Paradise, CA, zone 9. I know it's a long shot, but any ideas on this apple cultivar? Tree is 50+ years old and is part of an old orchard, so not a newer cultivar. Some fruit is ripening now, so an early summer variety that does not ripen all at once. Average size, wider than tall shape, green with varying degree of red striations. Flesh is white and crisp, not at all mealy and does brown fairly quickly. Superb sweet-tart flavor.