There seemed to be a lot of late, tail-end bloom(rat-tail) bloom this year
especially on Paulared. Every tree had 3-4 clusters on borse shoots into
mid-June. We did use one strep spray on several varieties with this
bloom. Also it is probably not a good idea to neglect cutting root suckers
that may eventually bloom and be susceptible to fire blight.
On Tue, Aug 11, 2015 at 12:07 PM, Glen Koehler <glen.koeh...@maine.edu>
> Maine had two bouts of fire blight weather during bloom, one at very
> beginning and second at very end. I suspect that the rapid shift to hot
> days just before and leading into bloom (after slow cool period from bud
> break to pink) may have shocked the trees and resulted in more straggled
> bloom than usual.
> While we have not had an epic fire blight year comparable to what
> other states have experienced in other recent years, there seems to be a
> transition this year. Originally fire blight was not a disease that
> required attention in Maine. That era ended about 15 years ago. Then,
> fire blight used to be something that showed up in a few orchards in some
> years, usually but not always relatively minor extent. This year, it seems
> that most orchards have a little bit of fire blight. No devastating
> epidemics this year, but a lot more than growers want to see.
> Following is off the cuff reply to apple grower dealing with fire
> blight strikes that keep showing up in Paula Reds. He was wondering if he
> can ever dig his way back out of recurring fire blight infections. The
> fire blight has been in the block at low level for past 3-4 years and
> despite repeated, (though not always immediate) sanitation removal, it is
> back again this year. Still not at catastrophic level but it does seem to
> be increasing year to year. Rough guess is that this year 20-30% of Paula
> Red trees in the block are affected. Most with only one or two strikes,
> but a few with considerably more. Unfortunately I think the trees are on
> M26. Across Maine. there seems to be much more fire blight on Paula Red
> than other cultivars this year. Honeycrisp and Cortland in this same block
> hardly affected.
> I'm looking for comments. Did I miss any key points? Anything
> erroneous? I'm aware of kasugamycin and other alternative materials, but
> this wasn't the place for getting into that kind of detail. I don't think
> we have strep resistant E.a., should get some more samples tested though.
> Is two early season copper applications likely to be any more helpful than
> one? Post harvest copper make any sense?
> Thanks for your help,
> Grower message: "Fire blight looks like heck in the Paula Red’s! We are
> just cutting what we can and summer pruning. Is there no hope?"
> Reply: " It should slow down with trees ceasing terminal growth. I'm
> sure you have other things you'd rather be doing, but getting rid of the
> fire blight now will at least cut down work load later, and might be the
> thing that prevents further spread that gets to the point where you are
> looking at replacing trees.
> Copper every spring. Strep on hand so you can react quickly to
> blossom blight infection period forecast that you need to check daily
> because they can change so fast. Factor fire blight into cultivar and
> rootstock selection. Blossom removal on first year trees. Fertility
> management to prevent overly lush growth. Consider Apogee where
> appropriate to reduce shoot growth and thus shoot blight spread. Daily
> monitoring and removal of fire blight strikes starting a petal fall until
> end of August. Strep on hand in case hail or strong wind storm creates
> risk of fire blight spread (up until strep PHI gets in the way).
> Be careful that you don't mix summer pruning and fire blight removal.
> They should be handled as two separate jobs. I suspect it would be best
> to complete fire blight removal first. Summer pruning before fire blight
> removal will create open wound surfaces. Going in after to handle fire
> blight material could mobilize bacteria which can infect those wounds.
> Thus, better to remove fire blight before creating summer pruning wounds.
> Same thing applies to sucker removal. Thoroughly sterilize tools after
> using them for fire blight removal before using for anything else. Ugly
> stub pruning to allow winter removal of cankers created by sanitation
> cuts. Don't leave fire bight cuttings in the orchard as fire blight
> bacterial can remain active in dried ooze for 2 years. Burn, bury, or
> compost the fire blight cuttings.
> It is possible to work your way out of a moderate fire blight
> outbreak. But it can take an extended period of sanitation vigilance.
> There are no silver bullets."
> Glen Koehler
> University of Maine Cooperative Extension
> Pest Management Office
> Voice: Office 207-581-3882, Cell 207-485-0918
> 491 College Avenue, Orono, ME 04473
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