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901.
Franck Rivano Malena Martinez Victor Cevallos Christian Cilas 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(4):541-552
Resistance of rubber tree clones to South American Leaf Blight (SALB) caused by the fungus Microcyclus ulei is normally assessed in specific large-scale clone trials, which in general entail a considerable amount of work. Four variables
are observed monthly on each tree over many years: disease severity and conidial sporulation intensity on young leaves, and
severity and stroma density on mature leaves. In order to simplify this field assessment method, we tested the resistance
of eight rubber tree clones to M. ulei in Ecuador in a Fisher block design with four replicates per treatment. Three months after planting, monthly observations
were made for a period of 12 months on the foliage focusing on the four variables, in order to quantify disease development.
Given the correlations between the four variables, assessment of conidial sporulation intensity on young leaves and stroma
density on mature leaves should be sufficient. The most suitable period to start the assessment was 6 months after planting,
for a duration of six to nine months. As repeated observations on the same trees were autocorrelated, it was possible to reduce
the assessment frequency to once every 2 months. To conclude, assessing the resistance of rubber tree clones to SALB in large-scale
clone trials can be optimized to reduce the number of observation times by 50%. 相似文献
902.
Eunice Golda Danièle Ndo Faustin Bella-Manga Sali Atanga Ndindeng Michel Ndoumbe-Nkeng Ajong Dominic Fontem Christian Cilas 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(3):385-397
In Cameroon and most countries of tropical Africa where Phaeoramularia leaf and fruit spot disease of citrus is reported, a total yield loss of 50–100% is common. For effective control of this
disease, it is imperative to understand how it originates, and which factors contribute to its development. To this end, the
environmental and biological characteristics of each tree from 39 sites located in 13 citrus production basins in the humid
zones of Cameroon were collected by means of a survey. Information was collected by interviewing heads of households, and
by visual inspection of trees and their environment. The independent variable was severity of the disease while the dependent
variables were environmental and biological characteristics. Climatic characteristics varied from one basin to another. The
13 citrus production basins were regrouped in five categories based on disease severity. Altitude, tree species and soil type
were the main factors influencing the disease severity. Thus the higher is the altitude, the more important is the disease
severity. Also, disease severity increased with increasing number of grape fruit, orange and pummelo trees. However, disease
severity was lower on trees growing on volcanic soils as compared with the other soil types. Further analysis of these factors
could lead to the development of a risk assessment model for Phaeoramularia leaf and fruit spot of citrus. 相似文献
903.
Veronika Apprich Joachim Spergser Renate Rosengarten Christine Hinterhofer Christian Stanek 《Veterinary dermatology》2010,21(4):335-340
Horn samples were taken from the hooves of eight horses with clinical signs of equine onychomycosis in at least one hoof capsule. None of the horses had a documented mycological history. The predominant alterations of the horn capsules were sand cracks, white line disease, brittleness (especially around the nail holes), parakeratosis and bruising. The horn samples were stored in sterile tubes for transportation and transferred onto Sabouraud Dextrose Agar and dermatophyte test agar for mycological examination within 6 h. Fungal cultures were incubated for 30 days at room temperature. Fungal identification was based on colonial morphology and microscopic examination of conidia. Horn samples were also stored at ?80°C until used for scanning electron microscopy (SEM). The fungal culture revealed that the hoof horn from all eight horses was infected with keratinophilic fungi. The keratinopathogenic fungi Trichophyton spp and Scopulariopsis brevicaulis were also detected in six horses. SEM revealed severe alterations of the horn structure in horn samples infected with keratinopathogenic fungi compared to horn samples from a sound hoof. The most evident changes were deterioration of the tubular structure of the horn wall, disruption of the horny layers, superficial lysis of cornified cells and the presence of fungal elements. Samples without dermatophyte or Scopulariopsis infection, in contrast, were similar to healthy hoof horn. 相似文献
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906.
Saar BG Freudiger CW Reichman J Stanley CM Holtom GR Xie XS 《Science (New York, N.Y.)》2010,330(6009):1368-1370
Optical imaging in vivo with molecular specificity is important in biomedicine because of its high spatial resolution and sensitivity compared with magnetic resonance imaging. Stimulated Raman scattering (SRS) microscopy allows highly sensitive optical imaging based on vibrational spectroscopy without adding toxic or perturbative labels. However, SRS imaging in living animals and humans has not been feasible because light cannot be collected through thick tissues, and motion-blur arises from slow imaging based on backscattered light. In this work, we enable in vivo SRS imaging by substantially enhancing the collection of the backscattered signal and increasing the imaging speed by three orders of magnitude to video rate. This approach allows label-free in vivo imaging of water, lipid, and protein in skin and mapping of penetration pathways of topically applied drugs in mice and humans. 相似文献
907.
Pascal Côté Rebecca Tittler Christian Messier Daniel D. Kneeshaw Andrew Fall Marie-Josée Fortin 《Forest Ecology and Management》2010
Forest management has been criticised in the last 20 years for its negative impact on the native species, structures and functions of the forest. Of many possible alternatives proposed to minimize these effects, the functional zoning (or TRIAD) approach is gaining popularity in North America. The goal of this approach is to minimize the negative environmental impacts of forestry while maintain timber supply by dividing the forest into three broad land-use zones: (1) conservation, (2) ecosystem management, and (3) wood production. In this study, we used a spatially explicit landscape model to simulate the effects of fire and six different forest management scenarios on a boreal mixedwood forest management unit in central Quebec. The management scenarios examined included the current practices scenario, a scenario proposed by the provincial government, and four TRIAD scenarios varying in the amount of forest allocated to each of the three zones. For each scenario, we examined the harvest volume, percentage old-growth forest or old forest managed to favour old-growth attributes, and effective mesh size of forest patches by 20-year age classes. With more area set aside for conservation and high-retention partial cut harvesting techniques designed to maintain the attributes of old-growth stands, all TRIAD scenarios resulted in higher percentages of stands with old-growth attributes than the current practices scenario and the government proposed scenario, and two of the four TRIAD scenarios also resulted in higher harvest volume over the long term. All forest management scenarios resulted in significantly lower effective mesh size than the fire-only scenario, but this difference was not as pronounced for the four TRIAD scenarios as for the current practice and government proposed scenarios. We conclude that the TRIAD approach has the potential to minimize some of the negative impacts of forestry on the landscape, while maintaining timber supply over the long term. 相似文献
908.
Dodick Gasser Christian Messier Marilou Beaudet Martin J. Lechowicz 《Forest Ecology and Management》2010
We examined how the density, growth and survival of sugar maple (Acer saccharum Marsh.) and yellow birch (Betula alleghaniensis Britton) regeneration are influenced by gap size, soil nutrient availability and understory vegetation. We used a factorial combination of (1) three gap sizes (small: <100 m2; medium: 100–300 m2; large: ∼1000 m2); (2) presence/absence of liming (92% CaCO3 at 500 kg ha−1, 1st year post-harvest); and (3) presence/absence of vegetation control (weeding twice a year; 1st to 3rd year post-harvest). We monitored height increment and survival of 1500 seedlings and saplings of both species from the 3rd to the 6th year post-harvest, and assessed density 6 years post-harvest. Both species exhibited a complex set of density, growth and survival responses across the combination of treatments. Compared to sugar maple, yellow birch had an overall lower density, greater growth, and similar survival rate; the two species attained maximum values in different gap size for density, and similar gap size for growth and survival. Liming had very little or no effect on the species. The growth of yellow birch was slightly but significantly greater when understory vegetation was controlled, particularly in medium and large gaps. These results suggest that a variety of canopy gap sizes can provide the right combination of understory conditions for regenerating these two functionally different tree species. 相似文献
909.
Urs Gimmi Thomas Wohlgemuth Andreas Rigling Christian W. Hoffmann Matthias Bürgi 《Annals of Forest Science》2010,67(7):701-701
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• Increased mortality of Scots pine (Pinus sylvestris L.) and spreading of deciduous trees are observed in the Swiss Rhone valley. Previous research identified climate change
effects as main drivers of this trend. On the local scale, we hypothesize that legacies from past anthropogenic disturbances
are superimposed on climate effects. 相似文献
910.
Abuseir S Nagel-Kohl U Probst D Kühne M Epe C Doherr MG Schnieder T 《Berliner und Münchener tier?rztliche Wochenschrift》2010,123(9-10):392-396
Based on ELISA results from randomly selected serum samples taken from 128 cattle from different administrative and urban districts in the federal state of Lower Saxony in Germany a seroprevalence estimate of Taenia saginata cysticercosis in this area was derived. This estimate was subsequently used to calculate the sample size required in an epidemiological study to determine the actual prevalence of this infection in the cattle population (n = 2 604 767) in this federal state. The sample size was calculated as 1518 and the samples were collected according to the distribution of cattle among the 48 administrative and urban districts in Lower Saxony. The samples were tested with an evaluated antibody ELISA. The results showed a positive antibody titre rate of 8.83% from the total tested samples. 相似文献
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