Friday, August 21, 2009

Landscape - More on Bacterial Leaf Scorch on Oaks

The following is more information on bacterial leaf scorch of oaks which can be seen in Delaware landscapes at this time.

Bacterial leaf scorch on oaks in the red oak group can be found now. Infected trees have leaves with brown leaf margins (like drought damage). Since we have not been in a drought, lack of water is an unlikely cause of the symptoms, but since the bacterial infection restricts water flow, drought symptoms appear. This is a debilitating disease that can take several years to a decade to kill the tree and there is no cure. Symptoms can be reduced or masked with oxytetracycline injections, but trees cannot be cured. Plant hoppers vector the bacteria from symptomless weed hosts and transmit it to oaks during feeding. If you have suspect trees, tests will confirm the presence of the bacteria in leaf petioles. Contact the Plant Diagnostic Clinic at 320-831-1390 or on the web for more information on testing. The web has many articles on BLS-- here is a good one

Leaf scorch symptoms on red oak. Photo from the Minnesota Department of Natural Resources Archive, Minnesota Department of Natural Resources,

Information from Bob Mulrooney, Extension Plant Pathologist, UD.

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