The Editors Gad Loebenstein, Ph.D., graduated from the Hebrew University of Jerusalem and joined the Agricultural Research Organization, Volcani Center, Israel. He served as Head of the Department of Plant Virology, Director of the Agricultural Research Organization and Chief Scientist of the Ministry of Agriculture. His major research interests are plant virus disease with emphasis on those in flower and bulb crops and natural resistance mechanisms of plants to viruses. His work was instrumental in establishing nurseries in Israel of carnations, roses and lilies. His published work includes more than 200 scientific and technical papers. He was appointed as Adjunct Professor at Tel Aviv University and at the Hebrew University, and in 1982 received the Rothschild Prize for Agriculture. Roger H. Lawson, Ph.D., is a Supervisory Research Plant Pathologist with the U.S. Department of Agriculture, Agricultural Research Service, in Beltsville, Maryland. He graduated from Oregon State University with a B.Sc. degree in Floriculture in 1959 and in 1963 received a Ph.D. degree from the same institution. He came to Beltsville in 1964 after completing a Fulbright graduate fellowship in The Netherlands. In 1981 he was appointed Research Leader of the Floral and Nursery Crops Laboratory in Beltsville, Maryland. He has served as Associate Editor of Phytopathology and Plant Diseases and as a Senior Editor of Phytopathology. His published work includes more than 250 manuscripts dealing with floral and nursery plants and the virus diseases that reduce crop quality. In 1989, Dr. Lawson was chosen as a Scientist of the Year by the Agricultural Research Service. Alan A. Brunt D.Sc., F.I. Biol. was educated from 1952 1957 at Exeter University where he was encouraged to study plant virology by the late Professor John Caldwell. From 1957 to 1962 he investigated viruses of cocoa in Ghana and, from 1962 to 1964, viruses of horticultural and tropical crops at Horticulture Research International (HRI). He has collaborated closely with many colleagues overseas, and is a consultant to the Food and Agriculture Organisation. He was elected to a Fellowship in the Institute of Biology in 1979, was appointed a Visiting Professor of Imperial College (London University) in 1991, and is now an Emeritus Fellow of HRI.