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nafex - Re: [NAFEX] Fireblight

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  • From: <dmnorton@royaloakfarmorchard.com>
  • To: "North American Fruit Explorers" <nafex@lists.ibiblio.org>
  • Subject: Re: [NAFEX] Fireblight
  • Date: Mon, 17 Aug 2009 19:20:17 -0500

Terminal buds are the buds located on the end of a shoot. Let me refer you to http://pubs.ext.vt.edu/422/422-025/422-025.html that will give you a clearer understanding of the physiology of pruning and the effects of summer pruning.

You do need to prune out fireblight as soon as it appears. If you can wait until the treminal buds have set (will produce no more new shoots) all the better. There is much physiology involved in the concept of summer pruning and its timing and it can vary by variety. Let me quote form the above article:

"Summer pruning involves the selective removal of leafy shoots during the growing season. Responses to summer pruning vary with time of pruning, severity of pruning, tree vigor, geographical location, and variety. Several researchers evaluated summer pruning during the 1980s and several general statements can be made about the practice.
Summer pruning reduces within-tree shade and usually improves fruit red color development and sometimes improves flower bud development. Summer pruning removes leaves that produce photosynthates (sugars) for growth of all tree parts. Summer pruning sometimes reduces fruit size and sugar levels.

Due to reduced whole-tree photosynthesis, summer pruning suppresses late-season trunk enlargement and root growth.

Summer pruning does not suppress shoot elongation the following season. Summer pruning reduces late-season photosynthesis, and theoretically should reduce the accumulation of reserve carbohydrates within the tree that are used for early season growth. However, results from most pruning experiments indicate that the response to a certain type of pruning cut will be the same regardless of the time of year the cut was made."



Hope this helps!


Dennis Norton
Royal Oak Farm Orchard
Office (815) 648-4467
Mobile (815) 228-2174
Fax (609) 228-2174
http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
http://www.revivalhymn.com
----- Original Message ----- From: "William C. Garthright" <billg@inebraska.com>
To: <dmnorton@royaloakfarmorchard.com>; "North American Fruit Explorers" <nafex@lists.ibiblio.org>
Sent: Monday, August 17, 2009 9:53 AM
Subject: Re: [NAFEX] Fireblight



There is no more risk to your trees for fire blight from summer pruning than there is from pruning out fire blight in the summer.


But I pretty well HAVE to prune out the fireblight right away, don't I? If I don't want it to spread?

I figured that there was some risk it would spread, but more risk if I didn't get rid of the infected areas. So I've got some choice about other summer pruning, but not about that, I thought.


And, once again, once the terminal buds have set, fire blight risk in minimal if not completely gone.


I'm not sure I understand that, Dennis. What do you mean?

Well, this is the first year I've had fireblight, and I don't know much about it (my county extension office didn't know anything about it, either). But from what I've read, it will infect a tree through an injury, right? So if I'm pruning off a bunch of new growth, won't that just multiply my chances that it will spread to that tree (especially when I know that fireblight is in the area)?

I would like to summer prune my apples and pears (probably not this year, at this point, but in general), but I didn't want the fireblight to spread. Yes, I pruned off the infected branches, but I figured that I didn't have much choice in that. And the disease is supposed to be dormant in the winter, so I figured that dormant pruning would be OK (and I've got to prune SOMETIME).

I'd hate to get rid of the Suncrisp apple, especially since it's one of four planted in one spot (and they're tied together to keep them all upright). That's one of the problems with that method. (Heh, heh. I, for one, don't have a "cult-like enthusiasm" for it. It definitely has its advantages, but I'd do things differently if I had to do this all over again. Not the basic idea, maybe, but probably not four in one spot like this.)

And although I've got a nice strong sprout from the root, where I suppose I could graft a new variety (though I've never done any grafting), it's not a dwarfing rootstock. Instead, all four of these apple trees had a dwarfing interstem. OK, they've done really well, but it would make replacing the Suncrisp harder to do.

Anyway, thanks for the comments. I AM learning here, though slowly. :-)

Bill
Lincoln, NE (zone 5)

--
I'm not going to buy my kids an encyclopedia. Let them walk to school like I did. - Yogi Berra







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