2007 Annual Report 1a.Objectives (from AD-416) Assess the source and the impact of the purple top disease phytoplasma on potatoes in the Columbia Basin. 1b.Approach (from AD-416) Conduct field and laboratory experiments to investigate the susceptibility of different cultivars commonly grown in the Basin to purple top phytoplasma. Documents Trust with WA State Potato Commission. Log 32769. 3.Progress Report This report serves to document research conducted under a Trust agreement between ARS and Washington State Potato Commission. Additional research details can be found in the report of the parent project 5352-22000-016-00D 'Biorational Control Methods for Insect Pests of Potato'. For the second year, field experiments to determine the impact of the potato purple top disease in the Columbia Basin are being conducted. The studies are looking at the susceptibility of different potato cultivars important to the Columbia Basin and different plant growth stages to the BLTVA phytoplasma that causes purple top disease. The experimental potato plants are being monitored for disease symptoms. At harvest tubers will be tested for the phytoplasma and processed to assess the tuber quality. ADODR STATEMENT: Monitoring of activities and progress on this project was accomplished by direct supervision of on site employees, and use of e-mail and telephone to communicate with off site collaborators.