Treesearch

The stem-boring weevil, Mecinus janthinus (Germar), is a promising, well established classical biological control agent for the exotic invasive weed Dalmatian toadflax (Linaria dalmatica (L.) Mill.) (Scrophulariaceae). In this paper we present readily apparent rostral characters that can be used for sex differentiation of live stem-boring weevils at low magnification. These characters can be used by workers with little training to accurately sex weevils and can be used to rapidly determine sex ratios of field populations to improve timing of collection for redistribution.

Although the need for universally instituting formal risk assessment (RA) in the screening and approval process for non-native biological control (BC) agent releases has been widely acknowledged for the past several years, little seems to have been accomplished in terms of codifying this practice within a regulatory framework. Given the low success rate of classical BC and the documented environmental risks associated with previous releases, adopting standardized assessments of BC risks and benefits should not be further delayed.

Houndstongue, Cynoglossum officinale (Boraginaceae), is a biennial or short-lived perennial originating from montane zones in western Asia and Eastern Europe. Houndstongue reproduces by seed only, and was probably introduced to North America as a grain seed contaminant. This species was first reported in Montana from Sweet Grass County near Big Timber, Montana in 1900. As of 2006, houndstongue has been reported in 35 of Montana's 56 counties (http://invader.dbs.umt.edu). Houndstongue invades grasslands, pastures, shrublands, forestlands, croplands and riparian areas, and is an effective...

Saltcedar, also known by the common name tamarisk (Tamarix spp; Tamaricaceae taxonomic family), is a long-lived, invasive deciduous shrub or small tree intentionally introduced to North America from Eurasia for ornamental, wind break, and erosion mitigating purposes in the early 1800s. The spread of this species, both vegetatively from submerged stems and root sprouts, and sexually by seed, is optimized in riparian habitats. Saltcedar escaped controlled cultivation by the late 1800s with weedy populations reported in Montana since the 1960s. Until recent discoveries of saltcedar populations...

To date, there have been no reports of Dalmatian toadflax serving as a host for cucumber mosaic virus (CMV). Infestations of Dalmatian toadflax may serve as a reservoir of CMV, thereby facilitating aphid transmission of CMV to both agricultural crops and native plants. The goal of this study was to determine whether Dalmatian toadflax is a host for CMV. Dalmatian toadflax seedlings were randomly assigned to two treatments (18 replicates/treatment): no inoculation (control) and inoculation with CMV (Fast New York strain). The Dalmatian toadflax seedlings were inoculated by standard mechanica...

Bromus tectorum is a dominant winter annual weed in cold deserts of western North America. We followed patterns of seed carry-over and abundance of the pathogen Pyrenophora semeniperda over 5 years at B. tectorum-dominated shadscale (Atriplex confertifolia) and sagebrush (Artemisia tridentata) sites in southern Idaho. We hypothesised that more seeds could potentially carry over at the drier shadscale site because of minimal autumn precipitation, but that P. semeniperda, a pathogen that primarily kills dormant seeds, would have more impact at the drier site, where a higher density of...

Pathogen-seed interactions may involve a race for seed resources, so that seeds that germinate more quickly, mobilizing reserves, will be more likely to escape seed death than slow-germinating seeds. This race-for-survival hypothesis was tested for the North American seed pathogen Pyrenophora semeniperda on seeds of the annual grass Bromus tectorum, an invasive plant in North America. In this species, the seed germination rate varies as a function of dormancy status; dormant seeds germinate slowly if at all, whereas non-dormant seeds germinate quickly.

The mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Curculionidae, Scolytinae) (MPB), is a bark beetle native to western North American forests, spanning wide latitudinal and elevational gradients. MPB infest and reproduce within the phloem of most Pinus species from northern Baja California in Mexico to central British Columbia in Canada, and their geographic range is dictated by the distribution of both suitable host species and favorable climatic regimes (Safranyik 1978, Logan and Bentz 1999).

Hedysarum boreale Nutt. is a perennial legume native to western North America, with robust foliage in the late spring season. Due to its wide native range, forage value, and N2 fixation, H. boreale is of interest for rangeland revegetation and production. Seed cost is a major obstacle for utilization of H. boreale, primarily due to seed shattering and unreliable seed production, such that a need for improved germplasm exists. This study characterized the genetic relationships of H. boreale accessions, so plant breeders and geneticists will have the information necessary to maintain a broad...

Parsnipflower buckwheat is a perennial forb to subshrub with a branching woody stem. Leaves are covered with dense white hairs making the herbage appear a light green to blue-grayish color. The flowers are a creamy-yellow color and have six petals which are borne in simple or compound umbels. Plants of parsnipflower buckwheat can be distinguished from other closely related members of the genus by having a whorl of 5 to 10 leaves at midpoint of flowering stem; however in some subspecies this is not apparent (Freeman and Reveal 2005). The seeds, or achenes, are light to dark brown from 3 to...