2007 Annual Report 1a.Objectives (from AD-416) To develop more rapid and dependable methods of pathogen detection in order to enhance the production and maintenance of virus free tree fruit cultivars. 1b.Approach (from AD-416) Candidate viruses to be targeted for the development of diagnostic methods will be found by searching the literature and through correspondence with both tree fruit industry representatives as well as scientists in the field. Potential diagnostic approaches to be followed are the development of immunological test, possibly involving ELISA plate readers, and DNA amplification using PCR methods to provide tests for virus specific DNA sequences. Documents SCA with WSU. Formerly 5352-22000-015-29S (6/05). 3.Progress Report This report serves to document research conducted under a Specific cooperative agreement between ARS and Washington State University. Additional details of research can be found in the report for the parent project 5352-22000-017-00D 'Management of Insect Pests of Temperate Tree Fruit Crops'. a) Little cherry disease is a serious concern for sweet cherry growers in Washington and methods to verify its presence in Washington cherry orchards is critical for management of this disease. The two viruses known to produce little cherry disease were both found in Washington using newly refined reverse transcriptase methods. We also found significant sequence variation among little cherry virus 1 isolates from Washington, British Columbia, California, and Pennsylvania and these were distinct to isolates from Germany and Turkey. b) Cherry leaf roll virus infected pollen from infected and uninfected pollen from uninfected c.v. Van cherry trees was used to pollinate flowers on uninfected c.v. Bing cherry trees. Samples of cherry fruit, stem, and spur wood from pollinated flower clusters were tested for cherry leaf roll virus by ELISA and rt-PCR and showed virus transmission into all three substrates, most notably the fruiting spurs on the mother trees. 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.