Treesearch

On the 100th anniversary of the introduction of Cronartium ribicola into western North America, it is fitting to assess the philosophical foundation of plant pathology and forest ecology. We should ask whether this foundation provides sufficient understanding of blister rust, other diseases of North American forests, and general forest ecology to insure the application of biologically appropriate and sustainable management scenarios. Perhaps the most significant advances in understanding how host-pest interactions fit into the scope of biology have occurred in the last 10 years. This...

As part of a larger effort to assess the distribution and ecology of Armillaria species throughout western North America, we present preliminary survey results for the East Cascades of Oregon. Surveys and sampling were conducted on 260 0.04-ha plots, which were randomly located across diverse environments and geographic locations. Using DNA-based techniques for the identification of Armillaria spp., we identified three genetically-distinct species groups that comprised the ca. 450+ Armillaria samples. The association of Armillaria species groups with habitat is summarized based on detailed...

The spruce beetle, Dendroctonus rufipennis (Kirby), is an important mortality agent of native spruces throughout North America. The life-cycle duration of this species varies from 1 to 3 years depending temperature. The univoltine cycle (one generation per year) is thought to maximize outbreak risk and accelerate host mortality in established outbreaks. Prepupal diapause is associated with the semivoltine cycle (one generation per 2 years) and we investigated thermal conditions that result in diapause induction. Preliminary experiments used respirometry in an attempt to distinguish the...

Puccinia psidii is the cause of rust disease of many host species in the Myrtaceae family, including guava (Psidium spp.), eucalypt (Eucalyptus spp.), rose apple (Syzygium jambos), and 'ohi'a (Metrosideros polymorpha). First reported in 1884 on guava in Brazil, the rust has since been detected in South America (Argentina, Brazil, Colombia, Paraguay, Uruguay, and Venezuela), Central America (Costa Rica and Panama), Caribbean (Cuba, Dominica, Dominican Republic, Jamaica, Puerto Rico, Trinidad and Tobago, and Virgin Islands), Mexico, USA (Florida, California, and Hawaii), Japan, and most...

White pine blister rust, caused by Cronartium ribicola J.C. Fisch., was found on southwestern white pine (Pinus flexilis James var. reflexa Engelm., synonym P. strobiformis Engelm.) near Hawley Lake, Arizona (Apache County, White Mountains, 34.024°N, 109.776°W, elevation 2,357 m) in April 2009. Although white pines in the Southwest (Arizona and New Mexico) have been repeatedly surveyed for blister rust since its discovery in the Sacramento Mountains of southern New Mexico in 1990 (1,2), this was the first confirmation of C. ribicola in Arizona.

This paper describes the drying of ponderosa pine wood chips at low (20°C and 50°C) temperatures using a bench-scale batch pulsed fluidizer to evaluate both volatile pine oils (monoterpenes) and moisture losses during drying.

Introduction of Cronartium ribicola (white pine blister rust) greatly motivated development of tree disease control and research in America. Although foresters and pathologists have learned much in the past 100 years, more remains to learn. The most important lesson is that fear of blister rust has reduced pine regeneration more than the disease itself. Based on six decades of study, I share what I've learned on five topics of personal interest-the evolution of pines and rust, history of blister rust, effectiveness of eradication, influences of climate and Ribes, and importance of sustainin...

Because Armillaria species display different ecological behaviors across diverse forest ecosystems, it is critical to identify Armillaria species accurately for any assessment of forest health. To further develop DNA-based identification methods, partial sequences of the translation elongation factor-1 alpha (EF-1α) gene were used to examine the phylogenetic relationship among 30 isolates representing the ten North American Armillaria species: A. solidipes (=A. ostoyae), A. gemina, A. calvescens, A. sinapina, A. mellea, A. gallica, A. nabsnona, North American Biological Species X, A....

Vegetation covers nearly 30% of Earth's land surface and influences climate through the exchanges of energy, water, carbon dioxide, and other chemical species with the atmosphere (Bonan 2008). The Earth's vegetation plays a critical role in the hydrological, carbon, and nitrogen cycles and also provides habitat and shelter for biota that deliver essential ecosystem services, such as pollination. In addition, living foliage produces a variety of chemical compounds that can significantly influence the oxidation capacity (cleansing ability) of the atmosphere (e.g., Fuentes et al. 2000;...

Movements by stream fishes have long been the subject of study and controversy. Although much discussion has focused on what proportion of fish adopt mobility within particular life stages, a larger issue involves the lifetime movements of individuals. I evaluated movements of different sizes and ages of Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus) using a variety of sampling methods from 1996 to 2001 in a 40 km network of main-stem and tributary segments of the North Fork Little Snake River, Wyoming, USA. The probability of movement was related to the period of...