I may experiment with grafting Prunus cerasus (tart cherry) onto P. tomentosa or P. fruticosa seedlings, probably by T-budding. This should provide for a hardy, dwarf tree. Any comments?
Per Joe Real, I would be very careful about doing it at a time when the weather is dry and cleaning your tools with rubbing alcohol or similar. John S PDX OR
It would have an effect, but I am guessing that it would be ok if no rain. Here is the quote from Joe Real, who I only know from web sites, but who is an amazingly knowledgeable and generous plantsman. He lives in Davis, CA, which would be Mediterranean climate, with dry heat in summer and moderate rain in winter, very different from Michigan: "With respect to cherries, I will confirm your suspicion that we are almost cheating! One of the best tips that I can give you or to all other cherry and stone fruit grafters are these: 1. Never graft cherries when it is very humid or wet, drizzly or raining. When disease pressure is high, you would most likely injure or kill the tree, not only your graft. So wait for at least 2 days of dry spell to do your grafting to let it sufficiently dry out after the rains and 3 days more of rainless days in the forecast. 2. Some days before you graft, if there are dormant sprays you needed to do, to control fungicides, wait for it to take effect and then do your grafting thereafter. 3. Always use disinfectant on your pruning shears and knives. You can sterilize them with 1 part laundry bleach mixed with 9 parts water, and then rinse off with 70% alcohol. 4. Sterilize the destination limb or stem that you want to graft by spraying with alcohol or Lysol (that contains 79% alcohol). If you use 70% ispropyl rubbing alcohol, spray your hands also, it is good massaging fluid. Let the alcohol or lysol dry off, takes about 2 minutes before doing the cuts. 5. Spray also the scionwood and let dry. 6. Then use parafilm wrap, then rubber band over the joint, then parafilm wrap to cover the whole scionwood. The reason why I said we're almost cheating because California is almost always dry major part of the year except during winter. The disease pressure is very low, so most grafts are successful. I've done all types of grafts on cherry trees. I will do T-budding when I see the pink color on the swollen unopened buds. Sometimes when I find it difficult to lift the bark flaps for T-budding, I immediately switch over to chip budding. Same success rates, only that chip budding is a little bit longer time required to match perfectly. I am more concerned with the rain during the grafting than anything else. And we never prune cherries and apricots in the winter for the very same reasons of disease infection and contamination during wet season. I bark graft cherries whenever the bark is slipping. But I do love to do whip and tongue since I can do that one way earlier and it would free me up to graft the more demanding stone fruits like the peaches and nectarines which are better to graft during the bloom and when leaves are starting to push out. I use whatever scionwood I have, dormant or non-dormant. But I stop grafting whenever the air temperature in the forecast will exceed the low 90's. I'll just have to wait it out. But when a break happens that the next 10 days or so would be in the upper 80's to low 90's then I would resume.
