bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of different tillage systems on the composition of the seedbank
Authors: FELDMAN S. R. , TORRES C. ALZUGARAY. P. S , LEWIS P.
Published: November 2003

The soil seedbank of a wheat crop grown with four tillage systems (mouldboard plough, disk, chisel and no‐tillage) for 3 years was analysed. Density and composition of seedbanks varied according to tillage system and depth. The mouidboard plough crop had seedbanks with the lowest seed density and there was no difference in density or composition at 0‐5 cm and 5‐10 cm depth whereas no—tillage had a more dense seed bank, especially in the upper part of the soil profile. Diversity of seedbanks also increased from mouidboard plough, to disk, to chisel, to no‐titlage, which had the most diverse bank. Therefore, the data strongly support the hypothesis that the systems causing less disturbance allow the build‐up of a larger and more diverse soil seed bank.
The effect of grazing on seed production in Echium plantagineum
Authors: SMYTH M. J. , SHEPPARD A. W. , SWIREPIK A.
Published: November 2003

This study measured the effect of livestock grazing on the seed production and the seed‐bank of the annual weed, Echium plantagineum L., by comparing six sites across south‐eastern Australia. Maximum taproot diameter predicted seed production of ungrazed plants irrespectiveof site. Seed losses to flowering plants grazed in spring were calculated using the taproot diameter relationship. Moderate continual grazing pressure throughout the seeding period (December‐January) reduced seed production by at least 87%, although grazing was most destructive per unit of time in the first half of this period (peak seed production of the infestation). E. plantagineum has a strong c apacity to compensate for stock grazing should the stock be removed too early. Seedbanks generally increased following significant seed rain, although this trend was not always consistent. In manipulated quadrats, where seed production was reduced by atleast 90% for 4 years, germination of E. plantagineum was lower relative to controls from the second year and the seedbank was 10 times lower when measured in the fourth year. The implications of these results are discussed in relation to existing control strategies for this weed.
Effect of age on the germination of Cassinia arcuata seeds in storage and buried in soil
Authors: CAMPBELL M. H. , NICOL H. I.
Published: November 2003

Seeds of Cassinia arcuata R. Br. (sifton bush), collected annually from near Orange (1987‐92) and Boorowa (1987‐89). New South Wales. Australia, were stored in a laboratory at a mean temperature of 21°C and a mean relative humidity of 25% and germinated each year for up to 8 years. Seeds from the 1990 and 1992 Orange collections were buried 5 mm and 40 mm deep in the soil for 0.5‐2.7 years and the number and germinability of recovered seeds recorded. Germination capacity of seeds stored in the laboratory increased during the first 2 years of storage and then declined slightly in year 3 and markedly in years 4 and 5 to very low levels in year 6 and subsequent years. The seeds collected near Orange had nil germination after 6 years’storage, whereas Boorowa seeds still had 0.2% and 3.5% germination after 7 and 8 years’storage respectively. Seeds that failed to germinate were shown to be non‐viable by the tetrazolium test. There was no decline in germination rate during the first 3 years of storage, but, thereafter, there was a substantial annual decline, which would reduce the rate of establishment of seedlings in the field and render them susceptible to competition from improved pastures. The longer and deeper the burial of seeds in the soil and the older the seeds, the fewer seeds that germinated when recovered; meaned for both depths of buriai 23% of 0.9‐year‐old seeds that had been buried for 0.5 years and 3.4% of 5.1‐year‐old seeds that had been buried for 2.7 years were recovered in a germinable state. The main causes of loss during burial were germination in the soil and destruction by soil organisms.
Flame weeding: effects of fuel pressure and tandem burners
Authors: ASCARD J.
Published: November 2003

The effects of fuel pressure and burner arrangements using a covered flamer were studied in field experiments on Brassica napus L. and Sinapis alba L. as test species. The responses of the plants to the propane dose and ground speed were described by logistic models. By raising the fuel pressure, the effective speed required to obtain effective control was increased, with a minor increase in effective dose. The use of tandem burners instead of single burners did not increase the effective ground speed and was therefore less energy efficient. Temperatures under the flamer 1 cm above ground were measured by thermocouples in the laboratory. There was a high positive correlation of the maximum temperature or the temperature sum to the reduction of plant biomass in the field. The sigmoidal relation showed that increased temperatures produced an increased control of plants only up to a certain level. Thus, evaluating flame weeders based on temperature measurements alone without knowledge of the relationship between temperature and weed control is not recommended.
Weeds in slash‐and‐burn rice fields in northern Laos
Authors: RODER W. , PHENGCHANH S. , KEOBULAPHA B.
Published: November 2003

Slash‐and‐burn farmers in northern Laos consider weeds, insufficient rainfall and rodent damage as the most important constraints to upland rice (Oryza sativa L.) production. Labour inputs of 140‐190 days ha‐1 for weed control result in low labour productivity. Average weed cover observed in rice fields was 5.6, 4.1, 2.1, 1.7, 0.7 and 0.7 cm m‐1 (transect) for Chromolaena odorata (L.) King and Robinson, Ageratum conyzoides L., Commelina spp., Lygodium flexuosum (L.) Sw., Panicum trichoides Sw. and Corchorus spp, respectively. Chromoiaena odorata, which was introduced in the 1930s, has become the main fallow species and is considered a desirable fallow plant by most farmers. Average fallow periods reported for the 1950s, 1970s and 1992 were 38, 20 and 5 years respectively. Reduced fallow periods in the last decades have re‐suited in a marked increase in weeding requirements. Above‐ground biomass for rice stem, herbaceous plants and trees after rice harvest was 168, 67 and 60gm‐2 in 1991 and 115, 43 and 24 gm‐2 in 1992. Weeding at 14‐day intervals did not increase rice grain yield.
Weed seed germination after short–term light exposure: germination rate, photon fluence response and interaction with nitrate
Authors: MILBERG P.
Published: November 2003

Three laboratory experiments were carried out to answer certain important questions related to the use of‘photo control’as a weed–control strategy. The first experiment documented that seeds of Rumex obtusifolius L. and Silene noctiflora L. germinated more slowly in total darkness than after a short exposure to light, whereas there were no significant differences for Cerastium fontanum Baumg. This suggests that seedling emergence in total darkness would not only result in fewer seedlings, but would also be slower; hence the crop might be given a competitive advantage. The second experiment demonstrated that germination of C. fontanum and S. noctiflora showed a linear response to the logarithm of photon fluence. with levels >1 μmOl m‐2 being stimulatory. This suggests that a near–complete elimination of light during dark harrowing would give the best result. R. obtusifolius, however, had a sigmoid dose–response curve with a lower threshold for germination at 500 μmOl m‐2. Hence, this species had a clear threshold under which unnecessary germination was prevented. The third experiment tested for interaction between light and nitrate in their stimulatory effect on germination percentages. For Descurainia sophia (L.) Webb ex Prantl, R. obtusifolius and Thlaspi arvense L., but not for C. fontanum. such interactions were significant. This stresses the fact that light response will vary substantially depending on the seed's environment.
Reduced efficacy and enhanced degradation of carbetamide after repeated application in Australia
Authors: HOLE S. J. W. , POWLES S. B.
Published: November 2003

Following reports of poor weed control, the effectiveness of repeated applications of carbetamide atid propyzamide in controlling Lolium rigidum Gaud, (annual ryegrass) was examined under field conditions. Repeated applications of carbetamide or propyzamide were less effective in controlling L. rigidum than an initial application. A single application of carbetamide or propyzamide was sufficient approximately to halve the efficacy of a subsequent treatment with the satne herbicide. Laboratory incubations of soil linked the poor performance of carbetamide upon repeated application to an enhanced deg‐radation rate. We conclude that the repeated application of carbetamide or propyzamide results in less effective weed control under field conditions and that this can be partially avoided by rotation between carhetamide and propyzamide.
Rapid dissipation of atrazine in soils taken from various maize fields
Authors: PUSSEMIER L. , GOUX S. , VANDERHEYDEN V. , DEBONGNIE P. , TRESINIE I. , FOUCART G.
Published: November 2003

A laboratory study was carried out in order to measure the degradation rate of atrazine in 36 different soils taken from maize (Zea mays L.) fields in Belgium. These soils differed in their alrazme treatment histories. pH. organic matter content and type of organic and mineral fertili‐zation, Half‐lives of less than 10 days were found in more than 60% of the soils sampled. This rapid dissipation could be linked in a significant way to repeated pretreaiments with atrazine (intensive maize cropping) as well as to higher pH values (from neutral to alkaline), A low organic matter content might also be a factor explaining the rapid degradation of atrazine. but to a lesser extent than the first two factors. On the other hand mineral fertilization was shown to slow down atrazine dissipation. It is hypothesized that repeated treatments of atrazine cause a mi‐crobial adaptation to atrazine degradation and that acidic soil conditions impede this adaptation. To date, this is the first time that evidence for widespread accelerated degradation of atrazine has been reported.
Influence of application rate and manure amendment on cnloridazon dissipation in the soil
Authors: ROUCHAUD J. , NEUS O. , HERMANN O.
Published: November 2003

Plots of a sugar beet field in Belgium were treated pre‐emergence with 1.3, 1.95 or 2.6 kg a.i. ha‐1 chloridazon. Some of these plots had been amended 1 month before sowing with 50 1 ha‐1 cow manure. Soil samples were taken al regular intervals and analysed by gas‐liquid chromatography and gas‐liquid chromatography combined with mass spectrometry. During the first month following chloridazon application, soil dissipation followed apparent first‐order kinetics with soil half‐lives being independent of the dose, and were 37 days in the non‐manured plots and 96 days in the manured plots. After the first month, rates of chloridazon soil dissipation increased, giving the same residual chloridazon soil concentration of c. 0.25 mg a.i, kg‐1 in all plots 1.8 months after application. Residual levels remained at this concentration up to the third month after application, and then disappeared, leaving no delectable soil residues at harvest. Chloridazon soil dissipation thus occurred according to unusual kinetics.
Weed seedling emergence and seed survival: separating the effects of seed position and soil modification by tillage
Authors: MOHLER C. L. , GALFORD A. E.
Published: November 2003

Tillage causes both vertical redistribution of weed seeds and changes in soil physical properties. These two factors are rarely distinguished in studies of the impact of tillage on seedling emergence or seed survival. In this study, seeds of Chenopodium album L., Amaranthus retroflexus L., and Abutilon theophrasti Medik, were planted at particular depths in pots of undisturbed or stirred soil to separate these effects. Emergence and survival data were analysed by non‐linear regression to determine the nature of significant differences between treatments. Emergence increased with slight burial and then decreased exponentially at greater depths. Average emergence over all depths was generally greater in tilled sou than in unfilled soil, particularly for C. album and A. retroflexus. Seed survival approached a maximum with increasing depth. Average survival of seeds that did not produce emerged seedlings was greater in tilled soil than in untilled soil for C. album and A. retroflexus. Thus, tillage affects emergence and seed survival of weeds through changes in soil conditions independently of effects resulting from redistribution of seeds in the soil profile.
Assessment of the sample size to estimate the weed seedbank in soil
Authors: AMBROSIO L. , DORADO J. , DEL MONTE J. P.
Published: November 2003

It was found that, in order to estimate the number of weed seeds in soil with a desirable degree of accuracy and confidence level. the sample size depends to large extent on the spatial distribution pattern of the seeds in the soil. The seeds of most weeds found in cultivated soils are distributed according to one of two statistical distributions: Poisson or Negative Binomial. For an acceptable degree of accuracy in estimating the number of seeds in the soil, the sample size must be large, Taking this into account, in this study a practical solution based on a theoretical approach is proposed for the problem of establishing the sample size for a species distributed according to either statistical pattern. In addition, given the sample size, it was possible to determine the estimation error to be expected. This theoretical approach is compared with that proposed in previous studies. Two abaci, based on simple expressions, are provided to determine the sample size, according to the Poisson or the Negative Binormal distribution of the weed species. For Poisson distribution, the sample size is determined (given the desired maximum relative error estimation and the confidence level) as a function of only one parameter: the expected number of seeds per sampling unit m (estimaied by the sample mean). For Negative Binomial distribution, the sample size is determined as a function of two parameters: m and p (estimated according to the relationship between the sample mean and the sample variance). A sample size n nol very different from those given in previous studies is obtained, but the lower limit found for the n‐values is lower than that found in these studies.
Radiolabelling of isolated cuticles from foliar discs used as a test of cuticle biosynthesis
Authors: CHAMEL A. , VIOUGEAS M. A. , ASSARD N.
Published: November 2003

The radiolabelling of isolaled Hedera helix L, (ivy) leaf cutieles was investigated after incorporation of [14C]acetate in foliar discs Cuticle radioactivity greatly decreased as leaf age inereased. The percentage of radioactivity incorporated in the upper cuticles decreased from 0.5% to 0.08% of the total radioactivity of foliar dises from young to old leaves. Cuticle radioactivity was recovered in waxes, cutin and polar components. It was considerably greater for waxes when expressed in terms of cuticle mass. The methodology was validated using S‐ethyl‐dipropylthiocarbamate (EPTC). The radioactivity incorporation in cuticles was significanly reduced when 1 mm EPTC was deposited as a 20‐μL droplet on lo foliar dises 6 h before the incorporation of radiolabelled acetate. EPTC inhibited radioiabelling of wax and cutin fractions in the upper and lower cuticles. Some acetylenic fatty acid analogues inactivating lauric and oleic acid ω‐hydroxylases, used as acid and sulphonate forms in the same experimental conditions as EPTC, induced no reduction in cuticle radiolabelling. An inhibitory effect was observed only for the acetylenic and the saturated C12 fatty acid analogues, used as tetrabu‐tylammonium sulphonates, when applied directly in the liquid medium supporting foliar dises. Several assumptions are considered to explain the results of the present investigation.
Etude des adventices des vergers d'agrumes dans le Gharb (Maroc): aspects floristique, agronomique et écologique
Authors: BENSELLAM E. H. , BOUHACHE M. , TALEB A.
Published: November 2003

Résume

A partir de 108 stations dans lesquelles des relevés on été effectués en hiver puis en été dans les vergers d'agrumes de la région du Gharb, 216 espéces adventices appartemant à 47 families botaniques ont été recensées. Les annuelles (76%) et I'élément méditerranéen (54%) sont prépondérants et caractérisenl cette flore. Les notations d'abondance et de fréquence ont permis de dégager 29 espéces ayant une nuisibililé non négligeuble vis à vis des agrumes. Dix de ces espéees sont des géophytes particuliérement redoutables. Les variables édaphiques, texture et teneur en calcaire total, ont été les plus déterminantes pour expliquer la distribution des adventices dans la zone d'étude. La comparaison des diflérentes projections des modalités des facteurs à I'aide de 1′Analyse Factorielle des Correspondances a permis d'individualiser trois groupes homogenes d'especes.
Weeds and weed management in irrigated lentil in northern Sudan
Authors: MOHAMED E. S. , NOURAI A. H. , MOHAMED G. E. , MOHAMED M. I. , SAXENA M. C.
Published: November 2003

Weeds are a major constraint to increasing production of lentil (Lens culinaris Medik.) in Sudan, Field studies were conducted to determine the yield loss due to weeds, to identify the critical period of weed interference, to evaluate the activity of different herbicide mixtures in controlting weeds and their selectivity for lentil, and to evaluate different methods of weed control for developing an integrated weed management practice. At Rubatab. unrestricted weed growth accounted for up to 84% loss in yield. The critical period of weed control was between 2 and 4 weeks after sowing. However, a weeding regime experiment at Dongola, a cooler location with a longer growing season, indicated that the critical period was between 4 and 6 weeks after sowing. suggesting that the critical period might vary with the environmental conditions. The herbicides imazethapyr (0.05 kg a.i. ha‐1), terbutryn (1.0 kg a.i. ha‐1) and prometryn (1.0 kg a.i. ha‐1), each in a tank mixture with pendimethalin (1.2 kg a.i. ha‐1), were tolerated by lentil, controlled weeds effectively and significantly increased yields at Wad Hamid. Their efficacy in controlling weeds at Rubatab was low, however, because of the presence of Tephrosia apollinea (Del.) DC. and Melilotus indica (L.) All., which tolerated these herbicides. Efficacy was also reduced in heavier soils. One supplementary hand‐weeding at 4 weeks after sowing enhanced the performance of these herbicides under such conditions. A tank mixture of oxyfluorfen (0.24 kg a.i. ha‐1) with either terbutryn (1.0 kg a.i. ha‐1) or prometryn (1.0 kg a.i. ha‐1) also provided good weed control and increased yield of lentil at Wad Hamid. Application of a higher dose (1.5 kg a.i. ha‐1) of terbutryn and prometryn caused phytotoxicity. Irrigation before seed‐bed preparation reduced grass and broad‐leaved weeds by 58% and 40% respectively, and gave a 30% increase in grain yield over no irrigation. Pre‐emergence application of oxyfluorfen (0.24 kg a.i. ha‐1) and a supplementary hand‐weeding at 4 weeks after sowing gave excellent control of weeds and increased lentil yield by 57% over the weedy control. Thus, use of presowing irrigation, pre‐emergence herbicide and one hand‐weeding form an effective integrated package for controiling weeds in northern Sudan.
Effects of light and mechanical stimulation on coiling and prehaustoria formation in Cuscuta spp.
Authors: HAIDAR M A. , ORR G L , WESTRA P.
Published: November 2003

Irradiation of 4‐day‐old dark‐grown seedlings of Cuscuta campestris Yuncker and Cusctira indecara Choisy with I min of red light stimulated coiling and prehaustoria formation in excised upper 4‐cm segments of seedlings during a 48‐h dark period in which zeatin was applied. Coiling and prehaustoria development were completely reversed when irradiated with 2 min of far‐red light applied directly after red light. When deetiolated segments were subjected to prolonged exposure of pure blue light, or mixtures of ultraviolet‐A/far‐red, blue/far‐red or red/far‐red light, coiling and prehaustona development were induced. Blue light at photon fluxes lower than 1 μmol m‐2 s‐1 did not promote coiling and formation of prehaustoria. Mechanical stimulation caused tendrils to coil and form prehaustona in biue and blue/far‐red light, but not in darkness. Zeatin substituted for high irradiance blue light and mechanical stimulation caused coiling and prehaustoria formation.
Assessing the practical importance of weed evolution: a research agenda
Authors: JORDAN N. R. , JANNINK J. L.
Published: November 2003

If food production is to become more sustainable, weed management systems will become subject to many internal and external constraints; these may sharply limit the available range of weed control methods. If so, it will be imperative to preserve efficacy of acceptable weed control methods by defending these against weed adaptation. Moreover, rapid and ongoing weed adaptation may explain the persistent nature of yield losses to weeds despite technological advances. Research is needed to assess the practical importance of ongoing weed evolution. The first step is to determine the risk of rapid weed adaptation to diverse control measures. Experimentally, this risk can be evaluated by determining heritabilities of traits conferring resistance to control measures, and then using ecological genetic methods to measure the actual magnitude of selection for such trails. Models of multivariate trait evolution can be used to determine the net effect of evolutionary forces bearing on weed adaptation to an integrated weed management system (IWMS). It may also be possible to take a preventive approach by designing agricultural systems so that their large‐scale structure impedes weed adaptation to IWMS.
The influence of temperature and water potential on the germination of seven different dry‐stored seed lots of Stellaria media
Authors: GRUNDY A. C.
Published: November 2003

Experiments were made on seven dry‐stored seed lots of Steliaria media (L.) Vill to assess the effect of water potential and temperature on germination. These seed lots were from different sources and their age ranged from freshly harvested to 5 years in dry storage. Germination was recorded at regular intervals at five constant temperatures (5‐25°C) in all combinations with eight water potential regimes (from 0 to ‐1.4 MPa). The results showed that seed lot had a significant effect on the percentage, rate and spread of germination Differences in germination behaviour in the seed lots appeared to be related to the durations of dry storage. Freshly harvested seed exhibited signs of dormancy, with the lowest percentage and longest mean germination time. Seed lots that had been in dry storage for more than 1 year took increasingly longer to germinate, particularly under less favourable conditions. In contrast, germination percentages were highest in the 3‐year‐old seed. The constant temperature and water potential achieving maximum germination was independent of seed lot as was the water potential achieving the highest germination rates. However, the temperature achieving the highest germination rate was dependent on seed lot. The spread in germination time was largest for the freshly harvested and oldest seed samples. Rates of germination against temperature over the range of water potentials studied were complex.
Behaviour of alkyl oleates following foliar application in relation to their influence on the penetration of phenmedipham and quizalofop‐P‐ethyl
Authors: MERCIER L. , SERRE I. , CABANNE F. , GAUVRIT C.
Published: November 2003

The foliar penetration of four alkyl oleates (methyl to butyl) and their influence on the penetration of phenmedipham and quizalofop‐P‐ethyl was studied in barley (Hordeum vulgare L.), cleavers (Galium aparine L.) and pea (Pisum sativum L.). Loss of alkyl oleates from glass and plant surfaces was inversely related to the length of the alkyl chains and was assumed to be due to volatilization. All four alkyl oleates after application alone, readily penetrated into pea and barley leaves but much less into G. aparine. Penetration of methyl oleate appeared to be faster than that of butyl oleate. Both alkyl oleates were completely metabolized in barley and pea in 27 h, but not in G. aparine. The penetration of herbicides was from 2% to 10% in the absence of alkyl oleates. The penetration of phenmedipham was increased in the presence of all four aikyl oleates: to the greatest extent into pea (55‐80% after 27 h), to the lowest into G. aparine (20‐45%). In all three species, the effect of butyl oleate was higher than that of methyl oleate. The penetration of quizalofop‐P‐ethyl was increased to 10%, 30‐35% and 50% on G. aparine, pea and barley respectively. The length of the alkyl chains did not influence the effects of the alkyl oleates on the foliar penetration of quizalofop‐P‐ethyl.
The influence of interspecific interference on the seed production of Stellaria media and Hordeum vulgare (volunteer barley)
Authors: VAN ACKER R. C. , LUTMAN P. J. W. , FROUD‐WlLLlAMS R. J.
Published: November 2003

The effects of the density and proportion of both volunteer barley (Hordeum vulgare L.) and Stellaria media (L.) Vill. (common chickweed) on the seed yield of both species was investigated in linseed (Linum usitatissimum L.) and autumn‐sown field bean (Vicia faba L.). A model was created to estimate these effects. It was a combination of two models. The first was a simple linear model relating weed seed number m2 to weed dry weight m2. The second was an inverse linear model relating weed dry weight per plant to weed density. A very good relationship existed between barley dry weight and number of seeds m2 and between S. media dry weight and number of seed capsules m2. This relationship was relatively consistent between experiments. The inverse linear model provided a good estimation of the relationship between weed density and weed dry weight per plant for both barley and S. media. Model variables, however, differed between experiments. Using the combined model it was estimated that, in the absence of other weed species and at a density of 800 plants m2, S. media would produce between 4000 and 48 000 seeds m2, whereas volunteer barley, at a density of 400 plants m2, would produce between 2000 and 8000 seeds m2. The presence of barley always reduced S. media seed yield and a barley population of 100 plants m2 could reduce S. media seed yield by up to 79%. The presence of S. media reduced barley seed yield in only one of three experiments, in which a S. media density of 800 plants m2 reduced barley seed yield by up to 68%. It was concluded that interspecific weed competition should not be ignored as a factor in models of weed population dynamics
Biotransformation of [ring‐U‐14C]atrazine to dealkylated and hydroxylated metabolites in cell‐suspension cultures
Authors: SCHMIDT B. , SIEVER M. , THIEDE B. , BREUER J. , MALCHEREK K. , SCHUPHAN I.
Published: November 2003

The biconversion of [14C]atrazine to deaikyt‐ated and hydroxylated products was studied in heteroirophic cell‐suspension cultures of carrot (Daucus caroia L.), Agrostemma githago L. (corn cockle). Digitalis purpurea L. (purple foxglove), soyabean (Giycine max L. Merr; four different cultivars). Datura stramonium L. (thorn‐apple) and wheat (Tritician aestivum L.). During 48 h of incubation, the herbicide was biotransformed by all species; turnovers yields differed considerably and were between 10.1% and 88.0% of applied 14C. Differences were also observed among the soyabean cultivars (10.1‐73.5%). Hydroxy‐atrazine, de‐ethyl‐, deisopropyl‐ and de‐ethyt‐deisopropylatrazine formed in the cultures were identified by thin‐layer chromatography (tlc) (co‐chromatography with reference compounds); deaikyiated metabolites were also proved by gas chromatography–mass spectrometry (gc–ms). In addition, highly polar transformation products emerged that were not identified. Portions of non‐extractable residues were below 5% (one soyabean cultivar: 8.9%). Atrazine was metabolized by the cells, mainly to its dealkylated derivatives and hydroxyatrazine (totals of 9.4‐54, 5%), whereas portions of highly polar products were lower (0.1‐26.1%). Exceptions were A. githago (26.0 and 33.6%, respectively) and D, purpurea (4.5 and 25.2% respectively). Thus, plants generally contribute to the environmental degradation of atrazine.
Tithonia diversifolia (Mexican sunflower) in south‐western Nigeria: occurrence and growth habit
Authors: AYENI A. O. , LORDBANJOU D. T. , MAJEK B. A.
Published: November 2003

A reconnaissance survey of the occurrence of Tithonia diversifolia (Hemsl.) A, Gray in south western Nigeria was carried out along the major highways linking Ibadan to major towns be‐tween April and August in 1991 and 1992. The survey revealed that T, diversifolia is prominent along the Ibadan—Oyo—Ogbomoshollorin, Iba‐dan—Abeokuta and Oyo—lseyin—Saki roads, and common along the Ibadan—lwo—Osogbo—Offa, Ibadan—Ife—Akure, Ife—Ondo and Ibadan—Ijebu Ode roads It is rare along Ibadan—Ikeja, Akure‐Ado Ekiti—Kabba, Ilorin—Jebba, and Ijebu Ode—Benin City—Asaba roads. T. diversifolia is a shallow‐rooted annual/perennial broad‐leaved plant that grows to a height of 5 m or more and varies from highly branched at low populations (< 5 plants m‐2) to practically unbranched at high populations (> 30 plants m‐2). Under natural conditions in the Ibadan area (7°25′N, 3°54′E), T. diversifolia is established from seed in March—April, flowers between September and November and produces mature seed by Decemher—January. Seed is disseminated between January and March by shedding. Under frequent slashing or in a valley bottom with a high water table, or on river banks T. diversifolia behaves as a perennial shrub and flowering under this condition occurs sporadically throughout the year.
Dissipation of imazapyr, flumetsulam and thifensulfuron in soil
Authors: MCDOWELL R. W. , CONDRON L. M. , MAIN B. E. , DASTGHEIB F.
Published: November 2003

The degradation of imazapyr, flumetsulam and thifensulfuron applied at 500.40 and 30 g active ingredient (a.i.) ha‐1, respectively, to silt loam soil was studied under laboratory and field conditions. Herbicide residues were analysed by a lentil (Lens culinarits L.) bioassay. Results showed that temperature had a significant effect on herbicide degradation, whereas the impact of soil organic matter ami pH were less well defined. Half‐lives for imazapyr, flumetsulam and thifensulfuron in soil samples from the 0‐5 cm layer (6.4% organic carbon) at 15 °C were 125, 88 and 5.4 days, respectively, and 69, 30 and 3.9 days at 30°C. In soil sampled from the 15‐20 cm layer (3.5% organic carbon) half‐lives were 155. 70 and 6.4 days, respectively, at 15 °C and 77, 24 and 4.8 days at 30 °C, A field experiment investigated the degradation and teaching of each herbicide under two precipitation regimes [natural precipitation (208 mm), and natural precipitation plus 75 mm irrigation (283 mm) over 4 months to a soil depth of 25 cm. Thifensulfuron degraded rapidly, whereas residues of flumetsulam and imazapyr leached below 25 cm in both the low‐and high‐precipitasion treatments after 4 months. Significant imazapyr residues were still present in the soil to 25 cm depth after 3 months, A multi‐component model for herbicide dissipation was developed and evaluated using data from the laboratory and field experiments.
Degradation of bensulfuron‐methyl on various minerals and humic acids
Authors: SABADIE J.
Published: November 2003

The chemical degradation of bensulfuron‐methyl on various dry minerals (kaolinite, silica gel, alumina, H+ bentonite, montmorillonite KIO) and on solid humic acid was investigated at 30°C. Kaolinite presented a very low activity in comparison with the systematically higher degradation rates obtained using other selected minerals. An acceptable correlation with pseudo‐first‐order kinetics was frequently observed, allowing degradation rate constants to be established. The influence of the herbicide deposition technique used, sample stirring and moisture content were studied. Most of the solids selected, which have an acidic surface, induced only the breakdown of the herbicide molecule's benzyl‐sulfonylurea bridge. In contrast, the basic surface of alumkia preferentially induced sapontfication of the carbonie‐thoxy subsiituent fixed to the aromatic ring. The degradation compounds obtained generally remained stable, with the exception of phcnyl‐sulfonamide, which cyclized rapidly on alumina. The suggested degradalion path is similar to that previously proposed for chemical hydrolysis.
Allergic sensitization to indoor and outdoor allergens and relevance to bronchial hyperresponsiveness in younger and older subjects
Authors: Kerkhof M. , Postma D. S. , Schouten J. P. , De Monchy J. G. R.
Published: November 2003

Background:  Most previous epidemiological studies on the relationship between allergy and bronchial hyperresponsiveness (BHR) have made no distinction between sensitization to indoor and outdoor allergens. We studied the relationship between specific sensitization to allergen and BHR and further assessed whether this was different in young adults and older subjects.

Methods:  Specific IgE to indoor allergens (house dust mite and cat) and outdoor allergens (timothy grass and birch) were measured using the CAP System. BHR was defined as PD20 ≤ 2 mg methacholine. Multiple logistic regression analysis was performed to study independent relationships between BHR and specific IgE to indoor and outdoor allergens in 1018 young adults (20–44 years) and 909 older subjects (45–70 years).

Results:  In the older age group specific IgE to indoor allergens was associated with BHR at a lower level (class 2) than in young adults (class ≥ 3). Young adults with multiple sensitization had the highest risk of BHR. Subjects who were exclusively sensitized to pollen did not show increased BHR in both age groups. Total IgE had, independently of sensitization, only a significant dose–response relationship with BHR in the oldest age group.

Conclusions:  The association between sensitization and BHR is dependent on the nature of the allergen and the level of specific IgE. Furthermore, this study shows for the first time that total IgE is associated with BHR at older ages, independently of sensitization.
Montelukast improves symptoms of seasonal allergic rhinitis over a 4‐week treatment period
Authors: Van Adelsberg J. , Philip G. , Pedinoff A. J. , Meltzer E. O. , Ratner P. H. , Menten J. , Reiss T. F. ,   for the Montelukast Fall Rhinitis Study Group
Published: November 2003

Background:  Proinflammatory mediators such as the cysteinyl leukotrienes are important in the pathophysiology of allergic rhinitis. This study evaluated the efficacy and tolerability of montelukast, a cysteinyl leukotriene receptor antagonist, given once daily in the morning for treatment of seasonal (fall) allergic rhinitis for 4 weeks.

Methods:  This was a randomized, double‐blind trial with a placebo run‐in and a 4‐week treatment period. Patients (n = 1079) with a history of allergic rhinitis and a positive skin test to seasonal pollen allergens were assigned to placebo, montelukast 10 mg, or loratadine 10 mg. Symptoms were assessed with a daily diary.

Results:  Montelukast was more effective than placebo in improving scores for the primary endpoint of daytime nasal symptoms (P = 0.003) and the secondary endpoints of night‐time, composite, and daytime eye symptoms, patient's and physician's global evaluations of allergic rhinitis, and rhinoconjunctivitis quality‐of‐life (P ≤ 0.006). The positive control loratadine also improved scores for the primary endpoint (P ≤ 0.001) and the majority of the secondary endpoints (P < 0.03). When analyzed by week, the treatment effect of montelukast was more persistent than loratadine over all 4 weeks of treatment.

Conclusion:  Montelukast provided effective relief of seasonal allergic rhinitis symptoms when given once daily in the morning, showed significant and sustained improvement in symptoms of allergic rhinitis over 4 weeks of treatment, and was well‐tolerated.
The influence of the dietary intake of fatty acids and antioxidants on hay fever in adults
Authors: Nagel G. , Nieters A. , Becker N. , Linseisen J.
Published: November 2003

Background:  The objective of the investigation was to explore in a prospective study the associations between dietary intake of fatty acids, antioxidants and hay fever manifestation in adulthood.

Methods:  Three hundred and thirty‐four hay fever cases with adult onset of clinical symptoms from the European Prospective Investigation into Cancer and Nutrition (EPIC)‐Heidelberg cohort were identified during follow‐up and matched with 1336 controls. Dietary intake data were obtained by means of validated food frequency questionnaires. The influence of dietary fatty acid and vitamin intake on hay fever risk was estimated by means of unconditional logistic regression.

Results:  High intake of oleic acid was positively associated with hay fever [odds ratio (OR): 2.86, 95% confidence intervals (95% CI): 1.22–6.70], whereas high intake of eicosapentaenoic acid was inversely related to hay fever (OR: 0.45, 95% CI: 0.22–0.93). Furthermore, high β‐carotene intake increased the risk of hay fever (OR: 1.69, 95% CI: 1.09–2.63) while increasing intake of vitamin E was a protective factor (OR: 0.38, 95% CI: 0.17–0.85). In grouped analyses, the effects of β‐carotene and vitamin E were mainly observed among women and ex‐/current‐smokers; in these subgroups, linoleic acid increased the risk of hay fever.

Conclusions:  In conclusion, the present results provide further evidence that dietary factors might affect the risk of clinical manifestation of hay fever. However, the effects in smokers and women may suggest different biological mechanisms for the investigated nutrients, which need further research.
Comparison of FEV1 and specific airway conductance in assessing airway response to occupational agents
Authors: Larbanois A. , Delwiche J.‐P. , Jamart J. , Vandenplas O.
Published: November 2003

Background:  There is theoretical evidence that specific airway conductance (SGaw) could be more reliable than forced expiratory volume in 1 s (FEV1) for assessing changes in airway calibre. We investigated the changes in FEV1 and SGaw when assessing bronchial responses to occupational agents.

Methods:  SGaw and FEV1 were measured during inhalation challenges with various occupational agents in 174 consecutive subjects investigated for possible occupational asthma.

Results:  A decline in SGaw of 50% or greater was documented in 77 of 90 subjects (86%) who showed a ≥20% fall in FEV1 and in 11 of 84 subjects (13%) who failed to demonstrate such a fall in FEV1. Among subjects who developed a ≥20% fall in FEV1, those who failed to develop a ≥50% decline in SGaw had a lower baseline SGaw than those who did. Among the group without a ≥20% fall in FEV1, a ≥50% decrease in SGaw was associated with either an ‘intermediate’ fall in FEV1 (between 15 and 17% from baseline value) (n = 4), a significant postchallenge increase in nonspecific bronchial hyper‐responsiveness to histamine (n = 2), or both features (n = 3).

Conclusions:  A decline in SGaw of 50% or greater may provide useful complementary evidence of a bronchial response during challenges that produce equivocal results in FEV1.
Urticaria
Authors: Zuberbier T.
Published: November 2003

Urticaria has been known as a disease since antiquity. However, in the last decades an increasing understanding of the mechanisms involved in its pathogenesis has shown the high heterogeneity of different urticaria subtypes. Clear distinction of the subtypes is required not only to choose the correct measures in diagnosis and management, but also to interpret the available data in research. The subtypes can be grouped into spontaneous urticaria, which includes acute urticaria and chronic urticaria, the physical urticarias, special types of urticaria including, e.g. contact urticaria, and diseases related to urticaria for historical reasons, e.g. urticaria pigmentosa. Most urticaria subtypes have a profound impact on the quality of life and effective treatment is thus required in case the diagnostic procedures do not reveal a cause which can be treated. Although, for symptomatic relief, nonsedating H1‐antihistamines are the first choice in most subtypes of urticaria, double‐blind controlled studies have shown that dosages required may exceed those recommended for other diseases, e.g. allergic rhinitis. Alternative treatments should be reserved for unresponsive patients.
Cashew allergy: observations of 42 children without associated peanut allergy
Authors: Rancé F. , Bidat E. , Bourrier T. , Sabouraud D.
Published: November 2003

Background:  Cashew allergy seems to be increasingly frequent. The goal of the present study was to analyse the clinical features and results of investigations of 42 children with cashew allergy.

Methods:  The clinical features and results of skin prick tests, specific IgE assays, and food challenges were analysed.

Results:  The mean age at first allergic reaction was 2 years and the mean age at diagnosis of cashew allergy was 2.7 years. One in five children (12%) had a prior history of exposure to cashew nuts. Fifty‐six per cent had skin symptoms, 25% had respiratory signs and 17% had digestive signs. Eighteen children had proven, associated food allergies (pistachio, seven; egg, five; mustard, three; shrimp, two; cow milk, one). The mean wheal diameter of the skin prick tests was 7 mm (3–16 mm) and the mean specific IgE level was 3.1 kUA/L (<0.35–>100 kUA/L). Eight children had positive food challenges.

Conclusion:  The increase in cashew allergy is worrying because it affects young children who may have a reaction without ever having been exposed to cashews. Almost one‐third of children are allergic to pistachios, which belong to the same botanical family as cashews. Clinical history is generally and sufficiently suggestive to diagnose cashew allergy without recourse to food challenges.
Characterization of allergens of Anisakis simplex
Authors: Arlian L. G. , Morgan M. S. , Quirce S. , Marañón F. , Fernández‐Caldas E.
Published: November 2003

Background:  Anisakis simplex is an intestinal parasite of sea mammals. The larvae infect crustaceans, cephalopods and fish. Humans may consume A. simplex third stage larvae (L3) when eating infected raw or under‐cooked fish. Consumed larvae cause an inflammatory reaction when they penetrate the digestive mucosa. The larvae or their secretory/excretory products can sensitize humans and induce an immunoglobulin E (IgE)‐mediated allergic reaction. This parasite is now being implicated in numerous cases of allergic reactions after eating fish. The purpose of this study was to evaluate the allergenicity of proteins present in an extract of the third stage larva.

Methods:  Rabbit antiserum raised to A. simplex somatic extract (L3) was reacted by crossed immunoelectrophoresis (CIE) with the same somatic extract. Crossed radioimmunoelectrophoresis (CRIE) was also performed by incubating CIE gels first in the sera of 13 individuals with positive immunoCAP to A. simplex and then in radiolabeled anti‐human IgE.

Results:  Twelve to 16 antigen–antibody precipitin peaks were visualized on Coomassie blue stained CIE gels in which somatic extract was reacted with somatic‐antiserum. Autoradiography of CRIE gels showed that 18 different proteins bound IgE in patient sera. Individual patients had serum IgE directed at two to 10 different allergens. Five of these allergens were recognized by ≥50% of the patients. No allergen was recognized by every patient and no patient had serum IgE directed at all 18 allergens.

Conclusion:  Somatic extracts of A. simplex L3 larva contain a large number of allergenic molecules and there is significant variability between patients in their sensitivity and reactivity to these allergens.
Results of standard series patch testing in patients with occupational allergic contact dermatitis
Authors: Nettis E. , Marcandrea M. , Colanardi M. C. , Paradiso M. T. , Ferrannini A. , Tursi A.
Published: November 2003

Background:  In the workplace, the skin is at high risk of exposure to chemicals and other contaminants, and occupational dermatitis is an important field of study.

Methods:  We evaluated 230 patients referred to our clinic because they were affected by dermatitis suspected to be of occupational and allergic origin. They were tested with the allergens of the GIRDCA standard series, and with supplementary series when indicated.

Results:  Among the 230 subjects, 49 were positive only to supplementary series (26.3% of all allergic contact dermatitis), while 130 (69.9% of all allergic contact dermatitis) were considered to have an occupational allergic contact dermatitis diagnosed by the standard series alone. The most frequent occupations of the patients were health care workers and hairdressers/beauticians. The most common agents responsible for occupational allergic contact dermatitis were metals and para‐phenylenediamine.

Conclusions:  As the standard series detected a relatively low proportion of occupational allergic contact dermatitis, it is not adequate to recognize an occupational allergic contact dermatitis, certain supplementary series should also to be tested. However, even if such occupational series are used, we remain likely to continue to underestimate the frequency of occupational allergic contact dermatitis, because workers come into contact with a large number of substances that are often unknown.
Myocardial function and haemodynamics in extensive burn trauma: evaluation by clinical signs, invasive monitoring, echocardiography and cytokine concentrations. A prospective clinical study
Authors: Papp A. , Uusaro A. , Parviainen I. , Hartikainen J. , Ruokonen E.
Published: November 2003

Background:  The objectives of this study were to (1) describe the haemodynamic profile of patients with extensive burns during the early fluid resuscitation phase, (2) evaluate myocardial performance by invasive monitoring and echocardiography and (3) analyze the relations between serum cytokine (IL‐6, IL‐8, TNF) and natriuretic peptide (ANP, BNP) concentrations and myocardial function in these patients.

Methods:  Prospective, clinical study in a tertiary care burn centre. Invasive haemodynamic measurements including a pulmonary artery catheter, echocardiography, blood samples for cytokine and atriopeptide analyses. The follow‐up time was up to 72 h postinjury.

Results:  According to echocardiography, patients were hypovolaemic despite aggressive (median 7,9 ml kg−1 h−1, range 3.3–11.7) fluid resuscitation and adequate urine output (median 0.9 ml kg−1 h−1, range 0.46–1.35) during the first day postinjury. There were no consistent findings of hyperlactatemia, metabolic acidosis or low mixed venous oxygen saturations. Daily highest and lowest values of cardiac index and stroke volume index increased and the lowest and highest values of systemic vascular resistance decreased. Cardiac performance (stroke volume index) improved during the study period even though there were no initial signs of myocardial depression in echocardiography. Three patients received a dobutamine infusion based on clinical judgement. There was no consistent association between haemodynamic changes and plasma cytokine concentrations.

Conclusion:  Persisting hypovolaemia is evident in the resuscitation phase of extensive burns despite aggressive fluid therapy and the lack of classic signs of hypoperfusion. Cardiac performance improves during the first days after extensive burn injury without association with plasma cytokine profile.