I have a pear tree that blossomed and bore fruit but the fruit doesn't get any larger than a marble?

I suppose it needs fertilizer on a regular basis.
I have a pear tree that blossomed and bore fruit but the fruit doesn't get any larger than a marble?
sometime its best to talk to a person that works in garden/or a nursery.or even somebody that has a pear tree at home.I might suggest to give fertilizer before it blossemed/ like 4-6month.good luck..