Hi all interested in fire blight.
I have been working with fire blight ever since the epidemic we had in WNY
in the early 1990's.
I worked with Wayne Wilcox to validate a new model at that time Maryblyt
which would have warned us of the intense pressure we experienced the
previous year, but it was not yet implemented in the industry.
To be brief... when we talk about how many streptomycin sprays applied, it
is never relevant to me unless I know how it was timed and that a
predictive model for blossom blight was used to determine the timing -
Cougarblight or Maryblyt (a new windows version might be available soon).
No models are black and white and growers still need to call the shots -
like what was the actual temperature in the orchard site, and although it
did not rain, did you have a dew period in the orchard site that went
undetected.
I hope that all growers are incorporating a prediction model that is
validated in their region to best time blossom blight sprays as a starting
point for preventing an epidemic.
Pruning out strikes? Unless the tree shoots stop growing, and you have
hot, dry weather, it is difficult to not cut out the strikes without seeing
infection below the cut or in the new shoot that springs from the
strike. I have seen a lot of effort in removing strikes, and if just a few
per tree in large trees, it might be worth it, but in highly susceptible
trees that are vigorous and continue to get infected shoots and canker
blight, eventually you have to walk away and wait until dormant pruning
time to correct the situation, and follow up with copper pre-bloom,
well-timed strep sprays during bloom..etc. My experience is that growers
suffer an epidemic year, and then all pieces of the management puzzle are
put in place the following year and there is no fire blight the following year.
Let's hope that is the case and we don't lose too many M9, M26 rootstocks
in the meantime.
Sincerely,
Deborah I. Breth
Area Extension Educator - Team Leader
Cornell Cooperative Extension - Lake Ontario Fruit Program
Phone: 585-798-4265
12690 State Route 31, Albion, NY 14411
At 10:41 AM 7/15/2009, you wrote:
Axel,
I am sure Dave's intent was not to threaten you, only help make us all
aware of the requirements of federal law as it pertains to commercial
apple growing. We, as professional growers, have an obligation to abide
by federal law just as a physician has an obligation to abide by the
Hippocratic oath. Yes, we do take our selves very seriously...well,
except in the case of leprechauns....because we have to. Right now in
Illinois, we are facing a near epidemic with fire blight, which can wipe
out a commercial orchard in a matter of weeks. But we can use only
properly labeled products to control fire blight and can only apply those
products with the proper certification.
In light of our discussion on Fire Blight, we have been able to control an
outbreak we had here at Royal Oak Farm back in 2007. We had almost 1,000
trees in a block of 5,000 trees hit by Fire Blight and it took 6 employees
3 days working 10 hours per day to cut it all out. We did not sterilize
our chain saws, saws-alls, loppers or pruning shears. In 2008 we sprayed
our usual copper at the maximum rate, then at bloom we did our normal
orchard wide strep spray at maximum rate followed 5 days later with a
Mychoshield spray at maximum rate only in the affected block based on a
bloom period of just over 12 days. We then applied Apogee following the
standard rate to control growth.
This season we followed the same protocol with the dormant copper spray at
maximum rate, Strep spray at maximum rate, but since we had an very
extended bloom period of almost 3 weeks, we did an additional strep spray
orchard wide and the Mychoshield spray only in the block affected by fire
Blight in 2007. We have had minimal fire blight this season and have cut
out what we have seen immediately after spotting it. Each morning we have
an employee drive through each row of our tree rows and prune out any fire
blight he sees. So far we have not had any significant branch loss, only
minor stem loss.
Where we think we failed in 2007 was not doing the second strep spray
during bloom. We grow varieties that range from Pristine through Granny
Smith so we can see somewhat of an extended bloom period in terms of the
range of trees we grow. If lower spring temperatures are added to that,
we can see a very extended period as we did this past spring, which
happened to be the wettest on record. I won't even bring scab up in this
post!
Dennis Norton
Royal Oak Farm Orchard
Office (815) 648-4467
Mobile (815) 228-2174
Fax (609) 228-2174
<http://www.royaloakfarmorchard.com>http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
<http://www.revivalhymn.com>http://www.revivalhymn.com
----- Original Message -----
From: <mailto:axel.kra...@yahoo.com>Axel Kratel
To: <mailto:apple-crop@virtualorchard.net>Apple-Crop
Sent: Tuesday, July 14, 2009 1:36 PM
Subject: Re: Apple-Crop: Fireblight Update
Sorry, I meant to say use retromycin sulfate, which is perfectly legal to
use on plants, and even has the right EPA label, I just used neosporin as
a way to keep the powder on the cuts. I thought neosporin had bactrin in
it, apparently it doesn't. It would work equally well with silicon paste
or any other pasty substrate.
But anyway, I am truly sorry I ever even posted this. If someone isn't
even allowed to experiment and have someone on this list threaten with
Federal law, well, then so be it, given that this is the second nasty
E-mail I got, consider this to be my last post on this list. You people
take yourself way too seriously.
Good bye.
From: Dave Rosenberger <da...@cornell.edu>
To: apple-crop@virtualorchard.net
Sent: Tuesday, July 14, 2009 10:24:09 AM
Subject: Re: Apple-Crop: Fireblight Update
I've enjoyed reading the postings and opinions concerning how to manage
fire blight in Alex's Ernst Bosch apple tree. Those of us who have worked
with or experienced fire blight know that this disease is very difficult
to understand and manage. What works on one cultivar, in one year, or in
one location may fail to work on another cultivar/year/location and what
is cost-effective for one apple grower may be totally implausible in other
economic models. Thus, I'm not going to debate Alex's observations.
HOWEVER, I feel obligated to point out that within the boundaries of the
United States (and I believe that still includes California), application
of an antibiotic paste to pruning cuts is a violation of federal law. Any
product used in that manner would require a federal pesticide label from
EPA. That requirement applies to homeowners and hobby farmers as well as
commercial growers. So far as I know, no antibiotic pastes are labeled
for use on tree fruits to control fire blight. There are good reasons for
these regulations, but I won't take time to discuss them. The bottom line
is that using human or veterinary antibiotics on fruit trees or other crop
plants is both illegal and potentially dangerous.
> I posted a while back on an Ernst Bosch Apple tree that came down with
fireblight. I wanted to share with the group what had happened, although
I must say that after reading the latest Illinois Fruits and Vegetable
Crop news, I am grateful not to have to deal with the fireblight
outbreak that the Midwest is experiencing this year.
>
> We are not in a fireblight prone area due to our cool, dry conditions,
but this year, fireblight has broken out in a number of local orchards
thanks to a warm and humid, rainy and drizzly week in May. So this has
been a learning experience for me.
>
> I finally figured out how to deal with the fireblight infection, here
is what I did:
>
> Since only one of my 200 trees (of which 80 are apple trees on MM111)
came down with fireblight, my focus was to eliminate any further disease
vectors, so removal of the tree is the only solution. However, I am a
scientist by training, and my curiosity got me to play with the tree for
a bit to try to understand what is going on.
>
> Here are some of the observations:
>
> Step one was to cut, but to my dismay, the infection returned, even
after several cuts. Disinfecting the shears seemed irrelevant. The
morning dew collecting on the cuts would often turn orange, and the drops
would carry the infection to lower limbs.
>
> Step two was to try to figure out if the re-infection vector was
external, or the bacteria was already systemic in the cambium. So for the
next sets of cuts, my approach was to coat the cuts with a oily
antibiotic paste with a bactrin base (bactrin is a wide spectrum
antibiotic). The coating would prevent re-infection from external
sources, but not if the bacteria is systemic in the cambium. Sure enough,
another set of cuts lead to more infection, the ooze coming from under
the paste. It only took 24 hours for the wood to turn orange under the
paste, proof that the infection came from inside the tree, not from
external sources or from the pruning sheers.
>
> Step 3 was to prune back radically, past the node of the infected
branch. Upon close inspection, I discovered that the cambium had a darker
shade, Cutting into the darker shaded areas revealed healthy wood, but
the cut turned orange within 24 hours and would start to ooze. However,
cutting several inches below any slightly darkened areas did not cause
the wood to turn orange, and no re-infection took place.
>
> Step 4 was to douse the tree with antibiotic to make sure there is not
any residual fireblight bacteria on the tree. I used a combination of
bactrin and retromycin sulfate to treat the tree and surrounding mulch.
>
> At this point, it's safe to say the fireblight active infection is
gone, although I believe the bacteria is still in the tree, but dormant
for now even though there are no visible cankers. Since the tree is so
young, I plan on removing and replacing it after the harvest this
October. But before I do, I also plan on feeding the tree some heavy
nitrogen to get it to grow and see if the new growth will show signs of
re-infection.
>
> My conclusion for controlling fireblight is the following: the bacteria
travels much, much further than 6-12 inches, and one must cut past any
infected ambium: Chances are trees could carry fireblight even without
showing any active signs of infection.
>
> 1) Always coat the cuts with an antibiotic oil-based paste to prevent
re-infection from outside vectors.
>
> 2) The wood must be placed into a plastic bag immediately and not
allowed to touch anything else. So it's a good idea to cover any oozing
branch into a plastic bag and break off the branch, then do the pruning
so no ooze droplet hits any other part of the tree.
>
> 3) Always disinfect the sheers in case the previous cut was into still
infected wood. Preferred disinfection is a field heat treatement
disinfector, which should be used anyway to prevent any sort of disease
spread. You wouldn't want the doctor not to disinfect his surgical
instruments before treating you, a plant is no different.
>
> 4) Always observe for orange discoloration under the paste for the next
24 to 72 hours. If the orange discoloration returns, the cut was made
into more infected tissue, and you have to cut further.
>
> 5) After any infected tissue is removed and discarded, the tree needs
to be treated externally with an antibiotic to remove any residual bacteria.
>
> I cannot vouch that the above would work outside of Santa Cruz county;
when I see the pictures of fireblight in the midwest, it makes me wonder
how one would even deal with fireblight once it broke out, the only
reasonable approach seems radical removal, and preventative spraying in
the Spring.
-- ************************************************************** Dave
Rosenberger
Professor of Plant Pathology Office: 845-691-7231
Cornell University's Hudson Valley Lab Fax: 845-691-2719
P.O. Box 727, Highland, NY 12528 Cell: 845-594-3060
<http://www.nysaes.cornell.edu/pp/faculty/rosenberger/>http://www.nysaes.cornell.edu/pp/faculty/rosenberger/
--------------------------------------------------------------------------
The 'Apple-Crop' LISTSERV is sponsored by the Virtual Orchard
<<http://www.virtualorchard.net>http://www.virtualorchard.net> and managed
by Win Cowgill and Jon Clements
<<mailto:webmas...@virtualorchard.net>webmas...@virtualorchard.net>.
Apple-Crop is not moderated. Therefore, the statements do not represent
"official" opinions and the Virtual Orchard takes no responsibility for
the content.
Deborah I.
Breth 12690 State
Route 31, Albion, NY 14411
Area Extension Educator - Team
Leader Phone: 585-798-4265
Cornell Cooperative Extension - Lake Ontario Fruit
Program Fax: 585-798-5191
Specialist in Integrated Pest Management of Fruit
Crops Mobile: 585-747-6039
