Flowering crab apple tree blight

Asked May 31, 2016, 6:38 PM EDT

I bought a crab apple tree about a month ago, it had pretty flowers on it, and shortly after I planted it, the flowers died, and a large amount of the leaves have black spots and are shriveling up. The tree has a lot of new growth over the last month, so I know it is growing, but more and more of the leaves are turning black. Will this tree die, or is there anything I can do?

Barron County Wisconsin crab apple trees fruit trees

4 Responses

There are several possible causes. If you can take some closeup pictures of the leaves, this will help with the diagnosis.

Your crabapple may be one of the varieties that is susceptible to scab, a fungal disease that causes dark khaki green spots on the leaves. A protective spray program is necessary to protect susceptible varieties. See the following links for more details.

http://msue.anr.msu.edu/uploads/files/e2177.pdf

http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/managing-apple-scab/

If scab is the problem, you may consider replacing the tree with a variety that is more resistant to the disease.

There may be something else going on because usually scab infections do not move fast enough to kill flowers. Crabapple flowers are short lived--generally lasting only a week..

Some crabapples are prone to fire blight, a bacterial disease that causes blackened burned look to tender plant tissue. It would be unusual for this disease to find a newly planted tree so quickly.

Another cause of problems for newly planted trees is insufficient or too much water or too much fertilizer. This can cause leaf symptoms, flower decline.

Again, if you send some good pictures this will help with the diagnosis.

Here are 3 pics that I took of the crabapple tree, I don't know if this will help or not. But I am getting a lot of new growth on the tree, and within a short time, the nice green leaves get brown spots and shrivel up and fall off.

Yes, this looks like scab. There may be another reason why the flowers are dropping off prematurely...usually scab is not a cause of flower decline. I suppose if scab is particularly severe, nearby blooms could be affected as well.

Scab will be an ongoing problem every year. Wet years the disease will be worse. You will have to decide if you want to spray for it next year, live with the disease, or find a scab resistant variety replacement.

It is too late to treat the trees for scab this year--the disease is too advanced to have much effect.

Thank you so much for the info.