2012 Annual Report 1a.Objectives (from AD-416): Accelerate development of superior Hydrangea germplasm using wide hybridization, molecular markers, and ploidy manipulations. Develop, evaluate, and release improved germplasm of selected nursery crops species, including Hydrangea, Cornus, Clethra, and Styrax. Investigate physiological constraints with transplanting nursery crops and root system changes for better adaptation into production systems. Develop improved nursery production systems with an integrated approach of bio-plastic containers, plant water and nutrient use, and cultural management. 1b.Approach (from AD-416): Use wide hybridization to improve H. macrophylla. Use molecular markers for studying genetic relationships and creating genetic linkage maps in Hydrangea. Develop a polyploid series in H. macrophylla. Develop, evaluate, and release improved germplasm of Hydrangea, Cornus, Clethra, and Styrax. Evaluate germplasm for nursery production and landscape potential. Determine root growth, root quality and plant performance in non-traditional nursery containers. Determine transplantability and survivability of bare root trees during nursery production and in post harvest landscape settings. Determine the relationship of cyclic irrigation and low nutrient inputs with container-grown ornamental trees. Determine the influence of irrigation and nutrient inputs on bio-based materials for container nursery production. 3.Progress Report: Additional selections of cold hardy camellias were planted in field trials to evaluate for nursery production and landscape potential. Neonicotinoid insecticides for prevention of flatheaded borer attack on Acer rubrum was evaluated in combination with weed control in field plots. Evaluation of prototype bio-based nursery containers continued. An evaluation of nutrient input and irrigation management in container production for sensitive nursery crops was continued. 4.Accomplishments 1. Evaluation of yellow flowering deciduous magnolias. All selections of yellow flowering magnolias that are available in the market are reported to have yellow blooms; however, tepal color in this test ranged from light pink with some yellow coloration to dark yellow. An ARS scientist in McMinnville, TN evaluated 30 selections of yellow flowering deciduous magnolias for bloom color, bloom size, bloom duration, foliar powdery mildew resistance, and plant growth rate and size in USDA Hardiness Zone 6b. Flowering data was overlaid with date of spring leaf emergence. Magnolias that bloom before leaf emergence and have a distinct yellow flower color are considered more desirable as nursery landscape plants. Magnolia cultivars with distinct yellow flowers that escape spring frost damage and those resistant to foliar powdery mildew will allow this novel group of flowering trees to be more widely grown in areas of the country that frequently experience widely fluctuating temperatures during spring months. Review Publications Reed, S.M. 2012. ‘Spring Showers’ Japanese Snowbell. Journal of Environmental Horticulture. 30(2):110-111. Reed, S.M., Pooler, M.R. 2012. ‘Firefly’ Clethra. HortScience. 47(3):429-430. Fare, D.C. 2012. Evaluation of spectral light management on growth of container-grown willow oak, nuttall oak and summer red maple. Journal of Environmental Horticulture. 30:8-12.