Re: [Apple-Crop] Shopping list: Looking for insight on flyspeck, fire blight, pheromone trap thresholds

[David Kollas]

Glen:

I am glad to see your attention to the details of orchard pest control. 
It is not only
you who sometimes feels inadequate when planning just what can be done 
to save time
and money while maintaining minimal pest damage.

For you, I guess Flyspeck is the worse of the Flyspeck/Sooty Blotch 
category of summer
disease. For me, the worse has always been Sooty Blotch.  Since I began 
using the combination
of phosphorous acid with captan some years ago, as discussed in one of 
Dave Rosenberger’s
Scaffolds articles (June 22, 2009) ,the problem has been infrequent.  
This success has 
probably been aided also by knowing now that some number of hours (270) 
wet fruit is a factor
in when disease can appear if fungicide  is not present. I can’t 
believe that temperature of
those wet hours is not also involved, but I am not aware that anyone 
knows for sure.  

Your comments about Lesser Apple Worm reminded me that until I tried 
two years of orchard-wide
Apple Maggot trap-out in leu of insecticide, I did not consider LAW to 
be an orchard pest.  That
was about 25 years ago.  Since then I have seen LAW damage only where 
insecticide was
not present in the last 3 weeks of August.


David Kollas
Kollas Orchard, Tolland, CT
 


> On Jun 21, 2017, at 4:12 PM, Glen Koehler  wrote:
> 
> Seems like a good day to flaunt my ignorance in public
> 
> 1) Flyspeck
> Among some of us, what passes for conventional wisdom with regard to 
> flyspeck on apple has been that there is a lag period between the end of 
> primary scab and the risk of flyspeck infections such that fungicide 
> protection in the first few weeks after fruit set is not important.
> 
>I'm not sure that's true after reading Ismail, Batzer, Gleason Harrington 
> "Phenology of Infection on Apple Fruit by Sooty Blotch and Flyspeck Species 
> in Iowa Apple Orchards",  Plant Disease 
>  
> 100(2):PDIS-02-15-0137 · December 2015, 
> 
>Dave Rosenburger showed that maintaining protection in the weeks after 
> fruit set made a difference at harvest, which lines up with the Phenology 
> paper.  Plus Dave said that fungicide stops FS development while the 
> fungicide is active, but that after it wears off, FS resume progress towards 
> becoming visible.  So if you allow a portion of development time, stop it 
> with fungistat (vs. -cide), then you have a much shorter lag time between 
> last spray and possible emergence of visible flyspeck at harvest.  So 
> allowing unprotected growth hours in early summer is at the cost of early FS 
> progression in the fall. 
> 
> I am sharing this in hopes of irrefutable brilliance, or at least 
> observations from people who have kept up the literature or field trials to 
> shed light on this.  Bottom line I think the idea that we can wait until 2nd 
> generation flyspeck spores are available (if there even is a second 
> generation cycle, which for some FS species at least does not seem to be the 
> case) before you need to spray idea is a hypothesis not supported by 
> evidence.  
> 
> That all said, uncertainties around development time and residual 
> fungicide activity ends up saying that growers should maintain 21-day spray 
> interval for continuous protection, which does not conflict with a view that 
> FS risk starts early and just takes a long time to show because during mid 
> summer it's too hot, and that what really kicks development into gear is 
> leaking nutrients as the fruit sweeten and exude sugars in the weeks leading 
> up to harvest.  This is another idea Dave pitched and which is mentioned in 
> the Ismail et al article.  
> 
> So regardless of the logic, it may not matter if the spray recommendation 
> comes out the same.  But I'd like to have a less foggy idea about how this 
> mob of fungi operate.  Make for more interesting thought process instead of a 
> blanket 14 (captan alone) or 21 day vs. 2" rain rule (2.5" for Pristine).  
> Understanding the mechanics may not make a difference under normal weather, 
> but if we get either a long drought or prolonged wet period, understanding 
> the target organism could be useful for deciding how to adjust spray 
> intervals.
> 
>The only evidence I bring to this is a couple of incidents in past years 
> when heavy hurricane rains wiped out fungicide coverage in late August, and 
> subsequent to that flyspeck showed up right on time with a 270 temperature 
> mediated growth hour estimate for when they would appear in trees with FS 
> history/pressure.  Not exactly Nobel Prize worthy replicated science, but 
> kind of made me feel smart for a day or two and that I had some idea what was 
> going while flyspeck was busy growing from invisible to visible. 
> 
> 
> 2) Fire blight
>  Why is Regulaid specified as a penetrant 

Re: [Apple-Crop] Shopping list: Looking for insight on flyspeck, fire blight, pheromone trap thresholds

[Kushad, Mosbah M]

Hi Vince:
Regulaid and LI700 have different formulations that can each have different 
effects on different chemicals.. For example, Kasumin is more soluble in water 
than strep. and strep is insoluble in organic solvents like ether, ethanol, 
etc. (LI700 has PE-ether see blow), not sure about Kasumin.

Regulaid..  2-butoxyethanol (surfactant used in paint), poloxalene ( used as a 
stool softener and non ionic surfactant), monopropylene glycol (used as 
moisturizer in cosmetics)

LI700 … Methylacetic Acid (used as a solvent in paint, nail polish, and glue), 
Phosphatidycholine (soybased product), Alkyl Polyoxyethylene Ether (a non ionic 
surfactant that enhances penetration of certain chemicals through membranes).

Mosbah Kushad University of Illinois

From: apple-crop [mailto:apple-crop-boun...@virtualorchard.com] On Behalf Of 
Vincent Philion
Sent: Wednesday, June 21, 2017 4:15 PM
To: Apple-Crop discussion list 
Subject: Re: [Apple-Crop] Shopping list: Looking for insight on flyspeck, fire 
blight, pheromone trap thresholds

Hi!

Won’t answer about SBFS, but hopefully someone will. ;-)

My 2 cents for other disease stuff:

2) Fire blight
 Why is Regulaid specified as a penetrant adjuvant for use with 
streptomycin applications during bloom?  Does it have unique characteristics 
that make it better for this purpose than other penetrants such as LI700?

We don’t have Regulaid, but I can tell you substituting for LI700 doesn’t work 
for Kasumin. Never tried with Strep.

We had reduced efficacy when LI700 was mixed with Kasumin.


 If grower is applying captan at same time, has much strep efficacy is lost 
by not adding the penetrant to the mix to avoid captan phytotoxicity?

It’s interesting you mix strep with fungicides considering this should reduce 
strep efficacy:

Goodman, Robert N., 1964: Compatibility of streptomycin with some fungicides 
and insecticides. Plant Dis Reporter: 180-181


 If there is none or even minimal active fire blight in the orchard, is 
there reason to spray strep after hail damage?

I see none whatsoever.

 My take on it has been to not bother as long as you are just cutting fire 
blight out, and that it is more important to remove fire blight as soon as 
possible.

I didn’t change my opinion since we wrote that about 10 years ago. But this 
question keeps coming back.

Toussaint, V., et V. Philion. 2007. Natural Epidemic of Fire Blight in a Newly 
Planted Orchard and Effect of Pruning on Disease Development. In XI 
International Workshop on Fire Blight 793, 313‑320. ISHS.

Do we all agree that strep provides protection for a flower for about 2-3 
days?

Yes. But since the flower has a finite life and gets more difficult to colonize 
as it ages, there is no point in respraying the same flower.

  Though I can imagine scenario with temps around 90F where a single cohort of 
flowers could be vulnerable to a second fire blight infection period after 
receiving a strep application.

I can’t. Show me how this is possible!

Bye for now,

Vincent Philion, agr.






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Re: [Apple-Crop] Shopping list: Looking for insight on flyspeck, fire blight, pheromone trap thresholds

[Vincent Philion]

Hi!

Won’t answer about SBFS, but hopefully someone will. ;-)

My 2 cents for other disease stuff:

2) Fire blight
 Why is Regulaid specified as a penetrant adjuvant for use with 
streptomycin applications during bloom?  Does it have unique characteristics 
that make it better for this purpose than other penetrants such as LI700?

We don’t have Regulaid, but I can tell you substituting for LI700 doesn’t work 
for Kasumin. Never tried with Strep.

We had reduced efficacy when LI700 was mixed with Kasumin.


 If grower is applying captan at same time, has much strep efficacy is lost 
by not adding the penetrant to the mix to avoid captan phytotoxicity?

It’s interesting you mix strep with fungicides considering this should reduce 
strep efficacy:

Goodman, Robert N., 1964: Compatibility of streptomycin with some fungicides 
and insecticides. Plant Dis Reporter: 180-181


 If there is none or even minimal active fire blight in the orchard, is 
there reason to spray strep after hail damage?

I see none whatsoever.

 My take on it has been to not bother as long as you are just cutting fire 
blight out, and that it is more important to remove fire blight as soon as 
possible.

I didn’t change my opinion since we wrote that about 10 years ago. But this 
question keeps coming back.

Toussaint, V., et V. Philion. 2007. Natural Epidemic of Fire Blight in a Newly 
Planted Orchard and Effect of Pruning on Disease Development. In XI 
International Workshop on Fire Blight 793, 313‑320. ISHS.

Do we all agree that strep provides protection for a flower for about 2-3 
days?

Yes. But since the flower has a finite life and gets more difficult to colonize 
as it ages, there is no point in respraying the same flower.

  Though I can imagine scenario with temps around 90F where a single cohort of 
flowers could be vulnerable to a second fire blight infection period after 
receiving a strep application.

I can’t. Show me how this is possible!

Bye for now,

Vincent Philion, agr.






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