kaki sudden death syndrome revisited
At this time of year in my orchard, as in years prior, the surviving kaki persimmon trees stricken with this disease show the symptoms - vigorous growth full of blossoms that appeared over the previous few weeks die off in a matter of days. This year a tree which had not previously shown symptoms has developed a full blown case and provides some valuable clues as to the likely origin of the disease. The scionwood I know to have come from a tree that had withstood many cold winters over many years and as such would be unlikely to be harboring latent viruses, as they previously had ample opportunity to have caused disease. This points to the rootstock, the variable factor here, as the likely culprit. Whether the causative factor is infection or incompatibility is unclear but arguably of lesser importance as nothing much is to be done about either.
This observation leads to a few recommendations:
1) Choice of rootstock is key. I would think proven cloned rootstock gives the lowest chance of disease.
2) Once a tree shows signs of disease, the rootstock is implicated and it's a goner. Best to cut losses here and replace or regraft to American persimmon.