The Urban Forest in Peril
Detroit was once known as the "City of Trees". Thousands of beautiful elm trees lined the streets of Detroit and Grosse Point, and were prevalent throughout the surrounding suburbs. Alongside the elms stood the mighty oaks that we still have throughout our neighborhoods today. They were not the result of urban planning; they were the wild trees that have stood here since the civil war.
In the 1930's, a little known disease, Dutch Elm Disease (DED), was introduced into North America by elm logs imported from Europe. Some seventy years later, the devestation wrought by DED is evident in the almost complete absence of elms in southeast Michigan. Oak wilt is now threatening the mighty oak trees in our area and throughout the Midwest. Beacause oak trees comprise a signifigant percentage of our forests, both urban and rural, Oak Wilt is a serious issue that will severely impact our environment if not dealt with promptly and effectively.
Red Oak(Quercus rubra) Generally, rather shallowly lobed:
7-11 lobes. Leaves hairless, thin, and dull green.
Oak Wilt symptoms usually start in mid-May to early June, and continue throughout the summer. Affected trees initially show a bronzing or wilting of leaves on an individual branch or in a portion of the tree crown. The outer half of the leaf scprches and turns red or brown, while the inner half of the leaf remains green. Within a few weeks, the wilted leaves begin to drop. Wilting spreads throughout the tree canopy during the summer. Most red oaks are killed in one season.
Diseased red oaks cannot be saved and should be removed and destroyed. Infected members of the white oak family might be saved through costly systematic injections. Additionally, the repair of storm damage should be done promptly.
Our only defense against this disease is prevention in the case of red oaks, and early detection and treatment in the case of white oaks.
White Oak(Quercus alba) Leaf rounded with 7-9 lobes, pale on lower surface. Bark grey to white, shallowly furrowed, sometimes shaggy |
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