Robert D. Riggs was born 15 June 1932 in Pocahontas, AR. He received his B.S.A. and M.S. degrees from the University of Arkansas and received a Ph.D. in 1958 from North Carolina State College. He immediately assumed a position at the University of Arkansas and was appointed a professor in 1967. His entire professional career has been focused on efforts to find economical and environmentally safe methods to control soybean cyst nematode (SCN), one of the most serious pests of soybeans in the United States. In order to develop control measures for SCN, Riggs extensively studied the genetic variability of both the nematode and the soybean. With D. Schmitt, he defined 16 possible races of SCN using differential soybean varieties and encouraged development of standardized methods to determine races. With his students, Dr. Riggs further defined races using serology as well as isozyme and DNA analyses. Collaborative work with C. E. Caviness worked to determine the genetics of resistance to SCN and has resulted in the release of six disease resistant cultivars. Further studies have identified specific ultrastructural differences in the response of susceptible and resistant soybeans.
Dr. Riggs has also conducted research into the combined use of crop rotation and resistant soybean cultivars for the control of SCN. From studies of host range, genetic variability of the nematode, and race shifts in SCN resulting from prolonged use of resistance genes, Dr. Riggs developed a 3-year-rotation schedule that consists of a susceptible soybean cultivar, a resistant soybean cultivar, and a nonhost such as grain sorghum. The rotation schedule, which reduces SCN population levels and slows race shifts, is designed to enhance durability of resistant cultivars. It is the current SCN control strategy recommended by the Arkansas Cooperative Extension Service and is used by growers throughout the South.
Currently, Dr. Riggs is exploring the effectiveness of a fungus for the biological control of SCN. While investigating the reason for an unexpected decline in the SCN population level in a field, a student of Dr. Riggs discovered a fungus-infecting cysts and eggs. In both greenhouse and field tests, the isolated fungus has reduced SCN population levels. Further research has demonstrated at least four strains of the fungus, which differ in the stage of the nematode that is most easily parasitized. Work with industry is focused on producing formulations that will be effective and efficient for field application. Possible application for control of reniform and root-knot nematodes is also under study.
Dr. Riggs has provided leadership in the testing of soybean cultivars for resistance to SCN that led to development of resistant cultivars and better variety selection for growers. In 1981, he was the leader of the United States Germ Plasm and Biological Control Team to China.
Dr. Riggs teaches a core graduate course in nematology and has provided dedicated service on many important committees at the University of Arkansas. He is a charter member of the Society of Nematology, where he served as editor-in-chief of the Journal of Nematology from 1987 to 1990, and was president from 1993 to 1994. Dr. Riggs has received the Distinguished Service Award from the Southern Soybean Disease Workers, the Distinguished Faculty Achievement Award for Research from the University of Arkansas Alumni Association, the Outstanding Researcher of the Year Award from the Arkansas Association of Cooperative Extension Specialists, the USDA Honor Award in Environmental Protection, the Outstanding Plant Pathologist Award of the Southern Division of APS, and is a fellow of the Society of Nematology.
