Tokyo Tech News
Published: February 15, 2019
Each April, the sixteen majestic Somei Yoshino cherry blossom trees lining the wood deck in front of the Main Building on Ookayama Campus signal that spring has arrived in Tokyo. These iconic specimens, donated to Tokyo Tech by generous graduates in 1950, will turn 80 years old in 2020.
Like all living species, cherry blossom trees begin to deteriorate with age. Signs include dead branches, a decrease in the number of cherry flowers, and a general decline in vigor. To preserve this legacy left behind by former students, Tokyo Tech took measures to improve tree vitality in early 2016, carrying out root maintenance on all 16 trees.
Unfortunately, one tree — the fifth on the right when viewing the rows from the Main Building — exhibited faded blossoms and numerous dead branches in the spring of 2018. While fertilizer and irrigation measures were applied amidst close observation of the tree throughout the summer and fall, the Institute decided to perform another soil improvement procedure from January 25 to February 5.
After removal of the wood deck, a 20-cm layer of soil was spread onto an area of roughly 12 m by 9 m around the tree. While using compressed air so as not to damage the tree, soil improvement admixture and organic fertilizer were then inserted around the roots, including deep roots through holes dug into the ground. Workers once again executed recovery measures at the most effective time — in late January and early February — to ensure that work was completed after defoliation and before flowering.
For so many graduates, current students, faculty, staff, and members of the public, the Ookayama Campus sakura trees are synonymous with spring in Tokyo. Tokyo Tech hopes that, through its thorough maintenance efforts, these trees will continue to provide joy and tranquility to campus goers for many years to come.