Location: Southern Horticultural Research2013 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 germplasm 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. Evaluations 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:
This serves as the final report. The goal of this research was development of crape myrtle germplasm with resistance to Cercospora leaf spot and powdery mildew. Approximately 1000 seedlings were generated from crosses between susceptible and resistant crape myrtle parents by the Priciple Investigator. Plants were planted and screened at Auburn University’s Brewton Field Station for field resistance to the two diseases under ambient field conditions in south Alabama over two seasons after establishment. Field evaluation of the seedlings indicated that inheritance of resistance to Cercospora leaf spot was not qualitative. Gradations of resistance were identified in all families with a resistant parent. Approximately 3% of the population was selected for advanced screening. These elite individuals were retained for future efforts to breed for Cercospora leaf spot resistance in crape myrtle. Disease pressure for powdery mildew was not adequate at the site to discriminate between resistant and susceptible plants.