Treesearch

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...

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...

The Monterey pine aphid (Essigella californica) is a recent arrival in Australia, having first been detected in 1998. It quickly spread throughout the national radiata pine (Pinus radiata D. Don) plantation estate, causing seasonal defoliation and compromising tree growth in many areas. Selection of resistant radiata pine for deployment commenced in 2002, based on heritable defoliation in mature progeny trials. Further development of the breeding program requires efficient methods for screening later generation germplasm. Glasshouse and nursery-based screening trials, involving infestation...

Coniferous trees deploy a combination of constitutive (pre-existing) and induced (post-invasion) structural and biochemical defenses against invaders. Induced responses can also alter host suitability for other organisms sharing the same host, which may result in indirect, plant-mediated, interactions between different species of attacking organisms. Current range and host expansion of the mountain pine beetle (Dendroctonus ponderosae, MPB) from lodgepole pine (Pinus contorta Douglas ex Loudon)-dominated forests to the jack pine (Pinus banksiana Lamb.)-dominated boreal forests provides a...

Needle terpenoid composition was determined by using GLC-MS in Pinus halepensis (Mill.) trees that were infested and not infested by the scale insect Marchalina hellenica. The study area was within the Forest National Park of the Cape Sounion, southern Attica region, Greece. A total of 43 compounds, 32 of which were identified, were detected, including monoterpenes, sesquiterpenes, and neutral diterpenes. The healthy trees showed higher mean concentration for the monoterpenes fraction as well as for the diterpene fraction than the mean concentration of infested trees; whereas, the concentra...

Disease processes are dynamic, involving a suite of gene expression changes in both the host and the pathogen, all within a single tissue. As such, they lend themselves well to transcriptomic analysis. Here we focus on a generalist invasive pathogen (Phytophthora ramorum) and its most susceptible California Floristic Province native host, tanoak (Notholithocarpus densiflorus (Hook. & Arn.) Manos, Cannon & S.H. Oh). The advent of new sequencing technologies has made the study of non-model systems possible at a scale never before possible. We argue that this non-model system is ideal for...

The white pine weevil, Pissodes strobi (Coleoptera, Curculionidae), has serious impacts on Sitka (Picea sitchensis (Bong.) Carrière), Engelmann (P. engelmannii Parry ex Engelm.), and white spruce (P. glauca (Moench) Voss) plantations in British Columbia (BC), Canada. This weevil attacks the terminal leader of the tree, causing significant growth loss and deformities. Genetic resistance to this insect was demonstrated in early provenance trials in BC. This encouraged us to initiate a systematic search for resistant trees to confirm this resistance and to improve parent source selections,...