Is this fire blight or canker disease on my young pear tree?

Question: I noticed some black scabby looking bark on my young Summercrisp pear tree (see attached photos).

Is this anything to be concerned about? Do you know what this could be?

It's been in the garden for 3 years now, has never bloomed or made fruit, it's only about 6' tall with very little branching and little growth so far. This black scabby wood is on the main trunk of the tree. The branches above this section have buds that have yet to open this spring.

Thank you for any help you can provide!

responder: Patricia, UVM Extension Master Gardener Volunteer  Replied April 24, 2023, 2:49 PM EDT
response: Hi Natalie, Thank you for your question.    I asked Ann Hazelrigg, Director of Plant Diagnostic Clinic to help with this question.  She states: "This definitely is some sort of a canker. I would not guess fireblight but it is impossible to tell. It is basically academic what caused it: mechanical, fungal, bacterial, etc. I suspect the injury is interrupting the flow of water and nutrients upward so the portion of the tree above will die/not leaf out. The best thing to do at this point is to prune back to a healthy side branch and hope the tree improves. Be sure to mulch the tree, fertilize and do whatever you can to improve the vigor. A young pear could use 1/2-2 lbs 10-10-10 spread out to the dripline at this time of the year. You could keep it on the lighter side since you don't want to encourage fireblight." Here is some more information on your pear tree: The Summercrisp variety of pear was developed by the University of Minnesota for cold weather climates and produces fruits that are ready in August.  You mentioned that your tree has not blossomed or produced any fruit.  Do you have another pear tree that grows near it? The Summercrisp pear tree is typically not self-fertile, which means that a single plant will not produce fruits on its own. Instead, you will need to plant a companion pollinator plant nearby to allow for cross-pollination. Companion pollinator example would be a variety called Juicy Jewel or Parker.  (see "Pears Minnesota Hardy attached below). Pears | Minnesota Hardy (umn.edu) SUMMERCRISP PEAR - PYRUS 'SUMMERCRISP' | The UFOR Nursery & Lab (umn.edu) Fire Blight in Home Apple and Pear Orchards (psu.edu) Growing pears in the home garden | UMN Extension Happy Gardening!

responder: The Question Asker Replied April 24, 2023, 5:12 PM EDT
response: Thank you so much for your reply! This was very helpful. I do have a second pear tree 15ft away from this one, a Golden Spice pear (There are some apples around as well). All are about the same size, and were planted at the same time. There are a few side branches below this canker spot on the main trunk I can cut it back to. I will essentially be cutting the tree almost in half (close to 2/3rds of the top of the tree will have to be cut off). Will the tree survive if I cut it in half, even if it is back to a bud/branch on the main trunk? Thank you again!

responder: Patricia, UVM Extension Master Gardener Volunteer  Replied April 25, 2023, 11:49 AM EDT
response: Hi Natalie, I asked Ann to respond to you since she is an expert.    She states: "No, it should not hurt the tree. If the buds are coming out above the damage, she could leave it and the tree may heal itself. If that portion above the canker is dead and not leafing out, then it does no good to leave it in the tree, since it could provide inoculum (fungal spores/bacteria) that could pose an issue in other parts of the tree. If pruned back to a side branch, she could train that branch to become the main leader in the tree (upright top). It may need to be staked up when the new growth comes out but trees tend to do it on their own to some extent. She can do the pruning now or wait a bit to see if the above part is dead or not..The only time you don't want to do drastic pruning is if you cut the tree below the graft union. Then you would have a rootstock for the main tree, which has not been bred to produce good fruit. It is typically ok to prune any time in the summer as long as you are cutting back to a side branch. You DO NOT want to do "heading back" cuts just to a bud because that will cause a proliferation of growth from that area that would need to be thinned." Thank you for your question!  Good luck with your fruit trees! Pruning & Training Apple & Pear Trees | Home & Garden Information Center (clemson.edu)