Branch cankers caused by black rot

I've got a fair number of my young trees (going into their third leaf) with what look like very small black rot cankers on the first scaffold limbs. I am going to do a copper spray before 1/4 green but after that I was hoping to avoid allopathic treatments. Can someone tell me how seriously I need to take this disease? Can it be slowed/managed holistically? Will a healthy season help the tree shrug off the infection or should I break out the allopathic guns?

Nat Bouman
Growing cider varieties in Zone 5b
On B.118 at 18X24
Susquehanna County, Pennsylvania

What cultivars are they Nat ? Do you have photos? Correct diagnosis is important.
This may not relate to these trees specifically, but in general I am finding more and more that nasty canker issues have a whole lot to do with crotch angles in an unholy alliance with variety choices. Many times a tight crotch, or other tender parts of the tree (this includes lower trunk areas) are not notices as damaged in winter, and subsequently are infected with canker.

Also, there are few cankers that will benefit from any spray whatsoever. Nearly all options, copper includes, act as preventative not cure. In fact the only success I have had is surgery and cauterizing, and even that is of marginal success. Both holistic management, and ballistic approaches are mostly about prevention.

Hi Todd,

The small cankers or blisters don't seem to be more associated with the crotch of the tree. I have them on a few varieties but the Bedan seem to have more of them. Here is a photo (the tree is a Bedan). Sorry the image is so giant when you click on it.


Nat Bouman
Growing cider varieties in Zone 5b
On B.118 at 18X24
Susquehanna County, Pennsylvania



Edited 4 time(s). Last edit at 03/24/2017 08:36PM by Nathaniel Bouman.

Nat -

I agree with Todd on all of the above. Diagnosis is first of all key; unfortunately your picture is not loading for some reason or I would weigh in. And in my experience (which unfortunately is considerable), once you have a canker the best course of action is to prune it out and burn it.

This past year I started application of tree paste on some of our most affected older trees in an effort to slow the spread of black rot and the decline of the trees. They did have a great crop in 2016, however I'm not ready to report on efficacy. Paste will be applied again this year and I hope to keep doing it to see if it makes any difference. I've left control trees, however there are so many variables in play I think it will still be a guess at best.

Door Creek Orchard
Zone 5a in Wisconsin

Darn it. I'm really hoping the affected branches don't have to be pruned out because they represent my first scaffold in a lot of cases. Sorry I'm having difficulty with the image thing. Here's another shot.

An image pops up when I actually click on the box...I'll keep trying to figure it out.

Nat Bouman
Growing cider varieties in Zone 5b
On B.118 at 18X24
Susquehanna County, Pennsylvania

First off, both images work, Nathaniel. It's just best to open in a new tab rather than within the network website. (Our budget quasi works with image sharing, and that's how it is. And for the record, a surge in donations would certainly help me address this.)

I truly don't think "black rot" is getting into vigorous three-year old growth. You obviously have a situation here, and it's fungal, but it's beyond my knowing. On the other hand, you are not doomed. Keep up the holistic applications, emphasize competitive colonization (which is the idea behind tree paste), and encourage plant community/ fungal connections. Western growers would be thinking anthracnose but this isn't showing the "blast fibers" typical of that challenge. The amazing thing is how many variations on everything exists.

Lost Nation Orchard
Zone 4b in New Hampshire

Yes - both images work when I click on them. Not sure why the first one didn't previously. Apologies.

I agree with Michael that this doesn't look like black rot or anthracnose. But I, too, have no idea what it could be. Sorry not to be of more help. Michael's advice to continue with competitive colonization and holistic treatments seems like the way to go.

Door Creek Orchard
Zone 5a in Wisconsin

Thank you for the advice and thoughts. I will continue with the holistic treatments. I have heard that black rot can be associated with drought stressed trees and my trees were definitely drought stressed last season. But if it doesn't quite look like black rot to either of you then I'll rule that out for now.
After more poking around, white rot or Botryosphaeria dothidea might be a better fit, though I'm not any happier about it.

Nat Bouman
Growing cider varieties in Zone 5b
On B.118 at 18X24
Susquehanna County, Pennsylvania



Edited 1 time(s). Last edit at 03/26/2017 06:14AM by Nathaniel Bouman.