Hi Diane, We were busy answering questions in person while on the radio show Saturday, so sorry nobody answered the phone. Sounds like your arbutus has leaf spot and the best answer is to remove all infected leaves now and try to increase the air circulation. Put a fresh mulch around the roots to seal in any fungal spores that may have dropped. Your Bonfire begonia sounds very happy and that tuber will give you a lot of blooms this summer. It is possible to cut up the tuber much as you would a seed potato but you also risk allowing rot to invade the cut areas. I would be safe and just move the giant tuber to a larger pot and enjoy the explosion of blooms this summer. The humming birds will love you. Keep growing, Marianne Binetti