Treesearch

The goal of our research and development efforts is to generate new and/or improved selections of the American elm (Ulmus americana L.) with tolerance/resistance to Dutch elm disease (DED). The approaches we are taking for this effort include: 1) controlled breeding using known DED -tolerant selections, 2) controlled breeding using DED-tolerant selections and local escape/survivor trees from specific geographic areas to generate site-adapted and DED-tolerant selections, 3) screening of escape/survivor trees for tolerance to DED, and 4) identification of additional American elm escape/surviv...

The balsam woolly adelgid (BWA; Adelges piceae) and hemlock woolly adelgid (HWA; Adelges tsugae) have had a tremendous impact on native ecosystems with Fraser fir (Abies fraseri (Pursh) Poir), eastern hemlock (Tsuga canadensis (L.) Carrière), and Carolina hemlock (T. caroliniana Engelm. ) in the eastern United States since their introduction from Asia. They have also caused serious economic damage in Christmas tree plantations and nurseries. The Alliance for Saving Threatened Forests is engaged in research to complement other methods of adelgid control through the development of genetically...

Port-Orford-cedar (Chamaecyparis lawsoniana) has suffered high mortality from the pathogen Phytophthora lateralis in portions of its natural range in southwest Oregon and northwest California, as well as in horticultural plantings in North America, and more recently in Europe. A program to develop genetically resistant populations of Port-Orford-cedar is underway. This operational program began in 1996 and utilizes artificial inoculation of the roots of young seedlings (or rooted cuttings) to rate parent trees for resistance. A key step to any such program is to establish field trials: to...

Western white pine (Pinus monticola Douglas ex D. Don) is highly susceptible to the non-native, invasive pathogen Cronartium ribicola, the causative agent of white pine blister rust. The susceptibility of western white pine to blister rust has limited its use in restoration and reforestation throughout much of western North America. Fortunately, some genetic resistance to blister rust exists in western white pine, and several operational programs to select for resistance and develop orchards to produce resistant seed exist. These programs, such as that of the U.S. Department of Agriculture,...

Most resistance mechanisms against pests and pathogens in pine trees involve the production of chemical defenses. These defenses are not cost free and the production of secondary metabolisms is generally inversely related with other plant fitness correlates, such as growth. The existence of these negative genetic correlations imposes an important obstacle for breeding for resistance and productivity simultaneously. Increased susceptibility to pests and diseases is, indeed, a common side-effect of enhancing productivity in many tree breeding programs. In a companion communication (Sampedro...

Whitebark pine is considered one of the most susceptible white pine species to white pine blister rust, the disease caused by the non-native pathogen Cronartium ribicola. High mortality from blister rust and other factors in much of the range in the United States and Canada have raised serious concerns about the future viability of this high-elevation forest tree species (USFWS 2011). A major effort is now underway to collect seed for gene conservation, to evaluate trees for genetic resistance to blister rust, and to establish restoration plantings (Aubry et al. 2008, Mangold 2011; Sniezko...

In recent decades, climate change has facilitated shifts in species ranges that have the potential to significantly affect ecosystem dynamics and resilience. Mountain pine beetle (Dendroctonus ponderosae) is expanding east from British Columbia, where it has killed millions of pine trees, primarily lodgepole pine (Pinus contorta Douglas ex Loudon) over the last 10 years. In Alberta, mountain pine beetle is in portions of the lodgepole pine x jack pine hybrid zone and was recently intercepted at the western edge of jack pine (P. banksiana Lamb.) forests. There is a potential threat that...

American elm (Ulmus Americana L.) was a dominant species in floodplains and swamps of the Midwest before Dutch elm disease (DED) (Ophiostoma ulmi and O.novo-ulmi) reduced its populations. In many areas, ash (Fraxinus spp.) became dominant in these ecosystems. Emerald ash borer (EAB) (Agrilus planipennis), an introduced insect, is now spreading through the Midwest and killing up to 99 percent of ash trees in infested areas. In spring 2011, we began a restoration experiment to study reforestation of ash-dominated floodplains impacted by EAB through plantings of native tree species, including...

Powdery mildew, caused by Erysiphe alphitoides (Ascomycete), is the most frequent disease of oaks, which are also known to be host plants for Phytophthora cinnamomi (Oomycete), the causal agent of ink disease. Components of genetic resistance to these two pathogens, infecting either leaves or root and collar, were investigated in a full-sib family of Quercus robur L, that was vegetatively propagated by cuttings. Resistance to powdery mildew was assessed by two methods. First, inoculations with E. alphitoides were performed under controlled conditions on excised leaves removed from cuttings...

Pacific madrone (Arbutus menziesii Pursh, Ericaceae) is an important evergreen hardwood species in Pacific Northwest (PNW) forests that provides food and habitat for wildlife and has high value in urban environments. Reeves (2007) indicates that Pacific madrone provides habitat for numerous wildlife species, especially cavity-nesting birds. Its evergreen foliage provides browse, especially in the winter, for a number of animals. The berries are an important food for deer, birds, and other small mammals because they are produced in large quantities and may persist on the tree in winter when...