Re: [apple-crop] Kasugamycin for fire blight

[David A. Rosenberger]

Thanks for the follow-up information, Brian.  Using six strep sprays during 
bloom, while I can see how it may be necessary, does make me a bit more uneasy 
about selecting for strep resistance.  In northeastern United States, we often 
need two sprays during bloom, sometimes three, and very rarely four.  I’ve not 
been concerned about using four sprays if needed. However, I doubt that anyone 
has enough experience with the impact of 6 early-season sprays to be certain of 
the outcome.

One theory about how strep resistance develops (and I think this is still 
valid) is that the initial selection for resistance is not in Erwinia, but 
rather in other bacteria that exist in the orchard environment. These other 
bacterial species may then pass on the strep-resistance genes to Erwinia 
because bacteria have mechanisms for transferring useful DNA (i.e., DNA that 
enhances survival) from one species to another.  When strep is applied to apple 
and pear flowers in springtime, the over-all bacterial populations on leaves 
and in soil are still rather low because bacterial population build slowly as 
plants and soil warm up. Therefore,  there is less selection pressure for 
resistance in the non-Erwinia species when strep is applied during bloom as 
compared to after bloom.  Bacterial populations in the orchard environment 
increase very rapidly as temperatures rise, so summer applications of strep 
impact a much larger universe of bacteria and therefore are presumed to be  
more likely to trigger resistance that can later be transferred to Erwinia.

Strep is broken down in sunlight, but each application may contribute to 
residual accumulations in the ground cover, duff, or soil surface where the 
accumulation from multiple applications might persist long enough to enhance 
selection for resistance in soil bacteria as soil temperatures rise. I really 
don’t know how long strep persists in orchard soils, and there is undoubtedly 
huge variations depending on rainfall, orchard cover, soil type, etc.

I’m sending this post simply to indicate that there is still a lot of things we 
don’t know about how our agrichemical products impact the total orchard 
environment. Given that uncertainty, I’m still willing to bet, based on our 
history in the Northeast, that limiting strep applications to blossom time in 
areas that average only two or three strep sprays per year will never result in 
selection for strep resistance even if growers occasionally use one additional 
application after bloom to suppress trauma blight following hail or wind 
storms.  However, if you will need more than four strep sprays on a regular 
basis, that makes me a bit less comfortable and you may want to break up that 
string of strep sprays by including Kasumin in your blossom spray strategies.

On Mar 21, 2015, at 10:09 PM, Brian Heatherington 
mailto:beechcreekfa...@earthlink.net>> wrote:

No resistance from bloom sprays is good news. I have had no control problems 
with copper prior to green tip, strep timed by Maryblyt, Apogee to minimize 
pruning/harden shoots to possible shoot blight, and control of 
aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we had a 
long, extended bloom with Pink Lady. Maryblyt called for a total of 6 sprays 
(predicted EIP over 100), which exceeds most recommendations of 4 max. I went 
with the 6 applications and came out OK, but have always wondered if this might 
trigger resistance. I will stick with strep during bloom and leave the Kasumin 
for those that need it. I did just put in a block of CrimsonCrisp and haven't 
thought about putting copper on them. Good advice. Thanks.

On 3/21/2015 10:36 AM, David A. Rosenberger wrote:
While Kasugamycin works about as well as streptomycin, oxytetracycline is 
generally a bit less effective and has the disadvantage of preventing bacterial 
multiplication without killing off all of the bacteria contacted by the spray.  
Of the three antibiotics, it is my understanding that only strep is absorbed 
into apple tissue, thereby giving it a bit of an edge over both of the other 
products, especially in cases where a few infections might have been initiated 
a few hours before the product is applied.  Kasugamycin, like strep, kills 
bacterial cells that it contacts, but it has the disadvantage of being 
considerably more expensive than strep.

Some of my pathologist colleagues may disagree with me, but I see no reason to 
pay the extra price for kasugamycin in established orchards that have no 
history of strep resistance. (An exception would be in countries like Canada 
where the strep labels allow a maximum of 3 applications/yr.)  In eastern New 
York and New England, we have used strep exclusively for fire blight control 
for more than 60 years without encountering resistance.  Resistance to strep 
has only appeared in regions where nurseries or fruit growers have used it 
repeatedly during summer (as many as 12 times/yr) to prevent shoot blight. 
Thus, 

Re: [apple-crop] Kasugamycin for fire blight

[Jon Clements]

While dealing with getting Kasumin 2L registered here in MA, it was pointed
out that on the Federal label it says:

• Do not apply kasugamycin in orchards in which the soil has been
fertilized with animal waste/manure.
• Animal grazing in treated areas is prohibited. The public must be
notified by posting restriction signs along the perimeter of the treated
area.

Attached is the sign our state Ag Dept. is considering. No real guidance on
placement other than "perimeter of the treated area."

Just thought you might be interested...

Jon



On Mon, Mar 23, 2015 at 9:04 AM, David A. Rosenberger 
wrote:

>  Thanks for the follow-up information, Brian.  Using six strep sprays
> during bloom, while I can see how it may be necessary, does make me a bit
> more uneasy about selecting for strep resistance.  In northeastern United
> States, we often need two sprays during bloom, sometimes three, and very
> rarely four.  I’ve not been concerned about using four sprays if needed.
> However, I doubt that anyone has enough experience with the impact of 6
> early-season sprays to be certain of the outcome.
>
>  One theory about how strep resistance develops (and I think this is
> still valid) is that the initial selection for resistance is not in
> Erwinia, but rather in other bacteria that exist in the orchard
> environment. These other bacterial species may then pass on the
> strep-resistance genes to Erwinia because bacteria have mechanisms for
> transferring useful DNA (i.e., DNA that enhances survival) from one species
> to another.  When strep is applied to apple and pear flowers in springtime,
> the over-all bacterial populations on leaves and in soil are still rather
> low because bacterial population build slowly as plants and soil warm up.
> Therefore,  there is less selection pressure for resistance in the
> non-Erwinia species when strep is applied during bloom as compared to after
> bloom.  Bacterial populations in the orchard environment increase very
> rapidly as temperatures rise, so summer applications of strep impact a much
> larger universe of bacteria and therefore are presumed to be  more likely
> to trigger resistance that can later be transferred to Erwinia.
>
>  Strep is broken down in sunlight, but each application may contribute to
> residual accumulations in the ground cover, duff, or soil surface where the
> accumulation from multiple applications might persist long enough to
> enhance selection for resistance in soil bacteria as soil temperatures
> rise. I really don’t know how long strep persists in orchard soils, and
> there is undoubtedly huge variations depending on rainfall, orchard cover,
> soil type, etc.
>
>  I’m sending this post simply to indicate that there is still a lot of
> things we don’t know about how our agrichemical products impact the total
> orchard environment. Given that uncertainty, I’m still willing to bet,
> based on our history in the Northeast, that limiting strep applications to
> blossom time in areas that average only two or three strep sprays per year
> will never result in selection for strep resistance even if growers
> occasionally use one additional application after bloom to suppress trauma
> blight following hail or wind storms.  However, if you will need more than
> four strep sprays on a regular basis, that makes me a bit less comfortable
> and you may want to break up that string of strep sprays by including
> Kasumin in your blossom spray strategies.
>
>  On Mar 21, 2015, at 10:09 PM, Brian Heatherington <
> beechcreekfa...@earthlink.net> wrote:
>
>  No resistance from bloom sprays is good news. I have had no control
> problems with copper prior to green tip, strep timed by Maryblyt, Apogee to
> minimize pruning/harden shoots to possible shoot blight, and control of
> aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we
> had a long, extended bloom with Pink Lady. Maryblyt called for a total of 6
> sprays (predicted EIP over 100), which exceeds most recommendations of 4
> max. I went with the 6 applications and came out OK, but have always
> wondered if this might trigger resistance. I will stick with strep during
> bloom and leave the Kasumin for those that need it. I did just put in a
> block of CrimsonCrisp and haven't thought about putting copper on them.
> Good advice. Thanks.
>
> On 3/21/2015 10:36 AM, David A. Rosenberger wrote:
>
> While Kasugamycin works about as well as streptomycin, oxytetracycline is
> generally a bit less effective and has the disadvantage of preventing
> bacterial multiplication without killing off all of the bacteria contacted
> by the spray.  Of the three antibiotics, it is my understanding that only
> strep is absorbed into apple tissue, thereby giving it a bit of an edge
> over both of the other products, especially in cases where a few infections
> might have been initiated a few hours before the product is applied.
> Kasugamycin, like strep, kills bacterial cells that it contacts, but it has
> t

Re: [apple-crop] Kasugamycin for fire blight

[David A. Rosenberger]

I should have added one more thought:  Probably the very best strategy for 
avoiding selection for strep-resistant Erwinia amylova (Ea) is to prevent fire 
blight from becoming established in the orchard in the first place.  To that 
end, the integrated strategy that Brian described (copper early, strep as 
required by a timing model, and Apogee to make shoots more resistant) reduces 
the likelihood that he will ever have visible fire blight or even high 
populations of Ea in his blocks. You can’t get resistance if the pathogen of 
interest never becomes established, even if non-Erwinia species in the sprayed 
blocks may have detectable levels of strep-resistance.

On Mar 23, 2015, at 9:04 AM, David A. Rosenberger 
mailto:da...@cornell.edu>> wrote:

Thanks for the follow-up information, Brian.  Using six strep sprays during 
bloom, while I can see how it may be necessary, does make me a bit more uneasy 
about selecting for strep resistance.  In northeastern United States, we often 
need two sprays during bloom, sometimes three, and very rarely four.  I’ve not 
been concerned about using four sprays if needed. However, I doubt that anyone 
has enough experience with the impact of 6 early-season sprays to be certain of 
the outcome.

One theory about how strep resistance develops (and I think this is still 
valid) is that the initial selection for resistance is not in Erwinia, but 
rather in other bacteria that exist in the orchard environment. These other 
bacterial species may then pass on the strep-resistance genes to Erwinia 
because bacteria have mechanisms for transferring useful DNA (i.e., DNA that 
enhances survival) from one species to another.  When strep is applied to apple 
and pear flowers in springtime, the over-all bacterial populations on leaves 
and in soil are still rather low because bacterial population build slowly as 
plants and soil warm up. Therefore,  there is less selection pressure for 
resistance in the non-Erwinia species when strep is applied during bloom as 
compared to after bloom.  Bacterial populations in the orchard environment 
increase very rapidly as temperatures rise, so summer applications of strep 
impact a much larger universe of bacteria and therefore are presumed to be  
more likely to trigger resistance that can later be transferred to Erwinia.

Strep is broken down in sunlight, but each application may contribute to 
residual accumulations in the ground cover, duff, or soil surface where the 
accumulation from multiple applications might persist long enough to enhance 
selection for resistance in soil bacteria as soil temperatures rise. I really 
don’t know how long strep persists in orchard soils, and there is undoubtedly 
huge variations depending on rainfall, orchard cover, soil type, etc.

I’m sending this post simply to indicate that there is still a lot of things we 
don’t know about how our agrichemical products impact the total orchard 
environment. Given that uncertainty, I’m still willing to bet, based on our 
history in the Northeast, that limiting strep applications to blossom time in 
areas that average only two or three strep sprays per year will never result in 
selection for strep resistance even if growers occasionally use one additional 
application after bloom to suppress trauma blight following hail or wind 
storms.  However, if you will need more than four strep sprays on a regular 
basis, that makes me a bit less comfortable and you may want to break up that 
string of strep sprays by including Kasumin in your blossom spray strategies.

On Mar 21, 2015, at 10:09 PM, Brian Heatherington 
mailto:beechcreekfa...@earthlink.net>> wrote:

No resistance from bloom sprays is good news. I have had no control problems 
with copper prior to green tip, strep timed by Maryblyt, Apogee to minimize 
pruning/harden shoots to possible shoot blight, and control of 
aphids/leafhoppers at petal fall/1st cover. A few years ago, however, we had a 
long, extended bloom with Pink Lady. Maryblyt called for a total of 6 sprays 
(predicted EIP over 100), which exceeds most recommendations of 4 max. I went 
with the 6 applications and came out OK, but have always wondered if this might 
trigger resistance. I will stick with strep during bloom and leave the Kasumin 
for those that need it. I did just put in a block of CrimsonCrisp and haven't 
thought about putting copper on them. Good advice. Thanks.

On 3/21/2015 10:36 AM, David A. Rosenberger wrote:
While Kasugamycin works about as well as streptomycin, oxytetracycline is 
generally a bit less effective and has the disadvantage of preventing bacterial 
multiplication without killing off all of the bacteria contacted by the spray.  
Of the three antibiotics, it is my understanding that only strep is absorbed 
into apple tissue, thereby giving it a bit of an edge over both of the other 
products, especially in cases where a few infections might have been initiated 
a few hours before the product is applied.  Kasugamyci

Re: [apple-crop] Kasugamycin for fire blight

[Kerik Cox]

Hi Dave,

I've wondered about this. In several of our orchards. All of the 
epiphytes all nearly have 100% of the population strep resistance even 
at the start of the season, so in theory no applications of strep would 
just as bad as several. The predominance changes over the season and it 
makes me wonder if one of the species that comes in later in the season 
is more like to transfer the plasmid. Also, feel like there probably has 
to active cankers or shoot blight to get some Ea present before the 
transfer could occure. The other bacteria seem to be better epiphytes 
and it's getting hard to even get Ea on shoots in Kiersten's 
experiments. We do need more seasons of data though.


One theory about how strep resistance develops (and I think this is 
still valid) is that the initial selection for resistance is not in 
Erwinia, but rather in other bacteria that exist in the orchard 
environment. These other bacterial species may then pass on the 
strep-resistance genes to Erwinia because bacteria have mechanisms for 
transferring useful DNA (i.e., DNA that enhances survival) from one 
species to another.  When strep is applied to apple and pear flowers 
in springtime, the over-all bacterial populations on leaves and in 
soil are still rather low because bacterial population build slowly as 
plants and soil warm up. Therefore,  there is less selection pressure 
for resistance in the non-Erwinia species when strep is applied during 
bloom as compared to after bloom.  Bacterial populations in the 
orchard environment increase very rapidly as temperatures rise, so 
summer applications of strep impact a much larger universe of bacteria 
and therefore are presumed to be  more likely to trigger resistance 
that can later be transferred to Erwinia.



--
Kerik D.  Cox, Ph.D., Associate Professor
Plant Pathology and Plant-Microbe Biology Section
School of Integrative Plant Science
Cornell University
221 Barton Lab
NYSAES
630 West North Street   
Geneva, NY 14456 USA

E-mail: kd...@cornell.edu
Faculty Office: (315) 787-2401
Fruit Pathology Lab: (315) 787-2402 
FAX: (315) 787-2389

___
apple-crop mailing list
apple-crop@virtualorchard.net
http://virtualorchard.net/mailman/listinfo/apple-crop

Re: [apple-crop] Kasugamycin for fire blight

[Brian Heatherington]

  
  
I should be at 4 sprays or less (3 last
  year) most of the time. The six sprays occurred after the "year
  without a  winter" several years ago, when the low for the entire
  winter was 15F and that was only reached twice. We were 5 below
  here last year, and normally get plenty of consistent chill hours,
  which results in a uniform bloom. The need for alternate products
  will not be common. We're reaching tight cluster here this week,
  and projected bloom looks very consistent and uniform. In future
  years, when Kasumin drops in price and becomes more available, I
  think it might be a good option if a protracted bloom shows up
  again. I should mention that this problem has been unique to Pink
  Lady/Cripps Pink as its low chill requirement makes it a blooming
  machine. It is however the best apple we grow here, and it stores
  very well along with Fuji and Goldrush.
  
  Fascinating stuff: the transfer of DNA from other bacteria. I had
  no idea.

On 3/23/2015 9:44 AM, David A.
  Rosenberger wrote:


  
  I should have added one
more thought:  Probably the very best strategy for avoiding
selection for strep-resistant Erwinia amylova (Ea) is to prevent
fire blight from becoming established in the orchard in the
first place.  To that end, the integrated strategy that Brian
described (copper early, strep as required by a timing model,
and Apogee to make shoots more resistant) reduces the likelihood
that he will ever have visible fire blight or even high
populations of Ea in his blocks. You can’t get resistance if the
pathogen of interest never becomes established, even if
non-Erwinia species in the sprayed blocks may have detectable
levels of strep-resistance.
  
  
  

  On Mar 23, 2015, at 9:04 AM, David A.
Rosenberger 
wrote:
  
  

  Thanks for the
follow-up information, Brian.  Using six strep sprays
during bloom, while I can see how it may be necessary,
does make me a bit more uneasy about selecting for strep
resistance.  In northeastern United States, we often
need two sprays during bloom, sometimes three, and very
rarely four.  I’ve not been concerned about using four
sprays if needed. However, I doubt that anyone has
enough experience with the impact of 6 early-season
sprays to be certain of the outcome.
  
  
  One theory about
how strep resistance develops (and I think this is still
valid) is that the initial selection for resistance is
not in Erwinia, but rather in other bacteria that exist
in the orchard environment. These other bacterial
species may then pass on the strep-resistance genes to
Erwinia because bacteria have mechanisms for
transferring useful DNA (i.e., DNA that enhances
survival) from one species to another.  When strep is
applied to apple and pear flowers in springtime, the
over-all bacterial populations on leaves and in soil are
still rather low because bacterial population build
slowly as plants and soil warm up. Therefore,  there is
less selection pressure for resistance in the
non-Erwinia species when strep is applied during bloom
as compared to after bloom.  Bacterial populations in
the orchard environment increase very rapidly as
temperatures rise, so summer applications of strep
impact a much larger universe of bacteria and therefore
are presumed to be  more likely to trigger resistance
that can later be transferred to Erwinia.
  
  
  Strep is broken
down in sunlight, but each application may contribute to
residual accumulations in the ground cover, duff, or
soil surface where the accumulation from multiple
applications might persist long enough to enhance
selection for resistance in soil bacteria as soil
temperatures rise. I really don’t know how long strep
persists in orchard soils, and there is undoubtedly huge
variations depending on rainfall, orchard cover, soil
type, etc.  
  
  
  I’m sending this
post simply to indicate that there is still a lot of
things we don’t know about how our agrichemical products
impac