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What's this ?

Posted by Josh Klatt 
What's this ?
February 09, 2016 09:37PM
Black infection especially at old pruning sites on 4 calville blanc on antonovka.


Thanks !

Josh Klatt
Ohio River Valley
Zone 6b
Re: What's this ?
February 10, 2016 07:53AM
The black could well be sooty mold. It's the canker beneath that's your real problem. I don't think it's fire blight but rather black rot. It takes a year or two for this to establish on an old pruning cut. A look back at weather last season could confirm this if you didn't experience other fire blight strikes in 2014 or 2015. Exposed dead wood in old brush piles is often a primary vector of black rot. Pruning stubs don't help.

A "what's this" sort of post works well in Just Talk.

Lost Nation Orchard
Zone 4b in New Hampshire
Re: What's this ?
February 16, 2016 11:09AM
I appreciate the "what's this?" posts . . . I have seen a few random items over the winter that I was thinking of posting up for some HON pondering too. Thanks for priming the pump Josh.

The last photo, with the smaller diameter branch canker in your hand, looks similar to several FB cankers that I have been pruning out in my orchard from last seasons bad FB year out here in California.

Regardless, all cankers need to go . . . so goes my mantra this winter too.

Gopher Hill Apples
Zone 8 in California
Re: What's this ?
February 18, 2016 04:44PM
OK. I'll add my own "What's This?".

(Click on the image to see it full size)

This is a stem from a bush cherry, one of Bob Bors' selections, (Juliet, I think). I actually contacted Bob last year to ask him what he thought it was, and he responded that he has not heard of anybody having any problems with either fireblight or black rot in the bush cherries. It is obviously a canker of some sort, even if Bob says his bush cherries don't get same.

I noted while I was posting this that the two images in the Photobucket album immediately preceding this are of my apples which rotted on the trees last summer. I reckon these all must be related - is there something which affects both cherries and apples? (We have many wild "Pin Cherry" trees in the area, most of which are extensively covered in huge black rot cankers. A neighbour trying to grow plums has black cankers over all his trees.

Broomholm Orchard
Zone 5b in Nova Scotia
Re: What's this ?
February 19, 2016 03:42PM
The culprit is more than likely bacterial canker (pseudomonas syringae). David, I made a post on this in the Bacterial Opportunists category. It often affects all stone fruit. It is hard to distinguish in the growing season from black knot, (this may be what is present on your pins, despite them being less prone than black or chokecherry), but this affectation allows the gummosis to turn into a chunky black mass into the fall. Annoyingly, both remedies are removal of the affected tissue, hoping that trunks do not get infected. Rigourously upkept colonization of the tree by competitive organisms may be the only preventative, unless an equally vigorous showering of copper fungicides (not guaranteed regardless) is undertaken. For these reasons, we believe that in areas of plentiful wild vectors, stone fruits are a temporary crop needing constant replanting and so precocious varieties are suggested.

Walden Heights Nursery & Orchard
Zone 3 in Vermont
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