MR-1 is a monoecious muskmelon ( Cucumis melo L.) breeding line that was developed the by USD A to provide breeders and seedsmen with a source of high levels of resistance to both downy mildew, incited by Pseudoperonospora cubensis (Berk, and Curt.) Rostow., and powdery mildew, incited by Sphaerotheca fuliginea (Schlecht. ex Fr.) Poll. It is resistant to 2 undesignated races of downy mildew and to races 1,2, and 3 of powdery mildew.