Treesearch

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...

A unique feature of the American Chestnut Foundation breeding program is the use of volunteers to conduct most of the regional breeding that will help increase genetic diversity and preserve local adaptation in the products of our program. This effort is coordinated by the four authors of this abstract, who are employees of the Foundation. The Foundation has 16 state chapters spread over almost the entire range of the American chestnut (Castanea dentata (Marsh.) Borkh.). Fourteen chapters have active breeding programs. The chapter with the most advanced program, Pennsylvania, has been...

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...

Most species of pine and spruce synthesize and accumulate variable quantities of alkaloids in their tissues. These compounds express numerous types of biological activities in bioassay and could potentially offer resistance against enemies, although this function has never been confirmed for any known enemies of pine or spruce under natural conditions. The present study takes a complementary, and intensive, common garden approach to examine genetic variation in Pinus ponderosa Lawson & C. Lawson var. ponderosa C. Lawson alkaloid production. It also investigates the potential trade-off...

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...

Approximately 100 years ago, American chestnut (Castanea dentata (Marsh.) Borkh.) was rapidly removed as an overstory tree by the fungal pathogen Cryphonectria parasitica (the causal agent of chestnut blight). Currently, the most effective method of restoration involves the hybridization of American chestnut with the highly blight-resistant Chinese chestnut (Castanea mollissima Blume), with subsequent backcrossing of resistant stock to American chestnut sources. However, preliminary evidence suggests that backcross material may not have the cold hardiness needed for restoration in the...

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,...

Besides its high resistance to Chrysoporthe cubensis canker, Eucalyptus cloeziana F. Muell. is a highly valuable tree species for wood production. It can be used for furniture, electric poles, fence posts, and charcoal. Nevertheless, it is highly susceptible to the rust caused by Puccinia psidii, which limits its growth in areas favorable to infection. Since E. cloeziana does not interbreed naturally with other Eucalyptus species, its seedling plantations in Brazil are relatively uniform. Thus, the selection and multiplication of rust- resistant genotypes could constitute the best strategy...

The Resistance Screening Center (RSC) is operated by the Forest Health Protection unit of the U.S. Department of Agriculture, Forest Service, Southern Region, State and Private Forestry. The RSC is located at the Bent Creek Experimental Forest near Asheville, North Carolina. The center evaluates seedlings for resistance to disease, primarily fusiform rust (caused by Cronartium quercuum f. sp. fusiforme) and pitch canker (caused by Fusarium circinatum) as a service to tree improvement specialists, seed orchard managers, scientists, government agencies, research institutions, universities,...