Oak tree leaves have brown dots and brown patches

[wilson]

I have a very old (80+ years) large oak tree (i think it is a white oak - or has leaves like a white oak). We have many trees like this in our neighborhood (right outside of philly). I have notices that the leaves have a lot of brown/black in sized dots and most leaves have brown patches on them. Further, a few leaves have started to fall off the tree (although that may be normal on such a large tree).

I am worried that there is something wrong with the tree. We have had incredible amounts of rain in July and August, way way above normal. In addition, we havent had the sun much to dry up the ground. Are the roots just getting saturated and this is the result? Is there something i should be looking at?

Bob

 

[NYCHA FORESTER]

I sounds like a touch of Anthracnose (leaf disease - usually harmless just unsightly)

 

[Kneejerk Bombas]

You're probably seening Anthracnose. The wet conditions are good for fungus, so this year you'll see lots of fungal leaf diseases. If you drive around and look at the crabapple trees you'll see they look pretty bad too, even the ones that have been sprayed.
Leaf diseases are genrally not a big problem for trees. Even with the non productive brown parts of each leave, the rest can still function properly, and even if the whole leave falls off, it has contributed to the tree while it was green. If it's no too late in the season the tree may even sprout replacement leaves, for those that fall off.
If the tree is alredy under some stress, like construction damage or soil compaction, you may want to think of ways to reduce those stressors, typically water during times of drought, adding compost and/or woodchips to the root area, deadwood trimming, ect.
Spraying for anthracnose needs to be done in the spring as the leaves are just opening, so it's too late for this year, and next year it may not be wet enough for anthracnose to flourish.
Rarely, a tree will have the problem for several years running, or it's a high value tree, or under some stress, then would I reccomend a spray program. Even then, the results are hit and miss.

 

[Guy Meilleur]

I'm seeing a lot of anthracnose in oaks this year too. I hate spraying and hate saying "waitandsee" to clients who want cures, so I'll be trying cambistat on some.

 

[Toronado3800]

A friend of mine who horned his horticulture skills while working at a golf course diagnosed anthracnose on an Ash tree of mine last year. It lose plenty of leaves but rebounded nicely.

He also pointed out my habit of mulching my leaves with my mower around the tree was keeping damp moist leaf clumps on the ground too close to them. Now I just mow up my leaves in the usual pattern I mow the lawn. That way they get spread towards the middle of the yard.

 

[Guy Meilleur]

Originally posted by Toronado3800
Now I just mow up my leaves in the usual pattern I mow the lawn. That way they get spread towards the middle of the yard.

Absolutely, just as god and nature and the tree "intended". I once inventoried a bunch of old oaks in a neghborhood; the healthiest one got the same care from the owner as you now give yours.