I purchased a house in Oakland, CA one year ago that had a few backyard fruit trees including a citrus that produces both Lisbon Lemons and Seville oranges. Even when neglected it produced decent fruit , and with a little love it is now producing great quality fruit of both types. This is probably a 25 year old tree. I assume that it was planted as a lemon tree on Seville orange root stock and at some point started producing both. Should I be concerned that at some point the lemons will be completely taken over by the oranges? I'd say that the production is probably 60% Seville orange and 40% lemons currently. Ideally I want the tree to continue producing both, I am a chef and have made marmalade, used the juice in Yucatecan dishes like cochinita pibil and infused rum with the Seville oranges that were used in a cocktail at my restaurant, and the lemons have such great juice and fragrant zest that I bring them in and have the bar use them for our bar program instead of using commercially grown lemons that have the wax preservative coating on the skin. Are there things that I can do to maintain the balance on the tree, or is it nothing to worry about? Any advice is welcome.