Technical Abstract: During the spring and summer of 2001, Beet curly top virus (BCTV) reemerged as an important, economically damaging pathogen of sugarbeet, tomato and pepper in widespread areas of the western United States. These areas included California, the Snake river Valley of Idaho and the southwestern desert of west Texas and New Mexico. The disease was particularly severe in California where sugarbeet plants were severely stunted, and yields were reduced in large part due to losses from curly top disease. The resurgence of this disease along with efforts to reduce pesticide usage in agriculture demonstrates a real need to develop improved control strategies for this historic and persistent pathogen of sugarbeet. In order to develop new ecologically sound management and control strategies, it is necessary to understand the ecology of this disease with regard to strain prevalence over time, host range and vector relationships.