bluuebunny/crossref_metadata_2025 huggingface dataset:
Integrated pest management techniques in thistle suppression in pastures of North America
Authors: TRUMBLE J.T. , KOK L.T.
Published: July 2006

Thistles in the genera Carduus, Cirsium, Onopordum, and Silybum of the subtribe Carduinae have been the subjects of considerable research designed for chemical, biological, cultural, and integrated control in the United States. Problems and costs associated with chemical and cultural control techniques stimulated the introduction of biological control agents from many locations in Europe and the Middle East. Although some natural enemies have successfully suppressed thistle infestations, economic losses during the time lags between introduction and effective suppression prompted investigations into integrated control procedures. The rationale, history, and potential direction for thistle suppression has been documented in this manuscript.
Germination of Setaria chevalieri caryopses
Authors: ERASMUS D.J. , VANSTADEN J.
Published: July 2006

Germination studies were made on Setaria chevalieri caryopses (seeds). The seeds imbibed readily upon moist incubation. An after‐ripening period which followed a cyclic patlern was necessary for maximum germination. Freshly harvested seed germinated in the presence of light, but only very sporadically in the dark. The germination of dark incubated seed was improved if the seeds were subsequently exposed to light. This photodormancy became less pronounced with dry storage. Treatment with red light increased germination. but was reversed by far‐red light suggesting that a phytochrome system operates in the seeds. Sodium azide treatments did not stimulate germination in the dark but were effective in the presence of light.
Some studies on the competition between Avenu fatua L. and spring barley.II. Variation of A. fatua emergence and development and its influence on crop yield.
Authors: PETERS N.C.B. , WILSON ARC B.J.
Published: July 2006

The emergence and development of A fatua were studied in 23 spring barly fields in 1972 and nine in 1973 nautarally infested with yhe weed. Emergence occurred up to the four‐leaf stages of the crop. The mean number of days from drilling to 50% emergence of A fatua plants was 22 in 1972 and 36 in 1973.The majority of seeds were shed by early emerging plants in 1972, 79% and in 1973. 59% of A fatua plants had emerged by the two‐leaf stage of the crop and these plants produced 97 and 89% respectively of all the seed shed. In both years, A fatua plants emerging before the crop produced five times as many seeds per plant as those emerging between the crop two and three‐leaf stages. The earliest emerging plants were also the heaviest and had most stems per plant.In both years there was a significant relationship between the density of A fatua plants in the crop in spring and their mortality.A large variation occured between the sites in the number of A fatua plants that emerged by a given crop leaf stage. In 1973.insufficient numbers of sites were investigatesd to derive a relationship between time to A fatua emergence and crop yield loss, but in 1972, a given density of A fatua plants emerging at an early stage caused agreater crop yields loss than the same density emerging later. This was also evident to aleser extent in data derived from a similar series of 15 experiments in 1971.
Effet des matières organiques ajoutées au sol sur l'adsorption des herbicides. Influence de la composition des matières organiques
Authors: GAILLARDON P. , GAUDRY J.C. , CALVET R.
Published: July 2006

En fractionnant préalablement deux substrats organiques (une paille de blé et im fpom de luzerne broyés) nous avons tenté d'évaluer le pouvoir adsorbant, dans le sol, de leurs composants (substances hydrosolubles et lipidiques, héicelluloses, cellulose et lignine). La terbutryne et le diuron n'ont pas la méme affinité pour les composants des substrats. La lignine est plus adsorbante que les autres composants. Auregard de l'adsorption, les composants isolés constituent des classes hétérogènes et interagissent. Par suite il apparait difficile de décrore le pouvoir adsorbant des matières organiques non décomposées à partir de leur composition. La minéralisation, en modifiant la composition des substrats pourrait expliquer au moins partiellement les variations du pouvoir adsorbant des résidus carbones provenant de la décomposition des substrats dans le sol.
Influence of light, temperature and humidity on the translocation and activity of glyphosate in Elymus repens (=Agropyron repens)
Authors: COUPLAND D.
Published: July 2006

The effects of light, température and humidity on the performance and translocation of glyphosate in Elymus repens (L.) Gould (=Agropyron repens L. (Beauv.)), during the period of 48 h after treatment, were studied in controlled‐environment cabinets. Increases in the levels of all three factors resulted in increases in herbicide performance. In general, these differences were statistically significant at all treatment periods except the longest when almost full control was achieved. The results highlight the important influence of environmental factors on herbicide performance during the short‐term, post‐spraying period. The application of 14C‐labelled glyphosate to the adaxial leaf‐sheath surface resulted in very rapid uptake and was used as a method of treating plants to study herbicide translocation under different environmental conditions. Increased light levels and temperatures enhanced basipetal translocation to the crowns and rhizomes but increased humidity had no significant effect with this form of application.
Growth of Elymus repens (L.) Gould and Agrostis gigantea Roth. at different light intensities
Authors: SKUTERUD ROLF
Published: July 2006

Elymus repens (L.) Gould and Agrostis gigantea Roth. raised from rhizomes both responded to reduced light intensity by increased stem length, while the number of aerial shoots was reduced. The weight of the aerial parts was not influenced by a 50% reduction of the daylight intensity, but a further reduction of light caused a significant decrease in weight. The production of new rhizomes was more influenced by shading than were the aerial shoots. The consequence was an increase in the shoot/rhizome ratio.

The food reserve per bud measured as inter‐node weight in E. repens and A. gigantea was reduced only with intensive shading, and the vitality of the rhizomes appeared independent of light intensity.

Intensive shading in early as compared to late summer caused a reduction in the number and weight of aerial shoots, but not in the weight of new rhizomes. Light intensities equal to those found in a spring wheat crop allowed more E. repens growth than light intensities equal to those in a spring oat crop.

E. repens raised from seeds and grown at light intensities equal to those found in a cereal crop, showed insignificant rhizome production.
Selectivity factors relative to asulam for Senecio jacobaea L. control in Medicago sativa L. I. Retention, uptake and translocation*
Authors: HARPER DELBERT R. , APPLEBY ARNOLD P.
Published: July 2006

Senecio jacobaea L. and Medicago sativa L. plants grown in a glasshouse were treated with foliar applications of aqueous solutions of asulam. Retention on foliage, uptake and translocation were measured in both species. Retention was greater in S. jacobaea than in M. sativa when no surfactant was added and similar when surfactant was added. Addition of surfactant modified spray distribution and increased asulam uptake in M. saliva but did not in S. jacobaea. S. jacobaea translocated over twice as much asulam from the treated area as M. sativa. These data suggest that surfactant should not be added for maximum selectivity. Differences in species response to asulam treatments are partially, but not entirely, explained by differences in retention, uptake and translocation.
Effects of application method on the performance of some soil‐applied herbicides II. Field studies
Authors: ADDALA M. S. A. , HANCE R. J. , DRENNAN D. S. H.
Published: July 2006

Plots sown with a range of test species were treated with chlortoluron, nitrofen, propyzamide or terbutryne applied at several doses either by rotary atomizer (30 1 ha−1), conventional hydraulic nozzle (250 1 ha−1) or dribble bar (with orifices spaced at 2‐cm intervals) (520 1 ha−1). The performance of chlortoluron, propyzamide and terbutryne was similar with all the methods used, regardless of soil and weather conditions. Vertical movement in the soil was similar for each application method. Horizontal variability following dribble‐bar application was measured for chlortoluron and was very large across short distances but weed control was as uniform as with the other application methods.

In a further experiment, the phytotoxicity of chlortoluron applied by each of the three methods was less in a seed bed prepared by minimum tillage following straw burning than in a ploughed and cultivated seed bed. Activity following minimum tillage and straw baling was intermediate. This difference in phytotoxicity probably resulted from greater adsorption in the surface layers of the minimal cultivation treatments.
Les définitions d' ‘adventicee’ et de ‘mauvaise herbee’
Authors: GODINHO ISABEL
Published: July 2006

Rásumá

Les définitions d' ‘adventicee’ et de ‘mauvaise herbee’ en Français, de ‘weede’ en Anglais et de ‘Unkraute’ en Allemand ont été relevées dans la bibliographie. La difficulté de trouver une seule définition satisfaisante pour ‘weede’ et ‘Unkraute’ est insurmontable puisque ces mots ont deux sens et doivent par conséquent avoir deux définitions distinctes: (i) adventice, weed, Unkraut (sens écologique): plante qui croit spontanément dans les milieux modifiés par l'homme; (ii) mauvaise herbe ou malherbe, weed, Unkraut (sens malherbologique): plante indésirable.
Seed survival and periodicity of seedling emergence in four weedy species of Papaver
Authors: ROBERTS H. A. , BODDRELL JUNE E.
Published: July 2006

Seeds of Papaver argernone, P. dubium, P. lecoqii and P. rhoeas were collected in each of three or four years and mixed with the top 7·5 cm of sterilized soil confined in cylinders sunk in the ground outdoors and cultivated three times yearly. Except for P. argemone, no more than 6% of seeds produced seedlings in the autumn of sowing; seedling numbers were usually greatest in the following year and then decreased exponentially from year to year. Mean survival of viable seeds after 5 years ranged from 7·4% for P. lecoqii to 2·0% for P. argemone. Most seedlings of all four species emerged in early spring and early autumn; emergence of P. rhoeas was greater in spring than in autumn, but the reverse was true for the other three species.
Herbicides for injection into flowing water: acrolein and endothal‐amine
Authors: BOWMER KATHLEEN H. , SMITH G. H.
Published: July 2006

Treatment of flowing water by injection with acrolein is widely used in Australia and elsewhere for control of submerged aquatic plants. However, since acrolein has several disadvantages the amine salt of endothal has been assessed as an alternative for control of Elodea canadensis Rich., the most important species in blocking irrigation flow in south‐eastern Australia. Using an exposure time of 3 h in a static assay in the field the standard treatment with acrolein, nominally 15 ppm, was far more effective than endothal at about 5 ppm, similar results being obtained in spring, mid‐ and late summer. In a test over a range of concentrations in mid‐summer, acrolein gave 80% reduction of biomass at 2·8 ppm but endothal did not give this level of control even when more than 100 ppm was used. Endothal was also relatively ineffective when injected into flowing water.

Measurements of net photosynthesis and lethality suggest that the order of tolerance to acrolein is Potamogeton tricarinatus F. Muell & A. Benn., > E. canadensis ≥ Vallisneria gigantea Graebner, so that routine treatments with acrolein may contribute directly to changes in relative species dominance. Use of sublethal concentrations of acrolein stimulated the growth of E. canadensis relative to untreated controls, perhaps by reducing the competition of aufwuchs.
A simple bioassay for photosystem‐II inhibitors in water using in vivo chlorophyll fluorescence*
Authors: GOLDSBOROUGH L. G. , ROBINSON G. G. C.
Published: July 2006

A simple bioassay is described in which the increase of in vivo chlorophyll fluorescence of unialgal continuous, cultures is related to the concentration of photosynthetic inhibitors by a hyperbolic function. Concentrations of the herbicide terbutryne detected by the bioassay in an aquarium microcosm were generally within 2 μg 1−1 of estimates by gas chromatography. A multispecies bioassay approach is proposed, which combines high sensitivity with a wide operating range of concentrations.
Contribution à l'étude de la biologie de Solanum elaeagnifolium Cav. (Solanacées), adventice des cultures dans le périmètre irrigué du Tadla (Maroc)
Authors: TANJI A. , BOULET C. , HAMMOUMI M.
Published: July 2006

Solanum elaeagnifolium Cav. infeste actuellement 100 000 ha de cultures irriguées dans le périmètre du Tadla (Maroc Central). Sa forte capacité de reproduction végétative est liée d'une part à l'intensité des facons culturales et d'autre part, à son type biologique géophyte. Par ailleurs, elle se reproduit également bien par la voie sexuée: les graines produites en grand nombre germent dès le mois de Février date à laquelle les rejets apparaissent ce qui ne fait qu'accentuer son agressivité. Au Maroc, l'espèce fleurit en Mai et fructifie dès le mois de Juillet, l'hiver correspondant au repos végétatif. En conséquence, sa nuisibilité est généralisée et elle est plus particulièrement forte dans toutes les cultures de printemps (coton, maïs, sésame, etc.).
Actions of sodium hypochlorite and hydrogen peroxide on seed dormancy and germination of wild oats, Avena fatua L.
Authors: HSIAO ANDREW I. , QUICK WILLIAM A.
Published: July 2006

Sodium hypochlorite (NaOCl) can release dormancy of imbibed wild oat (Avena fatua L.) seeds. Treatments found effective included (i) immersing intact seeds in 800 mm NaOCl for 1 h followed by incubation on 5 × 10−4m gibberellin A3(GA3); (ii) immersing dehulled seeds in 800 mm NaOCl for 1 min followed by incubation on 5 × 10−4m GA3; (iii) immersion of dehulled seeds in much lower concentrations of NaOCl, e.g. 13 4 mm for 3 h followed by incubation on water; or (iv) incubating dehulled seeds on a low concentration of NaOCl. Based on the concentrations of each of the reagents required to produce equivalent responses, NaOCl is approximately 4–6 times more effective than hydrogen peroxide (H2O2) in triggering the onset of germination, and 6 times as effective in causing growth inhibition in the roots. These results suggest the modes of action of NaOCl and H2O2 in the termination of dormancy reside in a modification of the properties of the hull and seed coat membranes, and in the provision of additional oxygen to the seed.
Weed interference in maize, cowpea and maize/cowpea intercrop in a subhumid tropical environment. II. Early growth and nutrient content of crops and weeds
Authors: AYENI A. O. , AKOBUNDU I. O. , DUKE W. B.
Published: July 2006

Early growth and nutrient content of crops and weeds from weed‐free and weedy no‐tillage maize (Zea mays L, cv. TZB), cowpea (Vigna unguiculata (L) Walp. cv. VITA‐5) and maize/cowpea intercrop at populations of 40000, 50000 and 30000 + 40000 plants ha−1 grown on a loamysand Oxic Ustropept in a subhumid tropical location were monitored in the early and late 1979 cropping seasons. In the first 6 weeks of growth in the early season, cropping pattern had no effect on weed growth; weeds did not suppress crop growth significantly until 5–6 weeks after sowing and total crop dry weights were not affected by cropping pattern. Three weeks after sowing, weeds from weedy crop plots had taken up two to four times as much nutrient (N, P, K, Ca + Mg) as was taken up by corresponding weed‐free crops. In the late season, weed dry weight 6 weeks after sowing was depressed in the intercrop compared to monocultures and dry‐matter production of the intercrop was higher than those of monocultures. The resource use index (RUI), defined as the amount of an environmental resource used by a weed‐free crop divided by the combined amount of the same resource used by the corresponding weedy crop and the associated weeds, increased with age of crop and was higher for the intercrop than the monocultures only in the late season.
Evaluation du stock en semences de la morelle jaune (Solanum elaeagnifolium Cav.) dans le sol du Tadla (Maroc)
Authors: BOUHACHE M. , TANJI A.
Published: July 2006

Rásumá

A partir des échantillons de sol, prélevés dans quatre champs du périmètre irrigué du Tadla (Maroc Central) et choisis dans la zone la plus infestée par Solanum elaeagnifolium, des estimations de semences de cette adventice vivace, révèlent que la valeur moyenne du stock en semences dénombrées (semences mortes + semences viables) de S. elaeagnifolium est de 375 semences au m2 sur 60 cm de profondeur. Tandis que la valeur moyenne du stock en semences viables est de 163 semences au m2 sur 60 cm de profondeur, ceci représente en moyenne 43, 5% du stock total en semences dénombrées.

Le profil moyen de répartition des semences de S. elaeagnifolium dans le sol est le suivant: 71,7, 25,1 et 3,2% respectivement, dans les horizons 0–20, 20–40 et 40–60 cm. De même, la répartition verticale des semences viables suit le même profil que le stock total, ainsi nous trouvons que 73 et 27% des semences viables sont localisées respectivement dans les horizons 0–20 et 20–40 cm.
Aspects of the biology of Ehrharta erecta Lam.
Authors: McINTYRE S. , LADIGES P. Y.
Published: July 2006

Field and laboratory studies of the South African grass Ehrharta erecta Lam. are presented. Seasonal growth and the soil seed bank were monitored at Mornington, Victoria, where E. erecta is naturalized beneath native Leptospermum laevigatum F. Muell. scrub. Adult plant growth commenced in late autumn, following a severe reduction in green shoot material resulting from drought damage. Seedlings emerged in autumn and winter and coincided with a significant decline in the soil seed bank.

Germination trials indicated dormancy in fresh seed, which could readily be broken by a period of after‐ripening. Germination was also found to be inhibited by the presence of seed covering structures, but this effect diminished with time.

A growth experiment conducted at different light intensities demonstrated a high level of shade tolerance in E. erecta with the compensation point ranging from 0·82 to 0·98% of full daylight. In view of the speciese’ shade tolerance and other evidence, it is hypothesized that the availability of water restricts the ability of E. erecta to grow under very dense canopies and controls its seasonal growth and regeneration pattern in the field.
Allelopathic effect of Salvia syriaca L. (Syrian sage) in wheat
Authors: QASEM J. R. , ABU‐IRMAILEH B. E.
Published: July 2006

The allelopathic effect of Salvia syriaca L. (Syrian sage) was examined against wheat in glasshouse and laboratory experiments. The germination of wheat grains was delayed, and the development of wheat seedlings was decreased in laboratory experiments by both shoot and rhizome extract. The inhibitory effect of both extracts was most pronounced at 20°C compared with 10 or 15°C. Shoot extracts had more drastic effects than the rhizome extract on germination percentage, shoot and root lengths. In glasshouse experiments fresh and dried shoot of S. syriaca added to soil drastically decreased germination and development of wheat.
Use of wild Setaria viridis (L.) Beauv. to improve triazine resistance in cultivated S. italica (L.) by hybridization
Authors: DARMENCY H. , PERNES J.
Published: July 2006

Interspecific hybrids were obtained between two triazine‐resistant forms of the wild species Setaria viridis and the triazine‐susceptible cultivated foxtail millet (Setaria italica). The main agronomic characteristics of the hybrids were generally intermediate between the parental forms, except for fertility which was low. Some differences were observed according to the wild parent used. Progeny analysis confirmed the cytoplasmic inheritance of the resistance. The creation of resistant cultivars would allow the use of triazines in foxtail millet cultivation.
Control of Achillea millefolium L. (yarrow) by rotary cultivation and glyphosate
Authors: BOURDÔT G. W. , BUTLER J. H. B.
Published: July 2006

Various control strategies for Achillea millefolium L. (yarrow) were investigated in a dense stand of the weed at Lincoln College in 1977–1978. In early spring plots were either rotary cultivated or left undisturbed. In late spring, plots of both previous treatments were either left undisturbed, rotary cultivated or sprayed with glyphosate at 1·5 kg ha−1. The whole experiment was rotary cultivated twice 1 week later and sown with Hordeum vulgure L. cv. Zephyr (barley) at 144 kg seed ha−1. MCPA + dicamba at 0·9+0·15 kg ha−1 was applied to half of each plot when the second node was detectable (Zadok 32).

Rotary cultivation and glyphosate both substantially reduced the regrowth of A. millefolium but glyphosate reduced regrowth by a greater proportion when applied to undisturbed plants than when applied to plants regenerating after cultivation. Both gave a more than 95% reduction compared to the control (rotary cultivation only at sowing time) in the amount of A. millefolium present in the barley stubble in the autumn.

MCPA + dicamba caused seedling mortality but did not affect the numbers of primary shoots from rhizome fragments.

The grain yield of the barley increased from 2·91 t ha−1 when A. millefolium was not controlled to 4·23 t ha−1 with good control. The barley yield appeared to be restricted by competition from regenerating A. millefolium and by a nitrogen deficiency induced in some regimes by nitrogen immobilization in decaying rhizomes.
Uptake and phytotoxicity of chlorsulfuron in Zea mays L. in the presence of 1,8‐naphthalic anhydride
Authors: O'LEARY NORA F. , PRENDEVILLE G. N.
Published: July 2006

The sites of uptake of chlorsulfuron in maize (Zea mays L.) were investigated at three different growth stages. Exposure of seedling roots, or shoots separately, to herbicide‐treated sand over 4 days resulted in inhibition of both roots and shoots. Exposure of seedling roots to chlorsulfuron‐treated soil over 21 days severely inhibited both roots and foliage, while separate shoot exposure also reduced both foliage and root growth. After plant emergence, exposure of the crown root node, growing point and lower stem to treated soil reduced foliage and root growth, but exposure of the shoot above the growing point caused only slight inhibition of foliage and had no effect on roots.

The herbicide safener 1,8‐naphthalic anhydride (NA) applied as a dust (10 g kg−1 seed weight), or as a 50 mg 1−1 suspension in water to maize seeds, reduced the root inhibition by chlorsulfuron in 4‐day‐old seedlings. NA completely prevented both foliage and root injury when chlorsulfuron was placed in soil in the shoot zone before emergence, or in the shoot zone below the soil surface after plant emergence. NA slightly decreased injury to foliage, but not to roots when chlorsulfuron was placed in soil in the root zone before emergence. NA seed treatment protected both roots and foliage against injury from foliarly applied chlorsulfuron. Plants were also protected when a suspension of NA in water was sprayed on the foliage seven days before chlorsulfuron. When a mixture of NA and chlorsulfuron was applied to foliage, root injury was reduced more than foliage injury.
Effect of chlorsulfuron and 1, 8 naphthalic anhydride on uptake of 45Ca in maize
Authors: CROWLEY J. , PRENDEVILLE G. N.
Published: July 2006

The effect of chlorsulfuron on uptake of 45Ca was studied in maize (Zea mays L. cv. Earliking) plants grown from seeds dusted with 1, 8 naphthalic anhydride (NA). 45Ca absorption in sand‐grown maize was significantly decreased when chlorsulfuron was applied to the foliage but this was not so when seeds had been dusted with NA. Uptake of 45Ca was also reduced when either root or shoot soil zones were separately exposed to chlorsulfuron. When seeds had been dusted with NA, uptake of 45Ca from main roots was similar to that of untreated plants, but only when chlorsulfuron was localized in the shoot zone. NA did not counteract the severe reduction in 45Ca absorption when chlorsulfuron was localized in the root zone.
Behaviour of hard and permeable seeds of Abutilon theophrasti Medic. (velvetleaf)
Authors: HOROWITZ MENASHE , TAYLORSON R. B.
Published: July 2006

Experiments were carried out on seeds of Abutilon theophrasti (velvetleaf) to examine the germination behaviour of hard (impermeable) and soft (permeable) seeds and to test various physical and chemical treatments against hardseededness. There was no evidence, in fresh or in old seeds, of leachable germination inhibitors or of leachable compounds affecting hardseededness.

Marked differences were found between hard and soft seeds in respiration and leakage. Oxygen uptake was negligible in hard seeds. A rapid efflux of K+ ions from hard and soft seeds was detected during the first minutes of immersion. Subsequently, the rate of leakage of hard seeds decreased markedly. After 4 h of imbibition, conductivity measurements differentiated individual hard and soft seeds.

Abrasion, percussion and immersion in sodium hypochlorite had no effect on hard seeds, but mechanical scarification and immersion in sulphuric acid reduced hardseededness. Gamma radiation did not affect the hard coat but damaged the embryo. A. theophrasti seeds were exposed to organic solvents such as acetone. ethanol and methanol, and to pesticides such as butylate, EPTC, metham‐sodium, vernolate and methyl bromide, in liquid or gaseous phase. Some of the treatments reduced germination of soft seeds, but none, even methyl bromide, had any significant effect on the number or viability of hard seeds, proving their complete impermeability.
Studies in the growth of Pteridium aquilinum (L.) Kuhn. (bracken) 1. Regeneration of rhizome segments
Authors: DANIELS R. E.
Published: July 2006

The patterns of regeneration of Pteridium aquilinum (L.) Kuhn. (bracken) rhizome segments grown in pot culture are described. The overall capacity for regeneration was unaffected by the rhizome type planted, i.e., whether it consisted of only a length of frond‐bearing ‘short shoote’ or whether this was attached to part of the main storage and exploratory ‘long shoot’. In all cases rhizomes extended, produced new lateral buds and developed fronds during the first summer. Regenerative capacity was also similar for segments with or without apical buds. Different patterns of growth were observed in plants grown from different types of segment: in particular, more new lateral buds were produced on rhizome segments originally lacking an apex. As rhizomes extended, the distance between successive lateral buds increased. The results are discussed in relation to the possible roles of correlative inhibition and patterns of translocation between fronds and rhizomes and to information on field populations.
Dégradation catalytique de carbamates et amides acétyléniques. Herbicides sur bentonites homoioniques: aspects particuliers
Authors: SABADIE J. , COSTE C. M.
Published: July 2006

Rásumá

La dégradation chimique d'herbicides acétyléniques (amides et carbamates) est étudiée en phase sèche sur diverses bentonites homoioniques (Fe3+, Mn2+, Cu2+, Zn2+). La bentonite Zn présente une activité intéressante vis à vis du propyzamide. L'influence de la dispersion du métal (ex: Cuivre) et de l'humidité de l'argile ont étéétudiées. La spectroscopie Infra Rouge a permis de préciser les groupes fonctionnels du substrat impliqués dans l'adsorption et de mettre qualitativement en évidence le phénomène de dégradation précédemment étudié.
Management of submerged aquatic macrophytes with terbutryne: availance, phytotoxicity and persistence
Authors: BOWMER K. H. , SHAW K. , ADENEY J. A.
Published: July 2006

In ideal conditions (static assay with long exposure time) several species of submerged weeds (Myriophyllum propinquum A. Cunn, Potamogeton tricarinatus F. Muell and A. Benn, and Vallisneria gigantea Graebner) were controlled by terbutryne at initial concentrations of <0·2 g m−3. However, since water management practices in irrigation systems limit the contact time which can be imposed, the availance (concentration‐time integral required for effectiveness) was further investigated, using Elodea canadensis Rich., which is dominant and widespread in the irrigation systems of south‐eastern Australia. In many experiments in irrigation channels, where control was poor, contact times were probably inadequate. Other factors may also contribute to inefficiency, including poor penetration of the weed beds after surface application, protection by high loadings of aufwuchs (periphyton, bacteria, detritus and associated particulate matter) on the leaves in the autumn, and inhibition of photosynthesis in an unfavourable light climate. Weed control was improved by injecting the herbicide into Mowing water, before ponding the treated water in the channels in spring or summer for at least 11 days. Terbutryne residues in the water decreased with a first order half‐life of about 9–20 days. Therefore, terbutryne is unsuitable for pulse injection treatment of flowing water in summer. Instead, effective control might be achieved by ponding the treated water in the channels in spring before the period of great water demand for summer crops. Contaminated water would be discarded onto tolerant crops or fallow land or retained in the system for about 7 weeks to ensure degradation of terbutryne before reuse.
Chemical weed control in transplanted onion (Allium cepa L.) in the Sudan Gezira
Authors: And A. G. T. BABIKER , AHMED M. K.
Published: July 2006

Summary; Résumé; Zusammenfassung

Unrestricted weed growth reduced the yield of transplanted onions (Allium cepa L.) by 26–48%. Hand‐weeding once, 42 days after transplanting reduced the yield loss to 15%. Application of oxadiazon (1.1–1.3 kg ai ha−1), pendimethalin (1.2–1.8 kg ai ha−1), oxyfluorfen (0.14–0.43 kg ai ha−1) and chlorthal‐dimethyl (8.3–13.1 kg ai ha−1) resulted in yields comparable to the hand‐weeded control (82–126%). When sprayed at transplanting these herbicides gave excellent and persistent control of grasses (86–100%). However, they were less effective on broad‐leaved weeds (38–94% control).

Désherbage chimique de l'oignon repiqué (Allium cepa L.) dans la Gezireh soudanaise

La croissance incontrôlée des mauvaises herbes réduit le rendement des oignons repiqués de 26–48%. Un désherbage manuel, 42 jours après le repiquage, ramène la baisse de rendement à 15%. L'application d'oxadiazon (1,1–1,3 kg ma ha−1), de pendiméthalin (1,2–1,8 ka ma ha1), d'oxyfluorfen (0,14–0,43 ka ma ha−1) et de chlortal‐diméthyle (8,3–13,1 kg ma ha−1), a permis d'atteindre des rendements comparables aux témoins désherbés manuellement (82–126%). Lorsqu'ils ont été administrés au moment du repiquage, ces herbicides ont permis un contrôle efficace et persistant des monocotylédones (86–100%). Toutefois, ils se sont montrés moins efficaces à l'égard des dicotylédones (38–94% du témoin).

Chemische Unkrautbekämpfung in verpflanzten Zwiebeln (Allium cepa L.) in der Region Gezira (Sudan)

Ungehinderte Unkrautentwicklung in verpflanzten Zwiebeln (Allium cepa L.) verringerte die Ernte um 26–48%. Eine Handjätung, 42 Tage nach dem Auspflanzen, reduzierte den Ernteverlust auf 15%. Die Applikation von Oxadiazon (1,1–1,3 kg ai ha−1), Pendimethalin (1,2–1,8 kg ai ha−1), Oxyfluorfen (0,14–0,43 kg ai ha−1) und Chlorthal‐ dimethyl (8,3–13,1 kg ai ha−1) erbrachte Ernten, die mit denjenigen, der von Hand gejäteten Kontrollparzellen vergleichbar waren (82–126%). Diese Herbizide, zur Ausflanzzeit ausgebracht, ergaben eine ausgezeichnete und andauernde Kontrolle von Gräsern (86–100%), während die Wirkung gegen breitblättrige Unkräuter geringer ausfiel (38–94%).
Studies of Salvia reflexa Hornem. IV. Effects of watering frequency, drought and nutrient supply on growth and development
Authors: WEERAKOON W. L. , LOVETT J. V.
Published: July 2006

Summary: Résumé: Zusammenfassung

Plants of Salvia reflexa Hornem. grown in pots of soil were subjected to drought treatments in glasshouse conditions. Quite short durations of water stress significantly decreased leaf area, top and root dry weight and the plants rapidly adjusted their water loss below potential evaporation rates. The plants survived and recovered from periods of drought for up to 30 days but plants dehydrated, even after short droughts, did not attain the growth rates of undroughted plants. In an infertile soil, S. reflexa plants demonstrated a large requirement for applications of phosphorus. With phosphorus applied, the species was also very responsive to nitrogen, and where both nitrogen and phosphorus were applied there were smaller responses to sulphur and potassium.

Etudes sur Salvia reflexa Hornem. IV. Influence exercée sur la croissance et le développement de l'espèce par la fréquence des arrosages, la sécheresse et l'apport d'aliments

Salvia reflexa Hornem., cultivé en vases de végétation, a été soumis à des régimes de sécheresse en conditions de serre. Une sécheresse, même de durée assez courte, a amené une diminution significative de la surface foliaire et du poids sec des parties aériennes ainsi que des racines; les plantes ont vite fait d'adapter leur perte d'eau à des niveaux inférieurs au taux potentiel d'évaporation. Elles ont survécu et se sont remises après des sécheresses de 30 jours maximum mais les plantes déshydratées, même pendant des sécheresses de courte durée, n'ont plus atteint le taux de croissance des plantes i indemnes de sécheresse. En terre pauvre, les plantes de S. reflexa ont exigé de grands apports de phosphore. Après les apports de phosphore, l'espéce a également fait preuve d'un grand besoin d'azote. En présence de phosphore et d'azote, la réponse aux apports de soufre et de potassium était moins forte.

Untersuchungen an Salvia reflexa Hornem. IV. Einfluss von Wasserversorgung und Düngung auf das Wachstum

In Gewächshausversuchen mit Salvia reflexa Hornem, nahmen bei relativ kurzzeitiger Trockkenperiode die Blattfläche und die Trockenmasse des Sprosses sowie der Wurzeln signifikant ab, so dass die Pflanzen die Transpiration schnell unter die potentielle Evaporationsrate senkten. Sie überlebten Trockenperioden von bis zu 30 Tagen und erholten sich wieder, erreichten aber, auch nach kurzem Wassermangel, nicht dieselben Wachstumsraten wie Pflanzen, die nicht dieser Belastung unterworfen waren. Auf einem nährstoffarmen Boden zeigten S.‐reflexa‐Pflanzen einen hohen Phosphatbedarf. Nach Phosphatdüngung braucht die Art auch viel Stickstoff. Bei N + P‐versorgten Pflanzen ist der Bedarf an Schwefel und Kalium gering.
Effects of temperature, light and certain growth regulating substances on sprouting, rooting and growth of single‐node rhizome and shoot segments of Paspalum distichum L.
Authors: HUANG W. Z. , HSIAO A. I. , JORDAN L.
Published: July 2006

The rate of sprouting, rooting and early growth of both single‐node stem and rhizome segments of Paspalum distichum L. increased as incubation temperatures increase to about 30°C and then declined at 40°C. There was little growth at 10°C. Single‐node shoots remained viable at cooler temperatures after 1 days’incubation at 45°C, and 35% remained viable after 2 days’incubation at 45°C. Both shoot and rhizome segments sprouted and rooted at alternating temperatures of 45°C/28°C and 45°C/22°C. Generally sprouting and rooting of shoot segments were faster than in rhizome segments, but the response to temperature was similar for both sprouting and rooting of single‐node shoot and rhizome segments. Single‐node shoot segments sprouted faster in 16‐h day lengths than in the dark. Rooting was better in the dark at 10°C, unaffected by light at 22 and 28°C, and faster in the light at 35 and 40°C. Sprouting, rooting and early growth were enhanced by gibberellin A3, kinetin and indole‐3‐acetic acid. Shoots collected at different seasons differed in their sprouting and rooting responses at various incubation temperatures. These patterns varying in response to seasonal temperature fluctuations may provide a survival mechanism for P. distichum.
Behaviour of the herbicide EL‐107 in wheat and rape grown under controlled conditions
Authors: CABANNE F. , LEFEBVRE A. , SCALLA R.
Published: July 2006

The behaviour of 14C‐EL‐107 has been evaluated in winter wheat and rape, which are tolerant and susceptible, respectively, under field conditions. After 10‐ to 13‐days’growth under controlled conditions, seedlings were allowed to absorb the herbicide through the roots. Two experiments were conducted to study the absorption and the metabolism of EL‐107. Absorption was estimated during a 5‐day treatment at the rate of 1–47 μM, and metabolism was studied after a 1‐day treatment at 14.7 μM. The results showed that (i) rape plants absorbed more herbicide than wheat, and translocated less radioactivity into their shoots, and (ii) the metabolism of EL‐107 proceeded actively only in the shoots, where EL‐107 disappeared at similar rates in the two species, giving rise to the same metabolites. In conclusion, the respective degrees of susceptibility of the two species could be partly related to differences in the concentration of the herbicide in the roots, where it can exert its phytotoxic effect.
Effect of sodium 2,2,3,3‐tetrafluoropropionate on the germination, emergence, growth and survival of pasture species
Authors: CAMPBELL M. H. , MURISON R. D.
Published: July 2006

The effect of sodium 2,2,3,3‐tetrafluoropropionate (tetrapion) on the germination, emergence, growth and survival of pasture species was ascertained in petri‐dishes (21 days) and in soil (114 days). Tetrapion was applied with the water in the petri‐dishes and to the soil surface prior to sowing seeds 2‐mm deep in plastic‐lined glasshouse trays. The rates applied in the petri‐dishes were 0,0.093, 0.187, 0.375, 0.75 and 1.5 kg a.i. ha−1; the same rates, except 0.093 kg a.i. ha−1, were applied in the glasshouse. In the petri‐dishes tetrapion did not affect germination rate nor germination capacity of any species. However, it severely reduced shoot growth (22–78% for the lowest and highest rate, respectively) and moderately reduced root growth per seedling (4–44% for lowest and highest rate). In the glasshouse trays, lower emergence, at 27 days, of five of the sown species on the 1.5 kg a.i. ha−1 treatment compared with the control, was explained by depression of shoot growth. Emergence was not affected at any other rate. Between day 27 and day 114 there was a progressive decline in the number of living seedlings of all species; the magnitude of deaths increased with time and rate of tetrapion. The rating of species for tolerance to tetrapion was: Medicago sativa > Festuca arundinacea > Dactylis glomerata > Phalaris aquatica > Eragrostis curvula. Although Trifolium subterraneum seedlings survived low rates of tetrapion they were still affected at day 114 whereas seedlings of other species were recovering. As tetrapion is readily leached from the soil profile, desirable species must be sown after sufficient rain has fallen to wash it from the soil. In this way it is possible to kill weed seedlings that germinate soon after spraying as well as to establish improved species.
Influence of soil moisture on activity and persistence of the strigol analogue GR 24
Authors: BABIKER A. G. T. , HAMDOUN A. M. , RUDWAN A. , MANSI N. G. , FAKI H. H.
Published: July 2006

Germination of Striga hermonthica (Del.) Bentth seeds in response to the strigol analogue GR 24 was strongly influenced by soil moisture prior to, at, or after, stimulation. Exposure of seeds to excessive soil moisture contents (70% w/w) during conditioning resulted in a low response to GR 24. Transfer of Seeds from soil at 70% moisture to a lower moisture level (47%) for 2 days or more improved the response to GR 24 (37–58% germination), white air‐drying restored germination (88%). In Gezira soil the optimum soil moisture contents for maximum response to GR 24 were 44, 38 and 40% during conditioning, stimulation and germination, respectively. The corresponding figures for the sandy soil were 20, 22 and 22%, respectively. Persistence of GR 24 was similar in both soil types, but was strongly influenced by soil moisture content. The stimulant was stable in air‐dry soil, but a rapid loss was encountered in moist soil.
Interference of Sinapis arvensis L. and Chenopodium album L. in spring rapeseed (Brassica napus L.)
Authors: BLACKSHAW R. E. , ANDERSON G. W. , DEKKER J.
Published: July 2006

Interference of Sinapis arvensis L. (wild mustard) and Chenopodium album L. (lamb's‐quarters) in spring rapeseed (Brassica napus L.) was studied under field conditions in 1983 and 1984. Both weed species interfered with rapeseed early in the growing season, causing significant reductions in rapeseed dry weight by June of each year. Sinapis arvensis caused greater rapeseed grain yield reductions than did C. album. With weed densities of 20–80 plants m−2, rapeseed grain yield reductions ranged from 19 to 77% with S. arvensis but only 20 to 25% with C. album. Rapeseed yield reductions caused by mixtures of both weed species ranged from being less than to being equal to the sum of reductions caused by each weed alone, depending on the weed density and year of study. Both weed species were prolific seed producers capable of returning large quantities of seed to the soil. With weed densities ranging from 10–80 plants m−2, S. arvensis produced 5700–30 100 seeds m−2 while C. album produced 3100–63 600 seeds m−2.
Lack of prevention of chlorsulfuron‐induced inhibition by amino acids
Authors: GIARDINA MARIA CARMELA , DE AGAZIOand MARINA , GREGO S.
Published: July 2006

The amino acids valine and isoleucine, which had been indicated by Ray (1984) as antidotes against growth inhibition of pea plants induced by chlorsulfuron, were ineffective in preventing the damage induced by chlorsulfuron on the plasma membrane of maize roots as measured by K+ uptake. In addition, in seedlings of two corn genotypes and three pea genotypes grown in culture solution containing chlorsulfuron, growth inhibition was not alleviated by valine and isoleucine. However, in agreement with Ray's results, acetolactate synthase, the key enzyme of the biosynthesis of valine and isoleucine, was inhibited in vitro by chlorsulfuron in both maize and pea. It is suggested that the chlorsulfuron mechanism of action involves several sites.
Establishment and growth of Senecio jacobaea L. and Senecio erucifolius L. in grassland
Authors: WATT T. A.
Published: July 2006

Senecio erucifolius L. (hoary ragwort) has become conspicuous on roadside verges in southern England. Like Senecio jacobaea L. it is poisonous, so it might be a threat to animal production. In boxed swards the growth of S. jacobaea was less adversely affected by the greater competition from grass with a high level of nitrogen fertilizer than was the growth of S. erucifolius. Also, young S. jacobaea plants showed a much greater ability to regrow after their shoots had been cut at ground level. In a range of grassland managements S. jacobaea established better from seed than did S. erucifolius. Establishment of both species on molehills was poor because of the likelihood that the seedlings would be disturbed or even buried by fresh mole activity. Ten months after sowing, seedlings of S. jacobaea had persisted well in the higher nitrogen environment of ex‐cow‐dung patches, whereas S. erucifolius had not. Under intensive sheep grazing, in the absence of fertilizer, transplants of S. erucifolius had much greater root dry weights than did those of S. jacobaea. Also, in regrowth after cattle grazing on a fertilized sward, S. jacobaea plants had greater shoot dry weights than did S. erucifolius. Thus, although S. erucifolius can establish from seed in bare patches in an intensively grazed sward it is likely to be less persistent than S. jacobaea if the gaps are ex‐dung patches or if nitrogen fertilizer is applied.
Prognose‐Modell zur Erfassung des Rückstandsverhaltens von Metribuzin und Methabenzthiazuron im Boden und deren Auswirkungen auf Folgekulturen
Authors: PESTEMER W. , AUSPURG B.
Published: July 2006

Das Abbauverhalten von Methabenzthiazuron und Metribuzin wurde unter Freilandverhältnissen in einem sandigen Lehm mit Hilfe eines Computermodells simuliert, welches vor allem den dominierenden Einfluss von Temperatur und Feuchtigkeit auf den Abbau berücksichtigt, der vorher in Laborversuchen ermittelt wird. Hier ergaben sich in Abhängigkeit von den Inkubationsbedingungen (10–30°C, 20–90% WKmax.) fü Metribuzin Halbwertszeiten von 11–60 Tagen und für Methabenzthiazuron (MBT) von 42– > 1200 Tagen. Darauf aufbauend lässt sich für Freilandverhältnisse aus den täglichen Wetter‐aufzeichnungen für einen vorgegebenen Zeitraum der Herbizidabbau vorhersagen. Bei der Simulation des Metribuzin‐ und MBT‐Abbaus von Anfang Mai bis Ende August bzw. Anfang Oktober 1983 ergaben sich Halbwertszeiten von 21 bzw. 66 Tagen. Die im Freiland ermittelten Zeiten für eine 50%ige Konzentrationsabnahme betrugen 15 bzw. 62 Tage. Die potentiell pflanzenverfügbaren Anteile eines Gesamtrückstandes wurden aus den jeweiligen Verteilugskoeffizienten (Kd‐Werte), bei Berûcksichtigung des pflanzenverfügbaren Wassergehaltes im Boden, berechnet. Sie betrugen im verwendeten Boden für Metribuzin 77% und für MBT 16% des Gesam‐trückstandes.

Aus der Kombination der Modelle lassen sich, aufbauend auf dem ermittelten‘no‐observable‐effect‐level’(NOEL) und der simulierten Abbaukurve, Inaktivierungszeiten für die einzelnen Herbizide und Folgekulturen ableiten. Diese lagen z.B. bei Metribuzin zwischen ca. 3 (Möhre) und 13 Wochen (Buschbohne) und bei MBT zwischen 0 (Buschbohne) und 12 Wochen (Möhre).

Eine Kombination derartiger Modelle gibt einen Überblick sowohl über den Verbleib von Herbiziden im Boden als auch ihre Phytotoxizität gegenüber Kulturpflanzen und ist für eine praktische Anwendung hinreichend genau.
Nature of resistance to Striga hermonthica (Del.) Benth. parasitism in some Sorghum vulgare (Pers.) cultivars
Authors: EL HIWERIS S.O.
Published: July 2006

Ten Sorghum vulgare (Pers.) cultivars varying in tolerance to Striga hermonthica (Del.) Benth. parasitism were grown with or without Striga infection. Endodermal thickening, pericycle lignification and silica crystal deposition were studied microscopically and measured for infected and non‐infected sorghum cultivars. Although differences in the root character measurements were statistically significant they were not closely related to the response of the plant to infection. Low stimulant producing cultivars showed low or medium root cell thickening. The cv. Framida had both low stimulant production and high root cell thickening and was the best of the tolerant cultivars. High stimulant producing, tolerant cultivars generally showed heavy or intermediate cell thickening. The high stimulant producing, susceptible cultivar Debaikri also showed intermediate root cell thickening.‘Antibiosis', measured by the content of phenolic compounds in the plant, was then studied. Varietal differences in quality and quantity of phenolic substances in the roots and shoots of sorghum cultivars infected or non‐infected with Striga were observed. Infection increased total phenolic contents in both shoot and root extracts. Differences in the total phenolic content in the shoot of non‐infected cultivars did not reflect tolerance to Striga infection. The total phenolic acid content of the root extracts was closely related to the response of the host plant to Striga infection, tolerant cultivars having greater total phenolic acid content than susceptible ones.