Treesearch

The core distribution of Rocky Mountain bristlecone pine (Pinus aristata) extends from central Colorado into northern New Mexico with a disjunct population in northern Arizona (USA). Populations are primarily at high elevations and often define the alpine treeline, but the species is also found in open mixed-conifer stands with ponderosa (P. ponderosa) or pinyon (P. edulis) pines. On dry, exposed sites the stands are open and bristlecone is commonly the only species present. The combination of the pine’s adaptive traits with infrequent disturbance has enabled trees on these sites to attain...

Limber pine (Pinus flexilis) is being threatened by the lethal disease white pine blister rust (WPBR) caused by the nonnative pathogen Cronartium ribicola. The types and frequencies of genetic resistance to the rust in native populations before invasion are likely to determine the potential success of restoration or proactive measures.

The nine native species of white pines in the United States (four of which also occur in Canada) are all highly susceptible to white pine blister rust caused by the fungal pathogen Cronartium ribicola. Research and applied programs in the United States and Canada to develop resistant populations of white pine species have been underway for more than 50 years. The regional program based at the U.S. Department of Agriculture Forest Service’s Dorena Genetic Resource Center (DGRC; Cottage Grove, Oregon, USA) has the most experience and continuity and has been active for over 50 years. The DGRC...

Poplar (Populus spp.) leaf rusts caused by Melampsora species are considered among the most crucial sanitary problems threatening poplar stands worldwide. Several major resistance factors specific to poplar rusts have been identified, each of them discovered by using a single Melampsora species. Most of them are inherited from Populus species that did not co-evolve with the pathogen. The origin and function of such “exapted” resistance are thus called into question.

Sugar pine (Pinus lambertiana) and western white pine (Pinus monticola) are two important long-lived conifer species in forests of southwestern Oregon (USA) and elsewhere. Both of these white pine species have been in decline for decades due largely to the presence of the nonnative white pine blister rust, caused by the fungal pathogen Cronartium ribicola. Many land managers are interested in keeping these white pine species present in forest ecosystems or in managed forests, but the very high susceptibility of these species to the blister rust and the lack of information rating the...

The climates of central and southern regions of São Paulo state (Brazil) are suitable for pathogens such as Puccinia psidii, which causes a common and serious disease in eucalyptus plantations less than 2 years old. We studied the genetic variability of P. psidii in commercial plantations of Eucalyptus species by random amplified polymorphic DNA molecular markers. All 56 isolates of P. psidii analyzed showed high polymorphism and there was no evidence of preferential infection in different plant tissues. In the analysis of pooled pustules according to the clone of origin, we observed the...

Cronartium flaccidum is a serious pathogen of twoneedle pines, especially of Pinus sylvestris, in northern Fennoscandia (Samils et al. 2010). The rust spreads via a number of alternate hosts in natural forests and gardens, among which species in genera Melampyrum, Pedicularis, Vincetoxicum, and Paeonia are the most important known ones (Gäumann 1959; Kaitera et al. 1999). In northern Europe, the most important species is Melampyrum sylvaticum (Kaitera et al. 2005), while in southern Europe the respective species is Vincetoxicum hirundinaria (Gäumann 1959). Cronartium ribicola is a common...

On August 24, 2009, while working in Rocky Mountain National Park (Estes Park, Colorado, USA) on the Conserving Limber Pine Genetic Diversity for Possible Future Restoration at Rocky Mountain National Park project (see Schoettle et al. 2011, 2013, in press), a crew from the U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station (RMRS) noticed a small limber pine (Pinus flexilis) with a dead top along Highway 36 near the Many Parks Curve (fig. 1). The tree was about 2 m tall and 7 to 10 cm in diameter at breast height (d.b.h., 1.37 m) and occurred at about 3,000 m...

Land managers have commonly sought to discourage or prohibit camping near surface waters (e.g., lakes, rivers, streams, and springs), imposing regulations that prohibit camping within a specified distance from water. As Griffin presents, these camping setbacks from water within Forest Service Wilderness areas currently range from 50 to 1,320 ft, with 100 ft as the most common prohibition, followed by 200 ft, which is the distance recommended by the national Leave No Trace and Tread Lightly programs. An earlier survey by Washburne and Cole (1983) reported the following percentages of agency...

Limber pine (Pinus flexilis) and Rocky Mountain bristlecone pine (Pinus aristata) are important components of forest ecosystems in the southern Rocky Mountains, United States. Both species are susceptible to white pine blister rust caused by the fungal pathogen Cronartium ribicola. However, very little is known about the relative resistance of the two species. In this study, we used artificial inoculation of seedlings to compare the relative susceptibilities of these two species. The objective of the inoculation test was to compare the performance of seedlings from bulk seedlots of limber...