Hello Merry

In your pictures I do not see any evidence of fire blight. However the picture of the branches with leaves is against a leafy background and I can’t see those clearly.

Yes, there is an MSU plant and pest diagnostics Lab that you can email pictures and history of the tree. <personal data hidden> If they need samples they will ask you to send them.

Holding a plain cardboard or piece of paper behind a branch that shows die back while taking the picture from about a 12 inches away is very helpful for diagnostics( must be in clear focus, too). Also, you could wait for the sun to come to the other side and take the picture from the opposite side of the tree, if that side has clear sky. Consider doing this if you decide to email the problem to the diagnostic lab.

Here is a fire blight reference for you to compare with your tree. Also, there is a short list of resistant trees:

https://extension.umn.edu/plant-diseases/fire-blight#fire-blight-resistant-trees-that-are-hardy-in-minnesota-1760460

Depending upon when the tree was planted last year, it may not have gotten its roots established before winter and the ground froze. Another cause for dieback is lack of water. Small Trees need about 7-10 gallons of water per week. Lawn sprinklers do not provide that much.

Your tree appears to be planted too deeply in the soil. The base of the trunk where it branches out into the main roots flare out is called the root collar or the root flare. That should be at soil level, not covered with soil. You can replant this tree at the proper depth if it hasn’t been in the ground over 12 -15 months. Here is a guide on planting and care- https://trees.umn.edu/sites/trees.umn.edu/files/files/tree_owners_manual_0.pdf

Should you have to replace this tree there are fireblight resistant and apple scab resistant crabapple trees. Apple scab is probably the number one problem here in Michigan. Take a look at the list and choose one of those, such as Tina or Adams. More here-https://ecommons.cornell.edu/bitstream/handle/1813/56373/malus-res-orn-NYSIPM.pdf

Very good. Glad to help.