I’m really sorry to see your pictures, and I feel your pain. I’ve lost a dozen or so kakis and hybrids to this, and it always seems to hit around this time of year when the trees have put out an initial flush of leaves and look healthy. It starts at the tips of a few branches and works its way down the tree. Sometimes the trees survive one year only to succumb the next. I’ve had trees that were 4 or 5 years old and produced baskets full of fruit die within a few weeks. The D. virginiana rootstocks survive, but no kaki or hybrid graft that I’ve ever subsequently tried on them will grow beyond a few weeks. The scions will put out some leaves and look like they’re going to make it only to wither. I’m not sure it makes any sense here in the Southeast to destroy the infected rootstocks because we’re surrounded by wild trees that presumably carry the same pathogen. Initially I dug them up and burned them, but a few I’ve since regrafted with named D. virginiana cultivars that have grown well and produced fruit. I was so discouraged the first time I lost one of my older kaki trees, but now I just try to keep planting a couple young kakis every year to replace any that die (on average about 1 or 2 a year). Kakis bear relatively early and are such productive and low maintenance trees, that it’s hard to justify giving up growing them entirely just because a few will die suddently and unpredictably. I now look at them as a perennial fruit crop that needs regular replacing. We probably aren’t going to get the 100+ year old kaki trees here in the Southeast US unless some cultivars are resistant. I’ve lost Saijo, Sung Hui, Giombo, Tam Kam, Hana Gosho, Kasandra, Coffee Cake, Miss Kim and probably a few others. My oldest tree that never got infected was Tecumseh (though I eventually had to cut down that particular tree after 11 years to make room for a new septic drain field). I hope your other kakis survive and you don’t lose so many again in the same season. Growing fruit isn’t for the faint of heart!