Need some Jonathon Apple Tree Help

Hi, I could really use some help/ advice for an issue I am having with a Jonathon Apple Tree. I have planted a total of 7 trees ( different varieties ) within the last three months. These trees were both bare root and in the case of the Jonathon and a couple of others, it was a potted tree about 48” tall and looked great!  However, even though this Jonathon has been the best looking tree in the beginning, overall, the bare roots and the others are all doing great, while this one Jonathon seems to be struggling? The problem is that in the last month or so it has starting getting some yellow leaves, then the start to curl op, get brown and die.  This tree still is green a d has a lot of green leaves left, but I am starting to notice it is not as full as it was and looking not so good.  Just would like to know what is going on with it? I am née at growing trees so just not an expert on what the problem could be, and certainly want to keep the tree going and healthy.  Please help!  I truly appreciate all advice/ comments to help me address this issue!  Mike

Hi Mike, welcome to permies!

The Jonathan apple variety is highly susceptible to most of the major apple diseases, so it's probably not anything you're doing wrong, rather just a tree that is disease prone.

I've found this resource to be a good one for apples.

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.extension.purdue.edu/extmedia/BP/BP-132-W.pdf&ved=2ahUKEwiFvJOQnpbxAhVyElkFHbxoBP8QFjAJegQIHxAC&usg=AOvVaw03Mh3T5jCHBaolQQPrMmE-&cshid=1623643397004

Best of luck with your trees!

Thank you very much Steve!  I am new to the care of apple trees, so it has been perplexing.  I am looking at the site you sent me now!  Thanks again for the I formation!

Best regards,

Mike