Black Rot/Fire Blight on Apple Trees?

Asked February 19, 2019, 6:07 PM EST

Hello, We recently acquired a small orchard and have been trying our best to manage it organically. We use Neem oil for pests throughout the growing season and during spring. We have maybe three trees with a few more serious issues and I was wondering if you could provide any advice on how best to manage them. One problem is peeling bark, down to the wood, not on the whole trunk/branches, but localized. It appears that a tiny black bug or larvae is the culprit and I have sprayed neem in the hopes it will take care of them. The second one is one specific tree which lost a limb last year due to the weight of too much fruit. We pruned this back, but after this recent snow, a foot long section of the main trunk suddenly turned black. I thought fire blight, but reading about that says it is more likely when temperatures are above 65 F and right now it's still winter. Could it be black rot canker? And, if this is the case, should we remove the tree asap, or is it something that can be managed with copper or another minimally impactful spray? If we manage the black rot, will it always be liable to spread to adjacent trees? Any help would be much appreciated.

Lane County Oregon apple trees

1 Response

I will have to make some assumptions based on your text and no images. I do not think you have either fire blight or black rot but hard to tell. If all you were using last year was Neem then you likely have many disease problems that neem will not control. I suspect you have one of the several canker diseases of apple. Anthracnose is common and perennial canker is possible. Have a look at these sections and see if anything you read is familiar:

Take a sample into the Master Gardener clinic and see if they can help. If not then you can always send a sample up to the OSU Plant Clinic. A good diagnosis will get you farther down the road than guessing about it.