- 著者
-
高橋 郁雄
佐保 春芳
- 出版者
- 北方森林学会
- 雑誌
- 日本林學會北海道支部講演集
- 巻号頁・発行日
- vol.20, pp.181-186, 1972
The larch canker was reported in the Tokyo University Forest in Hokkaido in 1969. Its pathogen, Encoeliorsis laricina (E_<TTL>.) G_<ROVES> (Imperfect state : Brunchorstia laricina E_<TTL>.). was cultured on a potato-galactose-ager medium and fungus colonies on this medium were used for the inoculation experiments. The inoculations were made on Feb. 17, 1970 and March, 16, 1970 on the potted larch seedlings in the green house, quite earlier than the natural condition. The methods of inoculation was as follows. Each main stem and side branch of seedlings were sterilized with 80% alcohol and washed with water, and a peeling abrasion (4mm x 4mm) was made with a sterilized knife on the bark. The pieces of the mycelial colony were placed at the injured part. After that, the plants were placed in a moist chamber and held at the relative humidity of 80-100% and at 15℃ temperature for two weeks. Then, they were placed in the natural condition. Pycnidia were recognized on all inoculated seedlings such as, Larix gmelinii, L. g. var. Koreana, L. leptolepis and L. sibirica fifty days later. Many apothecia were observed on L. g. var. Koreana, a few were on L. leptolepis and few were on L. gmelinii and L. sibirica 476 days later. On the other hand, inoculations with conidia obtained from spore horns of pycnidia were made on May 13, 1970. Spore horns were stired in distilled water, this suspension was spread on the trunks and branches that were treated by sterilized stainless steel needle to make wounds (20 wounds in 4mm^2). After the spreading with the suspension, the plants were placed in a moist chamber for five days. The discoloration was observed on all of the treatment seedlings ten days later, and pycnidia were recognized on L. gmelinii, L. g. var. Koreana and L. leptolepis. No fruit bodies were found on L. sibirica. Under the results of the experiments, L. g. var. Koreana seemed to be the most susceptible to the fungus, and these results were similar to the field observations.