Don't be too disappointed- you rolled the dice, took a chance and now it's time to cut your losses, IMO. It was an experiment and because of Methely's high susceptability to black knot it seems it wouldn't be useful as stock for grafts even if it was hardy enough for your climate not to get cambium shakes and frozen flower buds. Better to start with a tree with known hardiness that you can graft your experiments to. Here, in S. NY, Methely is not worth growing at many sites just by virtue of being the typhoid Mary of black knot. I actually am surprised that this weakness is rarely noted in the literature.

Scott has mastered the origin of plum varieties better than I, but Methely is considered a J. plum and Toka a hardier hybrid. Methely is hardier than any other red-fleshed J. plum that I've grown from my observations of cold related cambium damage. The more commonly grown J. plum in Z 5 NY is Shiro. Most Euro plums are somewhat hardier- also flower later. Peach buds have over a 5 degree differential of hardiness between flower and vegetative buds. One year my orchard got down to -22 and leaves were fine but not flowers. Same with areas not quite as cold as I believe -19 pretty much kills off flowers. Areas that got much below -25 lost their peach trees. As I recall the same thing held true for plums that year.

Thanks again rayrose for your response and appreciate your offer to send scion wood. I was out of town and got back today, will take a picture of my methley plum and post it tomorrow. Regarding grafting, In the last week of Feb this year, I tried grafting morris and bruce plums scions that I got from folks I met in a local nursery event but both scions seem to have dried out, I don't see any life in them. I think I did not properly graft them, I can try again but not sure whether I can graft fruit trees in spring in Dallas. I'll reach out to you next winter for scions, please share the varieties of plums or other stone fruits you have. Thanks.

we just got through a big heatwave, no more dead branches yet. I didn't think it would need water since it has been planted here since 1962. last year we had a very dry summer, but near the end all we had was rain. we haven't had any excessive drought, I just planted some loropetalum bushes and they aren't wilting/drooping and I only watered them once last week.