Kaki sudden death syndrome -- help?

[ncdabbler]

@jrd51 I just saw your addition to your post on the other thread, so I’m responding here to keep everything together on the KSDS thread:

@jrd51

Edit: I saw your post (above) linking to the prior discussion. To my knowledge, SDS is not common here in the Northeast. There’s no population of wild DV trees except in a very few isolated places. But I lost a recently purchased tree last year, and i’m wondering whether I may have permanently introduced a pathogen than can now affect my other trees.

I guess i have to ask: For your trees that died, is there one source of rootstock or many? In my case, i have had no problem with rootstock purchased from Missouri or from trees purchased from Stark’s, England’s, JF&E, or Burnt Ridge. My one fatality was purchased from OGW.

My initial plantings of kakis in 2012-2014 all came from Edible Landscaping. Some of those trees are still growing well without any issues (Tecumseh, IKKJ, Maekawa Jiro, Wase Fuyu, Izu) but others died from KSDS (Sung Hui, Hana Gosho, Saijo, Fuyu, Tam Kam). I’ve transplanted many D. virginiana root suckers from the surviving EL grafted kaki trees and successfully used them as rootstock for kaki scions. I have lost some kakis that I grafted myself onto root suckers and seedlings, but it’s a relatively small percentage of those trees that got KSDS, and they grew well for several years before they died (Nikita’s Gift, Kasandra, Coffee Cake). I also have a couple of kakis from JF&E that have been healthy, and I’ve never lost a tree that I bought from them.

Most of the persimmons I grow now I grafted myself from scionwood that I purchased or received in trades. I once cut dormant kaki scionwood in February and traded it with someone else, but then that mother tree subsequently died of KSDS later that same year in the early summer (I can’t recall the variety off the top of my head). The person to whom I sent the kaki scionwood successfully grafted it before the mother tree in my yard died of KSDS and I was able to warn them about what had happened. Their grafted tree has been growing for years since then without any sign of KSDS. That’s only a sample size of one, but it makes me suspect that KSDS isn’t something that kaki trees will harbor for very long without exhibiting any symptoms like D.virginiana seems to do.

I initially tried regrafting kaki to the surviving rootstocks of trees that had died of KSDS many times with no success. Then I started destroying all the infected rootstocks. Now I’m assuming that most mature wild D.virginiana trees in my area are already infected, so I doubt that burning infected rootstocks will spare me from KSDS here. I’ve since grafted named D.virginiana varieties to infected D. virginiana rootstocks, and they have grown well and fruited with no apparent ill effects.

If the pathogen is indeed Xylella fastidiosa, then it would have hosts other than persimmons. X. fastidiosa is the pathogen that causes Pierce’s Disease in grapes and other plants, but it doesn’t seem to be a problem in colder climates. So that could help you avoid any future problems with it in your climate.

I would be cautious about grafting multiple persimmon varieties to the same rootstock, though, particularly if you’re grafting D. virginiana scions to a tree that also has kaki grafted to it. If the D. virginiana scions carry the KSDS pathogen, it could infect the rootstock and kill the kaki portions of the multi-grafted tree.

I don’t know this for a fact, but based on my experience I doubt that kaki scionwood that was cut when it was dormant would carry KSDS. My current thinking is that the pathogen is probably X. fastidiosa transmitted by xylem-feeders from resistant plants like D. virginiana.