two areas, and one was treated with nematicide. B. xylophilus DNA was detected in 33% of the trees examined. As the dead trees had no fresh feeding marks of M. alternatus, they were regarded as asymptomatic carriers, and their withering symptoms seemed to develop one or two years after the infection. While the asymptomatic carrier trees could not be identified in advance, no trees in the nematicide-injected group died, and 6 trees (19%) in the control group died due to asymptomatic infection of pine wilt disease. Thus trunk injection of nematicide was suggested to be effective to suppress disease development in the woods which included the asymptomatic carrier trees.

    Download PDF (1443K)
feedback
Top