Pin oaks grow tall and straight.
When 20 were planted around the edges of the University of Missouri’s Francis Quadrangle more than 60 years ago, perhaps the idea was to provide a living complement to the columns of the university’s first building that are the school's iconic symbol.
But a combination of age, soil conditions and overwatering have taken a toll and on Monday, the five identified as the most troubled were removed.
“These are the most hazardous of these trees,” said Pete Millier, director of landscape services and the Mizzou Botanic Garden. “They have been dropping limbs and it is normal and natural for pin oaks to drop limbs as they decline.”
The five trees to be removed are on the east and south sides of the quadrangle. They are the tree closest to the circle drive near the journalism school, the one just north of the sidewalk crossing the quadrangle in front of the columns, the tree southeast of the columns near the chancellor’s residence and the two on either side of the stairs leading into Jesse Hall.
Pin oaks typically live 80 to 100 years in ideal conditions but conditions in the quadrangle are less than ideal, Millier said. The soil is packed clay, slightly alkaline, and regularly watered. Pin oaks, like all red oaks, like deep soil with a heavy load of organic matter that is slightly acidic.
The trees did well enough early in their life cycle but after the university installed sprinklers to keep the grass green in summer, the extra water has sped up their decline, Millier said.
“That has thrown these trees for a curve, and they don’t like the alkaline conditions,” he said. “As they are declining in vitality and the age, they kind of melt back to the earth. Before you know it you have a nice trunk, but no branches and no leaves.”
No one has been hurt by falling branches but there have been some close calls, Millier said.
“From about Memorial Day weekend on there have been some accidents involving trees and people we would rather not happen at Mizzou,” he said.
During the removal, sidewalks near the trees will be closed, MU spokesman Christian Basi said. If the weather cooperates, the project should take about a week.
The trees will eventually be replaced with native trees in the white oak group. In addition, arborists will try to extend the life of the remaining trees by trimming deadwood, but expect that all 15 of the remaining pin oaks will need to be removed at some point in the future.
The botanic garden’s Friends Advisory Board established a tree commission to review and make recommendations for replacing the aging pin oaks, an MU news release about the removal stated. A fundraising campaign is underway to finance the replacements.
Swamp oaks planted in Carnahan Quadrangle are thriving and are one option. He also mentioned bur oaks, like the champion tree near McBaine, as examples of trees that will live for hundreds of years in the right conditions.
The wood from the trees to be removed cannot be salvaged, Millier said
“These trees are going downhill fast and we have determined a number have significant cavities in the trunk,” he said. “There is no point.”