Spots on maple leaves...

[logantree]

Haven't been here in a while, hope all are well.

I had a lady call me the other day concerned with spots on the leaves of her maple tree. The tree was planted in the spring of 2008, and has had no pruning thus far. Not much of a mulch ring around it at all. (I told her to make it about three feet out around the tree.) I've attached a picture of the leaves, and one of the whole tree. If anyone could assist in the diagnoses, I would appreciate it.

Thanks again

 

[S Mc]

Leaf spot fungi would be my first suspicion. Generally leaf spot caused by fungus are not a permanent nor very serious issue. This is a case where raking up the fallen leaves and disposing of them is recommended to reduce the innoculum.

You could take a sample to your local extension agency for confirmation.

Encourage your client to promote best cultural practices for her young tree. It is young to be needing pruning as yet but double check the depth it is planted, encourage a larger mulch ring and we always inform our clients of the inherent difficulties/risks of lawn care products that can adversely affect young and older trees.

Sylvia

 

[logantree]

Thanks S MC. I'll see if I can get a sample to the ext. agency. Is there any treatment for it, or is it just something you let run it's course?

 

[John Paul Sanborn]

Looks like the beginning of Tar Spot; which is usually just an aesthetic problem, but can cross the economic threshold and stress a plant. Especially if anthracnose was a problem earlier in the year.

Here is a search
http://www.dogpile.com/dogpile/ws/r...e/iq=true/zoom=off/_iceUrlFlag=7?_IceUrl=true

 

[BC WetCoast]

Sell her a dormant oil/lime sulphur pre-emergent spray for next spring.

 

[John Paul Sanborn]

Bordeaux mix was called for in most articles I've found, but a paper from Cornell in 87 found most standard fungicides worked well.

fungicide Rhytisma filetypeDF

Is the search string i used to find only PDF files, substituting DOC for PDF renedered fewer hits, but a couple different papers.

All were .gov or .edu URL's, I had hoped to find a pesticide label.

All articles advise good sanitation; but if you have me for a neighbor mulching all my leaves, it is an exercise in futility.