Treesearch

Western white pine (WWP) (Pinus monticola Douglas ex D. Don) is a long-lived forest tree species with a large native range in western North America. The tree species is highly susceptible to the non-native fungal pathogen, Cronartium ribicola, the causative agent of white pine blister rust (WPBR). Several types of genetic resistance to WPBR are present in WWP, of which the best documented is a hypersensitive-like reaction (HR) in the needles that conveys complete resistance (generally no stem infection) and is conditioned by a single dominant gene (Cr2). The HR resistance is rare, and its...

In Hawaii, koa (Acacia koa A. Gray) is a valuable tree species economically, ecologically, and culturally. With significant land use change and declines in sugarcane, pineapple, and cattle production, there is an opportunity and keen interest in utilizing native koa in reforestation and restoration efforts. However, moderate to high mortality rates in many of the low to moderate elevation plantings have impeded past efforts (fig. 1). The primary cause for this mortality, particularly in young plantings, is thought to be koa wilt, caused by Fusarium oxysporum f. sp. koae (FOXY) (Gardner...

Phytophthora cinnamomi (Oomycetes) causes root disease and basal canker on a number of hardwood and conifer hosts, including Pacific madrone (Arbutus menziesii Pursh) (figs. 1, 2), a broadleaf evergreen species whose range extends from coastal British Columbia to southern California (Reeves 2007). Increasing mortality of Pacific madrone and the related shrub species manzanita (Arctostaphylos spp.) has been seen in California forests (Fichtner et al. 2009) in recent years. Considered to be one of the world's most invasive species, P. cinnamomi is thought to have originated in southeast Asia...

Western white pine (Pinus monticola Dougl. ex D. Don) and whitebark pine (P. albicaulis Engelm.) are white pine species with similar latitudinal and longitudinal geographic ranges in Oregon and Washington (figs. 1 and 2). Throughout these areas, whitebark pine generally occurs at higher elevations than western white pine. Both of these long-lived forest tree species are highly susceptible to white pine blister rust, caused by the non-native fungus Cronartium ribicola, and both have suffered extensive mortality in many parts of their range (Aubry et al. 2008, Fins et al. 2001, Geils et al....

The Cronartium quercuum f.sp. fusiforme (Cqf) whole genome sequencing project will enable identification of avirulence genes in the most devastating pine fungal pathogen in the southeastern United States. Amerson and colleagues (unpublished) have mapped nine fusiform rust resistance genes in loblolly pine, suggesting that at least nine corresponding avirulence genes likely exist in the fungus. Identification of these avirulence genes would greatly facilitate selection of resistant pine genotypes for deployment to forest plantations. Based on work in other rusts, we anticipate avirulence...

The elite breeding populations of loblolly pine (Pinus taeda L.) in the North Carolina State University Cooperative Tree Improvement Program are intensively managed for short-term genetic gain. Fusiform rust disease, caused by the fungus Cronartium quercuum f. sp. fusiforme, is the most economically important disease in pine plantations across the southeastern United States, causing multi-million dollar annual losses. In order to cull susceptible crosses and progeny prior to field testing, seedling progeny of 51 crosses were challenged with bulked inocula of the fusiform rust fungus at the...

Fusiform rust disease in loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm. var elliottii) pine plantations in the southern United States causes multi-million dollar annual losses. The disease is endemic to the region. The fusiform rust fungus (Cronartium quercuum sp. fusiforme) infects young pine trees and develops galls on stems and branches. Single pathogen gene and single host (pine) gene interactions can predict phenotype (disease expression) with high accuracy (Wilcox et al. 1996). There are nine known pathotype-specific Fr genes in seven loblolly pine families. The R...

The introduced pathogen Phtyophthora ramorum has had a devastating impact on populations of tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H.Oh) in California and Oregon, where it causes the disease known as sudden oak death. Tanoaks are a keystone species ecologically, and one of the few species that are both killed by P. ramorum and contributes to its spread. While ecologically important, tanoaks were little studied prior to the onset of the sudden oak death epidemic, resulting in few intellectual or material resources on which to base a disease resistance research...

In 1998, Australia, Chile, and New Zealand agreed to work together in a program designed to test their elite breeding lines and to test for the genetics of resistance to pitch canker (causative organism Fusarium circinatum). Pitch canker was first discovered in the United States in 1946 and in California in 1986. The first discoveries in California were in ornamental plantings, and the disease was first found in native stands of Monterey pine (Pinus radiata D. Don) in 1992. By 1997, pitch canker was found in 22 counties in California, and the Board of Forestry established a "Zone of...

Swiss needle cast (SNC) of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), caused by the ascomycete fungus Phaeocryptopus gaeumannii, is associated with significant volume growth losses (20 to 50 percent) along the Oregon Coast. Although the pathogen is endemic, disease symptoms have intensified in coastal forests of Oregon and Washington since the early 1990s, reaching a peak of 177,691 symptomatic hectares detected in the 2011 aerial survey of western Oregon (fig. 1). This symptom expression is the highest in 16 years of survey, despite the conversion of tens of thousands of pure...