Please see attached photos of spherical growths on our Pin Oak, they are on...

Asked June 8, 2015, 5:35 PM EDT

Please see attached photos of spherical growths on our Pin Oak, they are on pretty much every leaf this year. This is the second year that we have seen these on our tree. We have had the tree since 2007 and have had no other issues. Please advise on type of fungus and treatment, if any. Thank you,

Ramsey County Minnesota oaks fungal disease

1 Response

Hi, and thanks for contacting AaE.

I suspect that your oaks are showing signs of a very common spring time ailment called Anthracnose.

This is a fungal disease that is common during cool, wet seasons of the year.
If these are young trees the damage may appear throughout the tree. On older plants , usually only the lower branches/leaves are affected.

While it seems to be alarming when the leaves start to blotch and fall out of season, it rarely causes long term effects. Usually trees will send out a second flush of leaves after the first batch has been lost. Mature trees can experience almost complete defoiliation for two or three years in row before they begin to die.

The best way to prevent this disease is to make sure that all of the fallen leaves are raked out and composted, or eliminated. Here is a link that will tell you more:
http://www.dnr.state.mn.us/fid/july97/0723974.html

Thanks for contacting AaE. Please do so again if you have further questions.