Strep is extremely stable if it is kept dry and out of direct light (e.g., in a
closed cardboard drum or foil package). It does break down in sunlight. I
don’t know if other components in the formulations might “age out” and become
less effective (e.g., less surfactant activity), but the strep itself should
remain stable.
Strep sprays are NOT a waste of money IF (1) inoculum is present at bloom, and
(2) weather conditions favor flower infection during bloom. Unfortunately,
none of the available models can predict whether or not inoculum is present in
any give orchard, so we end up spraying orchards that really would not need
protection if we had a way of knowing that they were free of inoculum AND that
that no inoculum would be brought to the orchard throughout the remainder of
the bloom period. Lacking such a tool, strep provides valuable protection even
though it may not be needed in many cases where it is applied. Of course, strep
applied during bloom does not prevent shoot blight if inoculum arrives in the
orchard only AFTER bloom is over, but shoot blight is generally far more severe
in orchards where there was at least a bit of blossom blight.
Bottom line is that strep does not resolve all problems with fire blight, but
without strep we would have a lot more orchards being bulldozed every year due
to fire blight epidemics. There are some relatively new alternatives to strep,
but all of them are either more expensive, less reliable, or (usually) both.
And the fact that I am promoting the value of strep sprays does not negate the
possibility that increasing copper nutrition could be beneficial. In fact,
applying a low rate of copper in all spring sprays as Lee Elliot has suggested
could be really beneficial in terms of reducing blight inoculum within the
orchard before and during bloom. However, I also suspect that in some years and
with some cultivars, those in-season copper sprays will cause at least a bit of
fruit russetting. Just because copper russetting has not be noted this year or
last year or even for the past five years, one cannot be certain that it will
NEVER be a problem.
********************************************
Dave Rosenberger, Plant Pathologist,
Hudson Valley Lab, P.O. Box 727, Highland, NY 12528
Cell: 845-594-3060
********************************************
> On Aug 18, 2015, at 10:58 AM, Fleming, William <[email protected]> wrote:
>
> Lee, can't help you on reading your date but we had a 35 lb. drum of strep
> dated 1972 that I didn't trust. Had the guys in the lab plate it out, it
> killed all the bacteria they introduced it to.
> The drum had been stored in a cool dry place
>
> Bill Fleming
> Montana State University
> Western Ag Research Center
> 580 Quast Lane
> Corvallis, MT 59828
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of lee elliott
> Sent: Tuesday, August 18, 2015 5:52 AM
> To: [email protected]
> Subject: Re: [apple-crop] apple-crop Digest, Vol 56, Issue 8
>
> Just my personal experience, dont know if any studies made, I think a lot of
> the problem is copper deficiancy, after doing leaf analysis, my copper levels
> were in the bottom of the scale, alsso in soil analysis, added Kocide 3000 to
> dormant spray, and small amount (2oz per 100 gal) in spring sprays, also
> copper added to herbicide spray, copper levels in leaf analysis came up but
> stil not normal, I have less FB and can see the difference. Also, nothing
> beats staying on top of the situation by walking the orchard every morning
> and cut it out before it spreads, this works well for small orchards like
> mine. Most of my FB is shoot blight, I think strep sprays are a waste of $$$.
> This my be because the strep is old, does anyone know how to read date of
> manufacture on the bag?? Lee Elliott, Apple Hill/ Upstart Nursery,
> Winchester, Illinois
> --------------------------------------------
> On Sat, 8/15/15, [email protected]
> <[email protected]> wrote:
>
> Subject: apple-crop Digest, Vol 56, Issue 8
> To: [email protected]
> Date: Saturday, August 15, 2015, 11:00 AM
>
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> Today's Topics:
>
> 1. Re: Looking for comments on fire blight management
> (Weinzierl, Richard A)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 14 Aug 2015 21:26:58 +0000
> From: "Weinzierl, Richard A" <[email protected]>
> To: Apple-crop discussion list <[email protected]>
> Subject: Re: [apple-crop] Looking for comments on fire blight
> management
> Message-ID:
> <f1da5cce7c3ebe43b873f3bd2ba709a73d62b...@citesmbx6.ad.uillinois.edu>
> Content-Type: text/plain; charset="utf-8"
>
> U of I Kane County Extension Office, 535 South Randall Road, St. Charles, IL
>
> Rick
>
>
> From: [email protected]
> [mailto:[email protected]]
> On Behalf Of Vincent Philion
> Sent: Friday, August 14, 2015 12:49 PM
> To: Apple-Crop <[email protected]>
> Subject: Re: [apple-crop] Looking for comments on fire blight management
>
> Hi Tim! nice to read you!
>
> I think there are more sources of fire blight bacteria in the general
> environment in the northeastern USA due to your woodlots and forests (with
> feral apples and native hosts such as Hawthorne) as contrasted with the
> treeless conditions around many eastern Washington orchards.
>
> I agree! But still is fascinating to see whole areas without FB and others
> with FB, despite similar weather.
>
> We often make ?false positive? predictions because of this = conditions are
> great for FB, but not FB develops because bacteria are simply not there. We
> have nice qPCR data throughout bloom to prove it.
>
> The bacteria (in the hypanthium) need to thrive in the nectary in order to
> reach numbers sufficient to switch on their virulence. Once this is
> accomplished you have an infection.
>
> Do you have a good reference for me on this specific topic?
> When I reviewed the literature, I only found a few things from Pusey. This
> might explain some cases.
>
> We can learn a great deal about interpreting models by looking at the
> weather data around the time that we are fairly certain that isolated
> infection events occurred. We can also look at when expected infections
> did not occur. It would be very helpful to me if any of you would share
> weather data including rainfall, hourly temperature (or daily temps) and
> especially leaf wetness readings. Please send data that covers days from
> first bloom to about 3 to 4 weeks after petal fall. Excel files are a real
> time saver.
>
> We?re Also looking for the same type of data?!
>
> Vincent
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