I am debating ordering quince as rootstock only, listed as Provence quince BA29C. How fireblight susceptible is it, if the cultivar is the exposed part? In other words, if the cultivar is going to die, it will. There is so much Bradford etc planted deliberately. and wild junk, that I have no hopes of real resistance.
I am going to dig wild callery-type from a farm near here, and try that, but callery I tried before did not work well. I grafted several last spring- when I checked them today, two OHxF333 grafts took, everything else was thrown off. I don’t have unlimited years and roots to figure out what will work. I want some espalier started, and fruit. I do have some on the OHxF333 that worked, we’ll see what survives rabbits and not the best choice of tree tubes.
To me, it’s percentages. If I’ll lose 5 out of 100…is that tolerable?
Must I have a guarantee of zero loss before making a purchase?
Maybe 30% loss is acceptable for some situations…such as seedlings.
I don’t think I’ve lost any quince (mostly ornamental ones) and maybe 1% of apples over a number of years to fireblight here in Kentucky.
20% is fine, I just don’t want to lose all. I assume my grafting will lose a percentage as well. Apples were fine, pears less so maybe 15-20% loss. I don’t know why. That’s all bench-grafted.
Weather is so variable here, they say Maryland is humid.
If it reassures you, I lost more pear grafts than apples too. 
From what I read pears grafted on quince are just mostly for the dwarfing aspects. I did not find many pears sold on quince rootstock. Most were on OHxF 333 or OHXF 87. If all the sellers are selling something on a certain rootstock I presume there is a reason. I read that most pears on quince have to have something in between the rootstock and then the variety grafted onto it.
Quince can be fine for 10 years and then get wiped out by fireblight. I’ve never found it to be any more resistant than the average pear.
Probably the question is … is it less resistant than average pear?
Not exactly scientific, but I have some pears in my yard on OHxF87. No appreciable fireblight issues. My neighbor has 2 fruiting quinces (I assume they are on some type of quince root) and they are badly deformed by multiple fireblight strikes he’s had to cut out. He doesn’t think he got it all and it keeps showing up and will probably finish off the trees this year. The trees were nice for 5 years and had just come into bearing and now he’s probably back to square 1.
I think the main benefit to quince root, besides the strong dwarfing, is that it can make some varieties be much more precocious. Personally, I wouldn’t risk it and would stick with the true pear rootstocks.
The main entry points for fire blight is on the top part of a tree. I have several pears on quince. They have thrown tons of suckers, but no blight. I prefer standard root stocks, but I put a few quince stocks in because they get slow fruiting pears to fruit faster. I’m more worried about deer stealing the fruit than fire blight.