`Black Ruby' is the newest plum released by the USDA stone fruit breeding program at Byron. This variety has large, firm fruit that ripens in early July, about 1 week after `Santa Rosa'. Fruit has reddish-black skin and yellow flesh. Eating quality is very good. `Black Ruby' has an upright tree similar to `Santa Rosa', except that tree health and vigor are much better than `Santa Rosa'. USDA has been breeding plums for the humid Southeast for 30 years. Goals are to combine large, firm, high-quality fruit with a disease-resistant tree that will live 8 to 10 years. Most plum varieties are short-lived in our area due to disease caused by Xanthomonas, Pseudomonas, and Xylella. Most existing varieties adapted to our climate have fruit unsuitable for commercial production. Previous USDA releases include “green plum” types `Robusto' (1980) and `Segundo' (1984); a yellow plum, `Byrongold' (1985); a black shipping plum, `Explorer' (1980); and the blood-fleshed, high-quality `Rubysweet' (1989).