Does your oak tree look bad?

It might be bacterial leaf scorch.  OR IT MIGHT NOT.  There is NO WAY to be certain except by laboratory analysis using an immune response test.  Of course, it’s always important to correctly diagnose a problem before deciding how to treat it.

The wet weather we have experienced this year has provided favorable growing conditions for many leaf diseases of trees – in the case of oaks these would be oak anthracnose, Tubakia leafspot, leaf blister, and powdery mildew.  (If you are trying to diagnose the cause of your oak’s disease symptoms by looking at pictures on the internet be aware that oak wilt disease has not yet been found east of the Susquehanna River in Pennsylvania).

None of these leaf diseases (all caused by fungi) normally warrant control measures.  They are very unlikely to permanently impact tree health, and probably won’t be an issue next year unless we get another very wet growing season.

Bacterial leaf scorch is a different problem.  The bad news is it will not go away (even if treated with antibiotics – don’t be misled).  The good news is that BLS alone is not going to kill your tree, at least not quickly and not without the combined impact of other factors.

Bacterial leaf scorch has had a lot of media publicity in the past several years.  Unfortunately, it seems like a few unscrupulous tree care “professionals” have risen to the occasion, victimizing unsuspecting customers by recommending inappropriate, or bogus, treatments, or by recommending removal of trees based on strictly visual diagnosis.  Bacterial leaf scorch CAN NOT BE DIAGNOSED WITH CERTAINTY WITHOUT A LAB TEST.  And usually a symptomatic tree will be suffering from other ailments such as chlorosis, pest problems, previous moisture stress, root damage, soil problems, etc. that may actually be a bigger factor than the disease.

Don’t be scammed. Get an accurate diagnosis before you make a management decision.  If in doubt get a second opinion, preferably from someone who has no financial reward at stake, such as your Penn State Extension office.

More information about bacterial leaf scorch is available in my article on this site.

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