Bitter Pit & Calcium NItrate

I have an apple that has previously shown signs of bitter pit, and I have therefore acquired some calcium nitrate with which to spray it. But I can't find out what strength of spray is required. Can anyone please advise.

Ian L

I would advise that you just make sure that the tree is very wll watered this year.  Mulch around it with a deep layer of compost.  Bitter pit is often caused by the tree not being able to take up enough calcium because of lack of water.