Greenspace: Have a tree that is sick? It may need a shot

Jim Hillibish

If you have a sick tree, do what medical doctors do — give it a shot.

Tree-trunk injections are a new option for diseased trees. Thousands have been saved in southeastern Michigan, says Dr. Dave Roberts, who in 2002 discovered the emerald ash borer in the United States.

Roberts used a test site with borer-infected trees. Up to 90 percent of some trees were diseased, he said. He injected them with an insecticide, and the trees recovered.

The process, offered by tree professionals, involves a needle pushed through the bark. It takes about five minutes.

The old way is to spray with chemicals or spread them around the trunk. Problems happen when this is done near humans, houses and animals.

Spraying can be tried only in still winds with no threat of rain. Injection can be done in any weather and results in no toxic pollution. The tree absorbs the chemical through its sap flow. This uses less pesticide.

The old injection way was to bore holes. The tree spent energy recovering from the wounds, when it needed that energy to fight its disease.

The new way involves a needle penetrating the bark and reaching the tree’s circulatory system that starts in its outer ring. The insecticide moves upward with the sap flow and concentrates in leaves and new growth.

Dr. Roberts presents his research at http:www.treeresearch.org

Send gardening questions to jim.hillibish@cantonrep.com