bluuebunny/crossref_metadata_2025 huggingface dataset:
Maternal inheritance of simazine resistance in a population of Senecio vulgaris
Authors: SCOTT K. R. , PUTWAIN P. D.
Published: July 2006

Inheritance of resistance to simazine was investigated in reciprocal pair crosses of resistant and susceptible genotypes of Senecio vulgaris. The simazine resistant genotypes had been selected in a screening experiment and were unaffected by 2.8 kg ha−1˜’a.i. simazine. Reciprocal differences for resistance and susceptibility to simazine in F2 families showed that resistance is maternally inherited. The practical implication of maternal inheritance is that a resistant field population will build up very rapidly from a very low initial frequency of the resistant genotype.
Selective herbicides for establishing weed‐free grass. I. Evaluation of ethofumesate and methabenzthiazuron
Authors: HAGGAR R. J. , KIRKHAM F. W.
Published: July 2006

The consequences of using two pre‐emergence herbicides on autumn‐sown perennial ryegrass (Lolium perenne L.) were measured over 3 years in a field experiment. Ethofumesate (2‐ethoxy‐2,3‐dihydro‐3,3‐dimethylbenzofuran‐5‐yl melhylsul‐phonate) and methabenzthiazuron [N‐(benzothiazol‐2‐yl)‐N, N'‐dimethylurea] were each applied at 0, 0.8, 1.6 and 3.2 kg ha−1 one week after drilling the grass seed. Monthly counts of plants per unit area and tillers per plant were made until the following April and the herbage dry weights of the major species were recorded at seven harvests.

Heavy infestations of Stellaria media (L.) Vill. and Poa annua L. occurred on untreated plots. Ethofumesate, and to a lesser extent methabenzthiazuron, proved effective in suppressing these weeds, only low rates being needed to control S. media. Both weeds needed to be controlled to achieve full benefits to the crop; control resulted in a 4‐fold increase in ryegrass tiller density by the first spring and a 6‐fold increase in ryegrass herbage was recorded at the first harvest in May. Some yield benefits were carried over into the second year but not into the third. In total, an extra 4.16 t ha−1 of ryegrass dry‐matter was harvested from plots treated with ethofurnesate at 0.8 kg ha−1 compared with the controls. The results are discussed in terms of defining optimum crop densities when pre‐emergence herbicides are used.
Action of propanil on in vivo chlorophyll a fluorescence in Echinochloa crus‐galli and rice
Authors: DANIELL H. , SAROJINI G. , KUMARACHINNAYAN P. , KULANDAIVELU G.
Published: July 2006

When sprayed as a post‐emergent, foliar herbicide propanil destroyed Echinochloa crus‐galli (L.) with little or no visible injury to rice, confirming its selective contact action. In treated rice leaves there was, however, a temporary decrease in dry weight, pigments, proteins and photosynthetic products followed by complete recovery in 4–5 days. In both rice and E. crus‐galli, at lower concentrations propanil inhibited the electron flow in a manner similar to that of DCMU, but at higher concentrations it damaged the primary electron donor.

In vivo chlorophyll a fluorescence kinetics determined at various times after spraying 1% propanil in the field confirmed progressive weed deterioration. Rice leaves showed a decreased fluorescence for a few hours but exhibited partial recovery from the effects of propanil within 6 h and total recovery within 48 h after spraying. When the leaves were infiltrated with propanil solutions there was good recovery of fluorescence in both weed and crop leaves at 0.01% while at 1% both were drastically affected. With 0.1% propanil, fluorescence in the weed leaves deteriorated progressively while the crop leaves recovered after 4 h of incubation. This suggests that the crop has also an effective endogenous detoxifying mechanism.
Relative persistence of MCPA, MCPB and mecoprop in Saskatchewan soils, and the identification of MCPA in MCPB‐treated soils
Authors: SMITH ALLAN E. , HAYDEN BRIAN J.
Published: July 2006

The persistence of MCPA, MCPB and mecoprop was compared at the 2 μg g−1 level, under laboratory conditions, in three Saskatchewan soils at 85% of their field capacity moistures and 20 ± 1°C. Following extraction of the soils with aqueous acidic acetonitrile, the methylated extracts were analysed gas chromatographically for herbicides remaining.

Breakdown of all three phenoxyalkanoic acids was rapid; the average half‐lives for MCPA, MCPB and mecoprop being < 7, 6 and 8 days, respectively. Degradation in air‐dried soils was minimal. The presence of MCPA as a degradation product of MCPB was confirmed in all moist soils.
Rapid detection of‘triazine resistant’weeds using chlorophyll fluorescence
Authors: ALI A. , MACHADO V. SOUZA
Published: July 2006

A simple and rapid method for the detection of triazine resistant plants is reported, based on chlorophyll fluorescence. Leaf discs were floated in phosphate buffer solution with and without 10−4 M alrazine for 2–4 h. Subsequently, the relative leaf chlorophyll fluorescence (LCF) was measured with a plant productivity fluorometer. Following herbicide uptake LCF in triazine susceptible plants was 2–3 times greater than in the untreated controls; no such LCF changes were observed in triazine resistant plants. Concentration and time course studies were conducted on several species having triazine susceptible and resistant biotypes. The use of this method for field extension purposes is described.
Activité des peroxydase, catalase et glycolate oxydase après traitement avec divers herbicides
Authors: DECLEIRE M. M. , HONOREZ Y. P. , van ROEY G.V.
Published: July 2006

Divers herbicides ont été administrés à des plantules de concombres de 17 jours, croissant sur solution nutritive. Les activités des peroxydase, catalase et glycolate oxydase ont été mesurées après 1, 2 et 3 jours dans les feuilles des plantules traitées avec des doses létales d'atrazine, de chlortoluron, de MCPA, d'alachlore et de dichlobenil. Les mêmes déterminations ont été effectuées après 5 h sur plantules préalablement pulvérisées au paraquat et au DNOC. L'atrazine et le chlortoluron ont inhibé l'activité de la peroxydase et stimulé légèrement celle de la catalase. Ces deux enzymes ont été activées par le MCPA, l'alachlore et le dichlobenil et après 3 jours, les rapports peroxydase/catalase ont été respectivement de 0.7; 7 et 14. Le DNOC et le paraquat ont inhibé la catalase. L'activité de la glycolate oxydase a augmenté dans les plantules traitées à l'atrazine, au chlortoluron, au MCPA et au DNOC et a diminué dans celles traitées au dichlobenil et au paraquat.
Soil persistence studies with [14C]MCPA in combination with other herbicides and pesticides
Authors: SMITH ALLAN E.
Published: July 2006

The persistence of [14C]MCPA at a rate equivalent to 1 kg ha−1 was studied under laboratory conditions in a clay loam, heavy clay and sandy loam at 85% of field capacity moisture and 20±1°C both alone and in the presence of tri‐allate, trifluralin, tri‐allate and trifluralin, malathion, Vitaflow DB, malathion and Vitaflow DB, bromoxynil, bromoxynil and asulam, bromoxynil and difenzoquat, dicamba, dicamba and mecoprop, linuron, MCPB, metribuzin, propanil, TCA, benzoylprop‐ethyl, diclofop‐methyl, and flamprop‐methyl.

Except in the soils treated with asulam, the half‐lives of [14C]MCPA in all three soil types were similar, being approximately 13±1 days, thus indicating that none of the other chemicals studied adversely affected the soil degradation of MCPA. In the asulam treated soils, the half‐lives of the MCPA were about 3 days longer than in non‐asulam treated soils; the effect was most marked in the clay loam.
Population regulation of Galinsoga ciliata and G. parviflora
Authors: RAI J.P.N. , TRIPATHI R.S.
Published: July 2006

The population response of the two sympatric annual weeds, Galinsoga ciliata (Raf.) Blake and G. parviflora Cav., which occur abundantly in croplands and early secondary successional communities in the north‐eastern hill region of India was studied in relation to sowing pattern (clump or scattered sowing), population density and soil moisture and texture.

In a given sowing pattern, seed germination of both species declined with increase in sowing density and moisture stress. However, sowing of seeds in clumps and an increased proportion of sand in soil enhanced the germination, Fewer weeds died in the population raised from scattered sowing than from clumped distribution. Plants grown at high moisture level matured earlier, and fertility of the survivors was negatively correlated with both density and moisture stress in both species although G. ciliata was less affected.

Seed output and dry matter yield per pot of both species increased with population density but the increase was not linearly related to the increase in plant numbers, and density‐induced reduction in seed output was observed at high densities. Galinsoga ciliata appears to tolerate greater density‐stress than G. parviflora. Asubstantial decrease in production of capitula, seeds and dry matter at low moisture level indicates the role played by soil moisture in regulating the population growth of the two weeds. An increased proportion of sand in soil resulted in significantly greater seed production in G. parviflora. Galinsoga ciliata also showed a similar trend although the differences were not statistically significant.
Compatible and antagonistic mixtures of diclofop‐methyl and flamprop‐methyl with herbicides used to control broad‐leaved weeds
Authors: TAYLOR H. F. , LOADER M. P. C. , NORRIS S. J.
Published: July 2006

In glasshouse experiments, the addition of four ‘pyridine herbicides’ (substituted picolinic and pyridyloxyacetic acids) to either diclofop‐methyl or flamprop‐methyl had little effect on wild oat (Avena fatua) control. This contrasts with the serious antagonisms which occur with 2, 4‐D and 2, 3, 6‐TBA. With wild and cultivated oat, l'‐methylheptyl (4‐amino‐3, 5‐dichloro‐6‐fluoro‐2‐pyridyl)oxyacetate (Dowco 433) was completely compatible with diclofop‐methyl and flamprop‐methyl, and there was evidence that its presence improved the control of wild oats. Picloram, 3, 6‐dichloropicolinic acid and triclopyr had only slight effects on phytotoxicity. The control of cleavers (Galium aparine) by picloram, triclopyr and Dowco 433 was not significantly reduced by addition of flamprop‐methyl.

Preliminary metabolism studies suggest that picloram does not greatly increase the rate of diclofop detoxification as do 2, 4‐D and 2, 3, 6‐TBA, and the observed compatibility could well be a direct consequence of this.

The absence in these greenhouse experiments of serious antagonism between the pyridine herbicides and diclofop‐methyl or flamprop‐methyl suggests that ‘tank mixes’ of these herbicides could be used for the control of both broad‐leaved weeds and wild oats.
The influence of temperature on germination of gorse (Ulex europaeus L.)
Authors: IVENS G. W.
Published: July 2006

The germination of U. europaeus seed was investigated at temperatures between 4 and 40°C on a thermal gradient bar. At constant temperature the germination rate increased linearly with temperature from a minimum near 0°C to an optimum at 18°C and then decreased to a maximum at 26°C. At still higher temperatures seeds became imbibed but only germinated when transferred to cooler conditions. Above 35°C viability was lost. The rate of imbibition prior to germination increased with temperature over the whole range. Germination was not increased either by a light treatment or by potassium nitrate.

Germination was not stimulated by a wide range of alternating temperature regimes and at mean temperatures below the optimum the germination rate could be adequately predicted from a formula based on performance at constant temperature. At higher temperatures the observed rates became progressively slower than predicted. Seeds from three different sources were tested, all showing similar relationships between germination rate and temperature but differing in the proportion of hard seed. The proportion was least with seed extracted from the soil, intermediate with a collection from the surface and greatest from pods. The findings are discussed in relation to germination in the field following clearing of gorse thicket.
A root bioassay procedure for the determination of chlorsulfuron, diclofop acid and sethoxydim residues in soils
Authors: HSIAO A. I. , SMITH A. E.
Published: July 2006

Measurement of the root lengths of pre‐ger‐minated oat seedlings (Avena sativa L. var. Sioux) grown in the dark in treated soils was used to assay residues of diclofop acid (2‐[4‐(2,4‐dichloro‐phenoxy)phenoxy]propionate) and sethoxydim (2‐[1‐(ethoxyimino)‐butyl]‐5‐[2‐(ethylthio)‐propy]‐3‐hydroxy‐2‐cyclohexene‐1‐one). Similar measurements involving maize seedlings (Zea Mays L. var. Sunny Vee) were also used to determine residues of the herbicide chlorsulfuron (2‐chloro‐N‐[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)aminocarbony]benzenesulfonamide) in soils. The procedure appeared to be reproducible with residues of chlorsulfuron, diclofop acid and sethoxydim being detectable at amounts of 0.001, 0.2 and 0.05 μg g−1 respectively.
The persistence and metabolism of isoproturon in soil
Authors: MUUD P.J. , HANCE R.J. , WRIGHT S. J. L.
Published: July 2006

The persistence of isoproturon in soil in pot experiments was the same whether or not the soil contained growing wheat (Triticum aestivum L.) plants, Panllel) work with radioactive isoproturon showed that the breakdown products were the same in the presence and absence of plants. Persistence in the field was reasonably well predicted by a simulation model using the results of laboratory incubation studies and field meteorological data.
Persistence studies with the herbicide sethoxydim in prairie soils
Authors: SMITH ALLAN E. , HSIAO ANDREW I.
Published: July 2006

The persistence of [14C]sethoxydim (2‐[1‐(ethoxyimino)butyl]‐5‐[2‐(ethylthio)propyl]‐3‐hydroxy‐2‐cyclohexene‐1‐one) at the 2 μg g−1 level was studied under laboratory conditions in three soils at 20°C and 85% of their field capacity moistures. Following extraction of the soils with methanol, the herbicide remaining was determined using radiochemical techniques. Loss of radioactivity was more rapid on moist clay loam and sandy loam, where the half‐lives were 12 days, than on heavy clay in which the half‐life was 26 days. Loss of radioactivity from air‐dried soils (15% of field capacity) was negligible with over 94% of the applied activity being recovered after 28 days.

The persistence of sethoxydim at a rate of 1 kg ha−1 was investigated under field conditions using small plots at three prairie locations for 3 successive years. Using an oat‐root bioassay procedure, no residues were detected in the 0–10 cm depths of any soils, any year, in September following May treatments.
The fungicide tridemorph as a selective herbicide for the control of Holcus lanatus in ryegrass and of Bonus sterilis in barly
Authors: WATT TRUDY A.
Published: July 2006

The potential of the fungicide tridemorph selectively to control established plants of Holcus lanatus L. in ryegrass (Lolium perenne L) and Bromus sterilis L. in barley (Hordeum vulgare L.) was examined in glasshouse trails. A dose of 4.2 kg ha−1 tridemorph gave selectively between H. lanatus and ryegrass similar to, but more costly than, that which would be provided by 1.2 kg ha−1 asulam. B sterilis was more sensitive to tridemorph than was barley. Two additives, glycerol and the oil‐surfactant mixture ‘PF’ enhanced this selectivity when tridemorph was applied at 2.1 kg ha−1.
Volunteer winter wheat: its effects and control in ryegrass seed production
Authors: WRIGHT D. , HEBBLETHWAITE P. D.
Published: July 2006

The effects of different populations of volunteer winter wheal and their control with ethofumesate and TCA on growth, seed yield and yield components of S.24 perennial ryegrass were investigated in lield experiments in 1978 and 1979.

Reductions in ryegrass seed yield due to the presence of wheat depended on the density of wheat and the number and dry weight of ryegrass tillers. The greatest percentage reduction in ryegrass seed yield occurred at high densities of wheat (300 plants m−2) when the number of ear‐bearing tillers and 1000 seed weight of ryegrass were reduced. When Ihe density of wheat was low (80 plants m−2) a smaller reduction in ryegrass seed yield occurred and the number of live wheat plants remaining gradually decreased. Within the range of wheat densities in these experiments (0–300 plants m −2) a 1% loss in ryegrass seed yield occurred for every 10 wheal plants m−2 present in the crop post winter.

Both herbicides caused a reduction in number of ryegrass tillers during growth but, except where TCA was applied at 12 kg ha−1 in November, ryegrass seed yields were not significantly reduced (in comparison with a wheat‐free control) and were always greater than those obtained in the presence of wheat where no herbicides had been applied. Levels of volunteer infestation of 300 wheat plants m−2 were controlled with minimum risk of crop damage by applications of 6 kg ha−1 TCA in either October or November, or by application of 1–9 kg ha−1 ethofumesate in November.
Einfluss von Pflanzenschutzmitteln einer Zuckerrüben‐Spritzfolge auf biologische Aktivitäten und auf den Abbau von Chloridazon im Boden. II. Gefäss‐und Laborversuche
Authors: DE FANG FAN , PESTEMER W. , MALKOMES H.‐P.
Published: July 2006

In Gefäss‐und Laborversuchen wurde das Abbauverhallen und die Pflanzenverfügharkeit von Chloridazon (Pyramin) allein und in Kombination mit anderen Pflanzenschutzmitteln einer Zuckerrüben‐Spritzfolge untersucht sowie deren Einfluss auf bodenbiologische Aktivitäten (Dehydrogenaseaklivität, Strohabbau).

Sowohl im Gefässversuch mit und ohne Pflanzenbestand als auch in den Laborversuchen zeigte sich bei allen Behandlungen nach einer kurzen lag‐Phase ein sehr schneller Abbau von Chloridazon, der offensichtlich von den anderen Präparaten unbeeinflusst war. Bei allen Varianten konnten durchschnittlich 10 Tage für eine 50% ige Abnahme der Ausgangskonzentration ermittelt werden. Der mit W asser extrahierbare Anteil des Gesamtrückstands lag in den verschiedenen Kombinationen bis eine Woche nach der Applikation bei durchschnittlich 43% und fiel danach innerhalb der nächsten Woche auf 0% ab. Der Strohabbau wurde durch Pyramin allein nicht verνdert, durch die gesamte Zuckerrüben‐Spritzfolge leicht stimuliert. Im Gefässversuch mit und ohne Pflanzenbestand wurde die Dehydrogenaseaklivilät durch Pyramin allein nicht wesentlich gehemmt, während in der Spritzfolge im unbewachsenen Boden leichte Depressionen auftraten. Im Labor wurde die Enzymaktivität durch Pyramin allein nur wenig, durch die Präparate der Spritzfolge stärker gehemmt.

Eine Korrelation zwischen den bodenbiologischen Aktivitäten und dem Abbauverhalten von Chloridazon kann nicht abgeleitet werden.
Influence of pre‐emergence herbicides on root development of Agrostis stolonifera sod*
Authors: BINGHAM S. WAYNE , SCHMIDT RICHARDE
Published: July 2006

Agrostis stolonifera Huds cv.‘Penncross’ and cv.‘Cohansey’(bentgrass) were maintained as a golf‐course putting green. Five herbicides were evaluated at normal (1 x) and three times normal (3 x) rates for Digitaria sanguinalis (L.) Scop (Crabgrass) control and influence on root development of sod. The herbicides were applied once (April), twice (April and August) and three times (April, June and August) annually. After application of 3 × rates, benfluralin (N‐butyl‐N‐ethyl‐2,6, dinitro‐4‐triflouromethylaniline) and chlorthal‐dimethyl (2,3,5,6‐tetrachloroterephthalic acid dimethyl ester) caused injury on both A. stolonifera cultivars. Shoot injury remained with repeated benfluralin treatments; however, injury was no longer apparent after the first application of chlorthal‐dimethyl. Terbucarb (2,6‐di‐t‐butyl‐p‐tolyl N‐methylcarbamate) completely killed both cultivars during the second year of the study. Bensulide (N‐[2‐(0,0‐di‐isopropyldithiophosphoryl)ethyl]benzene sulphonamide) and siduron (N‐(2‐methylcyclohexyl)‐N‐phenylurea) did not influence shoot growth of either A. stolonifera cultivars. Chlorthaldimethyl, bensulide and siduron allowed excelent sod rooting in both cultivars. The 3 × rate of the three herbicides did affect rooting of ‘Cohansey’ cultivar during the second year of the study, as did the 1 × rate of benfluralin. The benfluralin injury did not persist from one treatment time to the next, even at 3 × rates. Terbucarb restricted root growth for the entire year. Bensulide and siduron provided acceptable D. sanguinalis control and acceptable A. stolonifera tolerance under golf‐course green management and re‐establishment with turf.
EWRS Herbicide‐Soil Working Group: Collaborative experiment on simazine persistence in soil
Authors: WALKER A. , HANCE R. J. , ALLEN J. G. , BRIGGS G. G. , CHEN YUH‐LIN , GAYNOR J. D. , HOGUE E. J. , MALQUORI A. , MOODY K. , MOYER J. R. , PESTEMER W. , RAHMAN A. , SMITH A. E. , STREIBIG J. C. , TORSTENSSON N. T. L. , WIDYANTO L. S. , ZANDVOORT R.
Published: July 2006

The effects of soil temperature and soil moisture content on the rate of simazine degradation were measured in the laboratory in soils from sixteen sites located in several different countries. First‐order half‐lives under standard incubation conditions were significantly correlated with clay content, organic carbon content and soil pH in a multiple linear regression. The temperature dependence of degradation was similar in the different soils whereas the moisture dependence showed considerable variation between soils. Persistence of simazine was also measured in the same soils in the field and at live additional sites. Weather records from the different sites for the periods of the Held experiments were used in conjunction with constants derived from the laboratory data in a computer program to simulate persistence in the field. In general, the model overestimated residues in the field. About half of the calculated residues were within 25% of those observed, an accuracy sufficient for practical purposes, but on several occasions the discrepancies between calculated and observed residues were greater than 50%. Possible reasons for the discrepancies and requirements for further experiments are discussed.
Agronomic effects from the control of Agropyron repens in barley by pre‐harvest application of glyphosate
Authors: SHEPPARD B. W. , RICHARDS M. C. , PASCAL J. A.
Published: July 2006

Pre‐harvest application of glyphosate in barley at 1·44 and 0·72 kg ha−1 was compared with post‐harvest application at 1·44 kg ha−1 at six sites in south‐east Scotland, three sprayed in 1980 and three in 1981. Both levels of pre‐harvest application gave consistent 95–99% control of A. repens compared with 0–76% control from post‐harvest application. Yields of crops grown in 1981 were significantly increased after all the 1980 pre‐harvest treatments and after one post‐harvest treatment. No significant depressions in grain germination were recorded from the lower rate of pre‐harvest application but one significant depression was recorded from the higher rate. Combine harvesting throughput at a given grain loss level was significantly improved by pre‐harvest application and moisture content of grain at harvest was significantly reduced by up to 2·5%. Wheeling losses from pre‐harvest spraying ranged from 1 to 5%. Crop yield increases in the year after spraying compensated for herbicide and application costs plus any yield losses through tractor wheelings.
Control of Avena fatua L. and Cirsium arvense (L.) Scop. with mixtures of 3,6‐dichloropicolinic acid and four herbicides for control of A. fatua
Authors: O'SULLIVAN P. A. , Kirkland K. J.
Published: July 2006

Control of Avena fatua (L.) (wild oat) with diclofop methyl applied at 0·7 kg ha−1 at the two‐leaf stage and difenzoquat at 0·84 kg ha−1 at the four‐leaf stage in wheat (Triticum aestivum L.) under field conditions was good and not affected when either of these herbicides was mixed with 3,6‐dichloropicolinic acid as the monoethanolamine salt at 0·14, 0·20 or 0·30 kg ha−1. In the glasshouse, mixtures containing 3,6‐dichloropicolinic acid at rates as high as 0·6 kg ha−1 also did not affect control of A. fatua. When barban at 0·35 kg ha−1, or flamprop methyl at 0·56 kg ha−1 was mixed with similar rates of 3,6‐dichloropicolinic acid and applied at the two‐leaf and four‐leaf stage of A. fatua respectively, a reduction in control of A. fatua (antagonism) occurred under both field and glasshouse conditions. The herbicides for control of A. fatua did not influence the fresh weight suppression of C. arvense shoots obtained in the glasshouse with 3,6‐dichloropico‐colinic acid at 0·3 kg ha−1. Early tolerance of wheat (cv. Neepawa) was acceptable with all mixtures. Wheat yields with diclofop methyl or difenzoquat alone or in mixture with 3,6‐dichloropicolinic acid were increased over the yields from the A. fatua‐infested control.
Measuring spectral differences in vegetation canopies by a reflectance ratio meter
Authors: HAGGAR R. J. , STENT C. J. , ROSE J.
Published: July 2006

A simple, robust and inexpensive hand‐held meter is described which senses the presence of green vegetation against brown soil by measuring the ratio of near infra‐red (0·75 μm) to red (0·65 μm) radiances: ratios are higher for green canopies than for soil, due to strong absorption by chlorophyll of red wavelength and the high near‐infrared reflectance of healthy vegetation. Field tests showed that radiance data were correlated closely with plant density and growth stage. Such spectral assessments provide a rapid, nondestructive method of monitoring changes in green‐leaf biomass. Although only small differences in radiance values were recorded from monocultures of various non‐flowering species there was a positive correlation with content of white clover in five grass/clover swards. In addition to being a research aid, these findings confirm the potential of remote sensing of agricultural targets, e.g. detection of weed patches for herbicide spraying, or gaps in swards for sowing seed.
Effect of ammonium sulphate and related salts on the phytotoxicity of dichlorprop and other herbicides used for broadleaved weed control in cereals
Authors: TURNER D. J. , LOADER M. P. C.
Published: July 2006

In glasshouse experiments, additions of 10–100 g 1−1 ammonium sulphate enhanced the phytotoxicity to broadleaved weeds and cereals of several water‐soluble herbicides applied post‐emergence in 75–300 1 ha−1 with hydraulic nozzles. Studies with dichlorprop potassium salt and chickweed Stellaria media (L.) Vill. examined interactions between ammonium sulphate and environmental, application and formulation factors. Simulated rainfall immediately after spraying greatly reduced dichlorprop activity, whether or not ammonium sulphate was present. However, when there was an interval of 2–24 h between spraying and rainfall, the additive increased phytotoxicity. Surfactants tended to reduce dichlorprop phytotoxicity to Stellaria media, both in the presence and absence of ammonium sulphate. Certain other inorganic salts including sodium sulphate also enhanced phytotoxicity. Applications by rotary atomizer in very low spray volume (15 1 ha−1, 250–280 μm drops) were less effective than conventional 150 1 ha−1 applications. When very low volume application was used, addition of ammonium sulphate or nitrate tended to reduce activity further. In the field, ammonium sulphate significantly increased the effects against weeds of a commercial dichlorprop potassium salt formulation applied conventionally in 200 1 ha−1 spray volume. Neutralized phosphoric acid had a similar effect but a mixture of this additive and ammonium sulphate reduced phytotoxicity. Both additives slightly increased dichlorprop injury to barley.
Variation in ethofumesate tolerance in Lolium species and cultivars
Authors: FAULKNER J. S.
Published: July 2006

The ethofumesate tolerances of seventy cultivars of Lolium perenne L., L. multiflorum Lam. and L. x hybridum Hausskn. were investigated by growing seedlings in a glasshouse in a potting compost treated with a critical level of the herbicide. The incidence of seedling deformity and death varied among cultivars, and was generally higher in diploids than in tetraploids, and in L. perenne than in L. multiflorum. Cv. Palaver was outstandingly tolerant. Eight cultivars were re‐tested in pre‐ and post‐emergence field experiments and relative tolerances were similar to those observed in the glasshouse. At the recommended doses for selective weed control, ethofumesate caused some seedling death in susceptible varieties in the pre‐emergence experiment, and both seedling death and reduced herbage production in the post‐emergence experiment. It is concluded that both varietal genotype and environmental factors contribute to the risk of ethofumesate damage in the field.
Action de l'atrazine, du chlortoluron et du MCPA sur les teneurs en pyruvate, oxalacétate, cétoglutarate, glutamate et glutamine dans les feuilles et les racines de concombre (Cucumis sativus)
Authors: DECLEIRE M. , DE CAT W.
Published: July 2006

Des doses létales d'atrazine, de chlortoluron et de MCPA ont été administrées à des plantules de concombre (Cucumis sativus) de 17 jours croissant sur solution nutritive. La composition en acides cétoniques, glutamate et glutamine a été déterminée dans les feuilles et les racines après des délais de 1 à 4 jours.

Deux jours après l'application d'herbicides inhibiteurs de photosynthèse, les teneurs en cétoglutarate, oxaloacétate, pyruvate, glutamate et glutamine des feuilles sont respectivement de 11 à 20%; 30 à 54%; 43 à 50%; 101 à 112% et 49 à 65% par rapport aux témoins. Après 4 jours, elles sont de 16 à 22%; 31 à 56%; 26 à 42%; 71 à 75% et 180 à 205%. Dans les racines, le glutamate diminue dans la même proportion que le cétoglutarate tandis que la glutamine augmente les deux premiers jours et diminue la quatrième jour. Le traitement au MCPA ne modifie pas la concentration en cétoglutarate des feuilles mais l'augmente de 300 à 800% dans les racines.

L'analyse simultanée du cétoglutarate et du glutamate permet de caractériser la nature du traitement herbicide.
Factors affecting the development of populations of Oxalis pes‐caprae L.
Authors: LANE D.
Published: July 2006

As the control of Oxalis pes‐caprae L. is dependent upon treatment after the parent bulb has become exhausted and before the new bulbs have formed, experiments were conducted to test the uniformity of development of plants and to determine if adequate control could be expected from a single herbicide application. Inherent differences were observed in the time of emergence, and further differences could be induced by increasing the depth of planting or withholding water. Competition between plants was shown to retard the development of late‐emerging plants.

The physical removal of parts of the plant before bulb exhaustion had limited effect on bulb production, but reduced bulb weights and numbers when carried out after bulb exhaustion. Although not all parts of the plant were replaced by regrowth, no major changes in overall development were noted.
Critical period of weed competition in three vegetable crops in relation to management practices
Authors: WEAVER SUSAN E.
Published: July 2006

The critical period of weed competition was determined in three vegetable crops: early cabbage (Brassica oleracea var. capitata L.), pickling cucumbers (Cucumis sativus L.), and field‐seeded processing tomatoes (Lycopersicon esculentum L.). There were significant interactions between weed‐removal treatments, year, and row width. Cabbage yields were reduced if plots were not kept weed‐free for at least 3 weeks after transplanting or if weeds which emerged with the crop were allowed to remain longer than 4–5 weeks, Cucumber yields were reduced if plots were not kept weed‐free for up to 4 weeks after seeding or if plots remained weed‐infested longer than 3–4 weeks. Higher crop population densities (narrower row widths) in cabbage and cucumbers resulted in smaller plants, earlier competition from weeds, and therefore a shorter period that the crop could remain weed‐infested without suffering reduced yields. Yields of direct‐seeded tomatoes were reduced if plots were not kept weed‐free for up to 9 weeks after seeding or if weeds which emerged with the crop were allowed to remain longer than 5 weeks. In each crop the timing of the critical period of competition was verified by weed removal only during this interval. There was a true critical period in direct‐seeded tomatoes, but not in cabbage or cucumbers where a single weeding was sufficient to prevent yield losses.
Effect of temperature during burial on dormant and non‐dormant seeds of Lamium amplexicaule L. and ecological implications
Authors: BASKIN J. M. , BASKIN CAROL C.
Published: July 2006

Spring‐produced seeds of Lamium amplexicaule L. were dormant at maturity in May and after‐ripened when buried and stored over a range of temperatures, becoming conditionally dormant at low (5, 15/6 and 20/10°C) and non‐dormant at high (25/15, 30/15 and 35/20°C) temperatures. Conditionally dormant seeds germinated to high percentages at 5 and 15/6°C, and non‐dormant seeds germinated to high percentages at 5, 15/6, 20/10, 25/15 and 30/15°C. Seeds that became conditionally dormant at 5°C afterripened completely (i.e. became non‐dormant) after transfer to 30/15°C. Buried seeds that became non‐dormant in a non‐temperature‐controlled glasshouse during summer were still non‐dormant after 12 weeks of storage at 30/15°C, while those stored at 5°C for 12 weeks had entered conditional dormancy. Thus, low temperatures cause reversal of the afterripening that takes place at high temperatures, but not that which takes place both at low and at high temperatures. Low winter temperatures cause dormant autumn‐produced seeds and non‐dormant seeds in the soil seed pool to become conditionally dormant. The ecological consequences of these responses to temperature are discussed in relation to the timing of seed germination in nature.
Influence of metolachlor and the metolachlor protectant CGA 43089 on the biosynthesis of epicuticular waxes on the primary leaves of Sorghum bicolor Moench
Authors: EBERT E. , RAMSTEINER K.
Published: July 2006

Epicuticular wax synthesis by the primary leaf of Sorghum bicolor seedlings is inhibited when the germinating seeds are treated with 5 ppm metolachlor before germination. The composition of the free and esterified primary alcohols plus free and esterified fatty acids and aldehydes have been analysed. The predominant alcohol (75%) had 32 carbons while the 28‐ and 30‐carbon homologues accounted for 78% of the fatty acids. Treatment of the germinating seeds with metolachlor strongly inhibited formation of the C28, C30 and C32 alcohols. Synthesis of C30 and C32 fatty acids was decreased while that of the C26 homologues was somewhat elevated. Simultaneous treatment of the germinating seed with metolachlor and the herbicide protectant CGA 43089 (α‐[cyanomethoximino]‐benzacetonitrile) resulted in normal wax synthesis. The results lead to the conclusion that the protectant prevents metolachlor from inhibiting synthesis of the dominating C28 to C30 chain‐length constituents of the sorghum epicuticular wax.
Inventaire phytoécologique des adventices de la betterave sucrière dans le Gharb (Maroc)
Authors: TANJI A. , BOULET C. , HAMMOUMI† M.
Published: July 2006

Nous avons réalisé un inventaire phytoécologique de 122 stations sur les parcelles de betterave à sucre dans la région du Gharb (Maroc Occidental). Deux cent cinquante‐six espèces adventices ont été recensées, appartenant à quarante‐cinq familles botaniques, 80% des taxons environ étant des thérophytes, L'analyse différentielle de Czekanowski a permis de dégager quatre groupements phytosociologiques. Des groupes écologiques différentiels ont été distingués selon les caractères édapho‐climatiques (texture fine du sol, pH, calcaire total, pluviosité).
Weed interference in maize, cowpea and maize/cowpea intercrop in a subhumid tropical environment. III. Influence of land preparation
Authors: AYENI A. O. , DUKE W. B. , AKOBUNDU I. O.
Published: July 2006

The influence of no‐tillage and conventional tillage on the outcome of early weed interference in maize (Zea mays L., cv. TZB), cowpea [Vigna unguiculata (L.) Walp, cv. VITA‐5] and their intercrop at populations of 40000, 50 000 and 30 000 + 40 000 plants ha−1 was investigated on a loamy sand Oxic Ustropept in a subhumid tropical environment between April and July 1980. Both tillage treatments received 60 kg N, 30 kg P2O5 and 30 kg K2O ha−1. Although the weed spectrum was wider under no‐tillage, weed weight was only 52% of the weight recorded under conventional tillage 6 weeks after sowing and the average food energy yield reductions caused were 28 and 65%, respectively. Cropping pattern had no effect on plot weediness. With minimum or no weed interference, maize performance was better in conventional than no‐tillage but worse with prolonged weed interference. Cowpea responded more to weed interference than to tillage practice. Regardless of tillage practice and weed interference duration (up to 6 weeks) after sowing, maize monoculture produced the highest food energy yield, followed by maize/cowpea intercrop and cowpea monoculture in that order.
Pathogenicity of fungi and bacteria from the Sudan to water hyacinth
Authors: ABDELRAHIM A. M. , TAWFIG S.
Published: July 2006

Studies were made in the Sudan for microorganisms pathogenic to water hyacinth (Etchhornia crassipes Solms) for biological control purposes. Many fungi and bacteria were isolated from plant parts showing disease symptoms. Pathogenicity tests revealed that only five out of the twenty‐five fungal and bacterial isolates were damaging to the weed plant. These included Acremonium zonatum, Drechslera specifera and Fusarium equiseti. Phoma sorghina and a bacterium Bacillus sp. are reported for the first time as potential pathogens of water hyacinth. Pathogenic isolates were also found to produce toxic metabolites in liquid cultures.
Pénétration, translocation et métabolisme de dinitrophénols
Authors: PONT V. , COLLET G.F.
Published: July 2006

Nous avons disposé de DNTBP et de DNOC uniformément marqués au 14C sur le noyau benzénique. La pénétration foliaire et racinaire, ainsi que la translocation du DNTBP sont lentes. Il a été possible de mettre en évidence, après 3 jours déjà, des composés de dégradation très éloignés des herbicides de départ. Un catabolite cinquante fois moins actif que le DNTBP a été identifié: le méthyl‐2(hydroxy‐2′dinitro‐3′5′‐phényl)‐2 propanol‐1. Sur le plan biologique, le DNTBP et le DNOC exercent un effet dèsorganisateur des membranes lipidiques. Penetration, translocation and metabolism of dinitraphenols
Influence of particle size and type of formulation on phytotoxicity and persistence of atrazine
Authors: RAHMAN A.
Published: July 2006

The initial and residual activities of wettable powder formulations of atrazine comprising different particle sizes were investigated in field and glasshouse experiments. A flowable formulation was also compared with these. Oats were used as the test species for the glasshouse studies while in field trials effects on control of broadleaf weeds in maize were studied. No marked differences were noted in the activity of wettable powders of different particle sizes in the glasshouse as pre‐emergence applications. As a post‐emergence treatment the fine particle size was more phytotoxic than the coarse material, especially when a wetting agent was added to the spray solution. In the field trials, no appreciable differences in weed control or crop tolerance could be established regardless of the time or rate of application. The flowable formulation was less active than the wettable powders in some glasshouse experiments but no such trend was apparent in field trials. Bioassays showed that the residual activity of the flowable formulation was lower than wettable powder formulations in both glasshouse and field studies but no consistent differences were noted in the persistence of the three forms of wettable powders.
Weed interference in maize, cowpea and maize/cowpea intercrop in a subhumid tropical environment. I. Influence of cropping season
Authors: AYENI A. O. , DUKE W. B. , AKOBUNDU I. O.
Published: July 2006

Field experiments were conducted in the early and late cropping seasons of 1979 on a loamysand Oxic Ustropept in a subhumid environment in Nigeria, using 40000, 50000 and 30000 + 40000 plants ha−1 of maize (Zea mays L. cv. TZB), cowpea (Vigna unguiculata (L.) Walp. cv. VITA‐5) and maize/cowpea intercrop respectively. These indicated that weed interference effects on crops under no‐tillage depended on cropping season, cropping pattern and crop species. In the early and late seasons respectively, thirty‐five and twenty‐nine different weed species were recorded and weed dry weights of approximately 10·4 and 5·7 t ha−1 from the plots kept weedy throughout the season reduced corresponding food energy yields by 60 and 82%. Except for the intercrop, which in the early season showed significant yield reduction when exposed to 4 weeks’ weed interference after sowing, all cropping patterns needed more than 4 weeks’ interference to show significant yield reductions, regardless of cropping season. In the early season, weed interference accounted more for the yield reductions in monocultures than it did for those in the intercrop, but in the late season all cropping patterns were equally sensitive to weed association. Maize, which performed much better in the early season, showed greater yield reductions than cowpea under early weed interference but less under full‐season interference irrespective of cropping pattern and season. Cowpea seed quality was more reduced by intercropping than by weed interference in the early season but neither of these factors affected seed quality significantly in the late season.
Soil persistence studies with bromoxynil, propanil and [14C]dicamba in herbicidal mixtures
Authors: SMITH ALLAN E.
Published: July 2006

The persistence of bromoxynil (3,5‐dibromo‐4‐hydroxybenzonitrile), [14C]dicamba (3,6‐dichloro‐2‐methoxybenzoic‐7‐14C acid) and propanil [N‐(3,4‐dichlorophenyl)propionamide] at rates equivalent to 1 kg ha−1, were studied under laboratory conditions in a clay loam, a heavy clay and a sandy loam at 85% of field capacity and at 20±1°C, both singly and in the presence of herbicides normally applied with these chemicals as tank‐mix or split‐mix components.

The degradation of bromoxynil was rapid with over 90% breakdown occurring within a week in the heavy clay and sandy‐loam soils, while in the clay‐loam approximately 80% of the bromoxynil had broken down after 7 days. In all three soils degradation was unaffected by the presence of asulam, diclofop‐methyl, flamprop‐methyl, MCPA, metribuzin or propanil.

Propanil underwent rapid degradation in all soil treatments, with over 95% of the applied propanil being dissipated within 7 days. There were no noticeable effects on propanil degradation resulting from applications of asulam, barban, bromoxynil, dicamba, MCPA, MCPB, metribuzin or 2,4‐D.

The breakdown of [14C]dicamba in a particular soil was unaffected by being applied alone or in the presence of diclofop‐methyl, flampropmethyl, MCPA, metribuzin, propanil or 2,4‐D. The times for 50% of the applied dicamba to be degraded were approximately 16 days in both the clay loam and sandy loam, and about 50 days in the heavy clay.
Physical basis for the maternal inheritance of triazine resistance inAmaranthus hybridus
Authors: VAUGHN K. C.
Published: July 2006

In an effort to determine the physical basis of the maternal inheritance of triazine resistance inAmaranthus hybridusL. the fate of plastids and other organelles in developing pollen was investigated in triazine‐resistant and susceptible biotypes. In both types, immediately after microspore mitosis, the newly formed generative cells contained an array of organelles (golgi bodies, endoplasmic reticulum, plastids and mitochondria) similar to that in the larger vegetative cells. No selective exclusion of organelles from the generative cell was noted although only small plastids were present. The immature generative cells contained small vacuoles, within which degenerate organelles were frequently observed, and no ultrastucturally recognizable plastids were found in mature cells. Maternal transmission of the triazine resistance factor thus appears to be due to a selective destruction of paternal plastids.
Herbicide injections into stumps of aspen and birch to prevent regrowth
Authors: JOHANSSON T.
Published: July 2006

Stumps of birches (Betula spp.) and aspens (Populus tremula L.) in thinning stands and on clear‐felled areas were injected with herbicides by a modified bolt gun. Herbicides were formed into tablets and placed in a wedge of nylon. The wedge was fixed in the stem with the tablet placed close to the cambium. The tablets dissolved inside the tree. Injection doses were one tablet per 2·5 or 5 cm stump diameter and were done about 5 cm below the cut surface of the stump. The injector worked adequately. Injected stumps of both species produced few and shorter suckers than untreated stumps.
Dégradation catalytique de carbamates herbicides deposés sur bentonites homoioniques. II. Cas du chlorbufame
Authors: SABADIE J. , BASTIDE J. , COSTE C M
Published: July 2006

Rásumá

La dégradation chimique en phase sèche du chlorbufame a étéétudiée après dépôt à température ambiante sur diverses bentonites homoioniques (Cu2+; Ag+). Un schéma général de dégradation a étéétabli.
Orobanche crenata (Forsk) control in Vicia faba (L.) with glyphosate as affected by herbicide rates and parasite growth stages
Authors: MESA‐GARCÍA J. , GARCÍA‐TORRES L
Published: July 2006

The broomrape (Orobanche crenata Forsk) susceptibility to glyphosate applied on faba‐bean (Vicia faba L.) as affected by the parasite growth stages at the time of application was studied under field conditions. Glyphosate treatments delayed O. crenata emergence. Single glyphosate application to faba‐bean infected with O. crenata predominantly at the stage (a) (small nodule) and (b) (nodules with initial vestigial roots) resulted in a moderate to low control. When the stages (c) (shoot bud already visible) or (d) (shoot and vestigial roots well developed) were the predominant stages, an excellent control was achieved with a single glyphosate application at 60 g ha−1. Increased development stages, with the shoot emerged from the shoot bud, decreased its susceptibility to glyphosate.

La lutte contre Orobanche crenata en culture de férerole avec le glyphosate; influence des doses d'herbicide et du stade de développement du parasite
The survival of Alopecurus myosuroides Huds. seeds in soil
Authors: MOSS S. R.
Published: July 2006

The survival of Alopecurus myosuroides seeds was studied in soil under arable cropping and short term grass leys in which seed return was prevented. At two winter wheat sites, where weed seeds were sown, the mean annual seed decline was 73–83% over a 2‐ or 3‐year period. The rate of decline was similar with all the cultivation systems studied: ploughing, tine cultivation and direct drilling. Seeds buried initially by ploughing, and then not disturbed by cultivation, were slightly more persistent.

At five arable sites with natural populations of A. myosuroides, seed numbers declined to an average of 3% of the original amount present after 3 years, and to 1% after 4 years. Initial populations of over 50 000 seeds m−2 were recorded. Plant populations were not always proportional to the total seed content of the soil, especially on ploughed land.

Seed decline in two grass fields was similar to that under arable cropping. A. myosuroides plants were recorded in a wheat crop following a 2‐year grass ley. Weed plants did not persist in the vegetative state in grass used for conservation and grazing.

At all sites, appreciable quantities of seeds were still present in the soil after 2–4 years. Although a relatively small proportion of seeds survived, the actual number of seeds surviving was substantial. For this reason, it was concluded that any eradication policy is unlikely to be effective in a cropping system dominated by winter cereals.