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1.
Experiments are described to quantify the effects of temperature and leaf wetness duration on infection of groundnut by Phaeoisariopsis personata. Temperature response curves for conidial germination and infection were similar, with optima close to 20°C and minimum and maximum temperatures of about 8°C and 34 C, respectively. The effect of temperature on infection between 15°C and 26°C was slight. Lesions developed only if the leaf wetness period exceeded about 20 h, and the total wetness period necessary for maximum infection exceeded 160 h. The number of lesions resulting from a fixed amount of inoculum was several times greater if leaves were exposed to alternate wet and dry periods (intermittent wetness), compared with continuous wetness. With intermittent wetness the length of the dry period had little effect on the number of lesions, providing it exceeded 2 h. The response curve relating total wetness periods to lesion density was an exponential asymptote. 相似文献
2.
Controlled-environment studies of conidial production by Phaeoisariopsis personata on groundnut are described. With constant relative humidity (RH), conidia were only produced above a threshold (94·5% RH) and there was a linear increase between 94·5% RH and 100% RH. Conidial production was less with continuous leaf wetness (resembling heavy dew) than with continuous 98–99% RH, but it was similar with intermittent leaf wetness and intermittent 98–99% RH (8 h at 70% RH each day). With alternate high (≥97% RH) and low humidity, daily conidial production depended both on the duration of high RH and on the low RH value. With 99% RH at night (12 h), night-time conidial production decreased with the previous daytime RH. After conidial production had started, small numbers of conidia were produced even when the RH was well below the threshold (94·5%). Conidia were produced in continuous light when the photon flux density was 2 μmol/m2 /s, but production was completely inhibited with 60 μmol/m2 /s. With constant RH, more conidia were produced with a 12 h photoperiod than in continuous darkness. However, more than 75% of the conidia were produced in the dark. With continuous darkness, more conidia were produced during the night (18.00–06.00 h) than during the day, but this biological rhythm was overcome with a (light-night)/(dark-day) regime. With constant 98–99% RH there was a linear increase in conidial production with temperature between 10 and 28°C, and virtually no conidia were produced at 33°C. The daily production of conidia increased with time for 2 to 6 days, depending on the treatment. 相似文献
3.
Cultivating with a flexible tine harrow in the autumn reduced densities of Stellaria media (L) Vill., Galium aparine L. and Brassica napus L. plants and thinned the wheat crop. Effects were more severe with two passes at right angles (plant stands were approximately halved) than with a single cultivation. Despite crop thinning, wheat yields were not reduced by autumn harrowing owing to compensatory increases in 1000-grain weights. Summer biomass of S. media and G. aparine was reduced more by spring than by autumn harrowing, while biomass of B. napus was only reduced by autumn harrowing. It was concluded that weakly rooted climbing or scrambling species are more easily controlled by cultivating in the spring, while species that develop a tap-root are more readily controlled by cultivating at an early growth stage in the autumn. L'effet de différentes fréquences d'hersage en automne on au printempssur le blé d'hiver, etsur les controles suivants Stellaria media (L.) Vill., Galium aparine L. et Brassica napus L. Les façons culturales effectuées à 1'automne avec une herse à trilles flexibles réduisaient le nombre de Stellaria media (L.) Vill., Galium aparine L. et Brassica napus L. et éclaircissaient la culture de blé. Les effets étaient plus importantes après deux passages perpendiculaires (densité des plantes divisée par environ 2) que par un seul passage. En dépit de l'éclaircissement, les rende-ments du blé n'ont pas été réduits par le hersage d'automne grâce à une compensation par le poids de 1000 grains. La biomasse d'été de S. media et G. aparineétait plus réduite par un hersage de printemps que d'automne, alors que la biomasse de B. napus n'était réduite que par un hersage d'automne. Les espéces grimpantes et faible-ment enracinées sont done plus facilement com-battues par des travaux de printemps, alors que celles qui présentent un racine pivotante sont plus facilement combattues par un hersage d'automne, à un stade précoce. Die Wirkung verschieden häufigen Eggens im Herbst oder im Frühjahr auf Wintenveizen und auf die Bekämpfung von Stellaria media (L.) Vill., Galium aparine L. und Brassica napus L. Eggen im Herbst mit einer beweglichen Zinkenegge verringerte die Dichte von Stellaria media (L.) Vill., Galium aparine L. und Brassica napus L. und reduzierte den Weizenbestand. Die Wirkungen waren durch 2 Arbeitsgänge im rechten Winkel zu einander, wobei der Pflanzenbestand ungefähr halbiert wurde, gegenüber einer einzelnen Bearbeitung ver-stärkt. Aufgrund eines ausgleichenden Anstiegs des Tausendkorngewichts wurden die Weizenerträge trotz Ausdünnung der Bestände nicht durch Eggen im Herbst reduziert. Die Sommerbiomasse von S. media und G. aparine wurde mehr durch Eggen im Frühjahr als durch Eggen im Herbst verringert, während die Biomasse von B. napus nur durch Eggen im Herbst reduziert wurde. Daraus folgt, daß schwach wurzelnde und kletternde Arten einfacher durch Eggen im Frühjahr bekämpfbar sind, Arten mit einer Pfahlwurzel besser im Herbst zu einem früheren Entwicklungsstadium. 相似文献
4.
MICHAEL J. BOERO DVM MS J. EUGENE SCHNEIDER DVM JACOB E. MOSIER DVM MS DiplomateACVIM MARK M. GUFFY DVM MS DiplomateACVR HUGH C. BUTLER DVM MS DiplomateACVS HORST W. LEIPOLD PhD 《Veterinary surgery : VS》1989,18(4):322-327
A 1 cm defect was created in the proximal medial cortex of 12 tibiae, cancellous bone was removed from the site, and the bones were fractured by loading in torsion. The fractures did not occur through the donor sites and the fracture patterns and loads to fracture were similar for the treated tibiae and their untreated mates. Cancellous bone was harvested from the proximal medial aspect of both tibiae in nine adult horses. The soft tissue wounds were monitored for more than 10 days in seven horses and healing of the osseous defects was evaluated radiographically at regular intervals to month 6 in two horses. The site provided convenient access with the horses in lateral or dorsal recumbency, the anatomic landmarks were reliable, and the surgical procedure was simple and short. Complications occurred in only three incisions. 相似文献
5.
Various control strategies for Achillea millefolium L. (yarrow) were investigated in a dense stand of the weed at Lincoln College in 1977–1978. In early spring plots were either rotary cultivated or left undisturbed. In late spring, plots of both previous treatments were either left undisturbed, rotary cultivated or sprayed with glyphosate at 1·5 kg ha?1. The whole experiment was rotary cultivated twice 1 week later and sown with Hordeum vulgure L. cv. Zephyr (barley) at 144 kg seed ha?1. MCPA + dicamba at 0·9+0·15 kg ha?1 was applied to half of each plot when the second node was detectable (Zadok 32). Rotary cultivation and glyphosate both substantially reduced the regrowth of A. millefolium but glyphosate reduced regrowth by a greater proportion when applied to undisturbed plants than when applied to plants regenerating after cultivation. Both gave a more than 95% reduction compared to the control (rotary cultivation only at sowing time) in the amount of A. millefolium present in the barley stubble in the autumn. MCPA + dicamba caused seedling mortality but did not affect the numbers of primary shoots from rhizome fragments. The grain yield of the barley increased from 2·91 t ha?1 when A. millefolium was not controlled to 4·23 t ha?1 with good control. The barley yield appeared to be restricted by competition from regenerating A. millefolium and by a nitrogen deficiency induced in some regimes by nitrogen immobilization in decaying rhizomes. 相似文献
6.
A new system for soil studies 总被引：1，自引：0，他引：1
BRUCE E. BUTLER 《European Journal of Soil Science》1982,33(4):581-595
7.
DAVID STOLOFF D.V.M. M.S… ‡ HUGH C. BUTLER D.V.M. M.S. § MARK M. GUFFY D.V.M. M.S. † § HORST W. LEIPOLD D.V.M. PH.D. § 《Veterinary surgery : VS》1979,8(2):38-45
An 18-week study was conducted to evaluate orthotopic osteochondral transplantation of the proximal femur in the dog. Eighteen dogs were divided into 3 groups of 6 each. The first group received autografts, the second received fresh allografts, and the third received grafts that had been frozen in a bone bank for 24–28 days. The grafts were fixed in position using dynamic compression plates. The grafted limbs were maintained in a sling and thus were nonfunctional and non-weight bearing throughout the 18-week study. Postoperatively the dogs were given oral tetracycline to assess osteo- cyte viability. The dogs were radiographed at 2–week intervals and 1 dog in each group was euthanatized every 3 weeks. The femurs were examined using standard histopathologic and fluorescent labeling techniques. All femoral heads were luxated by the 2nd postoperative week. The bones of all the femoral heads underwent avascular necrosis and degenerative changes were present in the transplanted cartilage by the 6th postoperative week. During the first 18 weeks following transplantation there was little radiographic and histologic difference among the 3 types of grafts regarding the nature and rate of bone healing. Based on the data obtained from techniques utilized in this study, the femoral head, neck, and articular cartilage did not survive, while the femoral diaphysis did survive the transplantation process. Different techniques may alter to some degree the results obtained. 相似文献
8.
STANLEY D. WAGNER DVM MS H. RODNEY FERGUSON DVM PhD DiplomateACVS HORST LEIPOLD DVM PhD MARK M. GUFFY DVM MS DiplomateACVR HUGH C. BUTLER DVM MS DiplomateACVs 《Veterinary surgery : VS》1987,16(1):65-69
Forty-eight thoracolumbar disc spaces were approached by a dorsolateral muscle-separating technique in six mature dogs. Twenty-four of the discs were fenestrated and curetted, and the changes were followed radiographically and histologically for 16 weeks. Disc space collapse was visible radiographically immediately after the surgical procedure, and those disc spaces remained narrow throughout the observation period. Histologically, there was evidence of chondrocyte activation within 2 weeks in the excavated disc spaces. By 16 weeks, fibrocartilage had filled the void in the curetted disc spaces. 相似文献
9.
BAYO J. ADEYANJU D.V.M. Ph.D. HUGH C. BUTLER D.V.M. M.S. † HORST W. LEIPOLD Dr.Med.Vet. Ph.D. 《Veterinary surgery : VS》1982,11(2):52-59
Sixteen unrelated beagles, randomly divided into groups of four, were used in evaluating the role of therapeutic immunosuppression in the healing of fresh cortical bone allografts over a 16-week period. The four groups included: nontreated allograft, treated allograft, nontreated autograft, and treated autograft. A 2.7-cm tibial cortical graft was fixed orthotopically using a dynamic compression plate. Healing was evaluated by radiography and by gross and histologic studies at 2, 4, 8, and 16 weeks after surgery. The treated dogs were immunosuppressed with azathioprine for eight weeks postsurgery. The conclusions were that: temporary immunosuppression did not significantly alter healing of fresh cortical bone autografts; healing of fresh cortical bone allografts in immunosuppressed dogs was similar to healing of fresh cortical bone autografts; slight differences were observed in the healing of bone grafts in all groups after eight weeks; and cellular reaction typical of graft rejection was found in nontreated allografts, but healing still occurred. 相似文献
10.