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41.
The pathogenicity of Phytophthora cambivora to Mission almond seedlings was confirmed by twig inoculation in situ. An excised twig assay using four isolates of P. cambivora showed almond cvs Mission and Chellaston to be susceptible, whereas peach cv. Nemaguard, which is commonly used as a rootstock for almond, was resistant. P. cambivora isolates 179 and 108, the most and least aggressive, respectively, were selected for further studies. The excised twig assay was modified for screening micropropagated shoots in vitro for response to P. cambivora. Defoliated shoots were placed upright in agar medium colonized with the fungus, and development of necrosis was assessed over a period of 2-3 days. Shoots of Chellaston developed extensive necrosis and those of Nemaguard developed little necrosis, whereas shoots of hybrid selections from peach x almond crosses were generally intermediate in response. This method permits rapid and efficient screening of large amounts of material, and would be a useful adjunct to conventional almond breeding programmes. 相似文献
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43.
Wounds to bark were measured within a few months of being inflictedby red deer in Glenbranter Forest, Argyll. About 8000 treeson 240 permanent plots were monitored; all the wounds occurringover a period of seven years were examined. Wound length varied little between forest stages, averaging12 cm. Wound breadth was greater on older trees, averaging 5cm in Sitka spruce and 6 cm in Norway spruce for the pole andhigh-canopy* forest stages. A few wounds were large, maximumlengths being 95 and 80 cm in Sitka spruce and Norway sprucerespectively, but less than 20 per cent of the Sitka sprucewounds exceeded 100 cm2 in surface area. Seasonal variationin size was modest; wounds were longest in spring (AprilJune). Often a single tree received two or more wounds during the 3-or6-month-long observation periods. For Sitka spruce there were89 instances of multiple wounding and 142 of single wounding,but these single wounds contributed only 37 per cent of thetotal of 383 wounds observed. The area of trunk wounded wasmore dependent on the size of the largest wound than on woundnumber, multiple wounds often being small. Trunks received most damage between 50 and 100 cm above ground,the lower and upper limits of wounding being 2 and 150 cm. Thepeaking in the incidence of damage with regard to height wasmost marked in pole-stage forest, whereas wounds were spreadmore evenly up the trunks on younger trees. Wound height waslittle affected by season, mean basal heights being 68, 70,74 and 67 cm in winter, spring, summer and autumn. Woundingon the trunk was not correlated with aspect. 相似文献
44.
Some 2000 trees at 14 main sites in Glenbranter Forest, Argyll,were monitored during 19781990 for damage. Tree state(whether leaderless or with single or multiple leaders or trunks)and tree size were regularly recorded. Browsing of leaders depressed height increment by 510cm in the year of ocurrence compared with undamaged trees; therapid development of new leaders minimized the check in growth.Trees initially leaderless had equal height increment over ayear to trees initially with leaders if no damage occurred inthe year. At a subsidiary site where some trees were planted in smallexclosures, the trees protected from deer reached a safe heightafter five seasons of growth, unprotected trees reaching equalheight 1 year later. The girths attained when trees were 1015 years old wereon average only slightly depressed by earlier browsing damageto leaders, reductions at most equalling one year's increment. Many trees became multi-trunked, there being a significant relationshipbetween the percentage incidence of multi-trunking and the numberof occurrences of leader damage. Unbrowsed trees mostly becamesingle-trunked. We judge that the present high incidence ofmulti-trunking (45 per cent in our 915 year-old stands)results largely from deer browsing. 相似文献
45.
BRIAN W. ROSE DVM G. ELIZABETH PLUHAR DVM PhD Diplomate ACVS ROBERTO E. NOVO DVM MS Diplomate ACVS SCOTT LUNOS MS 《Veterinary surgery : VS》2009,38(8):954-960
Objective— To evaluate the fatigue life of partially stacked and fully stacked (1.5/2.0 and 2.0/2.7 mm) veterinary cuttable plates (VCP) in a fracture gap model of the distal aspect of the radius. Study Design— In vitro biomechanical study. Methods— Constructs (n=4/group) were assembled for each of 8 groups using 8‐hole plates (1.5/2.0 and 2.0/2.7 mm VCP) in the following configurations: unstacked; 2‐hole stacked centered over the gap (COG); 4‐hole stacked COG; and fully stacked. Plate(s) were secured to 2 separate polyvinylchloride pipe lengths, mounted to a mechanical testing system with a custom jig, and were loaded in axial compression for 106 cycles at 10 Hz or until failure at 6–60 N for the 1.5/2.0 mm VCP and 10–100 N for the 2.0/2.7 mm VCP. Differences in number of cycles, stiffness, and failure mode were recorded. Results— All construct failures occurred through a screw hole adjacent to the gap. Fully stacked and 4‐hole stacked 1.5/2.0 and 2.0/2.7 mm VCP withstood 106 cycles. Fatigue life and stiffness of the 1.5/2.0 or 2.0/2.7 mm unstacked constructs were significantly less than the other constructs. Differences were identified in stiffness among the 1.5/2.0 mm stacked constructs and in fatigue life among the 2.0/2.7 mm VCP stacked constructs. Conclusion— Four‐hole partially stacked VCP (either 1.5/2.0 or 2.0/2.7 mm) have comparable mechanical properties to fully stacked VCP. Clinical Relevance— Partial stacking of 2 holes of VCP on both sides of the fracture gap may provide sufficient strength for healing, but this premise must be tested in vivo. 相似文献
46.
Reasons for performing study: Multinucleated histiocytic giant cells (MHGC) are seen frequently in skin‐biopsy specimens from horses with inflammatory dermatoses. However, the prevalence, number and morphological types of these cells have not been reported. Objective: To determine the prevalence, number and morphological types of MHGC in equine inflammatory dermatoses, and the association of these cells with specific conditions. Methods: Skin‐biopsy specimens from 335 horses with inflammatory dermatoses and from 27 horses with normal skin were evaluated for the prevalence, number and morphological types of MHGC. Results: The prevalence and number of MHGC were greater in granulomatous dermatoses than in nongranulomatous dermatoses. Infectious and noninfectious dermatoses were not different in terms of prevalence or morphological types of MHGC. Foreign‐body MHGC were the predominant type in almost all cases. MHGC were not seen in normal skin. Conclusions: MHGC are seen in a wide variety of equine inflammatory dermatoses, especially those that are granulomatous. Number and morphological types of MHGC are of no apparent diagnostic significance. Potential relevance: MHGC are frequently present in a wide variety of inflammatory dermatoses in the horse. Because the prevalence, number and morphological types of MHGC are of minimal diagnostic significance, special stains and tissue cultures are necessary to confirm specific diagnoses. 相似文献
47.
Anastomosis group and pathogenicity of isolates of Rhizoctonia solani from potato crops in South Australia 总被引:1,自引:1,他引:1
G. R. BALALI S. M. NEATE E. S. SCOTT D. L. WHISSON T. J. WICKS 《Plant pathology》1995,44(6):1050-1057
Isolates of Rhizoctonia collected from the stems, roots, tuber sclerotia and soil of potato crops in Virginia and Lenswood, South Australia, were identified to anastomosis groups (AG). Of the 301 multinucleate isolates of Rhizoctonia solani tested, 90% were AG-3, 7% were AG-4 and 2% were AG-5; 12 isolates were binucleate Rhizoctonia spp. This is the first report of isolates of AG-4 and AG-5 causing disease in potato crops in South Australia. All AG-3, AG-4 and AG-5 isolates tested caused rhizoctonia disease symptoms on the potato cultivar Coliban in pathogenicity trials conducted under glasshotise conditions. Both AG-3 and AG-5 isolates caused black scurf and stem cankers, although symptoms of black scurf were less severe with AG-5. AG-4 isolates produced the most severe stem and stolon cankers of all isolates tested. The pathogenicity of tuber-borne inoculum was confirmed by growing plants from sclerotia-infested tubers. AG-8 isolates from diseased barley and wheat produced severe root cankers and caused loss of feeder roots on inoculated potato plants. Results suggest that rhizoctonia disease in potato fields in South Australia is caused by a combination of different anastomosis groups and this has important implications for crop rotations. 相似文献
48.
CHARLENE J. FERNANDEZ DANNY W. SCOTT HOLLIS N. ERB & RONALD R. MINOR 《Veterinary dermatology》1998,9(1):49-54
This retrospective study compared the Masson's trichrome staining properties of collagen in the skin of normal cats and cats with cutaneous asthenia or acquired skin fragility. A Masson's trichrome staining abnormality was seen in all ( n = 8) cats with cutaneous asthenia, three of four cats with acquired skin fragility, and none ( n = 10) of the normal cats. A grading system developed to classify the intensity and distribution of abnormally stained collagen fibres indicated that cats with cutaneous asthenia had higher scores ( P < 0.001) than normal cats. Cats with acquired skin fragility had intermediate scores that were not significantly different from either of the other two groups. 相似文献
49.
JOSEPH HARARI MS dvm dipiomate acvs THOMAS E. BESSER dvm phd diplomate acvm SCOTT B. GUSTAFSON dvm ms dipiomate acvs KATRINA MEINKOTH dvm 《Veterinary surgery : VS》1993,22(1):27-30
Bacteria in blood cultures in 30 dogs undergoing high-speed dental scaling and tooth extraction were examined. One or more positive blood cultures were identified in 9 of 30 (30%) dogs. Pasteurella spp. were most frequently (5 dogs) isolated and were sensitive to ampicillin, penicillin, cephalothin, chloramphenicol, tetracycline, amoxicillin with clavulanic acid, and sul-famethoxazole with trimethoprim. Twg groups of 15 dogs each, anesthetized or sedated but not undergoing dental procedures, served as non-dentistry controls. There were no significant (p < .05) differences between the number of positive cultures in dentistry and non-dentistry groups. In healthy dogs undergoing high-speed dental scaling and tooth extraction, the occurrence of bacteria in blood cultures was much lower than previously reported. The clinical significance of positive blood cultures was uncertain. 相似文献
50.