Re: [Apple-Crop] Fireblight

[Arthur Kelly]

We didn't get the shower Thursday night so not only did I not apply strep but 
we were 10 days out on a scab spray so I covered up today. 

Sent from my iPhone

> On May 21, 2017, at 9:16 PM, Glen Koehler  wrote:
> 
> Hi Art
> If a flower opened at 7am on Friday May 19, and you had sprayed strep 
> just before that, then that flower would not be protected.Using Sanford 
> temperatures (not too far from you), there were 193 Cougarblight heat units 
> between Friday morning 7am and 5pm on Friday.  
> 
> After Friday 5pm, heat unit accumulation fell off very sharply.  Only an 
> additional 25 units accumulated between Friday 5pm and a rain on Monday May 
> 22 (and no new heat units on Monday).   The total number of heat units from 
> Friday 7am to Monday morning would be 221.  The Cougarblight threshold for a 
> category II orchard (fire blight within 1 mile within the last two years) to 
> move from Caution to High infection risk is 200 units.   
> 
> So if that new flower was contaminated right as it opened, then presumably it 
> would have had just above the threshold of heat units to call for another 
> streptomycin application before a Monday rain.  That scenario seems unlikely 
> for several reasons.  First, almost all of the flowers except perhaps very 
> late blooming cultivars were already open by the time of a Friday morning 
> streptomycin application.  Second, the chance that a flower opens at 7am and 
> is immediately contaminated with fire blight bacteria seems low.
> 
>  If that hypothetical flower had opened at noon on Friday, May 19, then it 
> would have accumulated only 120 new heat units between opening and a Monday 
> rain (no additional heat units on Monday, only 12 new heat units on Tuesday 
> May 23).
> 
> All the above is for the assumption that you applied streptomycin after the 
> Thursday night / Friday morning shower, after daily high temperatures of 90 
> and 93 on Wed. and Thur May 17-18.
> 
> If streptomycin was not applied on Friday, then unprotected flowers that are 
> still open during a Monday rain (i.e. not too old for infection) would be at 
> Exceptionally high infection risk because many of those heat units are still 
> considered applicable for a Monday rain.
> 
> Note to other Maine growers:  Temperatures on Friday were much cooler in 
> Monmouth than Sanford on Friday May 19.  By Friday at 5pm in the scenario 
> described above, only 52 Cougarblight heat units had accumulated in Monmouth 
> (vs. .193 in Sanford).  While Monmouth has more bloom remaining for a Monday 
> rain, the heat units since Friday just aren't there.
> 
> But if you did NOT apple strep on Friday May 19, then a Monday rain would not 
> only been in the Exceptional risk rating, that risk would coincide with most 
> apple trees sitll being in full bloom.
> 
> - Glen
> 
> 
> 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
> UMaine Apple IPM https://extension.umaine.edu/ipm/programs/apple/
> Ag-Radar https://extension.umaine.edu/ipm/ag-radar-apple-sites
> Our Changing Climate: It's Real, It's Us, It's Bad, Experts Agree. There's 
> Hope
> 
> 
>> On Sun, May 21, 2017 at 3:52 PM, Arthur Kelly  
>> wrote:
>> Thanks, I was more wondering how close to try and get to the infection 
>> period due sometime tomorrow morning.  We are mostly
>> in bloom with some varieties nearly complete petal fall and others 
>> (honeycrisp) at full bloom.  There are very few flowers still to open and I 
>> expect that this will be the only strep spray necessary.  The forecast is 
>> slight chance of showers daily going forward.
>> 
>> Sent from my iPhone
>> 
>>> On May 21, 2017, at 2:13 PM, Vincent Philion  wrote:
>>> 
>>> Hi all, 
>>> 
>>> My two cents:
>>> 
>>> Although streptomycin is degraded by light, this doesn’t really matter: For 
>>> two to four days, the antibiotic keeps bacterial population at low levels 
>>> on sprayed flowers.
>>> 
>>> Once it’s degraded, the flower is also 2 to 4 days older and there is 
>>> simply not enough time left for the bacteria to multiply back to 
>>> detrimental levels and infect.
>>> 
>>> Pusey demonstrated quite well that as flower age, they carry less bacteria 
>>> and become increasingly more difficult to infect.
>>> 
>>> Bottom line: Opened flowers that are sprayed stay protected for the life of 
>>> that flower.
>>> 
>>> As Quan underlined, you should mostly concentrate on flowers unopened at 
>>> spraying time:
>>> 
>>> 1) How many flowers weren’t open on the last strep spray?
>>> 
>>> 2) Will the weather for these flowers be conducive for bacteria 
>>> multiplication and infection?
>>> 
>>> If so, then you need to consider additional sprays for unsprayed flowers.
>>> 
>>> Trapman and myself developed RIMpro-Erwinia to help manage which flowers 
>>> are at risk and at need 

Re: [Apple-Crop] Fireblight

[Vincent Philion]

Hi!

Once a flower opens, it needs to get contaminated by an insect and then the 
population needs to multiply to 100,000 before wetting, otherwise the infection 
is a dud.

That takes 36 hrs when the conditions are perfect for the bacteria (28°C, 
82°F), and considerably longer when the temperature is cooler.

In other words, spraying the day before the infection is never a problem.

In most (if not all) scenarios, sprays every 48 hours covers all the risk.

Of course, longer intervals are quite sufficient when the temperature is 
cooler. Optimizing spray frequency was our goal when we designed RIMpro.

Vincent


Le 21 mai 2017 à 15:52, Arthur Kelly 
> a écrit :

Thanks, I was more wondering how close to try and get to the infection period 
due sometime tomorrow morning.  We are mostly
in bloom with some varieties nearly complete petal fall and others (honeycrisp) 
at full bloom.  There are very few flowers still to open and I expect that this 
will be the only strep spray necessary.  The forecast is slight chance of 
showers daily going forward.

Sent from my iPhone

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Re: [Apple-Crop] Fireblight

[Arthur Kelly]

Thanks, I was more wondering how close to try and get to the infection period 
due sometime tomorrow morning.  We are mostly
in bloom with some varieties nearly complete petal fall and others (honeycrisp) 
at full bloom.  There are very few flowers still to open and I expect that this 
will be the only strep spray necessary.  The forecast is slight chance of 
showers daily going forward.

Sent from my iPhone

> On May 21, 2017, at 2:13 PM, Vincent Philion  wrote:
> 
> Hi all, 
> 
> My two cents:
> 
> Although streptomycin is degraded by light, this doesn’t really matter: For 
> two to four days, the antibiotic keeps bacterial population at low levels on 
> sprayed flowers.
> 
> Once it’s degraded, the flower is also 2 to 4 days older and there is simply 
> not enough time left for the bacteria to multiply back to detrimental levels 
> and infect.
> 
> Pusey demonstrated quite well that as flower age, they carry less bacteria 
> and become increasingly more difficult to infect.
> 
> Bottom line: Opened flowers that are sprayed stay protected for the life of 
> that flower.
> 
> As Quan underlined, you should mostly concentrate on flowers unopened at 
> spraying time:
> 
> 1) How many flowers weren’t open on the last strep spray?
> 
> 2) Will the weather for these flowers be conducive for bacteria 
> multiplication and infection?
> 
> If so, then you need to consider additional sprays for unsprayed flowers.
> 
> Trapman and myself developed RIMpro-Erwinia to help manage which flowers are 
> at risk and at need for a spray. This model is very different from Cougar and 
> Maryblyt and is proving more reliable.
> 
> 
> Vincent Philion, agr., M.Sc.
> Microbiologiste/Phytopathologiste (pomiculture)
> 
> Institut de recherche et de développement en agro-environnement
> Research and Development Institute for the Agri-Environment
> 
> www.irda.qc.ca
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Re: [Apple-Crop] Fireblight

[Vincent Philion]

Hi all,

My two cents:

Although streptomycin is degraded by light, this doesn’t really matter: For two 
to four days, the antibiotic keeps bacterial population at low levels on 
sprayed flowers.

Once it’s degraded, the flower is also 2 to 4 days older and there is simply 
not enough time left for the bacteria to multiply back to detrimental levels 
and infect.

Pusey demonstrated quite well that as flower age, they carry less bacteria and 
become increasingly more difficult to infect.

Bottom line: Opened flowers that are sprayed stay protected for the life of 
that flower.

As Quan underlined, you should mostly concentrate on flowers unopened at 
spraying time:

1) How many flowers weren’t open on the last strep spray?

2) Will the weather for these flowers be conducive for bacteria multiplication 
and infection?

If so, then you need to consider additional sprays for unsprayed flowers.

Trapman and myself developed RIMpro-Erwinia to help manage which flowers are at 
risk and at need for a spray. This model is very different from Cougar and 
Maryblyt and is proving more reliable.


Vincent Philion, agr., M.Sc.
Microbiologiste/Phytopathologiste (pomiculture)

Institut de recherche et de développement en agro-environnement
Research and Development Institute for the Agri-Environment

www.irda.qc.ca
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Re: [Apple-Crop] Fireblight

[Zeng, Quan]

Step can generally last for 2-4 days without rain.  As it is degradable by sun 
light, it lasts longer in over cast days than in sunny days. Rain can wash some 
off but at least strep is more systemic than other antibiotics such as 
tetracycline. However, as it does not penetrate into unopened flowers, you 
would still need to consider putting done another application again 2 days 
later to make sure the newly opened flowers are protected by strep if the 
prediction models suggest a high disease pressure in your region.

Quan

Quan Zeng, PhD
Assistant Scientist & Bacteriologist
Department of Plant Pathology & Ecology
The Connecticut Agricultural Experiment Station
123 Huntington Street, P.O. Box 1106
New Haven, Connecticut 06504
phone: 203-974-8613


From: apple-crop <apple-crop-boun...@virtualorchard.com> on behalf of 
kellyorchards <kellyorcha...@gmail.com>
Sent: Sunday, May 21, 2017 12:14:15 PM
To: Apple-Crop
Subject: [Apple-Crop] Fireblight

How long will strep protect blossoms that were open at the time
of application?




Art Kelly
Kelly Orchards
Acton, Maine
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[Apple-Crop] Fireblight

[kellyorchards]

How long will strep protect blossoms that were open at the time 
of application?




Art Kelly
Kelly Orchards
Acton, Maine___
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