bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of controlling Alopecurus myosuroides Huds. and Avena fatua L. individually and together, in mixed infestations on the yield of wheat
Authors: WILSON B. J.
Published: July 2006

Mixed infestations of Alopecurus myosuroides and Arena fatua growing in wheat were controlled individually or together in three experiments. Difenzoquat and ciofop‐isohutyl were applied at the early tillering or early stem extension stages of the crops. Early control of both species resulted in significantly higher yields than later control, even though weed emergence was incomplete at the early applications. Herbicides, re‐applied at the second date, improved the control of wild‐oats hut not of black‐grass; yields were not enhanced by this second application Halving the dose of herbicide gave little reduction in weed control or crop yield at the early date, but there was a greater response to dose with the later application. Yields were lower where only one weed was controlled. This work shows the need for broad spectrum control early in the life of the crop to safeguard yield where black‐grass, and wild oats occur together in large numbers.
The ecological life cycle of Thlaspi perfoliatum and a comparison with published studies on Thlaspi arvense
Authors: BASKIN JERRY M. , BASKIN CAROL C.
Published: July 2006

Thlaspi perfoliatum L. is an introduced winter annual that grows in waste places, but it is not a troublesome agricultural weed. Seeds are dormant at maturity in spring, afterripen during summer and germinate in autumn. Non‐dormant seeds that fail to germinate in autumn are induced into secondary dormancy by low winter temperatures and cannot germinate the following spring. These seeds afterripen during summer and germinate in autumn if conditions are suitable. Vernalization is not an absolute requirement for flowering. However, it shortens the time to flowering, and vernalized plants produce many more flowers and seeds than non‐vernalized plants. Results from studies on seed germination and flowering of T. perfoliatum are compared to published studies on the life cycle of Thlaspi arvense L., an introduced species that is a serious agricultural weed which behaves both as a winter and a summer annual.
The response of resistant and susceptible plants to diclofop‐methyl
Authors: HOERAUF ROLAND A. , SHIMABUKURO RICHARD H.
Published: July 2006

Wild oat (Avena fatua L.) plants sprayed at the 2‐or 3‐leaf stages of growth with diclotop‐methyl developed chlorosis over the entire leaf blade of all leaves. The leaves became necfrotic 7days after spraying Shool growth was inhibited. In wheat (Triticum aesicum L cv.Waldron) discrete chlorotic areas developed only where the herbicide convicted the 2nd or 3rd leaf with no visible injury so new growth uf'ter treutment. Growth inhibition of susceptible oat (Avena sativa L. cv. Garry) was sensitive to placement of diclutop‐methyl near the upica and meristematic sites of the plant. Chlorosis and necrosis were independent of herbicide placement. Selective herbicide placement induced chlorosis only or both chlorosis and growth inhibition Root growth in wild oat and barley (Hordeum rulgare L. cv. Dickson) was strongly inhibited by 1–0 μM diclofop‐methyl. Wild oat shoots were killed when seedlings were root‐treated with 10 μM diclofop‐melhyl. The 100 μM rool treatment killed barley shoots but only stunted the growth of wheat shoots by approximately 50%. In root‐ireated wheat plants the shoots were turgid and developed a light purple colour, whereas in foliar‐treated plants the shoots developed discrete chlorotic areas.
The movement of 2,4,5‐trichlorophenoxyacetic acid into the leaves of Rubus procerus P.J. Muell and its effect on chloroplast ultrastructure
Authors: BRETHERTON G. , HALLAM N. D.
Published: July 2006

Examination of the fine structure of Rubus procerus leaves following application of 2.4.5‐trichlorophenoxyacetic acid a field does shows that the chloroplast is a side of herbicide action and that by 1 week after spraying the leaves show changes indicative of accelerated senescence. Both aqueous and non‐aqueous methods were used to isolate chloroplasts following treatment of leaves with radioactive 2.4.5‐T. Chloroplast isolation using the non‐aqueous method indicated an accmulation of radioactivity in that organelle.
Histological studies on the effects of benzoylprop ethyl and flamprop methyl on growth and development of wild oats*
Authors: MORRISON I. N. , HILL B. D. , DUSHNICKY L.G.
Published: July 2006

Wild oats were trealed with benzoylprop eihyl and flamprop methyl alone or in combination with other herbicides and the effects on plant growth studied using histological techniques, Benzoylprop ethyl caused severe reductions in the growth of both the leaves and internodes of treated plants, Evidence was obtained which indieaies that cell division as well as cell elongalion was inhibited. The effects of flamprop methyl on plant growth were similar lo those observed for benzoylprop ethyl. Both compounds interfered with normal differentiation of vascular tissues which could account for retarded development of the higher internodes and shoot apex of treated plants. Of the various herbicides applied in combination with the wild oat herbicides, 2,4—D was more antagonistic than MCPA. while bromoxynil was the least antagonistic. Plants treated with benzoylprop ethyl plus 2.4—D had increased cell, leaf and internode lengths compared to plants treated with benzoylprop ethyl alone. Reductions in cell and internode lengths of plants treated with the herbicide combinations were not always proportional lo dry weight reductions.
Chemical control of Crotalaria goreensis and other weeds in Macroptilium atropurpureum
Authors: HAWTON D.
Published: July 2006

The effects of several selective herbicides, combinations of diuron with activated carbon, slashing and stale seed bed treatments were tested in five field experiments conducted at Walkamin, Queensland, Australia to determine the best methods of controlling weeds, particularly the legume Crotalaria goreensis Guill. & Perr., in crops of Macroptilium atropurpureum (DC.) Urb. cv. Siratro, grown for seed. Alachlor alone and combinations of trifluralin with either alachlor or propachlor were effective in preventing weeds causing a yield reduction in one experiment but not in a second. Trifluralin plus propachlor was more effective in controlling broad‐leaved weeds while trifluralin plus alachlor was more effective in controlling grasses. Activated carbon effectively protected M. atropurpureum from diuron damage but the control of weeds, particularly grasses, was not effective. Stale seed bed treatments involving three sequential applications of diquat prior to planting the crop was the most effective method of controlling C. goreensis.
Influence de la Pendiméthaline sur les méristèmes radiculaires de Allium cepa L.
Authors: BEURET E.
Published: July 2006

La Pendimèthaline exerce une action milodépressive ainsi qu'une action mitoclasique très nettes sur les méristèmes radiculaires dAillium Cepa L. Le seuil de mitodépression se situe entre 10 et 1 M. alors que l'effet mitoclasique est encore sensible à 0.1 M. Les effets du traitement se marquent également par une inhibition de la croissance des racines, ainsi que par un épaississemcnt de la zone mèristématique.
Effect of canopy cover, seeding depth, and soil moisture on emergence of Centaurea maculosa and C. diffusa*
Authors: SPEARS B. M. , ROSE S. T. , BELLES W. S.
Published: July 2006

The effects of canopy cover, seeding depth, and soil moisture on emergence of Centaurea maculosa Lam. and C. diffusa Lam. were studied. Canopy cover had no effect on ermergence rate (seedlings/day/100 seeds) of either species. Seeds of both species emerged faster when placed on the soil surface. Emergence rate decreased as seeding depth increased. Both species required more than 55% initial soil moisture to initiate emergence, with 65–70% being optimum. Percentage emergence followed exactly the same trend as emergence rate. C. maculosa had better emergence characteristics over a wider range of conditions than C. diffusa, possibly being some of the reasons for the former having a wider geographical distribution in the United States and Canada.
Indices and criteria for comparing the tolerance of strawberries to herbicides in dose‐response experiments
Authors: CLAY D. V.
Published: July 2006

Three indices were used to assess the tolerance of strawberries to herbicides in different experiments. Tolerance was compared using a tolerance index. TI. (= ED value of the lest herbicide/ ED value of a standard herbicide). The degree of response to increases in dose was compared by calculating a dose‐response index, RI (= ED50/ED20 value) for each herbicide and the speed of action by a speed of action index. SI (=time to minimum ED value, test herbicide'time to minimum ED value, standard herbicide).

The optimum time of the final assessment varied according to the mode of action of the herbicides being tested. There was generally good agreement between ED values obtained from scores of plant condition and from fresh weight measurements. ED20 values gave more useful estimates of relative tolerance than ED50's where the degree of response to increasing doses was different.
The use of separate root and shoot tests in the screening of herbicides for strawberries
Authors: CLAY D. V.
Published: July 2006

The tolerance of strawberries to herbicides was tested by applications to the roots of plants growing in sand and by foliage applications to plants grown in compost, and compared with tolerance in the field. Dimefuron was safe as a foliar application but much more toxic than simazine when applied in sand or in the field. Metamitron caused slight injury as a foliar spray; in sand and in the field it was intermediate in toxicity between simazine and lenacil. At normal rates propachlor was safe as a foliar spray and much safer than lenacil when applied in sand. High rates had no adverse effect in the field.

Ethofumesate and pendimethalin caused some temporary stunting when applied to foliage, but were less toxic than lenacil when applied to roots in sand. Field applications of both herbicides at 1–1.5 kg/ha were safe. Foliage sprays of bentazone, oxadiazon and oxyfluorfen severely damaged the sprayed leaves, but these herbicides were less active than lenacil when applied to the roots. In the field they caused severe leaf damage, but by the end of the growing season the plants had recovered.

The experiments demonstrated the value of separate root and shoot activity tests for indicating which herbicides merit further field testing.
Tests of soil fertility following repeated applications of MCPA, tri‐allate, simazine and linuron
Authors: FRYER J.D. , LUDWIG J.W. , SMITH P.D. , HANCE R. J.
Published: July 2006

The following herbicides were applied annually from 1963 to experimental plots of appropriate crops grown in monoculture: MCPA 1.7 kg ha−1, triallate 1.7 kg ha−1, simazine 1.7 kg ha−1 and linuron 0.84 kg ha−1 (applied twice per year). Before the eighth treatment in 1970, nutrient status, pH and growth in greenhouse tests of a range of plants were similar in soils from treated and control plots. There were no significant differences in yield when several test crops were grown in the field plots in 1977.

In a similar experiment which ran for 6 years, the same herbicides were applied twice per year at twice the above rates on each occasion (three times a year at 1.7 kg ha−1 in the case of linuron) to uncropped plots. Three years after the last treatment, there were no differences in extractable nutrients, pH, soil structure and crop yield on treated or control plots. These results support the conclusion from the main monitoring of the experiments reported elsewhere that annual treatments with these herbicides have had no adverse affect on the soil.
The biology of African feather grass (Pennisetum macrourum Trin.) in Tasmania, II. Rhizome biology
Authors: HARRADINE A. R.
Published: July 2006

The rhizome biology of Pennisetum macrourum was studied in a series of field and glasshouse experiments. The total available carbohydrate content of rhizomes remained between 15 and 22% of dry weight throughout the year, with fluctuations, related to the seasonal growth pattern. The percentage regeneration or rhizome fragments of one, two and four nodes buried at 15 cm was 13, 33 and 57, respectively. Thirty percent of 4‐node rhizome fragments regenerated from a depth of 25 cm. In 11 desiecation experiment, regeneration of 3‐node rhizome fragments occurred until rhizome moisture content was reduced to 14%, The time taken to reach this moisture content varied from 4 to 10 days depending on the temperature. The significance of these results for the control of P. macrourum is discussed.
Adsorption de quelques phénylurées herbicides par des acides humiques
Authors: GAILLARDON P. , CALVET R. , GAUDRY J. C.
Published: July 2006

L'adsorption de plusieurs phcnyluré (diuron, linuron. mtox‐ uron, isoproturon) par des acides humiques augmente lorsque le pH diminue, Lëtablissement de liaisons hydrogène entre les molécules herbicides el les groupements fonctionnels non disso‐ ciés des acides humiques pourrait expliquer cet effet, Compars au calcium, au mème pH, les cations Fe3+, Al3+, Cu2+ ne modifient pas l'intensité de l'adsorption mais, compte tenu de la composition ionique des acides humiques, on peut supposer l'existence d'interactions entre les molcules herbicides et ces cations fixs sur les acides humiques.
Johnsongrass (Sorghum halepense) growth characteristics as related to rhizome length
Authors: LOLAS P. C. , COBLE H. D.
Published: July 2006

Growth characteristics of johnsongrass [Sorghum halepence(L) Pers] grown in the field from rhizomes 2.5, 5, 10, 15, 20, or 25 cm long were studied in a sandy loam soil for 2 years.

Plant height, number of leaves per plant, number of tillers per plant, and fresh weight of new rhizomes and shoots were significantly dependent on the length of the planted rhizome 20, 40, 60, or 80 days after planting. All growth characteristics increased significantly as the length of planted rhizome increased from 2.5 cm to 10 cm to 25 cm Growth characteristics of Johnsongrass plants grown on rhizomes of adjacent lengths (differing by 5 cm) generally were not significantly different. Longer rhizomes (15, 20, or 25 cm) initiated new rhizome growth much earlier (about 20–30 days) than shorter rhizomes (2.5, 5, or 10 cm) Although all rhizome lengths showed a parallel growth potential, the lunger rhizomes were capable of more and faster growth, especially early after planting. It is suggested that Johnsongrass plants associated with longer rhizomes in the field as a result of limited tillage, coupled with their faster growth rate, are expected to interfere with crop production earlier than plants on shorter rhizomes unless controlled.
Mode of action of thiocyanate and iodide in relation to IAA metabolism
Authors: STEPHEN NORMAN H. , COOK GORDON T. , DUNCAN HENRY J.
Published: July 2006

Whole plant studies have reaffirmed that of the halides and pseudohalide thiocyanate, only iodide and thiocyanate possess defoliant properties. Established work has indicated their possible involvement with IAA (indole‐3‐acetic acid). In vitro studies have suggested that IAA destruction is not through a direct interaction between IAA and the halides and pseudohalide but depends on their conversion to the halogen or pseudohalogen which can then destroy IAA. This may be accomplished by the peroxidase enzyme system for iodide only and docs not provide a mechanism for thiocyanate activity. However, both iodide and thiocyanate have chemical oxidation potentials suitable for their conversion to the halogen or pseudohalogen respectively via the photosynthetic apparatus. Hence, this would provide an explanation for then activity and the apparent inactivity of bromide, chloride and Buoride which would be oxidized very slowly or not at all.
Availability to plants of herbicide residues in soil. Part II: Data for use in vegetable crop rotations
Authors: PESTEMER WILFRIED , STALDER LUKAS , ECKERT BEATE
Published: July 2006

The response of a variety of vegetable crops to fifteen herbicides was estimated in culture solution over concentration ranges chosen to correspond with those that might occur in soil solution. Examples are given to show how these results can be used, in conjunction with the method for estimating the available herbicide residues (in Part I), to decide which crops may safely be sown in soil containing a herbicide residue.
Persistence studies with [14C] 2,4‐D in soils previously treated with herbicides and pesticides
Authors: SMITH ALLAN E.
Published: July 2006

The persistence of [14C] 2,4‐D at a rate equivalent to 1 kg/ha was compared under laboratory conditions in samples of heavy clay, sandy loam, and clay loam at 85% of field capacity moisture and 20 ± 1°C which had either received no pre‐treatment, or had been pre‐treated for 7 days at the 2 μg/g level with the herbicides benzoylprop‐ethyl, diclofop‐methyl, dinitramine, flamprop‐methyl, nitrofen, picloram, tri‐allate, trifluralin, and a combination of tri‐allate and trifluralin. The breakdown of [14C] 2,4‐D was also studied in the same soils that had similarly received pre‐treatments of 2 μg/g of the cereal seed dressing Vitaflo‐DB, the insecticide, malathion, and a combination of Vitaflo‐DB and malathion.

In each soil type, the half‐life of the 2,4‐D was similar regardless of whether the soil had, or had not, received any pre‐treatment, indicating that none of the chemicals investigated adversely affected the soil degradation of 2,4‐D.
Translocation of 14C‐glyphosate in johnsongrass (Sorghum halepense L. Pers.) as affected by growth stage and rhizome length
Authors: C.LOLAS P. , COBLE H.D.
Published: July 2006

Summary: Résumé: Zusammenfassung

Studies were conducted in the green house on 14C‐methyllabelled glyphosate translocation in johnsongrass as affected by rhizome length and growth stage. The amount of 14C measured by the liquid scintillation technique in the rhizomes (2‐8%) increased with rhizome length (10, 20 or 30 cm) and tended to increase with growth stage (15‐30 cm tall, 45‐60 cm tall, or at seedhead), but the amount of 14C per g fresh rhizome weight was almost similar in all cases. Of the total amount applied per plant (0·2 μCi) about 1/3 or less remained on the treated leaf area, while another 1/3 was a absorbed into the treated leaves. Autoradiographs showed that the 14C label moved to all plant parts, basipetally and acropetally.

Migration du glyphosate 14 C chez le sorgho d'Alep (Sorghum halepense L. Pers.) en relation avec le stage de croissance et la longueur du rhizome

Des recherches ont été effectuées en serru sur la migration du glyphosate marqué au 14C sur le méthyle, chez le sorgho d'Alep, en relation avec la longueur du rhizome et le stade de croissance. La quantité de 14C mesurée par la technique de scintillation liquide dans les rhizomes (2 à 8%) s'est accrue avec la longueur du rhizome (10, 20 ou 30 cm) et elle a eu tendance à augmenter avec le stade de croissance (Hauteur 15‐30 cm, hauteur 45‐60 cm ou épiaison), mais la quantité de 14C par gramme de poids frais de rhizome est restée Presque identique dans tous les cas. Environ 1/3, ou moins, de la quantitéà la surface des feuilles traitées par plante (0,2 μCi), est restéà la surface des feuilles traitées cependant qu'un autre 1/3 a été absorbé dans less feuilles traitées Les autoradiographies ont montré que le 14C marqueur a migré dans toutes les parties de la plante, dans le sens basipète et dans le sens acropète.

Translokation von 14C‐Glyphosat in Johnsongras (Sorghum halepense L. Pers.) in Abhängigkeit vom Wachstumsstadium der Pflanzen und der Rhizomlänge

Im Gewächshaus wurden Versuche über die Translokation von 14C‐Glyphosat in Johnsongras (Sorghum halepense L. Pers.) in Abhängigkeit vom Wachstumsstadium der Pflanzen und der Rhizomlänge durchgeführt. An den Rhizomen stieg der Gehalt von 14C(2–8%), gemessen mit der Flüssig‐Szintillationstechnik, mit zunehmender Rhizomlänge (10, 20 oder 30 cm) an und nahm tendenziell auch mit fortschreitendem Pflanzenwachstum zu (15–30 cm und 45–60 cm Sprosslänge oder nach dem Rispenschieben); jedoch blieb die Menge pro g Rhizomfrischgewicht beinahe konstant. Von der insgesamt ausgebrachten Menge pro Pflanze (0.2 μCi) blieben bis zu 1/3 auf der behandelten Blättern absorbiert wurde. Die Autoradiographie zeigte, dass der 14C markierte Teil in alle Pflanzenteile sowohl basipetal wie auch akropetal transportiert wurde.
Atrazine dissipation in irrigated sorghum cropping in southern New South Wales
Authors: WAIN D. J. S
Published: July 2006

Dissipation of atrazine after pre‐emergence application to irrigated grain sorghum was investigated in an experiment on a Birganbigil clay loam at Yanco Agricultural Research Centre in the Murrumbidgee Irrigation Areas of New South Wales. Dissipation followed first‐order kinetics with a half‐life of 70 days. This rate of disappearance did not differ significantly between application rates of 2.5 and 10 kg/ha. Removal of volunteer plant growth with non‐residual chemicals or by cultivation during the winter fallow periods had no significant effect on the levels of atrazine residues in the soil and dissipation rate did not differ significantly between the 2 years of the experiment. A laboratory incubation experiment demonstrated that dissipation of atrazine in Birganbigil soil was more rapid than in three other soils from the Murrumbidgee and Murray Valleys. Dissipation rate and atrazine adsorption were both correlated with the organic carbon content of the soils, which ranged from 1.43% to 0.72%. There was no correlation between either dissipation rate or adsorption and clay content, even though clay contents ranged from 37 to 78%.
Paraquat tolerant Lolium perenne L.: effects of paraquat on germinating seedlings
Authors: FAULKNER J. S. , HARVEY B. M. R.
Published: July 2006

A cultivar of Lolium perenne L. (Causeway) selected for tolerance to foliar‐applied paraquat was shown also to be tolerant at seed germination and establishment.

When seeds were germinated in paraquat solutions (1, 3, 9, 27 ppm), Causeway was more than ten times as tolerant as a normal cultivar of L. perenne.

When germination and survival were studied in a soil which had been sprayed with paraquat (0.0, 0.3, 0.9, 2.7 kg/ha) before sowing, Causeway was nearly three times as tolerant as a normal cultivar. Holcus lanatus L. was about equal to normal L. perenne, but Poa trivialis L. was less tolerant. Phytotoxicity was greater in a 10.5% organic than a 4.8% organic soil.

It is concluded that the mechanism of paraquat tolerance operates in the non‐photosynthetic tissues of germinating seedlings as well as in the photosynthetic tissues of older plants, although the degree of tolerance varies according to the mode and stage of application of the herbicide. There might be advantages in using a paraquat tolerant cultivar of L. perenne when direct drilling grass after sward destruction by paraquat.
Weed control in rainfed groundnut (Arachis hypogaea L.) in the Guinea savanna zone of Nigeria
Authors: LAGOKE S. T. O. , CHOUDHARY A. H. , TANKO Y. M.
Published: July 2006

Field trials were conducted to evaluate herbicides for weed control in groundnut from 1977 to 1979. The pre‐emergence herbicides used were alachlor and metolachlor, applied alone or mixed with terbutryne. Some treatments were followed either by post‐emergence bentazone or by one supplementary hoe‐weeding. In the southern Guinea savanna zone, where early grass weed control was more important, alachlor or metolachlor at 1.5 kg ha−1 gave adequate weed control and pod yields comparable with that of the hoe‐weeded check. There was no advantage in adding terbutryne, or in supplementary hoeweeding or post‐emergence bentazone application. In the northern Guinea savanna zone, grass and broad‐leaved weeds were equally important. Application of alachlor, metolachlor or mixtures with terbutryne (2:1) at 1.5 kg ha−1 required post‐emergence application of bentazone or supplementary hoe‐weeding for effective weed control and high pod yield. The reduction in pod yield on untreated control plots ranged between 18 and 70% of the best treatment in these trials.
The influence of irradiance and water deficit during fruit development on seed dormancy in Datura ferox L.
Authors: ANCHEZ R. A. , EYHERABIDE G. , de MIGUEL L.
Published: July 2006

The effect on seed dormancy of exposing the mother plants to different environmental conditions was studied in Datura ferox. Reducing incident radiation and withholding water to provoke water stress, during the period from fruit set until seed ripening, caused a decrease in the degree of dormancy of the harvested seeds. A significantly smaller amount of the basic fraction inhibitors was found in the seeds with the lesser degree of dormancy. It is suggested that one of the ways in which the environmental conditions to which the mother plants are exposed can influence seed behaviour is by changing the endogenous inhibitor levels
Effects of some herbicides on soil enzyme activities
Authors: And HAZEL A. DAVIES , GREAVES M. P.
Published: July 2006

Effects of glyphosate, paraquat, trifluralin and atrazine on activities of dehydrogenase, phosphatase and urease in one soil were measured. Only glyphosate at 21.6 kg/ha was found to inhibit the enzyme activities and generally the results were not statistically significant. Enzyme activity associated with micro‐organisms proliferating in soil supplemented with lucerne meal was similarly not affected by the herbicides. Interpretation of results from enzyme activity measurements in soils treated with herbicides is discussed. It is proposed that effects of natural stress can be used to judge the relative importance of herbicide induced change.
Control of Avena fatua and Fagopyrum tataricum with tank mixtures of linuron or linuron + MCPA and sequential applications of linuron, and post‐emergence A. fatua herbicides
Authors: O'SULLIVAN P. A.
Published: July 2006

Linuron (0.21 and 0.28 kg/ha) and linuron + MCPA (0.21+0.56 kg/ha) in a tank mixture with field rates of barban, difenzoquat and flamprop‐methyl reduced the phytotoxicity of these herbicides to Avena fatua. When linuron was applied immediately following or 6 days after the A. fatua herbicides no reduction in phytotoxicity to A. fatua occurred, suggesting that the antagonism may be occurring as a result of physical or chemical incompatability when the herbicides are mixed together. The possibility of obtaining broad‐spectrum weed control with one trip over the field by applying linuron and one of these wild oat herbicides separately but at the same time using a double‐boom, double‐tank system deserves evaluation. When linuron was applied in a tank mixture (0.21 and 0.28 kg/ha), immediately after, or 6 days after diclofop‐methyl (0.70 kg/ha), there was no reduction of A. fatua control, and wheat tolerance to the tank mixture was good. This tank mixture offers potential for control under field conditions of A. fatua and some broad‐leaved weeds in one spray operation. Linuron + MCPA (0.21+0.56 kg/ha) in a tank mixture severely reduced A. fatua control with diclofop‐methyl. No loss of phytotoxicity to Fagopyrum tataricum occurred when the A. fatua herbicides tested were tank mixed with linuron or linuron + MCPA. Lutte contre Avena fatua et Fagopyrum tataricum avec des mélanges extemporanés de linuron ou de linuron + MCPA et des applications successives de linuron et d'herbicides de postlevée actifs contre A. fatua
Comparaison de la germination et de la croissance de biotypes sensibles et résistants aux triazines chez quatre espèces de mauvaises herbes
Authors: GASQUEZ J. , DARMENCY H. , COMPOINT J.P.
Published: July 2006

Par des observations sur la germination dans différentes conditions et sur le développement végétatif en conditions non compétitives, les auteurs comparent des biotypes sensibles et résistants de quatre espèces chez lesquelles on a découvert des populations résistantes: Chenopodium album, Amaranthus retroflexus, Solanum nigrum et Polygonum lapathifolium. Malgré des niveaux de signification différents les résultats indiquent un meilleur développement végétatif des plantes sensibles, Cependant, ces données peuvent être modulées selon les conditions de croissance. Par ailleurs, les valeurs élevées des variances des caractères mesurés traduisent une hétérogénéïté très importante, au moins dans les lots sensibles. En revanche, les semences des plantes résistantes de Polygonum lapathifolium et, dans une moindre mesure, d'Amaranthus retroflexus germent plus facilement aux basses températures. A la lumière de ces données les auteurs discutent les avantages que peuvent conférer ces caractéristiques aux différents lots, mais surtout soulignent la nécessité de considérer chaque espèce séparément et de prendre en compte la nature des génotypes comparés. Enfin, il est difficile, à partir de telles donnés et tant que l'on ignore précisément le déterminisme de la résistance, d'en déduire dans les stations d'origine et en l'absence de traitement, une moindre valeur adaptative des résistants par rapport aux sensibles.
Comportement de substances herbicides dans le sol en fonction de leur structure chimique
Authors: BASTIDE J. , GANTIER J. M. , COSTE C.
Published: July 2006

Des études d'adsorption et de dégradation d'analogues du propyzamide [dichloro‐3,5‐N‐(dimethyl‐1,1 propynyl‐2) benzamide] dans différents sols ont été réalisées. Une bonne corrélation entre adsorption et teneur en matière organique des sols a été trouvée. Cette adsorption est reliée linéairement à un paramètre hydrophobique (coefficient de partage octanol — eau). Par contre la dégradation dans différents sols de ces composés ne montre pas de relation simple avec la nature des sols ou avec la structure chimique des composés. L'importance de ces phénomènes sur les résultats de biotests est aussi analysée.
Control of problem weeds of maize on the Transvaal Highveld (South Africa). I. Tagetes minuta L.
Authors: MALAN C. , VISSER J.H. , GROBBELAAR N.
Published: July 2006

A number of herbicides and herbicide mixtures which are being used for the post‐emergence control of weeds in maize on the Transvaal Highveld, have been tested for their efficiency in the control of problem weeds. The evaluation was done under standardized conditions. The influence of the herbicides on the plants was evaluated by using the following bioassay methods: percentage mortality and the percentage dry mass difference between the test plants and the control 10 days after treatment.

Recommendations are made as to which herbicides could be used most effectively on problem weeds post‐emergence in maize fields. The developmental stage (age) at which each herbicide is most effective, has been determined.
Selective herbicides for establishing weed‐free grass: The effect of mixtures and sequences of herbicides, including ethofumesate and methabenzthiazuron
Authors: KIRKHAM F. W. , HAGGAR R. J.
Published: July 2006

Two field experiments compared various sequences of ethofumesate, methabenzthiazuron and mecoprop, and mixtures of metamitron, ethofumesate and methabenzthiazuron for their control of Poa annua L. and Stelluria media (L). Vill. during the establishment of autumn‐sown perennial ryegrass (Lolium perenne L.).

In experiment 1 pre‐emergence treatments required a second, post‐emergence spraying to give complete control of P. annua. Grass seedlings reappeared in early spring following ethofumesate treatment, but populations built up earlier where methabenzthiazuron had been used. The most successful treatment was ethofumesate at 1.4 kg a.i. ha−1 followed by 0.7 kg a.i, ha−1 in spring. Methabenzthiazuron at 0.8 kg a.i. ha−1 followed by ethofumesate at 0.7 kg a.i. ha−1 in December was also effective. Methabenzthiazuron at 1.6 kg a.i. ha−1 damaged ryegrass but was effective as a secondary treatment at lower doses in spring. Most treatments controlled S. media satisfactorily, but this sometimes increased the yield of P. annua.

Metamitron greatly reduced tiller numbers of P. annua in experiment 2, especially when sprayed with methabenzthiazuron. Only treatments which included ethofumesate controlled S. media adequately but there was no advantage in combining this herbicide with any other for controlling P. annua.
Some studies of competition between Avena fatua L. and spring barley I. The influence of A. fatua on yield of barley
Authors: WILSON B. J. , PETERS N. C. B.
Published: July 2006

A. fauta reduced yields of spring barley in the majority of 51 experiments carried out during 1971 and 1972. Infestations ranging from 8 to 662 seedlings/m2 in the spring resulted in yield reductions varying from nothing to 72%; in 11 experiments these exceeded 1–2 t/ha. Reductions in yield were poorly correlated with numbers of seedlings, panicles or wild oat seeds produced. However, there was a good correlation between yield loss and the dry weight of wild oats at harvest.

Growth and competitive effects of wild oats differed between the two years. Grain losses were due mainly to reductions in the numbers of ear bearing barley tillers. The influence and significance of the effect of competition on the size of barley grains is discussed.
Effects of EPTC, fluorodifen and monuron on transpiration and photosynthetic oxygen output in Eupatorium odoratum plants
Authors: ETEJERE E. O.
Published: July 2006

The influence of foliar sprays of EPTC, fluorodifen and monuron on transpiration and photosynthetic oxygen output of Eupatorium odoratum plants is demonstrated. Foliar sprays with 100 ppm EPTC or monuron led to a significant decrease in transpiration for a continuous period of 14 days. Treatment with 100 ppm fluorodifen led to a noticeable increase in transpiration during the first eight days. All three herbicides significantly reduced photosynthetic oxygen output from the Eupaiorium plants. EPTC and monuron however, gave greatest effect. Reduction in transpiration from the plants was due to stomatal closure while reduction in photosynthetic oxygen output was due to both stomatal closure and probably also inhibition of the Hill reaction.
Metabolism of 14C‐buthidazole in corn (Zea mays L.) and redroot pigweed (Amaranthus retroflexus L.)*
Authors: HATZIOS KRITONK , PENNER DONALD
Published: July 2006

The pattern of buthidazole {3‐[5‐(1,1‐dimethyl ethyl)‐1,3,4‐ thiadiazol ‐2‐y1]‐4‐hydroxy‐1‐methyl‐2‐imidazolidinone} metabolism and its potential contribution to crop selectivity were studied in tolerant corn (Zea mays L., ‘Pioneer 3780’) and susceptible redroot pigweed (Amaranthus retroflexus L). Thin‐Layer Chromatographic (TLC) analysis of methanol soluble extracts revealed that both corn and redroot pigweed seedlings metabolized buthidazole in a similar manner but at different rates. At comparable time periods redroot pigweed contained a greater percentage of unmetabolized 14C‐buthidazole than did corn. A major unidentified metabolite with polar properties was formed faster in corn that in redroot pigweed and appeared to be important for the observed crop selectivity of buthidazole. Additional metabolites of buthidazole formed in both species had TLC properties similar to those of the amine, urea, and dihydroxy derivatives of buthidazole.
Experiments with isoproturon for the control of weeds in winter cereal crops
Authors: PONCE R. GONZALEZ , SENAS J. RODRIGUEZ
Published: July 2006

Isoproturon controlled Phalaris spp., Lolium spp., Avena sterilis L. and Papaver rhoeas L. in winter cereal crops, the dosages applied being in accordance with the different texture of the soils on which the herbicide was tested in the province of Toledo (Spain).

The competitive effects of the weeds, particularly Avena sterilis were ascertained on a range of cereal parameters, not only those influencing yield, but also the grain weight/straw weight ratio.

The influence of climatic and edaphic conditions on the efficiency of the herbicide was also investigated.
Environmental conditions and isozyme polymorphism in Chenopodium album L.
Authors: MOUEMAR A. AL , GASQUEZ J.
Published: July 2006

Electrophoretic variations within four enzyme systems (α‐esterase, acid phosphatase, malate dehydrogenase and leucine amino peptidase), were studied for various garden and field populations of Chenopodium album. A correlation was found between the degree of polymorphism for the electrophoretic traits and environmental conditions. The amount of phenotypic polymorphism is very high in gardens, intermediate in an untreated and, low in herbicide‐treated fields and nil for a triazine resistant population in a maize (Zea mats L.) monoculture. Furthermore, the tetraploid versus hexaploid ratio is higher within garden populations. Higher variability in garden populations is due, in part, to a high proportion of polymorphic phenotypes, and in part to a low effect of selection pressure in such types of habitat. Although there is a difference between phenotypes of populations from acid soils and those from more basic ones, we cannot be sure that the variation of polymorphism is due only to selection.
Biological activity of dinitramine in soils
Authors: OKAFOR L.I. , SAGAR G.R. , SHORROCKS V. M.
Published: July 2006

The influence of soil organic matter and soil moisture content on the bioactivity of dinitramine was investigated in laboratory and greenhouse experiments. Adsorption increased directly with soil organic matter content and inversely with soil moisture content. Phytotoxicity to soybean (Glycine max (L.) Merr.) was inversely related to soil organic matter content while the toxicity of the herbicide to French bean (Phaseolus vulgaris L.) was directly related to the soil moisture content from 20 to 100% of field capacity. Dinitramine is active in the vapour phase, and volatilization and bioactivity were directly related to soil moisture content and inversely related to soil organic matter content. Variability in the performance of soil incorporated dinitramine in the field seems very likely, depending as it does on soil moisture content and soil organic matter content.
Effect of atrazine and methabenzthiazuron on oxygen evolution and cell growth of Chlorella pyrenoidosa
Authors: GONZALEZ‐MURUA C. , MUNOZ‐RUEDA A. , And F. HERNANDO , SANCHEZ‐DIAZ M.
Published: July 2006

Cultures of Chlorella pyrenoidosa Pringsheim were grown photoautotrophically in the presence of two concentrations (0·25 and 0·50 μm) of atrazine and methabenzthiazuron. The cell density and chlorophyll content were greatly reduced in presence of both herbicides. These herbicides affected net photsynthesis equally without affecting oxygen uptake. However, cell division was more inhibited by atrazine than by methabenzthiazuron, but chlorophyll content per cell was more inhibited by methabenzthiazuron than by atrazine.
Effect of seed age and cultivation on seedling emergence and seed decline of Avena fatua L. in winter barley
Authors: WILSON B. J.
Published: July 2006

Avena fatua was sown in a cultivation experiment in the autumn of 3 successive years. For each population seedling emergence and viable seeds in the soil were recorded for 4 years in crops of winter barley in which new seed production was prevented.

About half of the seeds sown were recovered after 1 year. In subsequent years viable seeds in the soil declined more rapidly with tine cultivation than with ploughing. After 4 years up to 5% of the original seeds were still viable. One population exhibited greater seed dormancy than the other two populations, due it is thought to higher summer rainfall and the greater availability of moisture during seed maturation.

Most seedlings emerged in the autumn and spring, between 12 and 18 months after sowing. A total of 950 seedlings emerged from 12 000 seeds sown; 21% of these seedlings came from new seeds (< 1 year old), 57% from seeds 1–2 years old, 14% from seeds 2–3 years old and 8% from seeds 3–4 years old. Autumn seedlings arose fairly evenly from all age groups while spring seedlings mostly came from the 1–2‐year‐old seeds. With tine cultivation total seedlings over 4 years represented 9–7% and with ploughing 6–2% of the original seeds sown. A. fatua was more persistent than in previous experiments in spring barley, which suggests that control measures would have to be applied for longer in a succession of winter cereals than spring‐sown crops to reduce A. fatua to low populations.
Growth of seedling Achillea millefolium L. (yarrow) in association with pea (Pisum sativum L.)
Authors: KANNANGARA H. W. , FIELD R. J.
Published: July 2006

When Achillea millefolium L. (yarrow) seedlings were grown in the field in association with a pea (Pisum sativum L.) crop vegetative growth of yarrow was significantly reduced by 6 weeks after emergence. Flowering was totally suppressed while the pure stand of yarrow developed flower clusters at 13 weeks after seedling emergence. Rhizome development occurred at 8 weeks after seedling emergence in the pure stand, but not until 15 weeks when grown with pea.

The early suppression of seedling yarrow in a glasshouse experiment was associated with root interference, although by 5 weeks shoot interference by pea plants was important in reducing yarrow growth. The greatest suppression of yarrow occurred when both roots and shoots of the two species were allowed to interfere. Yarrow had low aggressivity against pea when grown in various combinations in a replacement series experiment in the glasshouse.
Herbicide‐resistant crops: yield penalties and weed thresholds for oilseed rape (Brassica napus L.)
Authors: FORCELLA F.
Published: July 2006

An expérimental procedure was designed to provide a simple model for types of analyses necessary to determine weed density thresholds for advantageous use of crop plants engineered for herbicide resistance. Oilseed rape (Brassica napus L., cv. Tower) biotypes resistant (RES) and susceptible (SUS) to atrazine were used as model crop plants, and wild oat (Avena fatua L.) was used as the model weed. Along a wild oat density gradient equivalent to 0–128 plants m−2, RES plants consistently experienced biomass and yield reductions of approximately 10–20% compared to SUS plants. When atrazine was applied at 1.5 kg ha−1 to control wild oats competing with RES plants, RES biomasses and yields were stabilized at the same level as that where 25–30 wild oats m−2 reduce yields of SUS plants. This implies that with wild oat densities of 25–30 plants m−2, it becomes agronomically advantageous to crop with RES plants plus atrazine rather than to crop with higher‐yielding SUS plants.
Competition between vegetative plants of wild oat (Avena fatua L.) and wheat (Triticum aestivum L.)
Authors: MARTIN M. P. L. D. , FIELD R. J.
Published: July 2006

Competition between wild oat (Avena fatua L.) and wheat (Triticum aestivum L.) was studied in two experiments; a replacement series model and a technique for separation of root and shoot systems. Wild oat and wheat in association resulted in a relative yield total very close to unity showing that the two species were‘crowding for the same space’(or competing for the same resources) and were‘mutually exclusive'. Wild oat was more competitive than wheat, as shown by its aggressivity relative to wheat, relative yields, shoot dry weights and other plant attributes. The greater competitive ability of wild oat was predominantly due to its greater root competitive ability, while the two species had similar shoot competitive ability. Root competition had a much greater effect on the relative performance of the two species than did shoot competition. The effects of root and shoot competition were additive.
Some effects of the herbicide EL‐107 on cellular growth and metabolism
Authors: LEFEBVRE A. , MAIZONNIER D. , GAUDRY J. C. , CLAIR D. , SCALLA R.
Published: July 2006

Effects of the herbicide EL‐107 (N‐[3‐(1‐ethyl‐1‐methylpropyl)‐5‐isoxazolyl]‐2,6‐dimethoxy‐benzamide) on the growth of dicotyledonous plants are described. The herbicide did not inhibit germination but reduced the growth of rape (Brassica napus L.) by half at 0.0057 mg l−1. The most characteristic symptom induced was a swelling of the apical regions, and histological observations of root tips of Polygonum persicaria and rape revealed a progressve disappearance of the meristematic zone, which was replaced by enlarged cells almost devoid of cytoplasm. Growth of cells of Acer pseudoplatanus L. and soybean (Glycine max L.) cultured in suspension was also inhibited by EL‐107, which induced a characteristic change in the cell morphology to an enlarged, rounded shape. EL‐107 apparently did not block cell division; at a high concentration it produced some inhibition of protein synthesis, but in Acer cells only. In both types of cell cultures it inhibited, to some extent, the incorporation of glucose into cell wall material.
Comparison of the uptake, movement and metabolism of fluroxypyr in Stellaria media and Viola arvensis
Authors: SANDERS G. E. , PALLETT K. E.
Published: July 2006

The uptake, movement and metabolism of fluroxypyr* is compared in two contrasting weed species, Stellaria media (susceptible) and Viola arvensis (moderately resistant). Similar rates of uptake occurred in both species, with a rapid cuticular uptake of 50% of that applied within 4 h. Total uptake by the underlying leaf tissue reached 66.6% and 70.8% in S. media and V. arvensis after 7 days. In translocation studies, in which 14C‐fluroxypyr was applied to previously sprayed plants, 5.1% of applied 14C‐activity was translocated from the treated leaves of S. media after 1 day, which increased to 42.2% after 7 days, recovered mainly from the stem tissue. In V. arvensis translocation was similar after 24 h however, after 7 days over 40% of applied 14C‐activity remained in the treated leaves and only 9.7% was translocated, mainly to the developing leaves and apical tissue. 14C‐activity extracted from the cuticle was the methylheptyl ester of fluroxypyr in both species. In the treated leaves and apical tissue, 14C‐activity was the free acid of fluroxypyr and polar conjugates with a significantly greater proportion of the acid in S. media. It is concluded that the resistance or V. arvensis is partially due to reduced translocation and greater conjugation than in the susceptible S. media.
Temperature requirements for after‐ripening in buried seeds of four summer annual weeds
Authors: BASKIN J. M. , BASKIN CAROL C.
Published: July 2006

Freshly matured, seeds of the four summer annuals Ambrosia artemisiifolia, Polygonum pensylvanicum, Amaranthus hybridus and Chenopodium album were buried in soil at (12/12 h) daily thermoperiods of 15/6, 20/10, 25/15, 30/15 and 35/20°C and at a constant temperature of 5°C. After 0, 1, 3 and 5 months, seeds of each species at each temperature were exhumed and tested at a 14‐h daily photoperiod at all six temperatures. Fresh seeds of A. artemisiifolia and P. pensylvanicum did not germinate at any temperature, those of A, hybridus germinated to 4 and 64% at 30/15 and 35/20°C, respectively, and those of C. album to 11–20% at 25/15, 30/15 and 35/20°C. Seeds of A. artemisiifolia and P. pensylvanicum, which germinate only in spring, required exposure to low (5, 15/6°C) temperature to after‐ripen completely (i.e., to gain the ability to germinate over a wide range of temperatures), and little or no after‐ripening occurred at high (25/15, 30/15 and 35/20°C) temperatures. Seeds of A. hybridus and C. album, which germinate in spring and summer, required exposure to low temperature to after‐ripen completely, but at high temperatures they rapidly gained the ability to germinate at high temperatures. Regardless of the burial temperatures and species, when after‐ripening occurred, seeds firs germinated at high and then at low temperatures. The minimum germination temperature for a species decreased with after‐ripening temperature and with an increase in the length of the burial period.