The present disclosure concerns triploid hybrid watermelon plants characterized by a tolerance to powdery mildew (PM) and capable of producing seedless fruits with a total soluble solid (TSS) in the range of 10% to 13%, and a red fruit flesh. In some embodiments, the triploid plants are resistant to at least one of PM1 and PM2 races. The present disclosure also concerns seeds of said triploid watermelon plant, and any progeny of such plant. Further provided by the present disclosure is a diploid watermelon line having tolerance to PM and being capable of pollinating a tetraploid watermelon to produce a triploid hybrid, as well as the tetraploid watermelon and methods of producing said triploid plant from said diploid and tetraploid plants.