Vine decline or collapse on cucurbits is a syndrome that can be caused by several phytopathogenic agents and is frequently associated with the attack of several of them. Acremonium cucurbitacearum and Monosporascus cannonballus are two of the main fungal pathogens associated with this syndrome. The pathogenicity of these fungi was evaluated for 19 muskmelon (Cucumis melo) and two watermelon (Citrullus lanatus) cultivars usually cultivated in Brazil. All cultivars tested were highly susceptible to these pathogens except for the combination watermelon-M. cannonballus. The importance of continuing the study with other cultivars using the methodology described is discussed.