The interspecific hybrid squash (Cucurbita maxima × C. moschata) rootstock ‘Carnivor’ is resistant to Fusarium oxysporum f. sp. niveum (FON) but susceptible to Meloidogyne incognita, the southern root-knot nematode. A new citron (Citrullus amarus) rootstock ‘Carolina Strong Back’ is resistant to FON and M. incognita. The objectives of this study were to determine if an interaction between M. incognita and FON race 2 occurred on ‘Carnivor,’ ‘Carolina Strong Back,’ or watermelon ‘Fascination,’ which is susceptible to FON race 2. In 2016 and 2018 field experiments, plants of non-grafted ‘Fascination’ and ‘Fascination’ grafted onto ‘Carnivor’ and ‘Carolina Strong Back’ were inoculated with one of four pathogen treatments: no pathogens, M. incognita alone, FON alone, or both pathogens. In both years, 20 g wheat grain colonized by FON was added to the transplanting holes, while in 2018, an additional 10 g was applied per 0.3 m of row in infested plots. M. incognita was applied as 2000 eggs (2016) or eggs plus juvenile nematodes (2018) to seedlings before transplanting. After 9 weeks, incidence of Fusarium wilt and area under the disease progress curve did not differ when hosts were inoculated with FON alone or with FON and M. incognita together. Plants not inoculated with FON did not wilt. Fusarium wilt was greater on nongrafted watermelon (78% incidence) than on both grafted rootstocks and lower on ‘Carnivor’ (1%) than on ‘Carolina Strong Back’ (12%) (P≤0.05). In 2016 after 16 weeks, ‘Carnivor’ had a greater percentage of the root system galled than the other two hosts, and watermelon had more galling than ‘Carolina Strong Back.’ In conclusion, cucurbit rootstocks that are susceptible and resistant to M. incognita retain resistance to FON when they are co-infected with M. incognita. Partial Funding provided by the Specialty Crop Block Grant Program at the U.S. Department of Agriculture (USDA) through Grant 14-SCBGP-CA-0006 (The CucCAP Project)