CHEMICAL FALLOW CONTROL OF NUTSEDGE

Summary. Field experiments were conducted to find a herbicide for complete control of nutsedge ( Cyperus rotundus L.). We applied seventeen herbicides and some of their combinations as chemical fallow. EPTC and CP-31675 (6- tert -butyl-2-chloro-o-acetotoluidide) gave good but only temporary control of nutsedge. Dichlobenil at 2·5 or 5 lb/ac gave fair control for 1 year. Rates of 10 or 20 lb/ac of dichlobenil controlled nutsedge completely for 1 year but severely reduced the yield of oats planted 5 months after application. The highest rate completely killed tubers and prevented reinfestation for 1 year. Analyses indicated no residue of dichlobenil or of its metabolite, 2,6-dichlorobenzoic acid, in vegetative parts and seeds of oats planted 5 months after application of 2.5, 5 or 10 lb/ac of dichlobenil. At equivalent rates the herbicide TH-073-H (N-hydroxymethyl-2,6-dichlorothiolbenzamide) gave control of nutsedge similar to that with dichlobenil. The combinations of 8 lb/ac amitrole-T and 10 lb/ac dichlobenil or TH-073-H were just as effective in controlling nutsedge shoots and tubers as dichlobenil or TH-073-H applied alone. The mixture of dichlobenil plus CP-31675, each at 5 lb/ac, gave excellent control of nutsedge and tubers for 1 year. The herbicides terbacil ( 3-ter -Nbutyl-5-chloro-6-methyluracil) or Du Pont 733 ( 3-tert -butyl-5-bromo-6-methyluracil) at 10 lb/ac provided almost complete control of nutsedge. Application of terbacil to plants aged 4–6 weeks gave better results than application to mature nutsedge in the fall.
La lutte chimique contre le cypirus     

Use of a laryngeal mask airway in rabbits during isoflurane anesthesia

The purpose of this study was to find out if an LMA (#1 LMA‐Classic) would provide a better airway than a face mask in spontaneously breathing anesthetized rabbits, and to test if it could be used for mechanically controlled ventilation. Sixteen rabbits (4.1 ± 0.8 kg, mean ± SD) were assigned randomly to three treatment groups; face mask with spontaneous ventilation (FM‐SV; n = 5), LMA with spontaneous ventilation (LMA‐SV; n = 5), and LMA with controlled ventilation (LMA‐CV; n = 6). Rabbits were anesthetized in dorsal recumbency using a circle circuit at constant ET isoflurane (2.3%, Datex airway gas monitor) and constant rectal temperature (38.85 °C) for 2 hours. PaCO₂, PaO₂, minute volume, tidal volume (Wright's respirometer), and Pe CO₂ were measured at 15 minute intervals. Two individuals in the FM‐SV group had PaCO₂ >100 mm Hg (>13.3 kPa). One rabbit in the FM‐SV had PaO₂ <80 mm Hg (<10.7 kPa). All FM‐SV rabbits showed signs of airway obstruction and two were withdrawn from the study at 45 and 90 minutes, respectively, because of cyanosis. Tidal volume could not be measured in the FM‐SV group. No signs of airway obstructions were observed in either of the LMA groups. Four rabbits in the LMA‐CV group developed gastric tympany, and one of these refluxed after 110 minutes. The significance of differences between the two spontaneously breathing groups and between the two LMA groups were measured using Wilcoxon's rank sum test (with significance assumed at p < 0.05). There were no statistical differences between FM‐SV and LMA‐SV in any variable tested. PaCO₂ and Pe ′CO₂ were less in the LMA‐CV group than in the LMA‐SV group, while PaO₂, tidal volume, and minute volume were all more. We conclude that biologically, the LMA provides a better airway than the face mask during spontaneous breathing and that it can be used for IPPV, but that gastric tympany is likely to occur during IPPV.     

Morphological characteristics of blood cells in monitor lizards: is erythrocyte size linked to actual body size?

Blood cell morphology and count are not uniform across species. Recently, between‐species comparisons revealed that the size of red blood cells is associated with body size in some lizard taxa, and this finding was interpreted in the context of the metabolic theory. In the present study, we examined the numbers and the size of blood cells in 2 species of monitor lizards, the mangrove‐dwelling monitor (Varanus indicus) and the savannah monitor (V. exanthematicus), and we compared these traits in individuals of different body size. The results revealed that during the course of ontogeny, the size of red blood cells increases with body mass. Because the mass‐specific metabolic rate decreases with body size and the cell volume‐to‐surface ratio decreases with the cell size, changes in the erythrocyte size might be the result of oxygen transport adjustment.     

Revival of a well-known, but ignored correction term for χ2 in linkage analysis with small samples

The ‘classical’χ² test is routinely applied in linkage analysis. The values customarily used, however, are only approximations since continuous χ² terms are used instead of discrete multinomial terms. This error becomes increasingly important as the sample becomes small. In this note, a well-known correction term for improvement of this approximation is revived and numerically calculated for some interesting cases from linkage studies.     

Climate change record in subsurface temperatures: A global perspective

Analyses of underground temperature measurements from 358 boreholes in eastern North America, central Europe, southern Africa, and Australia indicate that, in the 20th century, the average surface temperature of Earth has increased by about 0.5 degreesC and that the 20th century has been the warmest of the past five centuries. The subsurface temperatures also indicate that Earth's mean surface temperature has increased by about 1.0 degreesC over the past five centuries. The geothermal data offer an independent confirmation of the unusual character of 20th-century climate that has emerged from recent multiproxy studies.     

Effect of adenosine infusion on isoflurane MAC in dogs.

Adenosine is a potent analgesic in people and reduces the MAC of halothane in dogs. The purpose of this study was to determine whether adenosine reduces the MAC of isoflurane in dogs. Seven beagles (four males and three females) were anesthetized and randomly assigned to receive adenosine (0.3 mg kg^–1 minute^–1; 6 mL kg^–1 hour^–1, IV) or saline (0.9%, 6 mL kg^–1 hour^–1IV). After an interval of ≥7 days, each dog was reanesthetized and treated with the alternate infusion. Anesthesia was induced and maintained with isoflurane in oxygen. Dogs were intubated and instrumented for measurement of mean systemic arterial blood pressure and airway concentration of isoflurane and end‐tidal partial pressure of carbon dioxide. The MAC for isoflurane was determined using the tail‐clamp technique. Baseline MAC values were 1.25 (1.15, 1.35)% [median (minimum, maximum)] and 1.25 (1.05, 1.45)% before the saline and adenosine treatments, respectively. After 2 hours of infusion with saline or adenosine, MAC values were not different (p = 0.156) and were 1.25 (0.95, 1.35)% and 1.05 (1.00, 1.25)%, respectively. Two hours following the end of each infusion, the MAC values for saline and adenosine treatment groups differed significantly (p = 0.015), but by no more than the normal variation inherent in this study, and were 1.15 (1.15, 1.35)% and 1.05 (1.05, 1.25)%, respectively. Mean arterial blood pressure was 93 (74, 123) mm Hg for saline treated dogs and 67 (52, 72) mm Hg (p = 0.008) during adenosine infusion. End‐tidal carbon dioxide was not different between the two treatment groups. We conclude that adenosine administered at 0.3 mg kg^–1 minute^–1had no effect on isoflurane MAC in dogs, but decreased mean arterial blood pressure.     

Antifungal activity of bergenin, a constituent of Flueggea microcarpa

The antifungal activity of bergenin against some plant pathogenic fungi, namely, Alternaria alternata , A. brassicae , A. carthami , Fusarium udum , F. oxysporum f.sp. ciceri , Curvularia lunata and Erysiphe pisi , was studied. Bergenin as its monosodium salt was effective against all the fungi and the effective dose for complete inhibition of spore germination varied from 15 μg mL⁻¹ for F. udum to 125 μg mL⁻¹ for E. pisi . Experiments on the effect of bergenin on powdery mildew development under glasshouse conditions revealed that it can control powdery mildew of pea at 2000 μg mL⁻¹ by postinoculation treatment, the results being comparable with those of carbendazim (1000 μg mL⁻¹) and wettable sulfur (2000 μg mL⁻¹). It affected hyphal elongation and the number of primary and secondary branches.