Greater Injury Research Articles

Interactions of Foliar Insecticides Applied with Pyrithiobac

Field and greenhouse experiments were conducted to determine the effect of selected insecticides on cotton when applied in combination with pyrithiobac. In the field, acephate, azinphos-methyl, bifenthrin, chlorpyrifos, dicrotophos, esfenvalerate, malathion, methomyl, or oxamyl was applied foliarly with the sodium salt of pyrithiobac at 70 g ae/ha. Pyrithiobac plus malathion resulted in greatest injury when compared with other treatments. There were no differences observed in fruiting characteristics of cotton. Cotton yield was lower with oxamyl, methomyl, and chlorpyrifos when applied in combination with pyrithiobac in one of three experiments. In greenhouse experiments, injury due to pyrithiobac was greater in a cool (21 C day, 13 C night) temperature than in a warm temperature (30 C day, 21 C night), but differences were less than 15%. Pyrithiobac plus malathion in the cool environment injured cotton more severely 7 DAT than either pesticide alone. Adding insecticides to pyrithiobac did not influence injury in the warm environment.

Developmental patterns of expected consequences for simulated bicycle injury events.

Bicycle injuries follow a developmental pattern that differs from that of most injuries, where toddlers and individuals in young adulthood are most at risk. Children in late childhood and early adolescence appear most at risk for bicycle injuries. The present study of 2nd-grade, 4th-grade, 6th-grade, and undergraduate college students documented that after videotaped simulations of bicycle injury events, younger children anticipated greater injury severity and more fear than older children and adolescents. The potential influence of reduced expectations for injury with increasing age is described, and challenges are advanced for establishing the link between lowered injury expectancies and increased risky behavior.

Prevention of lung reperfusion injury in rabbits by a monoclonal antibody against interleukin-8.

Re-establishing blood flow to ischaemic tissues causes greater injury than that induced during the ischaemic period. This type of tissue injury, reperfusion injury, is involved in frostbite, multiple organ failure after hypovolaemia and in myocardial infarction. Depletion of neutrophils alleviates reperfusion injury, implying a causal role of neutrophil infiltration. Among members of the recently discovered family of chemotactic cytokines (chemokines), interleukin-8 (IL-8) is a major neutrophil chemotactic and activating factor produced by various types of human cells. We investigated its pathophysiological role in a rabbit model of a lung reperfusion injury. Reperfusion of ischaemic lung caused neutrophil infiltration and destruction of pulmonary structure, as well as local production of IL-8. Furthermore, the administration of a neutralizing monoclonal antibody against IL-8 prevented neutrophil infiltration and tissue injury, proving a causal role of locally produced IL-8 in this model.

Oxyfluorfen Under Clear Polyethylene Film Controlled Weeds in Transplanted Cucurbits

Oxyfluorfen (0.28, 0.42, 0.56, and 0.84 kg ai ha−1) under clear polyethylene film was evaluated for weed control, crop injury, and effects on yields in transplanted muskmelon, cucumber, and summer squash. Numerous narrowleaf and broadleaf weeds were effectively suppressed by 0.42 ha−1of oxyfluorfen. Crop injury, occurring soon after transplanting, was reported in New York and North Carolina. Injury was usually transient, and injured crops frequently grew more vigorously than those grown on untreated black polyethylene mulch. Muskmelons were consistently the most tolerant of the three crops. At high rates, yields of squash and cucumber in 1988 were reduced in New York and North Carolina, respectively. In greenhouse studies, positioning the cotyledons under the polyethylene film caused greater injury in all three crops than when cotyledons remained above the plastic.

Insecticides Do Not Affect Cotton (Gossypium hirsutum) Response to Imazaquin and Imazethapyr

Field and greenhouse experiments evaluated interactions of soil-applied insecticides and imazaquin and imazethapyr on growth and development of cotton. Imazaquin and imazethapyr were applied PPI at 0 to 6 and 0 to 16 g ae ha−1, respectively, in the greenhouse (plus a no-insecticide control), and 0 to 72 g ha−1in the field in combination with aldicarb, disulfoton, and phorate (without a no-insecticide control) applied in the seed furrow. Cotton shoot fresh weight in the greenhouse experiment decreased linearly as herbicide rates increased. Greater reductions in shoot fresh weight were noted with imazaquin than with imazethapyr. Compared with no insecticide, the methylcarbamate insecticide aldicarb and the organophosphate insecticides disulfoton and phorate did not affect cotton response to either herbicide. In the field, cotton injury increased while stand, yield, and maturity decreased as herbicide rates increased. Delayed maturity was due to a lower percentage of bolls produced on sympodia from main stem nodes four to nine. Imazaquin caused greater injury, greater reductions in stand, greater delays in maturity, and lower yields than did imazethapyr. Earlier maturity was noted with aldicarb-treated cotton. Compared with aldicarb, disulfoton and phorate did not alter cotton response to imazaquin or imazethapyr.

Rose (Rosa dilecta) Response to Simulated Herbicide Drift

This study evaluated the response of rose to different herbicides applied as simulated drift. Chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]benzenesulfonamide}, thifensulfuron {3[[[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino]carbonyl]amino]sulfonyl]-2-thiophenecarboxylic acid}, bromoxynil(3,5-dibromo-4-hydroxybenzonitrile), 2,4-D[(2,4-dichlorophenoxy)acetic acid], glyphosate [N-(phosphonomethyl) glycine], and a combination of 2,4-D and glyphosate were applied over the top of established rose plants at 1/3, 1/10,1/33, and 1/100 of the maximum labeled rate for grains. All herbicides injured rose. The greatest injury was from chlorsulfuron and 2,4-D, and the least injury was from bromoxynil and glyphosate. Plants recovered from the injury caused by all treatments except for the highest rates of chlorsulfuron and 2,4-D, which continued to show significant injury at the end of the growing season. Although all herbicides had characteristic symptoms, some of these were very similar to those caused by other stresses. Therefore, because of the potential ambiguity of visual symptoms, any allegation about herbicide drift should be based on a report of all symptoms and should be supported by residue analysis.

Ionic mechanisms of anoxic injury in mammalian CNS white matter: role of Na+ channels and Na(+)-Ca2+ exchanger

White matter of the mammalian CNS suffers irreversible injury when subjected to anoxia/ischemia. However, the mechanisms of anoxic injury in central myelinated tracts are not well understood. Although white matter injury depends on the presence of extracellular Ca2+, the mode of entry of Ca2+ into cells has not been fully characterized. We studied the mechanisms of anoxic injury using the in vitro rat optic nerve, a representative central white matter tract. Functional integrity of the nerves was monitored electrophysiologically by quantitatively measuring the area under the compound action potential, which recovered to 33.5 +/- 9.3% of control after a standard 60 min anoxic insult. Reducing Na+ influx through voltage-gated Na+ channels during anoxia by applying Na+ channel blockers (TTX, saxitoxin) substantially improved recovery; TTX was protective even at concentrations that had little effect on the control compound action potential. Conversely, increasing Na+ channel permeability during anoxia with veratridine resulted in greater injury. Manipulating the transmembrane Na+ gradient at various times before or during anoxia greatly affected the degree of resulting injury; applying zero-Na+ solution (choline or Li+ substituted) before anoxia significantly improved recovery; paradoxically, the same solution applied after the start of anoxia resulted in more injury than control. Thus, ionic conditions that favored reversal of the normal transmembrane Na+ gradient during anoxia promoted injury, suggesting that Ca2+ loading might occur via reverse operation of the Na+)-Ca2+ exchanger. Na(+)-Ca2+ exchanger blockers (bepridil, benzamil, dichlorobenzamil) significantly protected the optic nerve from anoxic injury. Together, these results suggest the following sequence of events leading to anoxic injury in the rat optic nerve: anoxia causes rapid depletion of ATP and membrane depolarization leading to Na+ influx through incompletely inactivated Na+ channels. The resulting rise in the intracellular [Na+], coupled with membrane depolarization, causes damaging levels of Ca2+ to be admitted into the intracellular compartment through reverse operation of the Na(+)-Ca2+ exchanger. These observations emphasize that differences in the pathophysiology of gray and white matter anoxic injury are likely to necessitate multiple strategies for optimal CNS protection.

Tolerance to Steering Wheel-Induced Lower Abdominal Injury

Anesthetized swine were tested for biomechanical and injury responses to lower abdominal steering wheel loading. The lower abdomens of 25 subjects were impacted with a segmented steering wheel. Tests included a wide spectrum of velocities, from 1.7 to 12.4 m/s, and forced abdominal compressions of 7.0%-54.5% of the vertical thickness of the lower abdomen. Lower abdominal injuries included contusions and lacerations of varying severity and frequency in the mesentery, the small and large bowel, the spleen, and the cecum. Logistic regression correlations were performed to assess the probability of severe and greater injury with biomechanical indices such as peak velocity of deformation (Vmax), peak compression (Cmax), peak total force (Fmax), the maximum Viscous criterion (VCmax), and the product of maximum total force and maximum compression (FmaxCmax). Although Cmax, Fmax, and, to a lesser extent, FmaxCmax correlated reasonably well with the probability of severe and greater injury, the maximum Viscous criterion (VCmax) was the best correlate, establishing VCmax as the most effective predictor of an AIS greater than or equal to 4 injury risk for steering wheel loading to the lower abdomen.

Response of "Murcott" mandarine to storage temperature

Research into the effects of cold-storage and shelf-life on the hybrid mandarin «Murcott» showed the best results with storage at 6°C or 6°C for 6 days and 14°C for 1 day. Longer or lower temperature cycles: 6°C for 18 days and 14°C for 7 days; 2°C for 18 days and 14°C for 7 days; 2°C for 6 days and 14°C for 1 day, caused greater chilling injury and higher weight loss. The production of ethanol and other metabolites in the juice proved to be low during storage, especially at a constant 6°C or at 6°C for 6 days and 14°C for 1 day cycle, with a marked increase in shelf-life. No endogenous ethylene was produced, and due to their resistance to microbiological infection (with no post-harvest protection), these mandarins responded well to 2 months cold-storage, followed by 2 weeks of shelf-life under all the temperatures tested.

Euonymus Scale (Homoptera: Diaspididae) Effects on Plant Growth and Leaf Abscission and Implications for Differential Site Selection by Male and Female Scales

Effects of infestation by the euonymus scale, Unaspis euonymi (Comstock) on leaf abscission and growth of the woody plant Euonymus fortunei (Turcz) Rand.-Mazz. were measured in the field during 1985 and 1986. During the first summer, leaf abscission by infested plants significantly increased in August and September, coinciding with development of the second generation of scale insects. Infested plants suffered relatively greater winter injury than did uninfested plants, so that by spring 1986, they supported significantly lower stem and leaf weights. Reduction in root weight of infested plants was not evident until July of the second growing season. Proportionately more mortality of leaf tissue than of stem tissue occurred during the winter, so that the probability of plant tissue bearing over wintering females surviving until spring was nearly three times higher for stems than for leaves. We suggest that the characteristic distribution of U. euonymi with males mainly on leaves and longer-lived females on stems reflects the relatively greater risk to females of mortality from leaf abscission and from winter injury to leaves.

Ammonia-induced injury in pure cultures and natural populations of coliform bacteria

Ammonia-induced injury was investigated in pure cultures of Escherichia coli and Enterobacter aerogenes, and in natural coliform populations obtained from the oligotrophic Luxapallila and the eutrophic Sunflower Rivers in northern Mississippi. Pure cultures were affected by ammonia exposure as indicated by changes in the injury ratio (IR) of CFU on m-T7 agar/CFU on m-Endo agar. Ammonia concentrations between 0 and 20 (mg NH3-N/1) had little or no effect and concentrations between 40 and 80 caused the greatest injury. Natural coliform populations from the oligotrophic river were more prone to ammonia-induced injury than those from the eutrophic river. The results stress the need for the routine use of m-T7 media and the enumeration of injured cells when using the membrane filter procedure to ascertain domestic water quality.

Ammonia-induced injury in pure cultures and natural populations of coliform bacteria.

Ammonia-induced injury was investigated in pure cultures of Escherichia coli and Enterobacter aerogenes, and in natural coliform populations obtained from the oligotrophic Luxapallila and the eutrophic Sunflower Rivers in northern Mississippi. Pure cultures were affected by ammonia exposure as indicated by changes in the injury ratio (IR) of CFU on m-T7 agar/CFU on m-Endo agar. Ammonia concentrations between 0 and 20 (mg NH3-N/1) had little or no effect and concentrations between 40 and 80 caused the greatest injury. Natural coliform populations from the oligotrophic river were more prone to ammonia-induced injury than those from the eutrophic river. The results stress the need for the routine use of m-T7 media and the enumeration of injured cells when using the membrane filter procedure to ascertain domestic water quality.

Phytotoxicity and Yellow Nutsedge Control in Azalea and Liriope with Basagran (bentazon)

Abstract Tolerance of eight azalea cultivars and three liriope cultivars to two broadcast applications of Basagran at 1.1 and 2.2 kg/ha (1.0 and 2.0 lb/A) was determined in container studies. No injury was observed on azalea cultivars ‘Rosebud’, ‘Tradition’, ‘Delaware Valley White’ or ‘Elsie Lee’ 40 days after the second application of Basagran at 2.2 kg ai/ha (2.0 lb/A) plus crop oil. This treatment injured ‘Hershey's Red’ and ‘Girard's Rose’, but two applications of Basagran at 2.2 kg/ha applied alone or at 1.1 kg/ha (1.0 lb/A) with or without crop oil did not injure these two varieties. Slight injury (16%) was observed on ‘Corsage’ 20 days after the second application of Basagran at 1.1 kg/ha (1.0 lb/A), although no injury was seen with other treatments. Greater injury (22 to 35%) occurred to ‘Pleasant White’ 20 days after treatment when Basagran was applied twice at 1.1 or 2.2 kg/ha (1.0 or 2.0 lb/A) with or without crop oil. Injury to all azalea cultivars decreased with time, with no injury apparent 70 days after treatment. Greater injury (22 to 27%) was observed in variegated than green liriope or Liriope spicata (8 to 13%) 20 days after the second application of Basagran at 1.1 or 2.2 kg/ha (1.0 or 2.0 lb/A) with or without crop oil. Addition of crop oil improved the control of yellow nutsedge with Basagran at 1.1 or 2.2 kg/ha (1.0 or 2.0 lb/A).

Effects of photochemical smog on growth, injury, and gas exchange of pine seedlings

One-year-old seedlings of Pinus coulteri, P. pondersosa, P. jeffreyi, and P. sylvestris were exposed for 5 months to ambient photochemical smog (average 24-h monthly concentrations of ozone 0.067 to 0.108 ppm) in the San Gabriel Mountains of the Los Angeles Basin. Plants were grown in open-top chambers ("ambient-air" and "clean-air" treatments) and in outside plots. Rinsing of needles as well as scanning electron microscope observations revealed the highest deposition of particles to plants in the outside plots. No significant changes in growth in any of the studied species were observed. Exposure to photochemical smog had no significant effect on net photosynthesis and dark respiration in P. coulteri and P. ponderosa. Visual observation of injury showed that, by the end of the exposures, the P. ponderosa foliage in the ambient-air treatments was more damaged than in the clean-air treatment, but no negative effects on P. coulteri and P. jeffreyi foliage were seen. A tendency towards greater injury of P. sylvestris foliage in the ambient-air chambers and in the outside plots was also determined. Scanning electron microscope observations showed some subtle changes in the surface of P. coulteri and P. sylvestris in the ambient air treatment. Longer, multiseasonal exposures seem to be needed to study the effects of ambient concentrations of photochemical pollutants on forest trees.

Seasonal Variations in Jack Pine (Pinus banksiana)and White Spruce (Picea glauca)Tolerance to Glyphosate and Triclopyr

Seasonal variations in tolerance of jack pine and white spruce to glyphosate and triclopyr were investigated in field and growthroom studies. Foliar injury was higher in both species following field applications of herbicides in July during periods of active growth than in September and October when the plants were not growing actively. Herbicides applied to trees in the growthroom 3 weeks after bud break caused greater injury than applications either before or 14 weeks after bud break. White spruce tolerated both glyphosate and triclopyr better than jack pine. Triclopyr injured both species more than glyphosate. Chemical analysis and electron micrographs showed that the cuticular wax deposition on both species was greater in field-grown trees than in growthroom-grown trees and was greater at 14 weeks after bud break than at 3 weeks. Increased wax deposition with time after bud break may reduce herbicide uptake and may account partially for the increased tolerance of both species to glyphosate and triclopyr.

Cell Membrane Permeability and Ultrastructural Effects of Difenzoquat on Wild Oats (Avena fatua)

Effects of difenzoquat on wild oats grown under controlled environmental conditions were studied. Seedling height and fresh weight were significantly reduced 5 days after postemergence treatment. Dose-dependent increase in cell membrane permeability was detected after a 12-h exposure to the herbicide. Scanning electron micrographs showed normal leaf hairs and cuticular wax but swollen guard cells 10 days after treatment. Ultrastructural changes occurred before the visible symptoms. The primary effect of difenzoquat appears to be the disruption of the tonoplast and plasmalemma. The tonoplast showed greater damage than the plasmalemma. Secondary effects included damage to mitochondria and chloroplasts. Mitochondria were swollen and often ruptured, but the effect did not increase with the duration of exposure. Chloroplasts became spherical in shape, and their contents were also affected. The changes included: accumulation and then disappearance of starch granules, swelling of frets, fusion of granal thylakoids, detachment and then rupture of the outer membrane of the envelope, and clumping of ribosomes. By contrast, natural senescence caused greater injury of the plasmalemma than the tonoplast, a marked increase in size of plastoglobuli, and loss of starch grains without early accumulation.

A preliminary study of violent incidents in a special hospital (Rampton).

A six-month prospective study of violent incidents was carried out in a Special Hospital (Rampton). Comparisons were made with results from earlier studies in general psychiatric hospitals. As might be expected, incidents occurred more frequently in the Special Hospital. These incidents were also more serious in nature and resulted in greater injury. Although more patients in the Special Hospital were involved in incidents, only a small number of patients accounted for the majority of these. Female patients, who comprised 25% of the Special Hospital population, were involved in 75% of the incidents. Nursing staff were three times as likely to be assaulted as patients.

Influence of Rate, Method of Application, and Tillage on Imazaquin Persistence in Soil

Preplant-incorporated (PPI) applications of 280 g ai/ha of imazaquin {2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid} had significantly greater persistence than preemergence surface (PES) applications throughout the growing season in 1985. In 1984 there was no statistical difference in imazaquin remaining between PPI and PES treatments. Very little imazaquin was detected below 10 cm in the soil profile for all sampling dates each year. Imazaquin dissipated rapidly both years during the first 30 days following PPI and PES applications. A subsequent decrease in the dissipation rate occurred in the next 120 days of the growing season. Spring tillage had no significant effect on injury to corn (Zea maysL.) planted into the field the year following imazaquin application. Corn planted in 1986 into imazaquin-treated plots of 1985 had no growth reduction when compared to corn grown in plots where zero imazaquin had been applied. However, corn planted in 1985 into imazaquin applications of 1984 had significant injury. Greatest injury occurred where imazaquin had been incorporated, and injury increased as imazaquin rate was increased.

Norflurazon Selectivity in Two Biotypes of Guineagrass (Panicum maximum)

Phytotoxicity, absorption, translocation, and metabolism of root-applied norflurazon [4-chloro-5-(methylamino)-2-(3-(trifluoromethyl)phenyl)-3(2H)-pyridazinone] in tolerant narrowleaf and susceptible broadleaf guineagrass (Panicum maximumJacq. # PANMA) biotypes were examined under greenhouse and laboratory conditions. Dose response studies conducted in the greenhouse showed greater injury to the shoots of broadleaf than narrowleaf biotypes.14C-norflurazon absorbed was 0.3 and 0.5% and 1.6 and 2.4% of that applied, 3 and 7 days after application for narrowleaf and broadleaf biotypes, respectively. Of the total radioactivity absorbed after 3 and 7 days, 70 and 76% and 57 and 61% were translocated to the shoots of susceptible and tolerant biotypes, respectively. Gas chromatographic analyses revealed that broadleaf shoots had 3.08 μg/g dry wt of the parent compound while its tolerant counterpart had 0.40 μg/g dry wt, 7 days after application. The toxic parent compound was metabolized more rapidly to its non-phytotoxic desmethyl analog by narrowleaf biotypes, thereby preventing its accumulation in the shoots. Differences in absorption, translocation, and metabolism were responsible for the differential response of the two biotypes of guineagrass.

Quantitative histochemical evaluation of skeletal muscle ischemia and reperfusion injury

Acute arterial obstruction to the extremities is associated with significant morbidity and mortality. The evaluation of accompanying skeletal muscle injury has thus far been indirect and imprecise. Triphenyltetrazolium chloride (TTC) is an oxidation-reduction indicator which allows for the histochemical quantitation of skeletal muscle injury. In 21 anesthetized nonheparinized adult mongrel dogs, the isolated in vivo gracilis muscle underwent 4, 6, or 8 hr of ischemia with and without reperfusion. The muscles were excised and cut into 1-cm segments, representative muscle biopsies for electron microscopy were taken, each segment was stained in 1% TTC, and the total area of staining was measured with computerized planimetry. All control muscles stained completely with a dark red color. After 4, 6, or 8 hr of ischemia, quantitative measurements of muscle staining indicative of normal tissue were present in 98 ± 1%, 59 ± 5%, and 23 ± 9% of the total muscle areas, respectively. Six hours of ischemia followed by reperfusion was associated with only 36 ± 9% of the muscle being stained. Segmental TTC staining demonstrated that reperfusion was associated with greater injury, and less TTC staining, in the proximal portion of the gracilis muscle at the site of entry of the major arterial pedicle. The distal muscle did not demonstrate increased damage with reperfusion. It is hypothesized that protection of the distal muscle from reperfusion injury may be due to an absence of reflow farther away from the artery.