What does it matter if a rootstock is susceptible to fire blight, if the scion isn't?

I see the different rootstock and where they say such and such is not resistant to fire blight. But if you graft on that rootstock, isn’t the tree leaves and such based on the scion? I could ask about the same on other parts except maybe the roots.

I don’t understand. If the rootstock doesn’t influence the fruit itself, what about the other being influenced? I mean you get a Fuji apple from a scion, not a MM111 Fuji.

Maybe all scions are susceptible already? Idk.

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Good question, which i will gladly explain. Callery pear rootstock are resistant to fireblight , and kieffer scion are resistant to fireblight. This combination means that i have never lost a kiefer pear to fireblight. Maybe i want a comice pear, which is 100% going to get fireblight sooner or later. What i can do is grow my rootstock to 40" and graft comice to the rootstock tree. When fireblight hits the comice i can cut it off and graft on kieffer or whatever i want losing only the growth above 40" and not the roots. In this way in 2 or 3 years my tree has regrown and im eating pears again.


If rootstock is susceptible and FB gets into the root the tree is likely dead. FB can get into the rootstock easier than it might seem.

I lost a lot of sweet cherries due to a rootstock that was susceptible to bacterial canker. The scion looked good right up until the tree died suddenly.


I only have experience with Apples where the amount the rootstock’s resistance to FB did not make much difference in our orchard.

We lost a bunch of apple trees including dead rootstocks to FB on G11 and G41 which should be resistant or highly resistant (what?) to FB.

Lost around 1/5 of the trees on FB sensitive varieties like PL or Granny Smith.

The trees were about 3-4 feet apart and we saw Fireblight spread quickly in some years. We normally have FB problems even after well timed sprays of Streptomycin.