Measures taken to revitalize Ookayama's 75-year-old cherry blossom trees

Each year in spring, two rows of cherry blossom trees welcome students to the Ookayama Campus at the start of the new academic year. The 75-year-old trees, which line the deck in front of the Main Building, have been cherished for decades by students, faculty and staff, graduates, and local residents alike. Measures to improve tree vigor were taken from January 12 to February 19, 2016.

Cherry blossom trees under treatment in front of the Main Building

Deterioration in tree vitality

The Tokyo Tech Facilities Department has the arduous job of maintaining the condition of the cherry trees. Planted in 1950, many of the trees have recently shown an increase in the number of withered branches, and in 2015, the trees cast their leaves unusually early. According to an assessment by a professional arborist, the vitality of the trees was rapidly deteriorating.

While early treatment leads to the improvement of tree vigor, belated action impedes recovery as the condition of the trees declines year by year. The number of cherry flowers decreases and the risk of tree fall increases. Therefore, measures were taken to improve the vitality of the sixteen trees in front of the Main Building.

Ookayama Campus cherry blossom tree treatment:

• Recovery measures adopted at most effective time — January and February — after defoliation and before flowering
• Treated one row of cherry trees at a time in order to maintain pedestrian traffic at site
• Barricaded one row of cherry trees and removed deck boards
• Exposed roots of each cherry tree (up to 4 m in length, 1.5 m in width), covered with fresh soil, soil improvement admixture, organic fertilizer

Cherry tree root maintenance

Those interested in the history of Tokyo Tech's cherry blossom trees are invited to read more on Cherry Blossom Viewing.