Factors affecting development of Septoria tritici in winter wheat and its effect on yield

Severe infection with Septoria tritici occurred in four of five experiments designed to create a series of different disease epidemics. These experiments successfully identified periods suitable for infection. They also indicated the effect of sprays, timed before and after these periods, on disease development and yield.
Analysis of disease progress and weather records suggested that critical conditions for initial development of S. tritici occurred during early May at four sites. Heavy rain giving at least 10 mm on 1 day or a total of 10 mm or more on 2 or 3 successive days occurred at all four sites prior to the appearance of symptoms on a particular leaf layer, though less heavy rain may suffice to splash inoculum onto upper leaves in shorter, immature canopies where stem elongation is incomplete. At the fifth site, infection occurred later in May and disease failed to develop to a significant degree. At all sites, the length of the incubation period on any of the top three leaves was found to be between 396 and 496 degree days.
Control of winter epidemics of S. tritici had little effect on yield, whereas spray sequences commencing later than growth stage (GS) 31 but immediately prior to the critical periods provided the best disease control and yield benefit. Regression models incorporating, as independent variables, area under the S. tritici disease progress curve for any of the top three leaves from their emergence (GS 32-37) satisfactorily explained yield loss at the four sites where disease was severe. Consideration of leaf 2 or leaf 3 alone accounted for more than 82% of the variance at each site and a yield loss from infection of leaf 2 related to thermal time is suggested as 0.00265% per C per day from the appearance of symptoms.     

First record of Tapesia yallundae as the teleomorph of Pseudocercosporella herpotrichoides var. acuformis, and its occurrence in the field in the Federal Republic of Germany

Tapesia yallundae is reported for the first time in the Federal Republic of Germany. Apothecia were found on wheat and rye stubble at two sites in the north of the country and one in the centre, in April 1988. Isolates of Pseudocercosporella herpotrichoides var. acuformis were obtained from germinating single ascospores, identified on the basis of colony morphology, mode of conidial production and pathogenicity to wheat and rye.     

Observations of apothecia of Tapesia yallundae and the cultural phenotypes of their progeny

Apothecia of Tapesia yallundae, the perfect state of Pseudocercosporella herpotrichoides, were found in March 1989 on wheat and barley stubble at nine of 37 naturally infested sites and also at one inoculated site in Germany. Apothecia were found on about 1% of stems collected from the naturally infested sites and 5% of stems from the inoculated site, and were first found in the second week of March, coinciding with the onset of an early spring. Apothecia were not found on either green plants or second-year stubble. In total, 143 single-spore isolates were obtained from the apothecia and described according to a range of morphological characteristics. The majority were ascribed to P. herpotrichoides var. herpotrichoides. This is the first isolation of this variety from T. yallundae apothecia in Germany. Even single-conidial isolates from one apothecium showed much variation, some being like var. herpotrichoides, some like var. acuformis and some intermediate.     

Gaseous diffusion through peat

Relative gas diffusivity (D/D₀) was measured in peat cores equilibrated to set moisture tensions between zero and - l0 kPa, using the radioactive gas ⁸⁵Kr. A relationship between relative diffusivity and the air filled porosity was obtained, which showed lower values of D/D₀ at air-filled porosities above about 0.13m³m⁻³, and higher values at porosities below about 0.10m³m⁻³ than some of those found in the literature for mineral soils. The likely effects of shrinkage behaviour on drying in the field, on the relationship between D/D₀ and air-filled porosity, are discussed.     

Antagonism of endotoxin-induced disruption of equine gastrointestinal motility with the platelet-activating factor antagonist WEB 2086

The effect of pre-treatment with a selective platelet-activating factor (PAF) antagonist, WEB 2086, on the actions of low-dose endotoxin was evaluated in ponies prepared with gastrointestinal strain gauges. Endotoxin (0.1 microgram/kg i.v.) produced a marked reduction in gastric contraction amplitude and rate, and an increased frequency and reduced duration of jejunal phase III activity fronts (AFs). WEB 2086 (6.6 mg/kg) administered i.v. 10 min before the endotoxin, produced significant antagonism (P less than 0.001) of the effect of endotoxin on gastric contraction amplitude and rate. The combination of WEB 2086 and endotoxin produced gastric contractions of significantly (P less than 0.01) higher frequency than in the control studies. WEB 2086 also reduced endotoxin-induced abnormal phase III AFs in the jejunum and increases in heart rate and packed cell volume. These results provide evidence that endogenous PAF plays a role in mediating the acute effects of endotoxin on equine gastrointestinal motility.     

Analgesia in Dogs After Intercostal Thoracotomy: A Clinical Trial Comparing Intravenous Buprenorphine and Interpleural Bupivacaine

We prospectively studied 26 dogs that presented for intercostal thoracotomy. Dogs were pre-medicated with oxymorphone, induced with diazepam and etomidate, and anesthesia was maintained with isoflurane in oxygen. Preoperatively, animal patients were randomly assigned to one of two groups. Group 1 (n = 13) received buprenorphine (10 μg/kg intravenously [IV]) every 6 hours for 24 hours starting 10 minutes before tracheal extubation. Group 2 (n = 13) received 0.5% bupivacaine (1.5 mg/kg) administered interpleural (IP) by slow injection through a pediatric feeding tube fixed to the most dorsal aspect of the thoracotomy incision. Interpleural injections were administered with each dog placed in lateral recumbency with the incision positioned ventrally; IP injections were administered every 4 hours for 24 hours starting 10 minutes before tracheal extubation. All cases were monitored in the intensive care unit for 24 hours postoper-atively. The analgesic efficacy of each regimen was evaluated using a pain scoring system that included a subjective pain score, heart rate, and respiratory rate. Arterial blood pressure, arterial blood gases, oxygen saturation, body temperature, and changes in the electrocardiogram or neurological status were also noted. Significant increases in mean heart rate, respiratory rate, and total pain score occurred after surgery in dogs in the buprenorphine group. In contrast, dogs in the bupivacaine group had no significant changes when compared with their preoperative values. Dogs in the bupivacaine group had significantly decreased total pain scores and better PaO₂ and oxygen saturation values when compared with the dogs receiving buprenorphine. Hypoventilation did not occur in either group.     

Significance for exercise capacity of some electrocardiographic findings in racehorses

Summary Various cardiorespiratory and metabolic indices were assessed during treadmill exercise in Thoroughbred and Standardbred racehorses with T wave changes in 4 or more leads on the electrocardiogram or second-degree atrio-ventricular (AV) block, and in horses that had no abnormalities on clinical examination, resting electrocardiography or upper respiratory tract endoscopy. No significant differences in heart rate, plasma lactate concentration, arterial blood gases, oxygen uptake, run time, peak velocity, or blood and red cell volumes were found between normal horses and horses with T wave changes or second-degree AV block. These results indicate that some electrocardiographic findings that are considered by some clinicians to indicate cardiac dysfunction, may have little effect on exercise capacity.