Breeding Better Urban Trees-Problems, Practices and Potential

Importation of species or cultivars native to foreign countries has been, and will continue to be, an integral part of landscape-tree improvement in the United States. What is needed, in most exotic species, is a broader base of genetic variation from which superior selections and progenies can be developed. Seed source or provenance has been largely neglected in the past, but its importance is becoming recognized and appreciated. Still, the marketing practices of large commercial nurseries demand that only the most widely adaptable provenances will likely be recognized and propagated. Seed orchards are distinct possibilities for the continual production of superior trees in species where the need or desire for absolute uniformity is not great. The development of clones and cultivars based on single-tree selections will likely continue for the foreseeable future. Adequate testing of these cultivars will assure, that, in addition to the visual uniformity required in some landscape schemes, the cultivars will also be uniformly superior in survival traits. For cultivars propagated by budding or grafting, some attention must be paid to the provenance and adaptability characteristics of the rootstocks. Vegetative propagation is the norm in landscape-tree production and any improvement in rooting techniques or cell culture of difficult species could result in an abundance of new cultivars. Interspecific hybridization will continue to be important in developing new cultivars resistant to major disease and insect pests.

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Author(s): Frank S. Santamour, Jr.

Publication: Tree Improvement and Genetics - Southern Forest Tree Improvement Conference - 1977

Section: Session 1: Tree Breeding