Fire blight?

Asked June 14, 2018, 11:49 AM EDT

Is this fire blight? This is my second summer with this Wealthy apple tree, it's probably 4 years old on semi-dwarf stock. I noticed three of these marks on the main branch. I am new to apple tree growing. What should I do?

Broomfield County Colorado trees and shrubs

9 Responses

June 25, 2018.

Thank you for your question and photos of the Wealthy apple tree.

There are several possibilities accounting for the "marks" that are showing on what appears is the trunk of the tree.

One of the possibilities might be fire blight, as suggested by you. Fire blight usually begins affecting the outer branches and leaves before attacking the trunk of the tree. Attached is a reference for fire blight. Please, notice that the article has a picture of leaves affected by fire blight.

We have a few questions to ask of you that will further assist us in diagnosing the nature of the marks on the tree. (1) Would you be able to send us additional photos? A photo of the entire tree would be helpful. So, too, would be close up photos of the outer branches and leaves, if these are showing symptoms that are unusual. A photo at ground level would be useful, as well. (2) Would you also tell us when these marks first appeared? (3) Were these marks present last year? (4) Are you aware of the soil type in which the tree is growing, and if so, please describe it. (5) Is there mulch at the base of the tree, and, if so, what is the type of mulch? (6) How much water does the tree receive, amounts and frequency? (7) Has the tree produced fruit, and if so, did the fruit appear normal? Support stakes seem to be present in the photos. (8) Was strapping material attached to the stakes used to support the tree, and was this strapping material at the positions of the marks now being observed on the trunk? (9) Has the tree been sprayed for pests? (10) Has the tree been fertilized?

These are the typical questions we ask of clients when they call our office with an inquiry. Please, provide this additional information, if you are still wondering about the marks on the apple tree.

Finally, if you are a Broomfield resident, you may wish to call the City and County Forester at 303-464-5651 for suggestions as to what the marks may be. The Forester's office may be able to help you, as well.

1. Yes, I'll post more photos.
2. I only noticed these marks after this year's blossoms.
3. I don't remember these marks last year.
4. Soil type is typical CO - poor dirt and clay mix. We amended with garden soil, compost, pea gravel, and sand when we planted.
5. The mulch around the tree is washington cedar.
6. The lawn and trees get watered on average every 4 days for 40 minutes with sprinklers. I've soaked the trees a couple times this year with a hose on trickle.
7. I think I bought the trees after blossom last year. There was lots of fruit this year but I've removed all but a few.
8. Support stakes were added when the tree was planted. The support straps touching the tree are nylon webbing and not near the marks.
9. The tree has not been sprayed for pests.
10. The tree has not been fertilized yet.

Lastly, my winesap tree next to this wealthy tree is not effected.

Thank you for sending additional pictures and information.
As mentioned in first response, fire blight usually begins in leaves and stems. The leaves in the pictures look healthy and only a few seem to be curling. This may be the angle of the leaf in the picture but over all we do not see the dried dead looking leaves that comes with fire blight.
We have one more question for you- is there any oozing from the tree?
Thank you for your patience

Thank you for all your help!

No, there is no oozing from the tree.

The couple fruits I left have a soft brown spot or two each. I can send a photo later if helpful. I have not sprayed the tree.

This looks like it could be some kind of fungal disease, such as anthracnose. This disease rarely kills apple trees and it can be controlled by pruning away the diseased material and throwing those infected branches away. Prune when there is no rain forecasted.

Keeping the tree vigorous will minimize the effects of the disease. I recommend fertilizing, since you have not done that yet, and reassess your watering practices. Too much water and too little water can exacerbate problems or make trees more susceptible to infection. Also avoid getting the trunk or branched wet when irrigating.

Thank you