Damaged Chino Hills trees

Trees in front of the Montessori School of Chino Hills on Pipeline Avenue have been damaged because of topping, considered a harmful pruning practice.

By Marianne Napoles


A row of eucalyptus trees at 14635 Pipeline Ave. in Chino Hills are suffering after having been “topped,” a pruning practice known to be harmful.

Sean O’Connor, maintenance and operations manager for Chino Hills, said the topping has caused sunburn damage to the trunks of the red iron bark eucalyptus, turning them black.

“This is one of a number of reasons that trees should not be topped,” said Mr. O’Connor, a certified arborist. “Topping is not an accepted arboriculture practice and this pruning has caused significant damage.”

The trees are not owned by the city but belong to the Montessori School parcel.

Mr. O’Connor pointed out the shoots, or suckers, growing from the wounds of the trees, which is the result of a sudden loss of leaves.

He provided a link to the International Society of Arboriculture that describes topping as perhaps the “most harmful tree pruning practice known, despite more than 25 years of literature and seminars explaining its harmful effects.”

Topping is described by the society as indiscriminate cutting of tree branches to stubs or to branches not big enough to sustain the remaining branch. This type of pruning can remove 50 to 100 percent of a tree’s leaf-bearing crown. 

Leaves are the food factories of a tree and removing them can temporarily starve a tree and trigger survival techniques such as activating dormant buds and forcing the rapid growth of multiple shoots below each cut, according to the society.

If a tree doesn’t have the stored energy reserve to put out a new crop of leaves, it will be seriously weakened or die. Open pruning wounds are vulnerable to insect and disease infestations.

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