bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of repeated applications of fluazifop‐butyl, haloxyfop and sethoxydim on Elymus repens in strawberries
Authors: CLAY D. V. , LAWRIE J. , HERTZ L. B.
Published: July 2006

Fluazifop‐butyl, haloxyfop and sethoxydim with adjuvant oil were applied for three successive growing seasons to established strawberries infested with Elymus repens. The weed was virtually eradicated by three applications of haloxyfop (0.8 kg a.e. ha−1) in successive years. A similar effect was given by five applications of haloxyfop (0.4 kg a.e. ha−1) and fluazifop‐butyl (1.6 kg AI ha−1) in three growing seasons. Lower rates of haloxyfop and fluazifop‐butyl, and a high rate of sethoxydim (1.6 kg AI ha−1) applied five times were less effective, the ground cover of E. repens shoots not being reduced by the end of the experiment although weight of living rhizome was only 10‐30% of that on untreated plots.

Fruit yields on treated plots generally reflected the level of E. repens control, but there was some evidence of crop phytotoxicity from herbicide treatments. During the experiment E. repens untreated plots increased from about 30‐100% ground cover and reduced yield 13, 28 and 68% in successive years compared with weed‐free plots.
Weed control in squash and tomato fields by soil solarization in the Jordan Valley
Authors: ABU‐IRMAILEH B. E.
Published: July 2006

Black (BPE) and clear polyethylene mulches (CPE), 0.08 and 0.06 mm thick, respectively, were compared for their effectiveness for soil solarization over three seasons during 1986–1989 in weedy fields. Solarization for 6 weeks reduced weed growth and enhanced crop yields. However, further mulching with BPE after solarization with either BPE or CPE gave the best results. Not all weeds were sensitive to solarization. Some weed species were completely controlled; others were reduced to varying degrees; yet other weed species seemed to be enhanced by solarization. Solarization without further mulching was no better than farmer‐practice in reducing weed growth or in increasing crop yield. Weeds required further removal after the middle of the growing season. Any soil disturbance after solarization reduced the weed control effect of solarization. Crops grew best in plots after solarization with BPE if they were planted in the same mulch after it was perforated.
Using plant population biology in weed research: a strategy to improve weed management
Authors: NAVAS M.‐L.
Published: July 2006

The aim of this paper is to show the need for developing plant population biology studies in order to improve weed management when traditional approaches in weed science have failed, as shown by recent reviews on herbicide resistance. It is also suggested that the usual weed definitions do not reflect the new aims of weed ecology. The results of studies on the genetic, demographic and spatial variability of weed populations and their regulation by pests and pathogens are reported, and are discussed in the specific case of clonal perennial species.
Effects of tillage, application time and rate on metribuzin dissipation
Authors: SORENSON B. A. , SHEA P. J. , ROETH F. W.
Published: July 2006

Metribuzin efficacy and dissipation were determined in two silty clay loam soils following preplant (PP), pre‐emergence (PRE) and split (PP+PRE) application to tilled and no‐till soybeans in rotation with corn at Clay Center and Lincoln, Nebraska. A similar experiment was conducted in tilled and no‐till soybeans in rotation with wheat at Lincoln. Corn and wheat residue in no‐till plots reduced the amount of metribuzin that reached the soil by approximately 54 and 89%, respectively. No differences in weed control or soybean yield were observed between tillage treatments or time of metribuzin application in the corn‐soybean rotation. However, both weed control and yield were reduced in the wheat‐soybean rotation. Most of the metribuzin remained at the 0–5 cm depth, and dissipation was exponential. The mean metribuzin half‐life at the 0–5 cm depth across locations, tillage treatments, application time and rates was 11 days. The metribuzin half‐life was 4–19 days following PP application and 3–17 days following PRE application. The metribuzin concentration did not exceed 65 μg kg−1 at the 5–10 cm or 10–20 cm depths in any treatment, indicating that little metribuzin had leached from the surface soil after PP or PRE application. The finding of a higher metribuzin concentration at 5‐20 cm depth in tilled plots than in no‐till could be attributed to higher initial soil concentrations in the absence of crop residue.
Trifluralin effects on the development of cotton in arid zone soils
Authors: DORNAI D. , GERSTL Z. , CHEN Y. , MINGELGRIN U.
Published: July 2006

The effect of trifluralin on the growth and development of cotton plants in low‐organic‐matter soils from the northern Negev of Israel was studied. Trifluralin exhibited linear sorp tion isotherms on these soils, Trifluralin and dinitramine losses from soils under varying moisture regimes and application practices were determined in open systems. The data were fitted to both first‐order and biexponential kinetic equations. In about 50% of cases the biexponential kinetic model provided a better fit to the data, but no relationship could be found between the model parameters and environmental or soil properties. Losses were generally greater at field capacity than at 50% field capacity, and at 27°C than at 15°C, and in soils with a lower organic matter content. The trifluralin application rate was negatively correlated with vegetative growth parameters of cotton, but the correlation became weaker with increasing soil organic carbon content. Trifluralin delayed boll production in coarse textured soils, the longest delay occurring at higher application rates. It is concluded that in light soils that contain very little organic matter, trifluralin rates must be maintained at the minimum level required for adequate weed control to prevent damage to crops.
Cirsium arvense (L.) Scop. competition with winter wheat (Triticum aestivum L.)
Authors: MCLENNAN B. R. , ASHFORD R. , DEVINE M. D.
Published: July 2006

A series of field experiments was conducted to evaluate the competitive effect of Cirsium arvense (L.) Scop. on winter wheat (Triticum aestivum L. ‘Norstar’) yield. Grain yield at the centre of dense C. arvense patches ranged from 28–71% of the yield in adjacent weed‐free plots, based on measurements made at 11 experimental sites over a 2‐year period. The mean reduction in yield was 49%. Two models were used to describe grain yield reduction in terms of C. arvense shoot density: (a) linear regression of percentage yield reduction on the square root of shoot density, and (b) non‐linear regression, based on a rectangular hyperbola. Both models give similar yield loss estimates at commonly occurring shoot densities of C. arvense, but the non‐linear model accounted for more of the observed variation in grain yield. The major yield component affected by C. arvense competition was spikes per unit area, with kernel weight affected to a lesser extent.
Herbicidal control of Cirsium arvense (L.) Scop, roots and shoots in no‐till spring wheat (Triticum aestivum L.)*
Authors: DONALD W. W.
Published: July 2006

Summary: Résumé: Zusammenfassung

Three herbicide treatments were applied each year over a period of 4 years to Cirsium arvense (L.) Scop, infestations in no‐till spring wheat (Triticum aestivum L.) in North Dakota, USA. Both chlorsulfuron at 30 g ai ha−1+a non‐ionic surfactant and a mixture of clopyralid+2,4‐D at 70+280 g ai ha−1 gradually reduced Cirsium arvense shoot density, root biomass, and adventitious root buds over the 4‐year treatment period in two trials. These two treatments did not merely induce adventitious root buds to become dormant. They virtually eliminated roots to a depth of 50 cm by year 4. Tribenuron methyl at 10 g ai ha−1+ a non‐ionic surfactant was less effective in reducing shoot density and root biomass.

Lutte herbicide contre les racines et les tiges de Cirsium arvense (L.) Scop, dans du bli de printemps non laboure (Triticum aestivum L.)

Trois traitements herbicides ont été appliqués chaque année pendant 4 ans, contre des infestations de Cirsium arvense (L.) Scop, dans du blé de printemps (Triticum aestivum L.) non labouré dans le Dakota Nord, USA. Tant le chlorsulfuron à 30 g m.a. ha−+un surfactant nonionique qu'un mélange de clopyralide+2,4‐D à 70+280 g m.a. h− ont reduit progres‐sivement la densité des pieds de Cirsium arvense, la biomasse racinaire, et les bourgeons racinaires adventices pendant les 4 années de traitements dans les 2 essais. Ces traitements ont à peu près éliminé les racines sur une profondeur de 50 cm en 4 ans. Ces deux traitements n'ont pas induit de dormance des bourgeons racinaires adventices. Le tribenuron methyl à 10 g m.a. ha−+un surfactant non ionique a été moins efficace dans la réduction de la densité de plante et de la biomasse racinaire.

Chemische Bekämpfung von Cirsium arvense (L.) Scop, in direktgesätem Sommerweizen (Triticum aestivum L.)

In direktgesäter Sommerweizen (Triticum aestivum L.) wurdel in North Dakota. USA, Bestände von Cirsium arvense (L.) Scop, über 4 Jahre jährlich 3 Herbizidbehandlungen unterzogen. Sowohl Chlorsulfuron mit 30 g AS ha−1 nichtionischem Netzmittel als auch eine Mischung von Clopyralid+2,4D mit 70+280 g AS ha−1 verringerten die Sproßdichte der Acker‐Kratzdistel, die Wurzelbiomasse und die Adventivknospen an den Wurzeln in 2 Ver‐suchen graduell. Durch diese beiden Behand‐lungen wurden nicht nur die Adventivknospen dormant, sondem auch die Wurzeln bis zu einer Tiefe von 50 cm bis zum 4. Jahr fast ganz elimi‐niert. Tribenuron‐methyl mit 10 g AS ha−1 nichtionischem Netzmittel war hinsichtlich der Reduktion von Sproßdichte und Wurzelbiomasse weniger wirksam.
Soil solarization in Greece
Authors: VIZANTINOPOULOS S. , KATRANIS N.
Published: July 2006

Summary: Résumé: Zusammenfassung

Soil solarization (SS) was tested in outdoor conditions in mid Greece by mulching wet soil with transparent polyethylene sheets to examine its effectiveness as a weed control treatment in maize and soybean planted as second season crops. Three or 4 weeks of solarization gave bet‐ter weed control than preemergence herbicides and effectively controlled volunteer wheat (Triticum aestivum), Portulaca oleracea, Digitaria sanguinalis, Solanum nigrum, Amaranthus spp. and other weeds. The weed control effects lasted for more than 4 months. In mulched soil the maximum temperature at 7.5 cm depth was generally 7–9°C warmer than in the unmulched soil. Polyethylene thicknesses of 0.015–0.030 mm were equally effective. Plants grown on solarized plots out yielded those on clean weeded hoe treatments. The weed flora present caused maize and soybean losses of 20–48%. These losses would economically justify the use of polyethylene mulches.

Solarisation du sol en grece

La solarisation du sol (SS) a été testée en conditions extérieures en Grèce centrale, en recouvrant le sol humide avec des feuilles de polyéthylene transparent pour examiner son efficacité comme traitement herbicide sur du ma'is et du soja plantés comme secondes culturesde la saison. Trois ou 4 semaines de solarisation ont donné une meilleure destruction des adventices que des herbicides de pré1evée et ont détruit efficacement les repousses de blé (Triticum aesti‐vum), Portulaca oleracea, Digitaria sanguinalis, Solanum nigrum, Amaranthus spp. et d'autres adventices. Les effets herbicides ont duré plus de 4 mois. Dans le sol couvert le maximum de témpérature à 7.5 cm de profondeur a été généale‐ment de 7–9°C plus chaud qu'en sol nu. Des épaisseurs de polyéthylene de 0,015–0,030 mm ont é'té pareillement efficaces. Les plantes cul‐tivées sur parcelles solarisées produisent autant que celles sur des sols tenus propres par binage. La flore adventice présente a entrainé des pertes de maïs et de soja de 20–48%. Ces pertes justi‐fieraient économiquement l'utilisation de films de polyéthylène.

Boden‐Solarisation in Griechenland

In Mittelgriechenland wurde die Solarisation feuchten Bodens, überdeckt mil transparenter Polyethylenfolie, auf ihre Wirksamkeit zur Unk‐rautbekämpfung in Mais und Sojabohnen als 2. Kultur der Vegetationsperiode untersucht. Mit 3 oder 4 Wochen Solarisation ließen sich Weizenaufschlag (Triticum aestivum), Portulaca oleracea, Digitaria sanguinalis, Solanum nigrum, Amaranthus spp. und andere Unkräuter besser als mil Vorauflauf‐Herbiziden bekämpfen. Die Wirkung hielt > 4 Monate an. Bei der Solarisa‐tion lag die Bodentemperature in 7,5 cm Tiefe um 7.9°C höher als bei offenem Boden. Folien von 0,015.0,030 mm Stärke waren gleich wirk‐sam. Der Ertrag lag in den solarisierten Parzellen über dem gehackter Parzellen. In den unbehan‐delten Parzellen ging der Ertrag um 20.48% zurück, so daß die Solarisation unter Polyethylenfolie ein wirtschaftliches Verfahren ist.
Evolution des hydrates de carbone non structuraux chez la morelle jaune (Solatium elaeagnifolium Cav.)
Authors: BOUHACHE M. , BOULET C. , EL KARAKHI F.
Published: July 2006

Résumé: Summary: Zusammenfassung

Les teneurs en hydrates de carbone non structuraux (TNC) des racines, collets et tiges des in‐dividus de la morelle jaune (Solarium elaeagnifolium Cav.) issue des bordures, champ de cotonnier et verger d'oliviers ont été déter‐minées mensuellement pendant une année. Les racines et, dans une certaine mesure, les collets ont été les organes où les réserves glucidiques étaient les plus importantes. Ces glucides ont atteint leur niveau le plus bas au moment de la formation des boutons floraux. La reconstitution des réserves en TNC a lieu entre la floraison et la maturation des fruits sur une durée de 2, 4 et 5 mois pour les individus issus du champ de cotonnier, des bordures et du verger d'oliviers, respec‐tivement. L'évolution des TNC est plus influencée par le stade phénologique de l'espèce que par rhumidité et la température du sol. Les implications de ces réquitals pour définir une stratégic de lutte centre la morelle jaune sont également discutées.

Seasonal changes in non‐structural carbohydrates in silver‐leaf nightshade (Solanum elaeagnifolium Cav.)

The levels of non‐structural carbohydrates (TNC) in the roots, root collar and stems of S. elaeagnifolium collected from field margins, cotton fields and olive plantations were determined monthly over a period of 1 year. The roots, and to a certain extent the root collar, were the organs with the largest carbohydrate reserves. The carbohydrate level was lowest at the time of flower bud formation. There was a build‐up of TNC reserves between flowering and fruit maturation over periods of 2, 4 and 5 months from plants growing in cotton fields, field margins and olive plantations respectively. Changes in TNC are influenced more by the phenological stage of the plant than by soil humidity or temperature. The implications of these findings in defining a control strategy for this weed are discussed.

Saisonale Einlagerung von Kohlenwasserstoffen beim Ölweidenblättrigen Nachtschatten (Solanum eleagnifolium Cav.)

Die Gehalte unstrukturierler Kohlenwasser‐stoffe (TNC) des Wurzeln, des Wurzelhalses und des Sprosses von Solanum elaeagnifolium Cav. von Feldrainen, Baumwollfeldern und Olivengärten wurden monatlich über l Jahr hin bestimmt. Die Wurzeln und in bestimmten Maβe der Wurzelhals waren die Pflanzenteile, in denen die Kohlenwasserstoffe die wichtigsten Re‐servesubstanzen waren; sie hatten ihr nie‐drigstes Niveau zur Blütenbildung. Der Wiederaufbau dieser Reservestoffe zwischen der Blüte und der Fruchtreife dauerte bei den Pflanzen auf den Baumwollfeldern, den Feldrainen und den Olivengärten 2, 4 bzw. 5 Monate. Die Kohlenhydratbildung wurde mehrnach den Entwicklungsstadienals durch Boden feuchte und‐temperatur beeinflußt. Die Aspekte dieserUntersuchungsergebnisse für die Bekämpfung dieses Unkrauts werden diskutiert.
Paraquat resistance in a biotype of Vulpia bromoides (L.) S. F. Gray
Authors: PURBA E. , PRESTON C. , POWLES S. B.
Published: July 2006

Summary: Résumé: Zusammenfassung

A biotype of Vulpia bromoides from a lucerne field in Elmhurst, Victoria, Australia was shown to be resistant to paraquat in pot trials. Application of paraquat at 50 g a.i. ha−1 killed all of the plants of a susceptible Vulpia bromoides biotype but only 6% of the resistant biotype. The LD50 for paraquat of the resistant biotype was five‐ to sixfold higher than for the susceptible biotype. The resistant biotype was also resistant to the bipyridyl herbicide diquat, but was susceptible to glyphosate and metribuzin. Application of 100 g a.i. ha−1 paraquat at anthesis completely suppressed seed set of the susceptible biotype and reduced that of the resistant biotype by 95%. Seed set by the paraquat‐treated resistant biotype, however, showed little reduction in germination. This is the fourth species to have been found to be resistant to bipyridyl herbicides in this field, the others being Hordeum glaucum, H. leporinum and Arctotheca calendula.

Résistance au paraquat d'un biotype de Vulpia bromoides (L.) S. F. Gray

Un biotype de Vulpia bromoides issu d'un champ de luzerne à Elmhurst, Victoria, Australie s'est révélé résistant au paraquat lors d'essais en pots. Des traitements au paraquat 50 g m.a. ha−1 détruisaient toutes les plantes d'un biotype sensible de V. bromoides mais seulement 6% du biotype résistant. La DLV50 du paraquat pour ce biotype était 5 à 6 fois plus élevée que pour le biotype sensible. Le biotype résistant l'était aussi à l'herbicide bipyridyle diquat, mais était sensible au glyphosate et à la métribuzine. Des traitements au paraquat 100 g m.a. ha−1 au stade anthèse supprimaient complètement la production de graines du biotype sensible et réduisait de 95% celle du biotype résistant. Cependant, le pouvoir germinatif des graines issues du biotype résistant traité, n'était que peu réduit. Après Hordeum glaucum, Hordeum leporinum et Arctotheca calendula, c'est la quatrième espèce trouvée dans ce même champ résistante aux herbicides bipyridyles.

Paraquatresistenz eines Biotyps von Vulpia bromoides (L.) S. F. Gray

Ein Biotyp von Vulpia bromoides von einem Luzernefeld in Elmhurst, Victoria, Australien, erwies sich in Topfversuchen als paraquatresistent. Mit 50 g AS ha−1 wurden Pflanzen eines empfindlichen Biotyps abgetötet, jedoch nur 6% des resistenten. Die LD50 des resistenten Biotyps für paraquat war 5‐ bis 6mal höher als die des empfindlichen Biotyps. Der resistente Biotype war auch gegenüber dem Bipyridylherbizid Deiquat résistent, gegenüber Glyphosat und Metribuzin jedoch empfindlich. Nach Anwendung von 100 g AS ha−1 Paraquat vor der Blüte bildeten sich bei dem empfindlichen Biotyp keine Samen aus, bei dem resistenten waren sie um 95% vermindert; die dennoch gebildeten Samen keimten etwas weniger. Dies ist die vierte Pflanzenart, bei der eine Resistenz gegenüber Bipyridylherbiziden beobachtet wurde, die anderen sind Hordeum glaucum. Hordeum leporinum und Arctotheca calendula.
Estimation of economic thresholds for weed control in winter wheat
Authors: ZANIN G. , BERTI A. , TONIOLO L.
Published: July 2006

Summary: Résumé: Zusammenfassung

Thresholds for winter wheat weed control have been determined for different herbicides or mixtures effective against individual weed species. For Avena sterilis L. subsp. ludoviciana (Durieu) Nyman the economic threshold was between 7 and 12 plants m−2, for Alopecurits myosuroides Hudson and Lolium multiflorum Lam. it varied between 25 and 35 plants m−2, while for Bromus sterilis L. the values were just under 40 plants m−2. For Galium aparine L. the threshold was as low as 2 plants m−2, while for Vicia sativa L. it was between 5 and 10 plants m−2. Within the same species the different values of economic threshold result from the different costs and efficacy of herbicides. Nitrogen fertilization was important: in its absence, the competitiveness of B. sterilis and G. aparine was negligible, and it was not possible to calculate an economic threshold for some of the treatments which could not be justified economically.

Estimation de seuils économiqu.es de désherbage chez le blé d'hiver

Les seuils économiques de désherbage du blé d'hiver ont été determinés pour différents herbicides, seuls ou en mélanges, pour plusieurs espèces demauvaises herbes. POUT Avena sterilis L. subsp. ludoviciana (Durieu) Nyman, le seuil économique était compris entre 7 et 12 plantes m−2. PourAlopecurus myosuroides Hudson et Lolium multiflorum Lam., il variait entre 25 et 35 plantes m−2 et était juste au‐dessous de 40 plantes m−2 pour Bromus sterilis L. Pour Galium aparine L., le seuil était2 plantes m−2 et était compris entre 5 et 10 plantes m−2 pour Vicia sativa L. Les différences de seuil pour une même espèce sont dues aux différences de coût et d'ef‐ficacité des herbicides. Le rôle de la fertilisation azotVe Vtait important: en son absence, le pou‐voir compVtitif de B. sterilis et de G. aparineétait négligeable, et il n'était pas possible de calculer de seuil économique pour certains traitements, qui ne pouvaient se justifier économiquement.

Bestimmung von wirtschaftlichen Schadensschwel‐lenfiirdie Unkrautbekdmpfung in Winterweizen

Für verschiedenen Herbizide und ‐mischungen wurden entsprechend ihrer Wirksamkeit gegenüber bestimmten Unkrautarten Schadensschwellen zur Unkrautbekämpfung inWinterweizen bestimmt. Für Avena sterilis L. spp. ludoviciana (Durieu) Nyman lag die Schadensschwelle zwischen 7 und 12 Pflanzen m−2, fur Alopecurus myosuroides Hudson und Lolium multiflorum Lam. variierte sie zwischen 25 und 35 Pflanzen m−2, während die Werte für Bromus sterilis L. bei knapp 40 Pflanzen m−2 lagen. Bei Galium aparine L. war die Schadensschwelle ganz niedrig, nämlich 2 Pflanzen m−2, während sie für Vicia sativa L. zwischen 5 und 10 Pflanzen m2 betrug. Fiir ein und die‐selbe Art ist die okonomische Schadensschwelle je nach den Kosten und der Wirksamkeit der Herbizide unterschiedlich. Die Stickstoffdün‐gung ist zu beachten: wenn sie fehlt, ist die Konkurrenz durch Bromus sterilis und Galium aparine verachlässigbar, so daß keine gerechtfertigten ökonomischen Schadensschwellen berechnet werden konnten.
Effect of crop density on competition by wheat and barley with Agrostemma githago and other weeds
Authors: DOLL H. , HOLM U. , SØSGAARD B.
Published: July 2006

The effect of Agrostemma githago L. and other naturally occurring weeds on biomass production and grain yield was studied in winter wheat and winter barley. Naturally occurring weeds had only a negligible effect on barley, but reduced wheat grain yield by 10% at a quarter of normal crop density. The interaction between the cereals and A. githago was studied in additive series employing different crop densities. Growth of this weed species was strongly dependent on crop density, which was more important for controlling weed growth than it was for obtaining a normal grain yield. Wheat and especially barley had a better competitive ability than A. githago. Wheat and A. githago utilized resources for growth better when grown in mixture than when grown in pure stands as the relative yield totals were significantly larger than unity.
Losses in grain yield of winter crops from Lolium rigidum competition depend on crop species, cultivar and season
Authors: LEMERLE D. , VERBEEK B. , COOMBES N.
Published: July 2006

The competitive abilities of eight winter crops were compared against Lolium rigidum Gaud, (annual ryegrass), an important weed of southern Australia, as a potential strategy to suppress weeds and reduce dependence on herbicides. Two cultivars of each species were chosen to represent the range of competitive ability within each crop and grown in field experiments in 1992 and 1993. The order of decreasing competitive ability (with the ranges of percentage yield reduction from L. rigidum at 300 plants m−2 in parenthesis) was as follows: oats (Avena sativa L.), 2–14%; cereal rye (Secale cereale L.), 14–20%; and triticale (×Triticosecale), 5–24%; followed by oilseed rape, (Brassica napus L.), 9–30%; spring wheat (Triticum aestivum L.), 22–40%; spring barley (Hordeum vulgare L.), 10–55%; and, lastly, field pea (Pisum sativum L.), 100%, and lupin (Lupinus angustifolius L.), 100%. Differences in competitive ability of cultivars within each species were identified, but competition was strongly influenced by seasonal conditions. Competition for nutrients (N, P and K) and light was demonstrated. L. rigidum dry matter and seed production were negatively correlated with grain yield of the weedy crops. More competitive crops offer the potential to suppress grass weeds while maintaining acceptable grain yields. Ways of improving the competitive abilities of grain legume crops are discussed.
On the inheritance of tolerance to chlorotoluron application in wheat using a very efficient score test
Authors: SIXTO H. , SILVELA L. , ESCORIAL C. , GARCIA‐BAUDIN J.M. , CHUECA M.C.
Published: July 2006

We present a nondestructive, easy to handle, cheap, fast and efficient assay to score wheat responses to herbicides. The application of the assay is illustrated by the reactions of the bread wheat cultivars ‘Castan’ and ‘Recital’ to the urea her‐bicide, chlorotoluron. The results not only confirm the presence of a major tolerant allele controlling the differences in response between the two cultivars, but also, show the contributions of modifier genes present in ‘Castan’, ‘Recital’ and other related cultivars.
Alcoolyse et hydrolyse chimique du chlorimuron éthyle
Authors: SABADIE J.
Published: July 2006

Summary: Résumé

La coupure de la fonction urée est seule observée au cours de 1'alcoolyse (méthanol ou éthanol) et de l'hydrolyse (pH8) du chlorimuron éthyle à 30°C ou 50°C. La pyrimidinamine est quantitativement formée dans tous les cas accompagnée des carbamates correspondants (alcoolyse) ou du phénylsulfonamide (hydrolyse) quise cyclise facilement en saccharine (pH6). L'hydrolyse du substituant carbéthoxy porté par le noyau aromatique de l'herbicide devient prépondérante en solution alcaline. Les constantes de vitesse du premier ordre cinétique ont été précisées. La déméthylation du chlorimuron éthyle n'a pas été détectée.

Alcoholysis and chemical hydrolysis of chlorimuron ethyl

Alcoholysis (methanol or ethanol) and hydrolysis (pH8) of the herbicide chlorimuron ethyl at 30°C or 50°C involved only the breakdown of the urea function. The pyrimidinamine is always obtained in high yield along with the corresponding carbamate (alcoholysis) or phenylsulfonamide (hydrolysis). This compound was easily cyclized to saccharin (pH6). In alkaline solution, the carbethoxy substituent of the aromatic ring was preferentially hydrolysed. The first order kinetic constants were characterized. No formation of desmethyl chlorimuron was observed.
Weed communities in intensified cereal‐based cropping systems of the northern Guinea savanna
Authors: WEBER G. , ELEMO K. , LAGOKE S. T. O.
Published: July 2006

The dynamics of weed populations were ana lysed in intensified cereal‐based cropping sys tems of the northern Guinea savanna in Nigeria, A total of four common weed associations were identified through cluster analysis. Five factors describing soil fertility conditions and field his tory best differentiated the weed communities according to a discriminant model. The analysis shows that maize‐based cropping systems with a high frequency of cereal cropping and a low fre quency of noncereal cropping tended to be domi nated by weeds such as Commelina spp. and Kyllinga squamulata. As soil fertility declined, Vernonia spp. and Eclipta prostrata became more important. Increased frequency of noncereal crops in mixed cropping with cereals was associ ated with reduced incidence of weeds such as Leucas martinicensis, Oldenlandia corymbosa, Spermacoce verticillata, Litdwigia hyssopifolia, Celosia laxa, and,Ipomoea spp. Further diversifi cation of cereal‐based systems to obtain a re duced frequency of cereals is likely to increase the incidence of Dactvloctenium aegyptium in crop fields. The information provides guidance for technology development and transfer on weed control for intensifying systems in the northern Guinea savanna of Africa.
A bioassay method for formulation testing and residue studies of sulfonylurea and sulfonanylide herbicides
Authors: STORK P. , HANNAH M. C.
Published: July 2006

A bioassay method using the radicles of pea (Pisum sativum L.) and lupin (Lupinus angustifolius L.) was developed for the assessment of trials on herbicides of common use in the sulfonylurea class (chlorsulfuron, triasulfuron and metsulfuron‐methyl) and in the sulfonanylide class (flumetsulam and metosulam). Soils within a range of pH 5.8–8.4 with textures from sand to clay were used in these experiments. The sensitivities of the species were similar in chlorsulfuron and flumetsulam trials and their response range varied with soil type and herbicide, e.g. between 0.75 and 6.0 ng triasulfuron g−1 in the Wimmera grey clay and between 0.125 and 8.0 ng chlorsulfuron g−1 soil in the Mallee sand. The method was demonstrated in a wide range of uses, encompassing tests of the initial bioactivity of formulations of chlorsulfuron and flumetsulam, monitoring the field leaching and persistence of triasulfuron and measuring relative potencies between the classes, using metsulfuron‐methyl and metosulam. The bioassay response provided a high level of reproducibility and precision, which was measurable by the logistic curve‐fitting procedure. In each case, R2 values were >0.90 and lack‐of‐fit tests were clearly non‐significant at the 0.05 level. Chi‐square tests were used to measure differences between ED50's. The method does not require the pre‐germination and selection of seedlings, daily watering or root‐washing and results are obtained 7 days from sowing, providing favourable use for routine analyses and large‐scale trials.
Annual weed distributions can be mapped with kriging
Authors: HEISEL T. , ANDREASEN C. , ERSBØLL A. K.
Published: July 2006

The authenticity of weed distribution maps prepared by the geostatistical estimation method, kriging, was investigated. We concentrated on the total number of weed plants and the dominant weed genus Veronica spp. in a 2.1‐ha field of winter wheat. Different sampling distances were evaluated. Our analyses showed that kriging weed densities based on seedling counts collected in, 0.25.m2 circles in a sampling grid of approximately 10 m × 10 m gave good agreement with actual observations. Reducing the sampling grid to 20 m × 30 m gave poor agreement. New sampling methods combined with positioning devices and injection sprayers are discussed with reference to site‐specific weed management.
Estimating Taylor's power law parameters for weeds and the effect of spatial scale
Authors: CLARK S. J. , PERRY J. N. , MARSHALL E. J. P.
Published: July 2006

The spatial variability of weeds within fields was studied for six sets of count data. Heterogeneity for a given mean population density was measured using the variance of the counts between sample units at different locations; relatively large values of sample variance imply aggregation. The dependence of variance on mean was measured using the relationship known as Taylor's power law, ubiquitous in animal ecology but seldom used for plant populations. This was fitted to an extensive set of plant counts and 69 estimates of its parameters b, an index of aggregation, and log10a were computed. Estimates were corrected for bias when the number of samples was small. Overall, b varied between 1.32 and 2.61, and log10a varied between ‐0.85 and 1.58. agreeing well with previous estimates for both plant and animal populations. Parameter estimates varied with sample size and spatial sample scale, but unpredictably. Parameter values when species counts were combined were compared with individual species analyses. Knowledge of the likely range of these parameters for weed populations provides an important basis for future modelling of the relationship between weed density and crop yield loss.
Measurement and simulation of the movement of thiazafluron, clopyralid and metamitron in soil columns
Authors: COX L. , WALKER A. , HERMOSIN M.C. , CORNEJO J.
Published: July 2006

Adsorption and leaching of the herbicides thiazafluron (1,3‐dimethyl‐1(5‐trifluoromethyl‐1,3,4‐thiadiazol‐2‐yl)urea), metamitron (4‐amino‐4,5‐dihydro‐3‐methyl‐6‐phenyl‐1,2,4‐tri azin‐5‐one) and clopyralid (3,6‐dichloropicolinic acid) were studied in one sandy and two silty‐clay soils. Equilibrium adsorption coefficients (Kd) were measured using a batch equilibration procedure, and mobility was studied in repacked columns of the soils under fluctuating saturated/unsaturated flow conditions. Breakthrough curves (BTCs) were consistent with an inverse relationship between leaching and adsorption with greater mobility of the weakly‐adsorbed clopyralid than the more strongly adsorbed thiazafluron or metamitron. The BTC data were used to evaluate the LEACHP simulation model. Following model calibration with respect to hydrological parameters and some of the herbicide degradation rates, the best fits between predicted and observed data were with the less adsorptive and highly mobile clopyralid. In general, the model gave acceptable predictions of the timing of the concentration maxima and the shapes of the BTCs, although earlier breakthrough than that observed was predicted with the less mobile herbicides, thiazafluron and metamitron, in the silty‐clay soils. For metamitron, the total amounts leached were not predicted accurately, suggesting more rapid degradation of the herbicide in the soil columns than in the kinetic studies performed in a 1:1 soil:solution ratio shaken system.
Root growth inhibition of rice by bensulfuron
Authors: YIM KYU‐OCK , BAYER D.E.
Published: July 2006

Bensulfuron inhibited root growth of waterseeded rice (Oryza sativa L.) plants in a solution culture system. Rice root growth was more sensitive to bensulfuron than was shoot growth. A1 2.5 × 10‐9 M bensulfuron, plant height, number of leaves and number of roots were not significantly affected, while root growth was reduced, Seedlings treated 3 or 4 days after emergence showed a significant reduction of total root length by the second day after treatmeni. Root growth inhibition was proportional to duration of treatment; however, treatment for 2 days was necessary to affect root growth, Bensulfuron decreased the mitotic index and the mitotic height in root tips. At 5 days after treatment, only 0.7% of the cells were dividing and mitotic height was 68% of control
The role of peroxidase in the resistance of sunflower against Orobanche cumana in Russia
Authors: ANTONOVA T.S. , TERBORG S.J.
Published: July 2006

We present the results of a histochemical study comparing seedlings of races C and D of Orobanche cumana Wallr. (syn. O. cernua Loefl.) attacking sunflower (Helianthus annuus L.) in southern Russia. Three groups of O. cumana seedlings were distinguished according to the peroxidase content of the cells in the radicles: (1) those with neither extracellular nor intracellubr peroxidase and whose radicles have a smooth apex (these were classified as non‐infective): (2) those with a high peroxidase content of the nuclei and the cytoplasm layer adjacent to the cell wall, as well as excretion of peroxidase from the apex of the radicles: (3) those with a similarly high peroxidase activity in the parasite cells, but without extracellular excretion. The apices of the radicles of the last two groups are swollen. It is suggested that these belong to O. cumana races C and D respectively. The extracellular peroxidase in O. cumana race C reacts with phenolic compounds, which are lignin precursors of the host, resulting in host resistance due to the formation of lignin layers in sunflowers possessing the Or3 gene for resistance. The absence of extracellular peroxidase in O. cumana race D prevents lignin formation and enables the parasite to attach to the host vascular system. Comparison of these data with the information on the earlier O. cumana races A and B, and older sunflower cultivars, points to a crucial role of peroxidase in the process of breeding new sunflower cultivars and the evolution of new O. cumana races.
The effect of maize residues and tillage on emergence of Setaria faberi, Abutilon theophrasti, Amaranthus retroflexus and Chenopodium album
Authors: BUHLER D.D. , MESTER T.C. , KOHLER K.A.
Published: July 2006

Tillage and maize (Zea mays L.) residues at up to four times the base level had variable effects on the emergence of four annual weed species in the field. Environmental conditions varied during the three years of the research and interacted with residue and tillage to govern seedling emergence. When tillage affected Setaria faberi Herrm., emergence was greater in untillcd than tilled plots. The effect of residues varied among years. Abutilon theophrasti Medik, emergence from tilled soil was greater than from untilled soil in two of three years. Maize residue at two or four times the base levei reduced emergence. Amaranthus retroflexus L. emergence was often greater from untilled than tilled soil. The effect of maize residues on this species was dependent on tillage and precipitation. Chenopodium album L. emergence was affected by tillage and residues but differences over the three years were inconsistent. Results of this research indicate that tillage and residues interact with weed species, precipitation and other factors to regulate seedling emergence. The reduced soil disturbance and minimal weed seed burial associated with the elimination of tillage appear to have a greater impact on weed population dynamics than surface residues in non‐tillage maize production systems.
Gene flow within a population of the outbreeding Sinapis arvensis: isozyme analysis of half‐sib families
Authors: LEFOL E. , DANIELOU V. , FLEURY A. , DARMENCY H.
Published: July 2006

Progeny of several Sinapis arvensis L. plants sampled in a field were analysed for isozyme patterns at two highly polymorphic loci: esterasc and acid phosphatase. Allele frequencies of pollen subpopulations that effectively fertilized each separate sampled plant were compared. In spite of self‐incompatibility, large variations in allele frequencies were shown among pollen subpopulations. Non‐random mating owing to gametic selection and plant density effects were evidenced and could reduce gene flow within a population,
Environment and food of the budgerigar Melopsittacus undulatus
Authors: WYNDHAM EDMUND
Published: July 2006

Budgerigars range and breed over most of the interior of Australia. During a year, budgerigars may experience a maximal change in day length of about 5 h, and temperatures range from well below to above their zone of thermo‐neutrality. In the north of the budgerigar's range there is growth of pastures in summer and autumn and in the south there is growth in spring and early summer. In the arid interior, growth is irregular from year‐to‐year and varies from site‐to‐site. However, in northern arid regions growth tends to occur in summer and autumn; in southern arid regions in spring and early summer; and over most of the arid regions in most years there is some growth in run‐on areas.

In inland mid‐eastern Australia budgerigars ate only seeds of ground vegetation. These seeds were from about 0.5 to 2.5 mm in length, weighed between about 0.3 and 1.3 mg and had an energy content of about 18.9 kJ g‐1. Ata site on Mitchell grass plains Astrebla spp. were the main seeds eaten. At a site further inland the diet was more diverse: in the hot months of 1973–74 they ate mainly Boerhavia diffusa, Atriplex spp. and Astrebla pectinata, during the cold months of 1974 mainly Iseilema and an unidentified seed, and in spring 1974 mainly Atriplex spp. There was no evidence of special dietary requirements for breeding; in particular no requirements of soft, unripened seed or insect food to feed young. Males and females, adults and juveniles, and individuals in the same flock had similar diets.

Information from the literature and my data suggest there is considerable stability and seasonal regularity in the budgerigar's food supply.
The seasonal distribution and characteristics of bush fly Musca vetustissima Walker populations in south‐western Australia
Authors: MATTHIESSEN J. N.
Published: July 2006

In the agricultural region of south‐western Australia the bush fly Musca ventustissima Walker was found to occur permanently in the north‐eastern half but it died out during winter in the south‐west. The abundance of bush flies increased rapidly throughout the overwintering zone in early spring as a result of local breeding. Flies then dispersed south‐westwards, completely repopulating the region during October. Immigrant flies were large and therefore highly fecund, and of advanced reproductive maturity. Local breeding then rapidly increased the population. Maximum abundance occurred in mid‐spring in the north and east and in early summer in the south and west. Abundance was greatest in the north where large overwintering populations occurred, and in the far south where repopulation occurred early in the seasonal cycle of pasture growth so that the more favourable cattle dung produced flies that were more fecund than their immigrant parents. The abundance of bush flies declined throughout the region in summer, to negligible levels near the south‐west coast but, paradoxically, higher levels occurred inland where there were fewer cattle. On average, flies were smaller and reproductively younger in summer. In areas where irrigated pastures produced more favourable dung in summer, the patterns of abundance and other characteristics of flies did not differ substantially from those in comparable non‐irrigated areas. The abundance and other characteristics of a bush fly population 10 km from a cattle‐grazing breeding site were similar to those at the site, indicating that constant dispersal is the basis of the bush fly's ubiquity.
Species richness in vascular vegetation of the West Head, New South Wales
Authors: RICE BARBARA , WESTOBY MARK
Published: July 2006

We present data on vascular plant species richness, at the 0.1 ha scale and below, of sclerophyll vegetation on infertile sandstone, and some neighbouring types, in a non‐mediterranean climate area of temperate, east coast Australia The vegetation of sandstone is richer in species than is that of a permanently wet swamp (18/0.1 ha) or of more fertile soils (36, s.d.‐ 2). On sandstone, woodlands on moderate benched slopes (77, s.d. = 9) are richer in species than are the scrubs found on skeletal (56, s.d.= 7) or impeded drainage (48, s.d.= 8) soils, and this difference appears in the species‐area curve from 100 m2 up. Species richness of the sandstone vegetation, like its growth‐form mix, is very similar to species richness of South African fynbos and southwestern Australian heath. which supports the idea that the community properties of this sort of vegetation are not determined by climate but are determined by soils. The strong contrast in species richness, noted by Naveh & Whittaker (1979), between the mediterranean‐climate vegetation of South Africa and southwestern Australia on the one hand, and California and Israel on the other, need not be attributed to different evolutionary histories of the floras. The present environment, in the form of the soil factor, could well be the main determinant.
A comparison of detrended correspondence analysis and principal co‐ordinates analysis using four sets of Tasmanian vegetation data
Authors: BROWN M. J. , RATKOWSKY D. A. , MINCHIN P. R.
Published: July 2006

Indirect gradient analysis, which entails the elucidation of relationships between trends in community composition and underlying environmental or successional gradients, is a major objective of ordination in plant ecology. Two ordination techniques, detrended correspondence analysis (DCA) and principal co‐ordinates analysis (PCOA), were compared using three sets of Tasmanian vegetation data having known gradients and one set where the vegetation was expected to respond to diverse environmental variables. In every case, the results obtained by DCA were considered superior to, or at least as good as, those of PCOA. Hence, DCA appears to be the more suitable of the two methods for indirect gradient analysis.
A review of ecological applications of immunological techniques for diet analysis
Authors: CALVER M. C.
Published: July 2006

Immunological methods for the determination of animal diets are reviewed. The potential of immunology for identifying animal and plant foods of both vertebrates and invertebrates is discussed, and guidelines given for the selection of appropriate techniques for specific projects.
The structure and floristic composition of the rainforest of the Liverpool Range, New South Wales, and its relationships with other Australian rainforests
Authors: FISHER H. J.
Published: July 2006

The rainforest of the Eiverpool Range (ca 32° S) consists of discrete stands ranging from 1 to 100 ha in area. Its distance from the coast (ca 160 km) results in a relatively low (for rainforest) average annual rainfall of approximately 900 mm. The rainforest is described quantitatively in terms of the relative importance of its component woody species. One hundred and fourteen vascular plant species were found and identified within the rainforest stands, including 37 tree and 16 shrub species. Daphnandra micrantha is the most common tree species in the stands, while Acmena smithii is locally dominant at higher elevations. Following Webb (1978), the Liverpool Range rainforest is described as a noto‐microphyll vine forest. Alternatively, portions of the forest that are at higher elevations represent warm temperate rainforest, while the portions at lower elevations are more subtropical in character, although the two intergrade. The Liverpool Range rainforest has substantial floristic affinity with the rainforests of the southern coast of New South Wales.
The effect of severe defoliation on the subsequent growth and development of five rangeland pasture grasses of south‐western Queensland
Authors: BROWN R. F.
Published: July 2006

Young plants of five arid zone grasses. Cenchrus ciliaris, Astrebla lappacea, Artstida armata, Thyridolepis mitchelliana, and Digitaria ammophila, were heavily defoliated and their subsequent regrowth and development monitored and compared with that of intact plants. Defoliation impaired the development of both roots and plant tops in all species. Regrowth was inconsistent with theories of assimilated reserves stored in roots to support regrowth. The species differed in their apportionment of assimilate between competing plant parts. The differences were similar in both intact and defoliated plants. Both C. ciliaris and A. lappacea maintained a large root mass but produced few inflorescences whereas A. armata and D. ammophila did the opposite. T. mitchelliana had an intermediate pattern of allocation. Both D. ammophila and A. armata resumed flowering soon after defoliation. The different reactions to defoliation are discussed in relation to historical deterioration in pasture condition which may be linked with the prolific seeding capacity of A. armata.