2006年に徳島市城山に植樹されたホルトノキの苗木の現状 : 生育状況とホルトノキ萎黄病感染状況について（第二報）

This paper is an additional report of the 2016 survey report on the saplings of Elaeocarpus zollingeri (synonym: E. sylvestris) in Mt. Shiroyama in the Tokushima City. Since 1970s community of E. zollingeri in Mt. Shiroyama has continued to decline by Elaeocarpus yellows caused by phytoplasma. To prevent extinction 300 saplings were planted at the foot of the mountain by volunteers in 2006. In 2016, 10 years after planting, 40 trees had been alive, and the number has decreased to 29 in 2022. There were two other saplings near the planted area, presumably naturally occurring seedlings. The most grown tree was over 5 m in height, while there were 4 trees less than 1 m.
These saplings were checked for phytoplasma infection by nested PCR, and 9 saplings were found to be infected. However, none of them shows symptoms of the disease in appearance, and there is no difference in tree height compared to the uninfected saplings.
To prevent further loss in the future, poorly growing saplings should be transplanted into better conditions. Also, in areas with many surviving saplings, it is advisable to transplant several saplings to avoid overcrowding.