A national approach to leverage the benefits of tree planting on public lands

New Forests - The number of global initiatives for forest restoration, and the scope of these initiatives, continues to increase. An important tool for meeting objectives of these global...     

Interactions among Streptomyces griseoviridis,Fusarium root disease,and Douglas-fir seedlings

In a laboratory experiment, Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] Franco) seedlings had similar disease ratings when treated with known Fusarium isolates or concurrently with Fusarium and Streptomyces griseoviridis. When tested under greenhouse conditions and against known Fusarium isolates, more seeds germinated and survived as seedlings in control medium than survived in S. griseoviridis-inoculated medium or when S. griseoviridis and Fusarium were added together. A series of applications of S. griseoviridis as a soil drench to a crop of Douglas-fir seedlings did not affect seedling morphology. However, against resident levels of Fusarium, S. griseoviridis reduced Fusarium infection by 16%, but increased infection by F. oxysporum and F. proliferatum, two potentially pathogenic fungi, by 40%.     

Molecular Characterization of Fusarium oxysporum and Fusarium commune Isolates from a Conifer Nursery

ABSTRACT Fusarium species can cause severe root disease and damping-off in conifer nurseries. Fusarium inoculum is commonly found in most container and bareroot nurseries on healthy and diseased seedlings, in nursery soils, and on conifer seeds. Isolates of Fusarium spp. can differ in virulence; however, virulence and colony morphology are not correlated. Forty-one isolates of Fusarium spp., morphologically indistinguishable from F. oxysporum, were collected from nursery samples (soils, healthy seedlings, and diseased seedlings). These isolates were characterized by amplified fragment length polymorphism (AFLP) and DNA sequencing of nuclear rDNA (internal transcribed spacer including 5.8S rDNA), mitochon-drial rDNA (small subunit [mtSSU]), and nuclear translation elongation factor 1-alpha. Each isolate had a unique AFLP phenotype. Out of 121 loci, 111 (92%) were polymorphic; 30 alleles were unique to only highly virulent isolates and 33 alleles were unique to only isolates nonpathogenic on conifers. Maximum parsimony and Bayesian analyses of DNA sequences from all three regions and the combined data set showed that all highly virulent isolates clearly separated into a common clade that contained F. commune, which was recently distinguished from its sister taxon, F. oxysporum. Interestingly, all but one of the nonpathogenic isolates grouped into a common clade and were genetically similar to F. oxysporum. The AFLP cladograms had similar topologies when compared with the DNA-based phylograms. Although all tested isolates were morphologically indistinguishable from F. oxysporum based on currently available monographs, some morphological traits can be plastic and unreliable for identification of Fusarium spp. We consider the highly virulent isolates to be F. commune based on strong genetic evidence. To our knowledge, this is the first reported evidence that shows F. commune is a cause of Fusarium disease (root rot and dampingoff) on Douglas-fir seedlings. Furthermore, several AFLP genetic markers and mtSSU sequences offer potential for development of molecular markers that could be used to detect and distinguish isolates of F. oxysporum nonpathogenic to conifers and highly virulent isolates of F. commune in forest nurseries.     

Multiple viral plaques with sebaceous differentiation associated with an unclassified papillomavirus type in a cat

Abstract

CASE HISTORY AND CLINICAL FINDINGS

A 15-year-old neutered male domestic short-haired cat was presented due to multiple 0.5–2?cm-diameter crusting plaques in the left preauricular region, over the bridge of nose, and in the right periocular region. The plaques did not appear to cause discomfort.     

Establishment and growth of container seedlings for reforestation: A function of stocktype and edaphic conditions

A properly selected stocktype can greatly enhance reforestation success through increased survival and growth following outplanting. Implementing a robust stocktype trial using stocktypes of equal quality can ensure results lead to the best choice. Six container types, differing primarily in depth and volume, were used to evaluate the performance of ponderosa pine (Pinus ponderosa Laws. var. ponderosa) seedlings outplanted on two sites that varied in volumetric soil moisture content (θ), average temperature, and total precipitation (mesic and xeric). Seedlings in each container type were cultured specifically to achieve uniform seedling quality. After two growing seasons, seedlings planted at the mesic site showed high survival (>99%) and incremental growth gains of 147, 100, and 794% for height, root-collar diameter (RCD), and stem volume, respectively; container types exhibited differences in total height, RCD, and stem volume with larger containers generally yielding the largest seedlings. Seedlings planted at the xeric site experienced 83% survival, smaller growth gains (25, 46, and 220% for height, RCD, and stem volume, respectively), and also exhibited differences in height, RCD, and stem volume. Regression analysis revealed that for each site, initial seedling morphological characteristics were better at predicting absolute height, RCD and stem volume after the first year than after the second year, with initial seedling height offering the best predictive power (R² = 0.66, mesic site; and R² = 0.70, xeric site). Second-year absolute growth prediction was poorest on the mesic site (R² < 0.21). Regression analysis indicates that initial seedling characteristics lost predictive value with time, especially on the mesic site, as seedlings grew out of their initial, container-induced characteristics and become more limited by current environmental and genetic factors. Conversely, on a xeric site, where absolute growth was reduced, traits determined by the container type persisted longer. Selecting stocktypes for mesic site conditions may only be limited by the minimum growth gains desired. Conversely, xeric sites may benefit from deep-planted quality seedlings or carefully planted long-rooted, large container seedlings.