2010 Annual Report 1a.Objectives (from AD-416) To screen crape myrtle germplasm for host plant resistance to Cercospora Leaf Spot (CLS) and powdery mildew. Emphasis will be placed on maintaining ermplasm under ambient field conditions and other horticultural necessities. 1b.Approach (from AD-416) Crape myrtle controlled crosses and commerical clones will be placed at the cooperator's location and will be screened for CLS and powdery mildew. Evaluation will be made by the cooperator and by ARS scientists throughout the evaluation season each year. Germplasm with host plant resistance will be tested further in subsequent experiments. 3.Progress Report Screening for resistance to powdery mildew and Cercospora Leaf Spot (CLS) continues on the elite 110 seedlings selected from 2,000 original crape myrtle seedlings. Selections are rated for disease symptoms at least two times during the growing season. The 2009 season had a late frost and dry spring which delayed flowering. Little powdery mildew was observed on other crape myrtle clones growing in proximity to the test area but CLS pressure in the fall was severe. The 110 selections will be rogued based on 3 years data after the 2010 growing season. The ADODR or his representative meets regularly with the cooperating scientist, and these meetings include site visits.