Welcome! Log In Create A New Account


Fireblight Carryover

Posted by Robbie Anderman 
Fireblight Carryover
October 01, 2016 05:34AM
It's been quite the summer of dealing with fireblight. I'll write more about this soon.... After finishing with harvesting, etc

The question now is: with rampant fireblight in the neighbourhood on apples and pears... especially recurring on pears, even now, we are wondering whether trees that show no sign at all of infection might still be carrying contagion... namely, I'm talking of small nursery trees that have been grafted. Maybe 20 of them. Maybe three got fireblight signs, and were destroyed. The ones that remain look fine.

However, these were grown and grafted for a "customer" with her heritage scion wood. They look healthy, yet it's getting near time to send them to her.... Is it safe to do so?
Might the Edwinia have settled in and still be showing no signs of its presence.. yet might reveal itself next year in its new home?

If so, is there any way to prevent it from growing? Or actually eradicate it completely?
These are maybe 3 feet tall.

thank you,

Morninglory Farm
Zone 3b* in Ontario

Edited 1 time(s). Last edit at 10/05/2016 01:15AM by Michael Phillips.
Re: Fireblight Carryover
October 05, 2016 12:23PM
There's a powerful saying in the microbial world: Everything is everywhere.

It's not about the "presence" of fire blight, Robbie, but rather the opportunity for this bacterial disease to take off.

I doubt your grafted trees are infected on the vascular level if you've seen no signs of shoot dieback.

Which doesn't mean the disease potential is not on the surface of those trees . . . or the surface of other trees where those trees will go. Or perhaps even on you!

Too many growers do not understand the disease paradigm, frankly. It's not about medications to deal with the vector but rather system health to make the vector improbable. Don't allow the "stressed niche" (by means of an approach known as holistic orcharding) and the "everything everywhere" more often than not cannot take hold. Fire blight bacteria do not like a crowd thus the underlying strategy here will always be competitive colonization of blossom surfaces and the like.

Lost Nation Orchard
Zone 4b in New Hampshire

Lost Nation Orchard
Zone 4b in New Hampshire
Re: Fireblight Carryover
October 06, 2016 04:26AM
Thank you for your very philosophical response... and very helpful response. It's been quite the challenging year. I got a late start with pruning.... then kept it up while putting in the big garden... then amidst the gardening noticed fire blight among the blossoms... so on to pruning again... and then more pruning.... which kept up until September.. and there's still a few branches showing recurrence.

I will have to report on which pear trees are actually resistant... and which are not.... Gold Spice is certainly the most resistant, with Ure not far behind... depending on which other tree it is next to and how susceptible it is... John pear was not as resistant as expected. Kikusui Asian pear was hit hard. Tait had a mild case. South worth and Patten both took a hit, tho' not too bad. Eenie and Meenie (from ottawa) got decimated, as did two of their relatives.

I feel we got side tracked with spraying white vinegar... and then tamarack tea (as an antibiotic spray)... too late for that. Better would have been raw milk.. tho' we didn't have a source at the time.

We didn't want to summer prune and thus open more cuts into the vascular system... so the trees sure look weird with all the sucker growth and the ugly cut stumps. And to make it even more weird, the porcupines invaded again and kept taking down more branches... for the unripe fruit and recently for the leaves themselves. I hear they make a good pie.

And I really feel we need to get some cash to buy a bigger easier sprayer... the one on my back is tiring and can't reach the heights that pears can reach to..... Which would be the only way we can really take a holistic orchard approach it would seem.

The whole thing has been a shock after nearly thirty years of no fireblight.

And it threw my summer into tumult... putting me way behind in most commitments. Plus we mostly left the wild apple trees (which we've been pruning and grafting onto) to their fate... and most seemed to recover without any pruning. the blight stopped at a certain point and did not continue, like it did on the pears. A local friend with an orchard of 20+ trees who has been tending it for over 40 years, said he gets blight occasionally and just leaves it alone... that it takes out a few branches which he cuts off in winter... and then nothing for years... so he doesn't worry about it. Too many other things to deal with on a mixed farm. So I've relaxed about the apples any way.

Added to that is the absence of so many pears... and thus absence of much income.

So there's a bit of a contribution to this "bloody forum" for tonight. I hope it's not really bloody. Lots of sap floating around. And a good bit of pear and apple juice.... much of which will soon go into mason canning jars, "because we can" (and someday we'll find a better way to preserve it... and/or get a cider license.
I greatly appreciate you being there, Michael. I thank you while I'm climbing trees, pruning, picking, etc... and imagine you and all the forum people out there with me, out in your orchards relating intimately with your tree friends. Balancing on branches and ladders. Reaching for the good ones!.... while balancing on one foot, with the other balancing off to the other side... or some such similar motion/stance. A rare breed indeed. Thank you!!!!

Morninglory Farm
Zone 3b* in Ontario
Re: Fireblight Carryover
January 29, 2022 01:22AM
I just stumbled upon an eye-opening article regarding the lifecycle of Erwinia amylovora. Long story short: we're going to be growing a patch of heirloom tobacco this year as an interesting attraction in our historically tobacco-centric region, and I'm always thinking of new and exciting ways to intercrop under apple trees . . . so I thought, why not shade-grown tobacco under apple trees? I assumed tobacco might serve as a repellant for some pests, but actually, quite the contrary, it's looking like it may be a pest magnet (to some extent, also dispensing with pests when they literally die of nicotine poisoning), although what might overlap between apples and tobacco besides aphids is still something to hope for. Tobacco does have some interesting relations with beneficials: when attacked by certain pests, tobacco plants will release VOCs that attract pest predators; also, the sticky parts of the leaves trap small insects such as fruit flies, and these under-leaf buffets in turn attract plenty of beneficials, such as lacewings, that could directly benefit the apple orchard. Too much to hope that tobacco would overlap with and serve as a trap crop for curculio, I guess.

Anyway, long story actually, um, long, as I research this and absolutely plant a trial patch of dwarf tobacco under some apple trees this summer, I may file this under some devoted thread, but of course, I also looked into potential overlapping diseases between apples and tobacco (tobacco mosaic virus could be transmitted to apple trees), and stumbled upon this fairly recent (from 2017) article in Plant Pathology that looked at whether or not E. amylovora actually can survive on dead leaves over the winter, to serve as an infection reservoir come spring. The article is 'Necrotrophic behavior of Erwinia amylovora in apple and tobacco leaf tissue' [bsppjournals.onlinelibrary.wiley.com]

The tobacco angle was, the researchers happened to infect tobacco, a non-host for fireblight, with E. amylovora, as well, since it provoked a hypersensitive response in the leaf tissue. So of course, we all know to cut out dead and diseased-looking wood that may contain cankers during dormant pruning. But, while we certainly do our best to break down dead, fallen leaves for plenty of other disease reasons, I was not aware that E. amylovora was a potential concern there, as well. The life cycle of this pathogen is so much more complicated than the fly-by articles rattling on about shepherd's crooks and hot, wet conditions make it out to be! We learned a lot in this direction last year as we struggled to come up with the most ideal times to apply Agriphage in order to effect E. amylovora mortality.

Kordick Family Farm
Westfield, NC
Zone 7a

Edited 1 time(s). Last edit at 02/05/2022 01:18AM by Brittany Kordick.
Sorry, only registered users may post in this forum.

Click here to login