We never got a picture and your post was posted in a pretty obscure place...that's why you never got a reply. If you are still looking for answers, repost in the main Trees Forum WITH PICTURES!

Thanks for the clarification- I knew it was one of those. See, I told you I know pretty much nothing about gardening! ;)

Your tree still looks quite healthy. The yellowing at the leaf tips is most likely from the soluble salt levels increasing in the root zone. Every time you fertilize you build up salts. Periodic flushing with clear water washes them away. Have you every flushed the soil with clear water to wash out the salts?

Trees that are newly planted and not yet established do not perform according the calender like other older, more established specimens would. They do not yet have the root system established that would allow them to be more self-sufficient. That's why you need to provide extra water for at least the first two growing seasons. It is just getting ready to enter dormancy. October is pretty typical for that to happen just about anywhere in the US except for the deep South or SoCal. And dropping leaves is SOP for that process. Don't panic - the tree is fine. Just make sure it gets enough water (but never too much) until the fall rains come or in any extended dry periods. If it loses its leaves earlier than your other trees, NBD. It should leaf out again at the proper time in spring.