• 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 Breeding Science
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• v.41 no.2
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• pp.154-157
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• 2009

Pear has a gametophytic self-incompatibility (SI) system and its SI reaction is controlled by a single multi-allelic S-locus. 'Wonkyo Na-jasoojung 2' was selected from a cross between 'Wonwhang', early season major pear cultivar with high fruit quality and self-incompatible, and 92-18-79 (${S_4}^{sm}{S_4}^{sm}$) obtained from self cross of 'Osa-nijisseiki' (${S_2S_4}^{sm}$) (SM, stylar-part mutant), self-compatible bud mutant that originated from self-incompatible 'Nijisseiki' ($S_2S_4$) made in 2001 at the National Institute of Horticultural and Herbal Science, Rural Development Administration in Korea. '92-18-79' was selected as a self-compatible source through field investigation. It bloomed 1 day earlier than 'Osa-Nijisseiki' and similar to 'Wonwhang' in 2008. It is medium in tree vigor and spreading in tree habit. 'Wonkyo Na-jasoojung 2' is classified as highly susceptible to pear scab (Venturia nashicola) similar to 'Osa-Nijisseiki' and as resistant to black spot (Alternaria kikuchiana) similar to 'Wonwhang'. It had 65.7% fruiting rate by self pollination. The average optimum harvest time of 'Wonkyo Na-jasoojung 2' was 148 days after full bloom and it matured 2 days earlier than 'Osa-Nijisseiki' and 11 days later than 'Wonwhang'. The fruit is roundish oblate in shape and yellowish brown in skin color. Average fruit weight was 445 g and soluble solids content was 13.3 $^{\circ}Brix$. The flesh had abundant juice and negligible grit.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.42 no.1
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• pp.45-56
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• 2024

The purpose of this study was to suggest evaluation items and standards for diagnosing the growth status of protected trees designated and managed by the Korea Forest Service. The research results are as follows. First, based on the Cultural Heritage Administration's standards for evaluating the growth status of old trees, which are natural monuments, and related data, items related to the 'growth status of the above-ground part' of the trees were revised and supplemented. Simultaneously new items such as 'location', 'usability', 'artificial cover rate within the crown width', 'soil physical properties', and 'soil chemical properties' were discovered. By combining these items, six items were derived to evaluate the growth status of protected trees. Second, evaluation items made through visual inspection, such as 'tree vigor' and 'leaf color' in the 'growth status of the above-ground part', were replaced with quantifiable items such as measuring the electrical resistance value of the cambium or chlorophyll content. Third, 'artificial cover rate within crown width' was introduced as an item to evaluate the growth environment, and classification criteria for 'soil physical properties' and 'chemical properties' were presented. Fourth, a method to evaluate the health of protected trees was specified by combining 10 above-ground growth conditions, 3 growth environments, and 8 soil environment items. In addition, a record format for diagnosing the growth status was shaped up. The significance of this study is that it proposed an evaluation and recording method for protected trees, which do not have an evaluation system compared to natural monuments, but there were limitations in developing a method that takes into account the importance of each evaluation item. In order to overcome these, research should be conducted to evaluate effectiveness for each item and to replace qualitative evaluation of trees with quantitative evaluation based on scientific data.