You tried sealing them in a container with concentrated CO2 gas from dry ice or liquid CO2 or from reacting baking soda with vinegar?
Or tried the banana 
approach or both together?
Why not try Meader?
Supposed to be less astringent with good American persimmon taste.
Welcome to the group!
I don’t know about Sestronka but you have other info here.
I tried alcohol, CO2 from baking soda, bananas for ethylene, plus combinations. Plus heat. All on Prok. No observable impact.
Also I’ve previously asked forum members for ANY evidence that the measures that are helpful in astringent Asians will work in Americans. No one provided any. But there were many stories about failure.
All the success stories relate to Asian astringents.
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Well meader is a future possibility but to be honest I want another hybrid. Since it is backcrossed with Americana I assume it is going to be bigger than the big Americans. As I understand it, alot of the hybrids were created to make a more cold tolerant Asian tasting persimmon. I prefer the American butterscotch, rum toffee flavor. The Asians all seem to have a very strong betacarotene flavor even they are ripe. Sestronka is rumored to be a almost kaki sized and very American tasting.
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I would prefer the flavor of fully ripe Diospyros Virginia, or Texana is a good cultivar.
But we are back to size.
Wish I knew what Dar Sofiyivky tastes like.
Copper often delays tannin ripening, in several different ways:
- Increased Iron assimilation, resulting in increased Chlorophyll-A, resulting in increased Auxin, resulting in increased Cytokinins from root tips, Cytokinins stimulate vegetative growth & delay tannin ripening. If using Copper spray for diseases on a high tannin crops near harvest, avoid young leaves which produce Auxin.
- Copper increases auto immune system response. When leaves are eaten by invasive insects, tannins are produced as a self defense mechanism. Best to use a treatment to protect against invasive insects if using copper for disease.
- If using Copper spray on a high tannin crop, consult someone like @Richard who claims to know of Copper products which don’t increase tannin production.
I’m sure that most of the fruits were exposed to plenty of sun.
I assume that you mean copper in the soil? So if there is, then what?
…all go live at once. for instance, I can make single eBay posts for (each) tree to schedule to go for sale when I ask…@Zinhead
Have a good evening, buddy…
Many different wavelengths of light.
Most would increase Methoxypyrazines & tannin.
It is indirect sunlight, I believe a wavelength in the yellow which increases Ethylene.
Copper spray for diseases slows ripening.
If Copper is high in the soil is a major problem if too high.
I’m 14 miles down stream from a Copper mine in a flood plane.
I wash Copper from the soil with sulfuric acid then flush the soil, then pH balance long before planting anything!
Once something is planted that complicates things.
Mycorrhizae precipitate excess Copper, so that would help.
It’s a difficult problem to resolve.
There is research projects going on that focus on precipitating heavy metals via microbes.
But I don’t know of any products on the market other than Mycorrhizae which help.
Mycorrhizae turn sugar into Ethyl Alcohol which acts as a catalyst at precipitating Copper into Copper Carbonate crystals.
If soil dries out, Mycorrhizae die, then acid thunderstorms, Copper again dissolves.
So it’s like a temporary 
treatment rather than a fix.
I’m currently working on a foliar spray to resolve my problems.
Making progress, yet not vetted scientifically as a solution.
As I understand it:
Ripening in persimmons is a different process than loss of astringency.
Ethylene promotes ripening. Ethylene is not involved in astringency. FWIW, I had no problem getting Prok persimmons totally ripe. Adding bananas to increase ethylene had no obvious impact – the fruits were already ripe. IMO, any discussion of ethylene (or ethylene-enhancing treatments) is a distraction.
Ethyl alchohol (or technically, its metabolite acetaldehyde) reduces astringency in Asian astringent persimmons. That’s how PVNAs work. CO2 has a similar affect because (I’m dredging this from memory, so apologies in advance for any mistakes) anoxia promotes acetaldehyde and a CO2 atmosphere pushes out O2, which is lighter. But there’s no evidence of a similar process in American persimmons. So reducing astringency in American persimmons is a different puzzle.
FWIW, I do not spray my persimmons with copper. I have no reason to believe that there is excess copper in the soil. So copper is a wild goose chase.
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Meader is a fairly small-fruited American, and will be fully - and very - seedy if there is a male in the vicinity.
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@ZinHead
Given your analysis of N-pHuric last month, I believe you would do better to ask questions instead of providing answers with regard to plant nutrition and soil chemistry.
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The difference between different tannin genes in Diospyros & the importance of selecting for PCNA-type when doing interspecific hybrids.
https://web.archive.org/web/20180803163707fw_/http://journal.ashspublications.org/content/126/1/51.full.pdf#page=1&view=FitH
@ZinHead – Exactly! That’s why I’m so focused on JT-02. It’s father was the Asian PCNA variety Taishu. So presumably, JT-02 has 3 recessive (Asian) PCNA genes and 3 dominant (American) non-PCNA genes. With a single back-cross of JT-02, we can have offspring with 6 recessive PCNA genes. Voila!
The proportion of PCNA offspring should be approximately 3/6 x 2/5 x 1/4 = 5%.
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Okay, good point.
Further explanation of the role of copper:
It boosts a plants ability to do an (immune system response) to insects & disease.
When a plants leaves are eaten, it stimulates an immune system response.
During an immune system response (tannins, methoxypyrazines & pheromones) get manufactured at higher levels.
The pheromones can actually trigger an adjacent plant to also manufacture additional tannins.
Understood.
Hope you are successful.
I will be in line to buy.
Meanwhile I’m rolling the big boulders uphill.
LOL.
OK, got it re copper.
On the JT-02 backcross, I made it clear when I started the other more relevant thread that I was proposing work for someone else. I have no plan to breed trees myself. So I’ll be in line right behind you.
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