Quote from internet site: ''Sometimes the damage caused to apple fruit by bitter pit is mistaken for scab. However bitter pit scars remain very small whereas the scars from scab increase in size as the fruit grows. If you cut into a fruit affected by bitter pit the damage can often go to the centre of the apple.'' So there you have it.

Also Bitter pit tends to develop later in the season than scab.
Bitter pit does not show on the leaves either, there it is much more likely to be scab.

Great thanks, I can now try to control it. I wish I had more knowledge and experience but it will come hopefully. Until then I will be grateful for all your good advice.

Cecilia...this is how we all learn! I have learned so much from GoY friends. :)

Even if it's not bitter pit, it wouldn't hurt to give them a dressing of something with calcium in it as it is the deficiency of calcium that is often a cause of bitter pit. There are many fungicides for the treatment of apple scab.

What I have done with the trees which are susceptible to Bitter pit is to bore holes (with a large crowbar) around the tree where the branches end. The holes were then filled with Calcium and filled in.
That has to be done in February if it is going to be of any use though.
The other thing one can do is to spray the flowers when fully open with a Calcium solution. Never tried this as I am not happy spraying when there are bees around.
Bitter pit is more prevalent in acid soils than lime rich ones and only in certain seasons when the weather conditions are such as to prevent the tree from taking up calcium.
I spray with Copper sulphate for Scab, reasonably organic.

Thank you, I have acid sandy soil with lots of stones in it. I can get cow manure from a local farm so hopefully my soil will improve over the years. I will also remember about the calcium.

Don't forget that manure tends to increase acidity in soils. On a sandy well drained soil, it may be worth putting some lime on, but not at the same time as the manure.