American botanist (1903-1976).
Ralph Merrill Caldwell (June 27, 1903, Brookings, South Dakota – November 2, 1976, College Station, Texas) was an American plant breeder, mycologist, and plant pathologist. Through his work with the U.S. Department of Agriculture and Purdue University, he developed disease-resistant cultivars for a wide variety of plants, including widely-grown wheat cultivars. Caldwell was a member of the American Phytopathological Society, where he served as President of the North Central Division and Treasurer. He was a fellow of the American Phytopathological Society, the American Society of Agronomy, th