I pretty much agree with you. But here’s the brief history as I understand it: An observation of occasional early loss of astringency in MB and MB offspring gradually morphed through stages into an assertion that MB shares a non-astringency allele with J-PCNAs. This assertion got incorporated into the mythology of Morris Burton non-astringency. The misunderstand raises false hopes about breeding a non-astringent DV or hybrid using MB.
I started a thread recently attempting (among other things) to solicit more evidence. None appeared. Every respondent with experience with Morris Burton said basically that it needs to be fully red-ripe to lose astringency, and at least one grower complained in an old blog that his ripe fruit falling off the tree was still not non-astringent. It seems to me that the best inference from the collective evidence is that Morris Burton sometimes manages to lose astringency early, but the loss of astringency early (or at all) is not reliable.
Here’s the most relevant thread, conveying some of the history:
And here’s a key excerpt (my emphasis added):
<< The one variety that’s involved in all of the 4 that of been identified as having non-astringent characteristics is Morris Burton. There was a doctor Sekar at UC Davis who was an expert in identifying kaki varieties using electrophoresis. He wrote papers on the subject. In 1998 I had Dr. Sakar do some work for me with the object to identify virginiana/kaki hybrid’s and possible hybrids. As a basis in 1998 I did send him actively growing buds of Morris Burton and other D. virginiana in order that he could establish typical enzyme patterns for virginiana. In his report back to me he stated that Morris Burton appears to share an allele with kaki. I found that interesting and more interesting is that Morris Burton is involved in all of the 4 varieties that were observed to produce what Martha Davis and I call non-astringent fruit. That is some of the fruits could be picked off the tree while still firm with no astringency. >>
I’m not competent to assess the scientific work, but even if it is unimpeachable there is a huge gap between “appears to share an allele with kaki” and “appears to share the non-astringency allele with J-PCNA kakis.” And “some of the fruit” is not all or most of the fruit. Nevertheless, some people made that leap.
My interest in discussing Morris Burton was mainly to get us grounded. I do not believe that MB has the JPCNA allele. As I understand it, DV and DK separated millions of years ago, but the JPCNA mutation is probably only hundreds or thousands of years old. On the other hand, I am willing to believe that MB may be a relatively less astringent DV cultivar.
So my agenda was (1) to re-assess the evidence for early astringency in MB; and (2) to determine whether it is sensible to begin breeding a purely DV non-astringent variety, maybe starting with MB and its offspring.
FWIW, this is the thread that Richard dismissed without further explanation as “not constructive.”