I agree on the thought that mixed types on DV seems to be the culprit:
In 2003 I started converting most of my Chocolate branches with hybrids of both Dv and kaki scions. My tree was from Willis orchards and was about 4 years old. Willis said it was DV rootstock. It had fruited several years so I wanted to use it as a pollinator. On 5/20/2003 I Grafted on Chocolate: 1 ea Rosseyanka, David’s Candy: 1 ea, Nakitas Gift: 1 ea, Kasandra: 2 ea, Zima Kurhma, 1 ea
Failures: Great Wall 2 ea, Jin YongTam Gam: 1 ea, ZimaKhurma/Early Golden: 1 ea, Rosseyanka: 1 ea
Many of them budded out and started to look vigorously until I noticed one had black veins and was withered. Within about 2 weeks all had withered! I cut the entire tree down and burned it immediately. Pretty sure it was SDS.
I have other multiple variety trees that are doing fine
After having a very low success rate with persimmon grafts (2 of 12, one of which died over the winter) last year, I practiced my grafting technique in preparation for this spring. Then I attempted to graft 12 persimmon scions this spring using a hot callus pipe. My success rate was 1/12. It was very disappointing. And it was hard to figure out what went wrong. But it was suggested to me that the dv rootstock could have KSDS. A year and a half ago I had, just to see if they’d grow, planted a bunch of seeds from Kassandra fruit that was pollinated by Coffeecake or Chocolate. They were around 3 feet tall. Three of the scions were still alive even though their grafts had failed. Plus I had a few extra scions. So I tried grafting 6 scions to 6 Kassandra seedlings. Well, 2+ weeks later, 3 of 6 of the grafts on the Kassandra seedling have buds starting to open. So it seems like my dv rootstock is mostly infected. Do my Kassandra seedlings have the potential to also be infected? If the mother Kassandra tree and the males are grafted on dv rootstock and growing ok, does that mean the seeds produced would be clean?
The female-flowering “mother” tree (Kassandra) is healthy. The male-flowering PVNA “father” trees (Chocolate, Coffee Cake) are healthy. I can’t see any way that seeds produced by pairing these trees can be infected.
Actually, I’m skeptical that pollen from even an unhealthy tree could carry the pathogen. I’d guess that there’d have to be contact with the sap of an infected tree, e.g., in a graft, insect bite, pruning cut. But if so, then the scions from your failed grafts could be infected as a result of contact with the infected DV trees and could therefore now infect the seedlings.
Question: You have 3 scions from failed grafts, three from storage. How did these split among the 3 that are growing.
2 of the 3 scions from failed grafts and one scion from storage are now budding on Kassandra rootstock.
One of those started budding 4 days after it was grafted. So that seems like it was just used energy from the scion.
If the rootstock is infected, probably these scions are infected too. But if so, I find it hard to believe that those scions would break bud so quickly.
This leads me to wonder if the rootstock trees had some other defect.
In either case, if your success persists then starting your own seedlings will seem the way to go.
Is it known how this pathogen moves through the tree? If it follows sap flow, would there have to be some callusing to make that connection between rootstock and scion? There was pretty much zero callous on the failed grafts and I cut off any part of the scion that had been touching the rootstock so that I could reuse it. I guess we’ll get some more data points as these new grafts succeed or fail.
And I did plant some more seeds for future use, just in case.
