I found the following on a website:-
Fruit
Fruit can be high in sugar and can also be acidic. This will upset your dog's digestion and is best avoided.
Potatoes
Feeding potatoes is not recommended due to their high starch content, which is not very digestible to dogs and may cause problems.
I also read somewhere that you shouldn't give them too much brocolli. I think carrots are fine - when Fern was a pup we used to freeze one and that was good for a while til she got bored with it and it left a big wet patch
Also no to choc, onions, grapes, raisins etc but we all know that