Most research on cotton nematodes has been on the cotton root-knot nematode, Meloidogyne incognita. The reniform nematode (Rotylenchulus reniformis) is a relatively new and fundamentally different problem. It already has become apparent that the best ways to manage this nematode will be different as well. Root-knot nematode-resistant cultivars have been developed from G. hirsutum germplasm but the development of reniform nematode-resistant cultivars probably will require the transfer into Upland cotton of nematode resistance genes from other species of Gossypium. The most promising sources of resistance are within the species G. barbadense,
G. longicalyx, and G. arboreum.