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1.
In greenhouse and field experiments, an oil-in-water emulsion of unrefined corn oil and Silwet L-77 increased the biological weed control efficacy of Colletotrichum truncatum (Schw.) Andrus et Moore for control of the weed, hemp sesbania ( Sesbania exaltata [Raf.] Rydb. ex A.W. Hill). The surfactant – corn oil emulsion stimulated germination and appressoria formation in vivo and in vitro and delayed the need for dew. We hypothesize that the corn oil protected the conidia from desiccation during the dew-free period and the surfactant stimulated spore germination and appressoria formation. In field experiments conducted over 3 years, a single application of a 50% (v/v) unrefined corn oil tank mixture containing 0.2% (v/v) Silwet L-77 surfactant controlled hemp sesbania in soybeans an average of 95%. Aqueous fungal suspensions or adjuvants alone did not visually affect or control hemp sesbania. The soybean yields were significantly higher in the plots where weeds were effectively controlled. These results suggest that formulating C. truncatum in unrefined corn oil and surfactant greatly increases its infectivity and the biocontrol potential of this pathogen. 相似文献
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Soil structural quality, compaction and land management 总被引:3,自引:0,他引:3
B. C. BALL D. J. CAMPBELL J. T. DOUGLAS J. K. HENSHALL M. F. O'SULLIVAN 《European Journal of Soil Science》1997,48(4):593-601
Soil compaction is a concern worldwide, particularly where compactible soils are used for intensive agriculture in a wet climate. We have investigated the impact of compaction and the associated changes in soil structural qualities on crop production and environmental pollution. The overall objective was to develop soil management systems that provide suitable conditions for crop growth and minimize environmental damage. We ran large-scale field experiments studying the preservation of structural quality in arable and permanent grassland, using management systems such as the control or elimination of field traffic and the application of conservation tillage and zero tillage. We measured bulk density, shear strength, cone resistance, macroporosity, relative diffusivity, air permeability and water infiltrability to identify soil qualities that could be used for selecting suitable soil management. Along with crop yield, we measured environmental impacts, such as the emissions of nitrous oxide from the soil, which require the interaction of soil structure and water content near the soil surface. Soil structure influenced wetness, which affected trafficability, compaction and nitrogen retention. Measurement of properties that affect fluid storage and transport, such as macroporosity, provided soil quality indices that helped in recommending suitable soil management systems. Spatial variation of structure associated with wheel-track locations could be estimated rapidly using a cone penetrometer. Variation was particularly important in determining crop yield consistency. Crop productivity and soil structural qualities were preserved best when field traffic was eliminated. A reduced ground-pressure system successfully minimized compaction in grassland but was less effective in an arable rotation. Unless traffic is eliminated, good timing of operations is the most effective way to preserve soil structural quality. 相似文献
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BRADLEY R. JACKMAN DVM MS GARY M. BAXTER VMD MS DIPIOMATE ACVS RICHARD E. DORAN DVM MS Dipiomate ACVS DOUGLAS ALLEN DVM MS Dipiomate ACVS ANDREW H. PARKS MA VET MB Dipiomate ACVS 《Veterinary surgery : VS》1993,22(4):285-288
The medical records of 57 horses that had palmar digital neurectomy performed between 1984 and 1990 were reviewed. Neurectomies were performed either by transection and elec-trocoagulation (47 horses) or by the guillotine technique (10 horses). Middle-aged geldings, Quarter Horses, and Thoroughbreds were significantly over-represented when compared with the hospital population. Horses used as hunter/jumpers also appeared to be over-represented. Complications occurred in 17 (34%) of the 50 horses for which follow-up information was obtained. Recurrence of heel pain was the most common complication (14 horses). Palpable painful neuromas were detected in three horses. One year after neurectomy, 74% of the horses were sound; this decreased to 63% after 2 years. 相似文献
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P. D. ECKERSALL A. S. NASH† G. M. MARSHALL T. A. DOUGLAS 《The Journal of small animal practice》1986,27(6):411-418
Canine steroid-induced alkaline phosphatase (SIAP) has been measured quantitatively in an assay which depends on the finding that L-phenylalanine has a greater inhibitory effect on SIAP than on other plasma isoenzymes. The assay has advantages in precision, practicability and availability over other assays for SIAP. The steroid-induced isoenzyme was shown to contribute over 40 per cent of the total alkaline phosphatase (AP) activity in over 60 per cent of cases in which the level of AP was raised. 相似文献
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THE INFLUENCE OF SIZE OF SPRAY DROPLETS ON THE HERBICIDAL ACTIVITY OF DIQUAT AND PARAQUAT 总被引:1,自引:0,他引:1
G. DOUGLAS 《Weed Research》1968,8(3):205-212
Summary. Single droplets ranging in size from 250 to 1000 μ diameter and concentrations of diquat and paraquat over the range 0–09–0.75% ion were examined for herbicidal activity. Size of droplet and concentration of herbicide in the droplet were shown to have a marked influence on activity. An increase in droplet size above 250 μ increased herbicidal efficiency. An optimum was reached between 400 and 500 μ while activity fell off with a further increase to 1000 μ. 相似文献
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DOUGLAS ALLEN Jr . dvm ms Diplomateacvs NATHANIEL A. WHITE II dvm ms Diplomateacvs DAVID E. TYLER dvm PhD Diplomateacvp 《Veterinary surgery : VS》1988,17(1):10-14
The morphologic effects of induced intraluminal hydrostatic pressures (IHPs) of 0, 9, and 18 cm H2 O were evaluated in 33 isolated equine jejunal segments. Fifteen segments were distended with Tyrode's solution for 1 hour and nine segments for 4 hours. Tyrode's solution was added as needed to maintain the prescribed pressures. Nine other segments were left undisturbed for 4 hours after the initial distention period. On decompression of the intestinal segments, progressive peristaltic contractions resumed in all segments. Evaluation of intestinal sections by light microscopy and transmission electron microscopy showed edema of the villi and submucosa and separation of the epithelial cells adjacent to the basement membrane in all segments. The epithelial cell necrosis found in ischemic intestine was not seen. This study indicates that the necrosis found at the villous tips in distended sections of small intestine remote from the site of obstruction cannot be reproduced by IHP increases of 4 hours duration. 相似文献