What is causing these leaves to blacken at the edges?

[Gabler]

Species is Carpinus caroliniana. Infuse doesn't seem to be helping. Soil is mostly perlite with some diatomaceous earth. Right now, I'm watering approximately every other day.

 

[Piedmont Bonsai]

That happens to my american hornbeam in the summer but not to this extent.
It looks like sun burn on some of your leaves but on the one thats almost completely black it looks bacterial or fungal.
I would be inclined to remove the leaves that are turning black as it apears most are budless leaves anyways. move it into more shade once it really gets hot in your area and continue to spray preventatively

 

[Bonsai Nut]

Roots may be staying too wet... or your water may suck

How deep is that perlite/DE bed that they are growing in? And are you using well/rain/lake water? Or city water?

 

[Gabler]

It's in a grow bag filled to about six inches deep. The water comes from a well. I believe it's fungal. Last year, a nearby lilac had similar symptoms, and it caused leaf and twig dieback on various species including beech, sweetgum, and red maple. I suspected I was keeping my trees too wet, so I've reduced watering this year. Everything has been doing well, so I was disappointed to see it affected this tree again this year.

 

[rockm]

Is the tree kept on the ground?

 

[Gabler]

Is the tree kept on the ground?

Yes

 

[Gabler]

This is what I suspect, based on the damage I saw last year, but it's just a guess. I really have no idea.

Phytophthora - Wikipedia

en.wikipedia.org

 

[LeftHandLuke]

My favorite tree, of which I own none and of which I have killed one. I'm rooting for you. (Pardon the pun, if that was a pun.)

 

[Gabler]

My favorite tree, of which I own none and of which I have killed one. I'm rooting for you. (Pardon the pun, if that was a pun.)

It hasn't affected my bonsai trees, which I keep in a different area, just the stock I'm growing on the ground, so no great loss if a few die. Still, I'd like to find an effective treatment, if possible.

 

[LeftHandLuke]

I'd like to find an effective treatment, if possible.

Best of luck. Love those trees.

 

[AshleyMammal]

I’ve had the same this spring on a few of my trees - I had recently switched to a much stronger liquid fert (Elixir Growmore 11.11.11), used well within the max dosage recommended. I put it down to fertiliser burn, however, my trees have been on the wetter side this year and it could therefore be fungal. Interesting. I’d also be interested in a treatment!

 

[rockm]

Yes

I've had issues with fungal attacks tied to splashed soil from the ground. Ground soil is splashed on foliage and roots and something like this resulted. Moved the trees onto benches three feet up out of the splash zone and it stopped.

 

[The Barber]

I put down a thick weed barrier material on the ground to set my trees on to avoid soil splash. Been working great. Didn't want to build that much bench space.

 

[Gabler]

I use a watering can for my trees on benches but an oscillating lawn sprinkler for the growing bed. Maybe that has something to do with it.

 

[Gabler]

Best of luck. Love those trees.

I usually see fewer problems with Carpinus caroliniana than other species. Wild trees tend to have borers, so they're naturally resilient to mechanical damage, disease, etc. It's strange to see this tree affected.