A new and distinct plum tree variety, Prunus salicina, cv. . ‘Suplumfortynine’ is characterized by fruit having deep red flesh and a cling stone. The fruit is medium in sugar and has medium-low acidity. The fruit of the new variety ‘Suplumfortynine’ is also moderate in juice and has a sweet-mild flavor. The date of the harvest of the fruit of the new variety is earlier than for ‘Early Queen’ (U.S. Plant Pat. No. 8,583) and ‘Flavorosa’ (U.S. Plant Pat. No. 10,285). The fruit of the new variety ‘Suplumfortynine’ has fruit with deep red flesh compared to yellow colored fruit of ‘Early Queen’ (U.S. Plant Pat. No. 8,583). The fruit of the new variety ‘Suplumfortynine’ has red-dappled colored skin compared to dark purple skin of ‘Flavorosa’ (U.S. Plant Pat. No. 10,285).
