Ranger Steve’s Nature Niche – Oak Wilt Prevention

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Oak Wilt Prevention
by Ranger Steve Mueller

Winter is a time of reprieve from the spread of oak wilt pandemic disease until April. In the spring and summer simple efforts will slow the spread of the illness. Oak wilt is caused by the fungus Ceratocystis fagacearum transferred across the ocean. It is spreading through oak forests by different methods and killing whole stands of trees. Things we can do to save our “sturdy oak” neighbors is to avoid limb pruning from April through July.

Limb pruning creates wound openings where beetles can gain access to the inner bark. The beetles themselves will not cause life-threatening illness to the tree. Woodpeckers and various insect predators help control the native beetles. The foreign oak wilt fungus that gets on the beetle bodies from infected trees gets carried to other trees. Native oaks do not have adequate immunity protection for the new foreign disease.

We can help protect trees by not moving oak wood, such as firewood, to different areas. That will slow the spread. When planting oaks, it is good to plant them in isolation or with different tree species. The reason is underground oak roots overlap with roots of other oaks and the roots fuse together allowing sap to flow from tree to tree through a process called root grafting. This allows the disease to spread from oak-to-oak underground and can kill an entire forest.

Many of us are familiar with the process of grafting branches of tasty apple varieties to other apple trees to grow choice apples. Several different apple varieties can be grown on one tree by grafting.

When the oak wilt is spread underground by root grafting, it is necessary to bulldoze around infected forest stands to stop the disease spread by severing root connections. This is an expensive process. Preventing infection is the primary means that should be used to maintain a healthy forest and save tree friends.

Loss of beautiful community forest stands that supply timber, oxygen, animal homes, bird nesting sites, gorgeous moths, and beauty is heartbreaking. Dying of a treasured old mature tree in our yard is the loss of a friend. Behaving in a manner that protects tree neighbors that share our yards and neighborhoods enriches our community and lives. House shading by a tree in summer saves air conditioning energy and money.

It is wise to hire an arborist to inject systemic propiconazole fungicide in a treasured tree to prevent symptoms for up to two years in healthy oaks that are not already infected. Booster shots will be needed. White oak trees with early infection can be helped and possibly saved by the vaccine injection but red oaks are less likely to recover. White oaks have better resistance to the disease than red oaks. Unfortunately, the fungicide treatment vaccine does not prevent movement of the fungus through oak roots to other trees.

Prevention of disease spread is key to maintaining healthy oak forest communities. It is best done by using the fungicide vaccine, not moving wood, no oak timber cutting in summer, and pruning at the correct time of year.

It is logical to make the connection to other pandemics. Individual ash trees can be protected by vaccination from the exotic emerald ash borer, thought to have entered North America in shipping pallets shipped to Detroit. Pallets are now heat treated to kill foreign insects living in the wood. The economic damage is billions of dollars annually to human communities by emerald ash borers. The death of trees destroys nature niche habitat for massive numbers of species that depend on ash trees. Creation care is a religious responsibility for me.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at [email protected] – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

Photo: Joseph O’Brien, USDA Forest Service, Bugwood.org