bluuebunny/crossref_metadata_2025 huggingface dataset:
EVALUATION OF HERBICIDES FOR THE CONTROL OF COUCHGRASS, AGROPYRON REPENS (L.) BEAUV.
Authors: WATERSON H. A. , CRAIG J. , JOICE R.
Published: July 2006

Summary. Two techniques for the comparative evaluation for the control of couchgrass (Agropyron repens (L.) Beauv.) were tested in 1960, and it was concluded that the more practicable was the one in which known lengths (96 in.) of couchgrass rhizome fragments were planted in a plot of 10 × 2 ft. The rhizomes were allowed to grow and herbicides were applied when the shoots were 6–9 in. high. Two to 3 months later the rhizomes were carefully dug up, weighed, measured and dried. Dry weight of rhizomes was used as a measure of the quantity of couchgrass present. Four trials of spring applications, and two of autumn applications are reported.

Of the commercially available herbicides, amitrole‐T, TCA and dalapon were effective in that order, and presented no insuperable problems of persistence in the soil. Fenac and atrazine showed little promise. Spring applications of herbicides were considerably more effective than autumn treatments.

Essai d'herbicides pour la lutte contre Agropyron repens
EMERGENCE AND LONGEVITY IN CULTIVATED SOIL OF SEEDS OF SOME ANNUAL WEEDS
Authors: ROBERTS H. A.
Published: July 2006

Summary. Four replicated experiments were begun in successive years to study the behaviour of viable seeds of eleven species of annual weeds when mixed with a 3 in. layer of cultivated soil. The soil was confined in pots sunk in the ground outdoors, seedling emergence was recorded, and the numbers of viable seeds remaining at the end of the experiments were assessed. One experiment was continued for 3 years, the others for 5 lull calendar years after the freshly collected seeds had been sown.

Initial emergence was greatest with Stellaria media, Senecio vulgaris and Poa annua, and least with Chenopodium album and Thlaspi arvense. Subsequently, the numbers of seedlings which emerged each year declined at a rate which was constant for each species. In the fifth year after sowing, the number of seedlings of Senecio vulgaris was only 0.3% of the initial number of viable seeds, while for Thlaspi arvense and Veronica hederifolia the figure was 3.2%.

The proportions of viable seeds which produced seedlings ranged from 37 to 86%, while from 0 to 11% were still present in the dormant state after 5 years. Most species showed marked patterns in the seasonal distribution of emergence which were modified by variations in weather from year to year, but in any one year, the distribution of emergence was not influenced by the length of time the seeds had been in the soil.

Germination et longévité dans des sots cultivés de semences de quelques mauvaises herbes annuelles
EINIGE BEOBACHTUNGEN ZUR VERÄNDERUNG DER VERUNKRAUTUNG WÄHREND MEHRJÄHRIGEN GETREIDEBAUS UND VERSCHIEDENARTIGER UNKRAUTBEKÄMPFUNG
Authors: KOCH W.
Published: July 2006

Zusammenfassung. Auf einem stark verunkrauteten Feld (guter Lehmboden] wurde die Veränderung der Unkrautflora im Verlauf von 3 Jahren bei verschiedenartiger Unkrautbekämpfung (keine Unkrautbekämpfung; zweimal Blindeggen sowie Eggen im 3‐Blattstadium des Getreides; chemische Unkrautbekämpfung mit DNOC) beobachtet In diesem Zeitraum ging die Gesamtverunkrautung als Folge des guten Getreidestandes auch in den Parzellen ohne Unkrautbekämpfung erheblich zurück.

Durch jährlich wiederholte, intensive mechanische Unkrautbekämpfung wurde im Verlauf von 3 Vegetationsperioden die Gesamtverunkrautung gegenüber der Kontrolle etwas, der Bestand einzelner Unkrautarten wie Alopecunus myosuroides, Sinapis arvensis und Galeopsis tetrahit erheblich vermindert. Der prozentuale Anteil der grasartigen Unkräuter an der Gesamtverunkrautung entsprach bei Versuchsende dem der unbearbeiteten Parzellen.

Durch chemische Bekämpfung mit DNOC wurden im Vergleich zur unbehandelten Kontrolle Sinapis arvensis, Palygonum convolvulus, Galium aparine und die Gesamtverunkrautung stark reduziert, Alopecurus myosuroides dagegen stark gefördert. Das Artenverhältnis änderte sich zugunsten der grasartigen Unkräuter.

Some observations on changes in weed populations under continuous cereal cropping and with différent methods of weed control
THE USE OF ADSORBENTS AND SIMAZINE ON NEWEY PLANTED STRAWBERRIES
Authors: ROBINSON D. W.
Published: July 2006

Summary. A series of field trials was conducted to determine if the tolerance of newly planted strawberry runners to simazine could be increased by placing adsorbents in the vicinily of the root zone at planting time. Powdered steam‐activated charcoal was found to be the most suitable of seven adsorbents tested. Dipping the roots of runners in charcoal before planting was more effective and practicable than placing a similar quantity of charcoal around each runner at planting time. No significant damage was recorded in several trials in which dipped runners were sprayed with simazine at 1 lb/ac within a few days of planting.

Although new roots are likely to take up the herbicide as they grow away from the charcoal‐protected area around the plant, the protection provided by the adsorbent appears to be sufficient to enable the young plants to develop satisfactorily.

Utilisation d'adsorbants et de simazine sur des fraisiers récemment plantés
SELECTIVITY AND PHYSIOLOGICAL INACTIVATION OF SOME HERBICIDES INHIBITING PHOTOSYNTHESIS
Authors: van OORSCHOT J. L. P.
Published: July 2006

Summary. The effects of several herbicides on the rates of CO2 uptake and transpiration of intact plants were measured. A simple technique is described which reveals whether photosynthesis‐inhibiting herbicides are inactivated by plants. By this method, the inactivation of simazine by maize could be confirmed. Evidence is presented for physiological inactivation of monuron by Plantago lanceolata, of cycluron (OMU) and pyrazon by sugar beet, of N'‐(4‐butoxyphenyl)‐NN‐dimethylurea by of 5‐bromo‐6‐methyl‐3‐phenyluracil by flax. Certain plant species showed different reactions to some other new herbicides. The effect of herbicides in the culture solution on CO2 uptake by the leaves is probably largely determined by the rate of transpiration of the plants. Assuming that uptake in proportional to transpiration rate, estimates of the concentration of the herbicides inside the plant were made.

L'inactivation physiologique de quelques herbicides produisant une inhibition de la photosynthèse
THE USE OF HERBICIDES IN ALTERNATE HUSBANDRY AS A SUBSTITUTE FOR PLOUGHING
Authors: ARNOTT R. A. , CLEMENT C. R.
Published: July 2006

Summary. It is practicable to use herbicides as an alternative to ploughing grass swards for the preparation of a seedbed for the sowing of cereals and kale. The yields of spring barley and kale following a glaass/clover sward killed with 10 lb/ac amitrole‐T were similar to those obtained following ploughing. Yields of tip to 40 cwt/ac of winter wheat were obtained following grass swards killed with amitrole‐T compared with up to 45 cwt/ac after ploughing.

The ideal herbicide must kill all plants in a sward and have no residual toxicity to the subsequent crop. At 10 lb/ac, amitrole‐T killed most plants in the sword, but it was considered necessary to delay sowing for at least 3 weeks after spraying to minimize the danger of residual toxicity. Ploughing gave the lowest incidence of grasses persisting from the sward. Paraquat did not control clover and Agropyron repens, while broad‐leaved weeds were more common on the ploughed than on the sprayed land.

There were differences in the amount of nitrogen mineralized in ploughed and In undisturbed soil, but these were insufficient to affect crop yields materially. When a lower yield followed herbicidal destruction of the sward, this was not accompanied by a reduced percentage nitrogen content.

L'emploi des déherbants pour la rénovation des prairies
THE MOVEMENT OF PARAQUAT IN PLANTS
Authors: SLADE P. , BELL E. G.
Published: July 2006

Summary. A qualitative study of the movement of the herbicide paraquat from droplets applied to leaves of tomato plants, using 14C‐methyl‐labelled and 14C‐ring‐labelled paraquat dichloride and di(methylsulphate), has shown that it moves in the xylem with the transpiration stream. The chemical is as well transported from young leaves as from mature ones, and will move through a steam‐ringed petiole. The enhancement of the amount of paraquat transported from the treated leaves which occurs when treated plants are kept in darkness for a period following treatment and then exposed to light, is probably due to the greater movement into the xylem through undamaged tissue which can occur in the dark. Once the chemical has been absorbed into treated leaves, light‐induced damage is required for significant movement through the rest of the plant to take place, but the damage then inhibits further entry of paraquat into the xylem. The movement of paraquat in broad bean and maize is essentially similar, though the enhancement of movement by a period of darkness after application is much less marked.

La migration du paraquat dans les plantes
THE BIPYRIDYLIUM QUATERNARY SALTS
Authors: BRIAN R. C.
Published: July 2006

Summary. In a number of plant species, the biological activity of diquat and paraquat was increased by an increase in environmental humidity. This improved activity resulted from an increase in both uptake and movement.

High humidity was more effective after treatment than before it, and durations of 8 hr or more were required to produce the maximum effect. When periods of low humidity of up to 16 hr were interposed between treatment and high humidity, there was no significant effect on the activity of diquat in darkened tomato or sugar beet.

The increase in activity occurred both in the dark and in the light, and it is therefore concluded that humidity does not exert its effect by modifying the degree of stomatal opening.

Experiments were carried out with wheat using two air humidities combined with different soil moisture contents, ranging from saturated down to only 30% of water‐holding capacity. Greatest movement occurred where high air humidity was combined with low soil moisture, and least where low air humidity was combined with high soil moisture. It is concluded that diquat and paraquat would be most effective in the field when sprayed under dry soil conditions in late afternoon or evening when increased humidity (and darkness) can follow soon after treatment.

Les sels quatemaires de bipyridylium

Effet de l'humidité atmosphérique et de l'humidité du sol sur l'absorption et la migration du diquat et du paraquat dans les plantes
THE INFLUENCE OF ENVIRONMENT ON POTATO HAULM KILL BY DIQUAT AND ON ITS RESIDUES IN THE TUBERS
Authors: BRIAN R. C. , WARD JOYCE
Published: July 2006

Summary. The effect of various environments on the degree of desiccation and of residues in King Edward and Majestic potatoes was studied. The higher residues frequently associated with the variety King Edward are ascribed from glasshouse experiments to greater diquat movement; they could not be accounted for by differences in uptake between the two varieties.

In glasshouse experiments, uptake was increased both by high air humidities and reduced light intensities before and after treatment. Since earlier work with cocksfoot and wheat indicated that dry soil conditions markedly increased movement, it is concluded that dull, humid air conditions associated with dry soil would be most conducive to efficient haulm desiccation and also to highest residues in the tubers. Late afternoon or evening treatment often provides thes conditions, and residues were in fact least from morning treatment.

In the field, increases in haulm desiccation were associated with reductions in residues. As they were observed only at light intensities below 5000 lux, they are unlikely to occur in normal dull weather.

Rain falling soon after spraying did not reduce the extent of haulm desiccation or diquat residues.

Influence de I'enviromurtunt sur la destruction des fanes de pomme de terre par le diquat el sur ses
TUBER NECROSIS FOLLOWING THE DESICCATION OF POTATO FOLIAGE WITH DIQUAT
Authors: HEADFORD D. W. R. , DOUGLAS G.
Published: July 2006

Summary. Necrosis at the stem‐end of potato tubers following the application of diquat to the foliage is rare and has occurred mainly in seasons of low rainfall. Damage in the field has been associated with tuber residues of diquat of about ten times the normal level and the extent of damage has shown a linear relationship with the concentration of chemical in the tubers. Normally an increase in the dose of diquat applied causes only a slight increase in amount of chemical in the tubers, but under conditions where damage occurred, tuber residues increased markedly with increase in application rate.

The factors influencing diquat residues in potato tubers were examined in pot experiments. Highest residues were found when plants were subjected to drought and to a period of darkness following spraying at a time when senescence of the foliage had commenced and the tubers were still increasing in fresh weight. Further experiments at a similar stage of growth showed that high residues of diquat caused stem‐end rot only when plants were subjected both to a soil moisture stress sufficient to induce wilting before spraying and to reduced light intensity and a high atmospheric humidity after spraying. It is suggested that these conditions promote the rapid downward movement of a high concentration of diquat in the xylem.

In a preliminary experiment with a range of chemical desiccants, only sodium arsenite gave appreciable tuber damage when applied to the foliage.
EFFECT OF CULTIVATION ON THE NUMBERS OF VIABLE WEED SEEDS IN SOIL
Authors: ROBERTS H. A. , DAWKINS PATRICIA A.
Published: July 2006

Summary. In a 6‐year experiment with a naturally occurring population of viable weed seeds, the numbers in the top 9 in. of soil decreased exponentially from year to year in the absence of further seeding. The rates of loss were equivalent to 22% per year in undisturbed soil, 30% per year on plots dug twice a year (March and September) and 36% per year on those dug four times a year (March, June, September, December). Seed numbers of individual species also decreased exponentially, although not all at the same rates.

On the dug plots, the numbers of seedlings that emerged each year decreased exponentially once the regimes had become established. The proportions of the viable seeds which gave rise to seedlings in the course of a year were 7 % on plots dug twice and 9 % on those dug four times a year; although there was some variation, these proportions remained much the same from year to year. On undisturbed soil the number of seedlings that emerged declined rapidly, and in the 4th year represented no more than 03% of the viable seeds still present in the top 9 in. of soil.
SELECTIVITY OF 2,3,5‐TRICHLORO‐4‐PYRIDINOL AS A HERBICIDE FOR DIRECT‐SEEDED, FLOODED RICE
Authors: MOOMAW J. C. , KIM D. S.
Published: July 2006

Summary. Field and glasshouse experiments demonstrated (hat 2,3,5‐trichloro‐4‐ pyridinol (pyriclor) at 50–500 g/ha controls Echinochloa crusgalli in direct‐seeded rice. It prevented germination and restricted growth of the weed under both static and percolating water conditions, but allowed rice to germinate and grow normally. Pyriclor was most effective when applied early; treated plots gave higher yields than those hand‐weeded or sprayed with propanil. Grass weed control was as effective as that given by molinate or nitrofen at much higher rates. Dichlobenil inhibited rice germination, was toxic to young seedlings, and is therefore unsuitable for direct‐seeded rice. Molinate had a wider range of latitude in time of application than the other chemicals tested. Glasshouse experiments indicated that pyriclor moves down in percolating water but is adsorbed more readily in fine than in coarse‐textured soils.
THE PHOTOLYTIC DEGRADATION OF PICLORAM
Authors: HALL R. C. , GIAM C. S. , MERKLE M. G.
Published: July 2006

Summary. The effects of sunlight and ultraviolet light (253.7 nm) on 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) in a basic aqueous solution were investigated. Electron‐capture gas chromatography determinations showed that approximately 20% of a 2 × 10−2 M concentration of picloram was degraded for each 48‐hr exposure to ultraviolet light of an intensity of 200 μW/cm2. Decomposition by sunlight was slower and more variable.

Precipitation of the degradation products with AgNO3 indicated that two chloride ions were liberated for each molecule of picloram that was degraded. Titrations indicated that acids were formed in the degradation process, and ultraviolet spectra showed that the pyridine nucleus was destroyed. Chromatograms of the methylated decomposition products showed that at least five products were formed.

The effect of the addition of a free radical scavenger, hydroquinone, on the rate of decomposition was investigated but no definite conclusions could be drawn.

La dégradation photolytique du piclorame
TRANSLOCATION STUDIES WITH ENDOTHAL‐14C IN POTAMOGETON NODOSUS POIR.
Authors: THOMAS T. M. , SEAMAN D. E.
Published: July 2006

Summary. Plants of Potamogeton nodosus, a submersed aquatic, were treated with the di‐sodium salt of 7‐oxabicyclo(2,2,l)heptane‐2,3‐dicarboxylic acid‐14C (endothal‐14C). Gross radioautographs showed that the 14C label moved from mature photosynthesizing leaves and accumulated in the apices and developing secondary plants. Similar results were obtained with mid‐leaf, stem (internode) and winter‐bud applications. No move‐ment of radioactivity occurred following root treatment. The results indicate symplastic translocation of endothal‐14C when applied to the leaf, stem or winter bud. It is suggested that endothal can cause the death of plants by direct injury to root tissues subsequent to absorption.

Recherches sur la migration de l'endothal‐14C dans le Potamogeton nodosus Poir.
THE EFFECTS OF SHOOT REMOVAL ON THE RHIZOME CARBOHYDRATE RESERVES OF COUCH GRASS (AGROPYRON REPENS (L.) BEAUV.)
Authors: TURNER D. J.
Published: July 2006

Summary. Three box experiments examining the effects of shoot removal on rhizome carbohydrate reserves are reported.

During summer in England the optimum frequency of hand defoliation for maximum loss of carbohydrate was 10–14 days. As in previous experiments, high levels of soil nitrogen sometimes increased the rate of carbohydrate loss from 9‐in. rhizome pieces. This result was obtained when nitrogen was supplied as a nitrate, an ammonium salt, or urea.

Repeated applications of 2 or 4 oz/ac paraquat over a period of about 60 days reduced carbohydrate reserves to about 50% of the level obtained with the same number of hand clippings. It is suggested that paraquat may have been translocated to the rhizomes, the carbohydrate content of which may have been reduced by an effect of the paraquat on the respiration rate.

When plants which had been subjected to different methods and frequencies of defoliation were uprooted and buried beneath 2 in. of soil, there was a connection between the rhizome carbohydrate content at the time of burial, the ability of the plants to regenerate, and the rate at which new carbohydrate reserves built up during the following two months.
GROWTH AND SPRAY RETENTION OF WILD OAT AND FLAX IN RELATION TO HERBICIDAL SELECTIVITY*
Authors: HIBBITT C. J.
Published: July 2006

Summary. The growth of wild oat (Avena fatua L.) was accompanied by an increase in the amount of spray retained per plant and per unit weight of plant, probably because the projected area (plan view) increased as the plant became larger. Flax (Linum usitatissimum L.) retained a fairly constant volume of spray per plant from the 8‐leaf to the 35–40‐leaf stages, so that the spray retained per unit plant weight decreased considerably as the plants grew. This was related to the decrease in projected area as a proportion of the whole. There was also a difference in retentivity between the cotyledons and true leaves; the cotyledons retained ten to twenty times more spray per unit weight. These results suggest that maximum selectivity would be achieved by spraying at an advanced stage of growth.

Wild oat at the 3‐leaf stage retained more than half the aqueous spray in the two leaf axils, while flax retained most on the cotyledons. Distribution was shown to be a probable reason for selectivity. Addition of a surfactant greatly increased retention by both species, but although the effect of a spray on wild oat might thereby be increased, under certain conditions injury to flax might be increased and the margin of selectivity reduced.

Croissance et retention des bouillies herbicides par la folle‐avoine et le lin en rapport avec la sélectivité
THE HERBICIDAL ACTIVITY OF 2‐AMINO‐3‐CHLORO‐1,4‐NAPHTHOQUINONE
Authors: HAGIMOTO H.
Published: July 2006

Summary. An investigation was made of a now herbicide, 2–amino‐3–chloio‐1,4–naphthociuinone (ACNQ,), which appears to be promising for the control oi Echinochloa crus‐galli (L.) Beauv. in transplanted paddy rice [Oryza sativa L.).

In pot experiments in the glasshouse, seedlings of Echinochloa at different stages of growth were killed by ACNQ, at doses equivalent to 2–4 kg/ha (applied as granules) if they were submerged, but not if the shoots emerged above water. Activity was increased more by raising the level of water in the pot than by increasing the dosage. Emergent rice seedlings were little affected by ACNQ, up to 8 kg/ha, and the observed selectivity is considered to be due mainly to differences in plant height in relation to depth of water.

In laboratory experiments with rice seedlings grown without soil, the activity of ACNQ again increased with the depth of solution. Conversely, at a standard solution depth, there was a reduction in damage with advancing stage of growth, and the chemical had little effect once the leaf tip was above the solution surface.

The rate of leaching of ACNQ. through a sandy soil was slow and, at a dose of 2 kg/ha, persistence was about 15 days.

In evaluating new herbicides for paddy rice it is suggested that screening tests arc necessary on submerged as well as non‐submerged plants.

Activité herbicide de la 2–amino‐3–chloro‐1,′4–naphtoquimne. I. Activité herbicide et profondtur de de l'eau
EVALUATION OF HERBICIDE PERSISTENCE IN SOIL*
Authors: HOROWITZ M.
Published: July 2006

Summary. The persistence of ten herbicides in soil was tested in the glasshouse over a 5–month period, using an oat bioassay. Simazine and diuron were highly persistent, atrazine persistent, fluometuron, trifluralin, bromacil and noruron moderately persistent, and pyrazon, prometryne and ametryne of short persistence. Six of these herbicides were also included in a field experiment consisting of logarithmically sprayed strips on which oats were sown at ten intervals of 1 month; changes of herbicidal activity with time were evaluated by measuring the length of the strip showing herbicidal injury. Results corroborate those of the glasshouse experiments except for trifluralin which was more persistent in the field. Disappearance curves were generally sigmoidal. The more persistent compounds showed a long period of slow disappearance followed by rapid disappearance.
THE EFFECTS OF DIFFERENT LEVELS OF NITROGEN UPON CIRSIUM ARVENSE (L.) SCOP. PLANTS GROWN FROM SEEDS AND ROOT FRAGMENTS
Authors: HAMDOUN A. M.
Published: July 2006

Summary. Growth of Cirsium arvense plants was little affected by nitrogen level for the first 3 weeks of treatment, but differences between levels became apparent later. Shoot dry weight increased more than root dry weight at nitrogen levels of 35 ppm or more. The growth responses to nitrogen were similar in pattern in plants grown from seed and from root fragments, but growth was greater in fragment‐derived plants.

Effets de l'azote à diverses concentrations sur des plantes de Cirsium arvense (L.) Scop, issues de sentences ou de fragments de racines

Résumé. La croissance de plantes de Cirsium arvense fut peu affectée par la concentration en azote pour les trois premieres semaines de traitement mais des différences selon les concentrations se manifestérent par la suite. Le poids sec de la partie aćrienne s'accrut plus que le poids sec des racines a des concentrations en azote de 35 ppm ou plus. Les reactions de croissance provoquées par l'azote se déroulérent selon un processus analogue pour les plantes issues de semences et pour celles provenant de fragments de racines, mais dans ce dernier cas, la croissance fut plus importante.

Wirkung verschieden hoher Stickstoffgaben auf Cirsium arvense (L.) Scop, bei Aufwuchs aus Samen sowie aus Wurzelfragmenten

Zusammenfassung. Das Wachstum von Cirsium arvense zeigte wenig Abhangigkeit von der Höhe der Stickstoffgabe während der ersten drei Wochen nach der Applikation, wohl aber spater. Durch Stickstoffgaben von 35 ppm und mehr wurde das Spross‐Trockengewicht stärker gefördert als das Wurzel‐Trockengewicht. Die Reaktion auf Stickstoff entsprach bei atjs Samen gezogenen Pflanzen weilgehend derjenigen von Pflanzen, die aus Wurzelfragmenten hervorgegangen waren, doch war das Wachstum bei den vegetativ vermehrten Pflanzen allgemein stärker.
AVAILABILITY TO PLANTS OF PARAQUAT ADSORBED ON SOIL OR SPRAYED ON VEGETATION*
Authors: DAMANAKIS M. , DRENNAN D. S. H. , FRYER J.D. , HOLLY K.
Published: July 2006

Summary. Paraquat adsorbed on peat soils was available to plants in amounts as low as l/25th of their Strong Adsorption Capacity (SAG). In Begbroke soil the paraquat was available to plants only near the SAG. Paraquat sprayed at usual doses on the surface of peat soils and not incorporated reduced growth of seedlings of Lolium perenne L. placed on the surface. Seeds sown 6 mm below a sprayed surface were only affected in one soil at a high rate of application.

Hypocotyl uptake of adsorbed paraquat took place only with applications of more than 82 kg/ha in a peat soil and 230 kg/ha in Begbroke soil.

Paraquat on litter of sprayed plants was found to be available to plants through root uptake. Living leaves can also adsorb paraquat from sprayed leaves if they are in contact.

Disponibilité our les plantes du paraquat adsorbé sur le sol ou appliqué sur la végitation

Résumé. Le paraquat adsorbé sur des sols tourbeux fut disponible pour les plantes en quantités n'atteignant que 1/25 de leur capacité brute d'adsorption (GBA). Dans le sol de Begbroke, le paraquat ne fut disponible pour les plantes qu'au voisinage de la CBA. Le paraquat appliqué aux doses usuelles à la surface de sols toturbeux, et non incorporé, réduisit la croissance des plantules de ray‐grass placées sur cette surface. Les semences semées á 6 mm de profondeur sous une surface traitée furent affectées dans un sol seulement et á une dose d'application élevée.

L'absorption par I'hypocotyle de paraquat adsorbé se produisit seulement avec des applications à des doses supéieures à 82 kg/ha dans un sol tourbeux et 230 kg/ha dans un sol de Begbroke.

Le paraquat sur une litiére de plantes traitées se montra disponible pour les plantes par absorption racinaire. Les feuilles vivantes peuvent aussi adsorber le paraquat de feuilles traitées si elles sont en contact avec elles.

Pflanzenverfugbarkeit von im Boden adsorbiertem oder auf PJlanzen gespritztem Paraquat

Zusammenfassung. Im Moorboden adsorbiertes Paraquat war fur Pflanzen verfügbar in Mengen um 1/25 der Kapazität zur festen Adsorption (Strong Adsorption Capacity, SAG). In Begbroke‐Böden war Paraquat für Pflanzen nur ungefähr in der Höhe des SAG verfügbar. In normalen Aufwandmengen atif die Oberfläche von Moorboden gespritztes und nicht eingearbeitetes Paraquat verminderte das Wachstum von Keimpflanzen von atif der Oberfläche ausgesätem Lolium perenne L. Scchs Millimeter unterhalb der Ober‐flache eingesáte Samen wurden nur in einem Boden bei hoher Herbizidkonzentration beeinflusst.

Hypocotyle Aufnahme von adsorbiertem Paraquat erfolgte nur bei Aufwandmengen von mehr als 82 kg/ha in Moorböden und 230 kg/ha in Begbroke‐Boden.

Paraquat an Rückständen von behandelten Pflanzen war durch Wurzelaufnahmc für andere Pflanzen verfügbar. Ausserdem können lebende Blatter Paraquat von behandelten Blättern adsorbieren, sofern sie in Kontakt mit dicaen stehen.
SELECTIVITY OF SOME NEW HERBICIDES FOR DIRECT‐SEEDED FLOODED RICE IN THE TROPICS
Authors: And S. K. DE DATTA , BERNASOR P. C.
Published: July 2006

Summary. Granular formulations of several new herbicides were tested for control of weeds in direct‐seeded tropical rice. S‐(4‐chlorobenzyl)‐N N‐diethylthiolcarbamate (benthiocarb) and N‐(butoxymethyl)‐2‐chloro‐2′,6′‐diethylacetanilide (CP 53619) showed a high degree of selectivity between rice and weed seedlings. Applied 6 days after seeding, when grass weeds were at the 1‐2‐leaf stage, both herbicides gave excellent control of Echinochloa crus‐galli and other weeds, and caused little or no damage to rice cv. IR22.
INFLUENCE OF HERBICIDES ON THE UPTAKE OF COPPER IN HYDRILLA*
Authors: SUTTON DAVID L. , And BLACKBURN , STEWARD K. K.
Published: July 2006

Summary. Combinations of copper sulphate pentahydrate (CSP) at 1 0 ppmw of copper with diquat, paraquat, ametryne, atrazine, terbutryne or 2,4‐D at certain concentrations and contact times increased the copper content in hydrilla (Hydrilla verticillata Gasp.) in comparison with CSP alone. Combinations of CSP with fenac, dichlobenil, diuron, an amine salt of endothal or dinitrophenol had no effect on copper uptake. CSP plus 1·0 ppmw of ametryne exhibited a synergistic response on hydrilla as determined by dry weight, and was associated with a high concentration of copper. Phosphorus levels in hydrilla were reduced by diquat and paraquat. Hydrilla treated with CSP plus 0·1 ppmw of paraquat contained 32·4% less phosphorus than plants treated with paraquat alone. The phytotoxic effect of certain of these combinations on hydrilla may be due principally to an increased accumulation of copper and a reduction in phosphorus content.
SEASONAL DIFFERENCES IN KILL OF TWO KENYA BUSH SPECIES AFTER FOLIAR HERBICIDE TREATMENT
Authors: IVENS G. W.
Published: July 2006

Summary. In a series of foliar spray treatments on the deciduous Acacia drepanolobium Sjöstedt, a mixture of picloram+2,4‐D lulled a large proportion of the trees in May, the latter part of the principal rainy season, moderate numbers in November‐December, the subsidiary rains, and small numbers during the two intervening dry seasons. An ester formulation of 2,4,5‐T was generally less effective, but similar seasonal variations in kill occurred. At the time of maximum susceptibility, the rate of shoot extension growth was declining and new leaves were fully extended, but still succulent.

With the evergreen Tarchonanthus camphoratus L., the effectiveness of spraying was related directly to the growth rate of the shoots. The percentage kill was highest following application of picloram+2,4‐D in May‐July, the late long rains and first half of the long dry season, but low during the November‐December rains and short dry season. T. camphoratus is susceptible to foliar herbicide treatment over a longer period than A. drepanolobium, presumably because of its different seasonal growth characteristics.
STUDIEN ZUR VERTEILUNG VON 14C‐MARKIERTEM 2,4‐D IN VERSCHIEDEN EMPFINDLICHEN UNKRÄUTERN
Authors: SANAD A. J. , Und F. MÜLLER , RADEMACHER B.
Published: July 2006

Studies of the absorption and translocation of 14C‐2,4‐D in Chenopodium album L., Galinsoga parviflora Cav., Datura stramonium L. and Galium aparine L. in relation to their susceptibility gave the following results:

In G aparine (resistant) there was little transport of 2,4‐D applied to the leaves, and a probable relationship between resistance and the immediate binding of the 2,4‐D in the treated leaf. D. stramonium (relatively resistant) transported 2,4‐D in considerable amounts alter uptake through the leaf, while C. album (very susceptible) and G. parviflora (susceptible) were intermediate in respect of 2,4‐D translocation. No relationship between susceptibility of these four species and 2,4‐D uptake and translocation from the leaves could be established.

After application to the root systems of the four species, 2,4‐D was taken up and translocated in the shoot to varying extents. In G. aparine much 2,4‐D was taken up and translocated. In contrast to leaf application, the herbicide was not immediately converted into a strongly‐held immobile form. In C. album, G. parviflora and D. stramonium, however, no 2,4‐D was translocated in the shoot. There was thus no correlation between susceptibility and shoot transport of 2,4‐D in the four species studied.

Distribution du 2,4‐D marqué au 14C dans des espèces de mauvaises herbes présentant des sensibilités diverses
THE CHEMICAL CONTROL OF BARLEY GRASS IN DRYLAND LUCERNE
Authors: SOUTHWOOD O. R.
Published: July 2006

In a field trial, different doses of five herbicides applied in autumn and late winder were compared for the control of barley grass (Hordeum leporium Link) in dryland Lucerne.

Diuron at 1·1, 2·2, and 4·5 kg/ha and atrazine at 1·1 kg/ha were more effective in increasing Lucerne production than linuron at 4·5 kg/ha and various rates of dalapon and paraquat. Autumn application generally resulted in greater Lucerne production than late winter application. Most treatments reduced the amount of barley grass in the Lucerne. Diuron and atrazine also eliminated reduced the amount of barley grass in the Lucerne.

Atrazine, diuron and linuron had a strong residual effect and reduced the density of subterranean clover and barley grass in the autumn following treatment.
THE USE OF THREE SIMPLE, RAPID BIOASSAYS ON FORTY‐TWO HERBICIDES*
Authors: And B. A. KRATKY , WARREN G. F.
Published: July 2006

Three rapid bioassays were tested on forty‐two herbicides having several different modes of action. A 50% or greater inhibition of growth was found at 1 ppm with thirty‐one herbicides in one or more of the bioassays. Of the remaining eleven herbicides, seven were detected at 10 ppm, two at 20 ppm and two at 30 ppm.

The techniques used were a Chlorella bioassay, a root bioassay with sorghum, oat and cucumber and a shoot bioassay with sorghum and oat. The duration of the bioassays was 1, 2 and 4 days respectively. As a general rule, the Chlorella bioassay was especially sensitive to photosynthetic and respiratory inhibitors but not sensitive to herbicides with other modes of action, whereas the root and/or shoot bioassays were sensitive to most of the herbicides except the photosynthetic inhibitors. The use of the three bioassays simultaneously is suggested as a possible method for primary screening of herbicides.
EFFECTS OF ANNUAL DRESSINGS OF NITROGEN FERTILIZER ON WILD OAT INFESTATIONS
Authors: WATKINS F. B.
Published: July 2006

Nitrogen fertilizer in three forms, urea, sulphate of ammonia and calcium ammonium nitrate, was applied at three rates, 26, 52 and 104 kg N/ha, early (January) and late (May) during land preparation for three consecutive barley crops, to determine the effect of fertilization on wild oat populations.

On the fertilized areas there was significantly greater germination of wild oats prior to sowing than on the unfertilized areas, with calcium ammonium nitrate and sulphate of ammonia tending to be more effective in stimulating germination than urea. Despite the destruction of these heavy populations of wild oat seedlings by cultivation prior to sowing, in‐crop infestations of the weed were still heavy. Late‐applied nitrogen by comparison with the early application tended to produce greater numbers of wild oat panicles in the crop, particularly at the lower fertilizer rates.

The overall effect after three annual dressings of nitrogen was one of greatly increased wild oat seed reserves in the soil. These had increased five‐fold in no‐nitrogen plots, six‐fold in early‐fertilized plots and eight‐fold in late‐fertilized plots.

It was concluded that annual dressings of nitrogen fertilizer on winter cereals in wild‐oat‐infested areas led to an increase in the population of the weed. Some suggestions are made as to why nitrogen fertilizer stimulated wild oats to germinate, and the overall results are discussed in the light of the agricultural situation of the Darling Downs.
DEVELOPMENT OF CYNODON DACTYLON (L.) PERS.*
Authors: HOROWITZ MENASHE
Published: July 2006

Summary. Early development of Cynodon dactylon (L.) Pers, was studied on one‐node rhizome fragments planted at successive dates over a year. Aerial growth followed the changes in external temperature; in the cool season tops grew very slowly but remained alive. New rhizomes were formed only at temperatures exceeding 15–20°C. Flowering occurred in the warm season from May onwards. No relationship was found between flowering and rhizome formation. The age of plants forming new rhizomes decreased from 5 months for the January planting to less than 2 months for the May‐September plantings. Rhizome bud germination was maximal between 23 and 35°C, slow below 20°C and inhibited at 10°C.

The weight ratio of tops to subterranean parts of established plants was near 1 in winter, declined in March‐April and remained at 0·5–0·6 from May onwards.

An established sward of C. dactylon was sampled from September to November of the following year. Dry weight was lowest from January to mid‐April, rose in spring and decreased in late summer. Almost no rhizomes were found deeper than 45 cm. Underground parts from the 0–15, 15–30 and 30–45 cm horizons constituted 62, 26 and 12% of the total weight, respectively; rhizomes formed more than 90% of the total underground dry weight. In the warm season the dry weight of the subterranean organs amounted to 2, 0·7 and 0·4 kg/m3 of soil in the three horizons, respectively.

Percent dry matter in tops and subterranean parts was about 35–45% in the winter and 50–65% in the warm season. Up to 2% reducing sugars was found in various parts of the plants. The water‐soluble sugar content of rhizomes was high in November‐December, decreased in late winter, rose again in spring, and decreased in late summer.

Percent germination of rhizome buds fluctuated greatly during the year, but complete dormancy was never recorded. Newly‐formed rhizomes showed a high germinative capacity. Similar germination percentages were found on fragments with one node and those with several nodes.

Développement du Cynodon dactylon (L.) Pers.
STUDIES ON THE BIOLOGY AND CONTROL OF VAUCHERIA DICHOTOMA FOUND IN FRESHWATERS IN BRITAIN
Authors: DOWIDAR A. R. , ROBSON T. O.
Published: July 2006

Summary. Vaucheria plants collected from a ditch near Crowland and from the River Cherwell at Oxford in the first week of October 1970 were identified as V. dichotoma Ag. A nutrient medium is described which allows the growth and the production of organs of sexual reproduction of this alga. Preliminary studies on the control with diquat show that it must be exposed to a concentration of 2 mg/1 for 6 h for the herbicide to be effective. The presence of mud reduces the rate at which chlorophyll disintegrates and hastens the inactivation of diquat.

Etudes sur la biologie et la destruction de Vaucheria dichotoma. Ag. dans les eaux doucei de Grande‐Bretagne
FATE OF SEEDS OF SOME ANNUAL WEEDS IN DIFFERENT DEPTHS OF CULTIVATED AND UNDISTURBED SOIL
Authors: ROBERTS H. A. , FEAST PATRICIA M.
Published: July 2006

Summary. Freshly‐collected seeds of twenty species of annual weeds were uniformly mixed with 2.5, 7.5 or 15 cm of soil confined in cylinders sunk in the ground outdoors. The soil was either cultivated four times a year or left undisturbed, seedling emergence was recorded, and after 5 years the numbers of viable seeds remaining were determined.

Total seedling emergence from seeds incorporated to 2·5, 7·5 and 15 cm amounted to 75, 65 and 54% respectively of those added when the soil was cultivated, and 58, 36 and 21% where it was left undisturbed. The corresponding numbers of viable seeds remaining after 5 years were 2·3, 4·0 and 7·7% respectively for cultivated soil, and 6·8, 16·5 and 31·6% of the seeds initially added and then not disturbed. Individual species varied in their responses to increasing depth of incorporation and to cultivation; these differences are discussed in relation to the dormancy characteritics of the seeds.

Devenir des semences de quelques mauvaises herbes annuelles à différentes profondeur dans un sol cultivé et non cultivé
EFFECTS OF HERBICIDES ON THE PRODUCTIVITY OF FODDER MAIZE WITH ESPECIAL REFERENCE TO PRE‐EMERGENCE APPLICATIONS OF 2,4‐D‐AMINE
Authors: LUDWIG J. W.
Published: July 2006

Summary. The effectiveness of pre‐emergence applications of 2,4‐D for weed control in maize was studied In five experiments, in comparison with other herbicide treatments. 2,4‐D‐aimne applied before crop emergence gave satisfactory weed control if the subsequent conditions were wet, but post‐emerge nee applications only killed some species (Chenopodium album and Atriplex patula.) A combination of 2,4‐D‐amine, applied pre‐emergence to a moist soil and subsequently as a foliar spray, controlled completely C. album, A. patula, Stellaria media and Veronica spp. Pre‐emergence applications of simazine gave better weed control with less need for rain soon after application. Only A. patula was usually resistant. Pre‐emergence treatments of atrazine killed all weeds whilst linuron controlled S. media, A. patula., C. album and Sonchus oleraceus but not Veronica spp.

Irrigation experiments showed that weed competition for water was largely responsible for the depressions in the early growth of maize when the conditions were dry. Final yield largely reflected the degrees of weed control attained by the herbicidal treatments. Only 2,4‐D applied pre‐emergence, and followed by heavy rain caused a direct depression in yield.

Effects des herbicides sur la productivityé du mals fourrage avec référence particuliére aux applications en pré‐levée du 2,4‐D amine
LABORATORY EXPERIMENTS ON ‘CUT BARK’ TREATMENTS WITH HERBICIDES, USING CUTTINGS OF POPULUS EURO AMERICAN A‘I‐78′
Authors: TURNER D. J.
Published: July 2006

Summary. A laboratory method is described for studying the effects of introducing herbicides into the vascular tissues oi Populus cuttings. Of sixteen herbicides tested in this way, MCPA and picloram were the most phytotoxic. Ester formulations of growth regulator herbicides were less active than water soluble amine or inorganic salts. The phytotoxic effects of the latter were increased by supplying water to the cuttings before or after treatment or by applying the herbicide in a relatively large volume of water. A non‐ionic surfactant did not increase the effects of injected MCPA salt, approximately similar amounts of which moved both upwards and downwards in cuttings from the point of introduction.

Expériences en laboratoire sur des boutures de Populus × euroamericana “I‐78” traités avec des herbicides
Influence of Root Exudates on Orobanche Seed Germination*
Authors: HAMEED K. M. , SAGHIR A. R. , FOY C. L.
Published: July 2006

Broomrape (Orobanche ramosa L.) is a common root parasite of solanaceous, leguminous and other crops grown in the semi‐arid regions of the world. The seeds germinate when root exudates from host plants are released in their immediate vicinity (Lindley, 1853; Koch, 1887; Chabrolin, 1934). Brown et al. (1951a) reported that non‐host plants, such as flax (Linum usitatissimum L.) may stimulate Orobanche seed germination without being parasitized.

The stimulating properties of flax exudate were studied by Brown et al. (1951b). They reported that the stimulant was unstable in alkaline solutions, but moderately stable in weakly acidic media, which may indicate the presence of an acidic (lactone) grouping. Nash & Wilhelm (1960) reported that gibberellic acid in agar media stimulated O. ramosa seed germination. Abu‐ Shakra, Miah & Saghir (1970) found that pre‐treatment of 0. ramosa seeds with 100 ppm of gibberellic acid followed by incubation on a flax‐root diffusate agar medium gave a high (81·7%) germination.

The purpose of this study was to collect root exudates from three species of plants cultured under three experimental systems, namely (a) germ‐free, (b) glasshouse (non‐sterile), and (c) growth chamber (hydroponic, initially aseptic), and to evaluate their biological activity as germination stimulants for O. ramosa seeds. The plants used were tomato (Lycopersicon esculentum Mill.), sorghum (Sorghum vulgare Pers.) and flax. Exudate from marigold (Tagetes erecta L.) also was collected from germ‐free culture.
ECOLOGY AND CONTROL OF BLACKBERRY (RUBUS FRUTICOSUS L. AGG.)
Authors: AMOR R. L.
Published: July 2006

Summary. The growth and vegetative reproduction of eighteen taxa in the genus Rubus was investigated to determine the biological characters that distinguish weedy from non‐weedy Rubus spp. in Australia. Thickets of European blackberry (R. fruticosus L. agg.), 21 months old, were distinguished by their low height and many rooting cane apices, from non‐weedy Rubus spp. R. fruticosus agg. thickets had large radii, but this character was shared by thickets of some non‐weedy taxa, namely Scoresby selection, youngberry and boysenberry. Most Rubus spp. had few adventitious shoots on lateral roots and there were no Rubus seedlings near the thickets. It is suggested that R. fruticosus agg. has a higher weed status than the other taxa because of its ability to produce a high frequency of rooting at its cane apices.

Ecologie et destruction des ronces. I.
INVESTIGATIONS ON SKELETON WEED (CHONDRILLA JUNCEA L.) WITH PICLORAM AND 2,4‐D
Authors: GREENHAM C. G.
Published: July 2006

Summary. Picloram is decarboxylated to a negligible extent in roots of skeleton weed: applied to leaves it kills roots better than 2,4‐D; it penetrates leaves better than 2,4‐D and disrupts the translocation system more, does not leak considerably into the soil from roots by the time of appropriate harvests, yet is not as well translocated as 2,4‐D. Under such conditions its ability to kill roots to a greater depth is attributable to its greater intrinsic toxicity.

There is some evidence that under certain field conditions useful movement or uptake of picloram may occur via the soil.

Recherches sur Chondrilla juncea L. avee le plclorame et le 2,4‐D.
CHANGES IN THE NUMBERS OF VIABLE WEED SEEDS IN SOIL UNDER DIFFERENT REGIMES
Authors: ROBERTS H. A. , FEAST PATRICIA M.
Published: July 2006

Summary. In a 4‐year experiment with a naturally‐occurring population of viable weed seeds, the numbers in the top 23 cm of soil decreased exponentially in the absence of further seeding. The rates of loss were very similar on undisturbed plots which were left bare (34% per year), mulched with farmyard manure (31%) or grassed down (32%). On plots dug twice a year in March and September, the loss was 42% per year, and with frequent cultivation (dug seven times a year) it was 56% per year. The numbers of seedlings in any one year on plots dug twice a year represented approximately 6% of the viable seeds present at the start of the year.

Variations du nombre de semences viables de mauvaises herbes dans le sol selon différents régimes
SELECTIVE ACTION OF DIPHENAMID AND NAPROPAMIDE IN PEPPER (GAPSICUM ANNUUM L.) AND WEEDS
Authors: ESHEL Y. , KATAN J. , PALEVITCH D.
Published: July 2006

Summary. A comparison was made between diphenamid and napropamide with regard to phytotoxicity to pepper and weeds under glasshouse and field conditions. Diphenamid was considerably less phytotoxic than napropamide in inhibiting root elongation and shoot growth of pepper seedlings. Plant growth was reduced when the roots were exposed to either one of the herbicides, but growth of the shoot through treated soil was not adversely affected. Since diphenamid was found to be more leachable into soil, it might become more available to the roots and damage the crop plants. Graminaceous weeds were very sensitive to both herbicides, whereas several dicotyledonous weeds were more susceptible to napropamide. Selectivity of both herbicides at a late pre‐emergence application to direct‐seeded pepper was found satisfactory in two field experiments on different soil types.

Action sélective de la diphénamide et de la napropamide sur le piment et les mauvaises herbes