Mycosphaerella leaf spot on ash


We are now seeing this disease in the Emporia and Manhattan areas. With
all the concern about Emerald Ash Borer (EAB), many people may assume
the trees are being attacked by EAB. However, EAB has only been
confirmed in Johnson, Leavenworth and Wyandotte counties.
Mycosphaerella leaf spot causes small, brown spots that enlarge to
become blotches and may result in early leaf drop. Though this disease
looks serious, it is not. Defoliation this late in the growing season
will not hurt the health of the tree. Therefore, because this disease
appears sporadically and tree health is not harmed, we do not recommend
treatment. Furthermore, treatment would have to be preventative and
applied before the disease had infected the leaves. Applying a fungicide
now would have no effect.


By: Ward Upham


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