The young apple tree got sick

Dear gardeners, help out.

In the fall, I planted an apple tree seedling, in the spring it took root, began to grow, young branches with leaves appeared from the lower part, and then a few days ago the branches withered and lay to the ground.

I noticed dark reddish pimples on the trunk, a lot at the bottom, less towards the middle, and a lot at the top again.

I believe that this is some kind of disease, since I planted two seedlings, the neighbor 3 meters away feels great.

What could it be? How to fight?

I would really like to use traditional methods, without various chemicals.