Watermelon, Citrullus lanatus, is an important vegetable crop in the United States of which the annual watermelon crop value exceeded $534 million in 2021. In recent years, production has been disrupted by the rapid spread of a serious plant pathogen, Phytophthora capsici. The closest ancestors of today’s domesticated watermelon are thought to be Citrullus mucosospermus and Citrullus amarus, several accessions of which have known resistance to Phytophthora capsici fruit rot, but are untested in regards to stem and root rot. Popular commercially available cultivars, such as ‘All Sweet’, ‘Laelanau’, ‘Penghu’, and ‘Sunshade’, as well as Texas A
