Bernie Nikolai from Edmonton Alberta Canada is a member of some groups I follow on other forums. Bernie as many of you are aware has been responsible for importing Russian pears into Canada. Bernie recently posted this fascinating information that will benefit someone
“Pears Can Grow Well on Apple Trees…But…
You need an interstem compatible to both. Winter Banana is an apple compatible to both. You graft Winter Banana to your apple tree, then a pear onto Winter Banana, and it does very well. The photo below is Successful Falkenberg, a Russian pear, growing on my hardy Norland apple tree here in zone 3 with a Winter Banana interstem.
The problem is Winter Banana is not very hardy, and about half my interstems of it died last winter (-32C the coldest), and so did the pears grafted to it obviously. However Palmetta, an apple crab developed in Novosibisk, Siberia, seems also equally compatible with both pears and apples, and has survived to the tips after -50F in Fairbanks, Alaska. The parent trees of Palmetta have survived at the University of Alaska in Fairbanks for about 15 years, and have never even had tip dieback to my knowledge. So this is the one I am currently using. Pear grafts seem equally as healthy and vigorous as those on Winter Banana.
Lastly you do NOT need to graft the interstem, wait a year, then graft the pear to the interstem. You can do it all at once. Simply graft a pear to your interstem, then graft this “double stick” to your apple tree. About 2 out of 3 took for me, pear and apple interstem, so why waste a year? Worst case the interstem only takes, not the pear on the end, then you graft another pear to the interstem a year later in the spring.
Palmetta apple Could be a useful tool when you want to switch varieties in areas to cold to use winter banana as an interstem between apple and pear. I spoke with Bernie earlier today who agreed I can share his information on this forum. I belonged to a group called NAFEX at one point which Bernie is still part of that has a member base much like ours. The NAFEX group believes growing fruit is important as is sharing information about the process. Many of us are or have been part of that group at some point. Many of us were also part of gardenweb prior to houzz taking over or many still are following houzz. The home orchard society, California rare fruit growers and others have similar beliefs. The growingfruit.org group is where I post 98% of my information.