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Black Rot of Apples

Posted by Mike Biltonen 
Black Rot of Apples
March 21, 2013 04:11PM
Black rot in apples can obviously manifest itself in a variety of ways. Frog-eye leaf spot, woody cankers....in severe situations it can debilitate and/or even kill a tree. Outside of sanitation, what sprays or other methods are folks finding effective in combating this disease? There's a situation with a fellow orchardist down in the mid-Atlantic region where they've planted a small orchard with hard cider varieties (not sure which ones). They've been plagued with BR infections to the point that the trees are turning downhill. So we know there's an endemic "population"? What's the control outside of sanitation?

Mike Biltonen, Know Your Roots
Zone 5b in New York
Re: Black Rot of Apples
March 17, 2017 04:46AM
It's an old thread but I'd love to hear more about this too.
I let the 2015 drought stress my trees too much and now I've got a lot of limbs showing signs of black rot. The trees are young and I'd rather not prune out all the affected branches as I'd lose my first scaffold on a lot of trees. I was told copper can help. Any advice?

Nat Bouman
Growing cider varieties in Zone 5b
On B.118 at 18X24
Susquehanna County, Pennsylvania
Re: Black Rot of Apples
March 01, 2018 06:39PM
Bumping this up for any ideas. Restoring an older orchard, and am loathe to prune every & all infected limbs in a single year lest the trees lose too much limb/foliage.
Re: Black Rot of Apples
March 02, 2018 09:55PM
Hi Josh,

I just consulted with a new property owner who bought a large parcel of land that had a vineyard and orchard. There was substantial historic SW Injury in the orchard, evidence of past inadequate irrigation and plenty of evidence of Pseudomonas syringae infections in the stone fruit and Black Rot in the Apples.

Most of the black rot appeared tied to poor pruning practices and the tissue damage caused by the scorching of the cambium layer on the southwest sides of the trunks and side branching oriented in that direction too.

I advised that this problem didnt just show up this year and a thoughtful multiseason approach would be prudent.

Though it would be good to remove all of the diseased wood, they would have been radically altering many of the trees' scafolding and structure -- and that they should plan to keep a sharp eye on the trees and start planning for replacement branching now. That is, start looking for shoots, sprouts, buds, that can be encouraged and trained as replacements for the eventual surgery to come.

I dont think it is a good idea to leave black rot in a tree, for the long term, but in a rehabilitation situation, the sooner you can start to plan for the healthy future of the trees the better. Prune out as much of it as you can. If it is Black Rot you are dealing with it is only going to get worse and spread.

Just like your situation Josh, if you are going to be fully hands on in your holistic approach to rehabilitation of the orchard you are working with, you can eventually overcome most of the black rot . . . I say most, because you may find that some trees may be too far gone to save -- or to at least save to the point that they will be truly productive again, as they once were. In which case, have a removal strategy too & remove them, and begin to focus on your future orchard succession.

A note to Nathaniel's earlier question . . . Copper? and should you use it for Black Rot?

I feel, in a serious rehabilitation step towards bringing an old orchard back to health, cleaning the slate can be an important first step in turning the tide. Especially when you have limited past knolwedge of the orchard in question and when you have decomposing fungi as dominant players in the tree canopy.

If I were rehabilitating an older orchard deemed worth the effort, as you are describing, I would drop the "blue piano" (Michael's great visual for it) of copper on it and all the other trees in the orchard. Remember, you need to treat all the trees together, not just spot treatments. Then plan to do some serious pruning down the line. Half rotted trees and major branches may never be able to heal fast enough to outpace a future black rot (or another pathogen). Help your tree by removing the black rot eventually and completely, the best you can, with a multi year plan

Gopher Hill Apples
Zone 8 in California

Edited 1 time(s). Last edit at 03/02/2018 09:56PM by Paul Weir.
Re: Black Rot of Apples
March 17, 2018 07:05PM
Thanks for the thoughts, Paul. That generally reflects what I've been pondering, and good to hear the details filled in. Thanks!
Re: Black Rot of Apples
March 23, 2018 10:29PM
Hi, gentlemen -

We have a lot of black rot in our orchard (from old SW injury mostly), so I feel for you. I would second all of the above. Just wanted to mention biodynamic tree paste as well--I've been trying it to help nurse along some of our older trees and it seems to be helping a bit. There's a post about it elsewhere on the forum.

Of course, this is just anecdotal, no scientific proof for you.

Door Creek Orchard
Zone 5a in Wisconsin

Edited 1 time(s). Last edit at 03/23/2018 10:30PM by Liz Griffith.
Re: Black Rot of Apples
March 25, 2018 04:49AM
Hi Friends,

Wanted to add that for Copper, I have really been feeling good about Cueva for that tool in the box.

Less total copper -- metalic copper equivalent of only 1.8%

So, if you need to drop the blue piano, there are smaller versions of it that are pretty darn effective vs the entire Steinway!

Hi Liz, liking the plug for the biodynamic vibe you are feeling with your black rot counter attack!

We are on the cusp! Raising a toast for a successful 2018 everyone!

Gopher Hill Apples
Zone 8 in California
Re: Black Rot of Apples
March 25, 2018 07:11PM
Thank you, Liz and Paul! Will look more into those here. Cheers for a beautiful 2018!
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