A movie form the 1970's about a father and son and the son is dying.

The movie is called "the christmas tree" starring the actor william holden it came out in 1969 and the name of the same movie was changed to "when wolves cry" also 1969. The director is terence young. The movie is about a father and son and the son accidentally gets sprayed by a passing airplane that releasing pesticide and he gets cancer and dies under the christmas tree with a picture of a tractor that he drew and the dogs are howling at the end of the movie.

That's it, I saw it when I was 9 years old and always remembered the boy befriends the wolf and he dies under the Christmas tree on Christmas day. Thought it was cancer, forgot how he got it.