Farmall Cub

I have planted two Necterine trees about 3 years ago now, and I get lots of fruit on them but they only get as big as golf balls, and then they die and fall off. I live in PA. I'm not sure if they dont do well in the north or what. I lost one of the trees this year, I cant figure out whats wrong any Ideas would help. my peaches didnt do to good this year,the bees got to most of them.

Jack

We didnt get any nectarines OR peaches this year either here in central Il., they only make fruit every other year here, but this was a drought year so no fruit of any kind! thanks; sonny