Mycorrhizal symbiosis, a natural association between roots and certain soil fungi, can improve growth and increase stress resistance of many nursery crops. Field soils of four middle Tennessee and two eastern Tennessee nurseries were surveyed for their mycorrhizal inoculum potential (MIP), phosphorus (P) and potassium (K) concentrations, and soil pH. Arbuscular mycorrhizal (AM) fungi, which colonized seedlings of a Sorghum bicolor trap-crop, were recovered from all soils. Tissue samples were taken from young roots of three economically important tree species grown in nursery field soils: red maple (Acer rubrum L. `October Glory'), flowering dogwood (Cornus florida L. `Cherokee Princess'), and Kwanzan cherry (Prunus serrulata Lindl. `Kwanzan'). AM fungi, regardless of soil type, soil pH, or P or K concentration, had colonized young roots of all three species. Unless interested in establishing exotic mycorrhizae, ornamental nursery producers in Tennessee do not need to supplement field soils with these beneficial fungi.
W.E. Klingeman, R.M. Augé and P.C. Flanagan
W.C. Dunwell, D. Fare, M.A. Arnold, K. Tilt, G. Knox, W. Witte, P. Knight, M. Pooler, W. Klingeman, A. Niemiera, J. Ruter, T. Yeager, T. Ranney, R. Beeson, J. Lindstrom, E. Bush, A. Owings and M. Schnelle
The Southern Extension and Research Activities/Information Exchange Group-27 (SERA/IEG-27) is sponsored by the Southern Association of Agricultural Experiment Station Directors. Thirteen universities and the U.S. National Arboretum cooperate with official representatives from extension and research programs. The objective of the group is to identify, evaluate, select, and disseminate information on superior, environmentally sustainable, landscape plants for nursery crop production and landscape systems in the southeastern U.S. Plants are distributed to members responding to a request from cooperators for plant evaluation. Those who agree to cooperate are expected to grow the selected liner to landscape size, then transplant it in a landscape setting. The plant is rated for insect, disease, and cold damage, heat stress, growth rate, ornamental flowering and fruiting, fall color, commercial production potential, landscape potential, invasiveness potential, and insect disease transmission potential. Growth rate is evaluated annually by recording plant height and width. Initial bloom date is reported followed by bloom duration in days. Following evaluation, the group collectively and individually disseminates information gained from the plant evaluation system to a wide variety of audiences.