bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of asulam on the growth of tissue cultures of celery
Authors: WATTS M.J. , COLLIN H.A.
Published: July 2006

The response, of cell suspension and callus cultures of celery to asulim (6–600 μmoll−1) in the nutrient medium was compared with that of seedlings. The callus cultures were treated.at three slages of differentiation: undifferentiated callus, differentiated callus on which embryoids had developed to the globular and heart‐shaped stage, and finally plantlets which had secondary leaves and roots. Cell division in the suspension culture was enhanced at low concentrations (6 and 12 μmoll−1) and inhibited at higher concentrations Cell expansion was unaffecte by the presence of asulam In differentiated tissue the growth stimulation at low concentrations was absent. and there was a steady decline in accumulation of fresh weight with increasing concentration. Root length and number of laterals of intact seedlings showed a similar pattern, indicating that the response of the tissue to asulam was not radically altered by differentiation
The decline of propyzamide in soil under field conditions in the Netherlands
Authors: ZANDVOORT R. , VAN DORD D. C. , LEISTRA M. , VERLAAT J.G.
Published: July 2006

Two bio‐assay methods for determining the amount of propyzamide in soil were evaluated and compared with analysis by gas‐liquid chromatography. The root length assay with flax (Linum usitatissiimum L.) as well as the more time‐consuming shoot assay with canary grass (Phalaris canariensis L.) were sufficiently accurate when carried out under favourable growing conditions. However, gas‐liquid chromatography wilh electron‐capture detection was more sensitive to low concentrations of propyzamide and also to moderate concentrations when the soil organic matter content was high

As the organic matter content of the soil increases, propyzamide becomes less available to plants. The rate of decline does not seem to be influenced by Ihe type of soil.

A few months after autumn treatment the rate of disappearance of propyzamide was fairly high in the field, even at low temperatures. The rates of decline under summer conditions were in Ihe expected range.

When selecting the next crop, it should he taken into account that propyzamide residues may be present in the soil for several months after application.
Effect of intervals between application and tillage on glyphosate control of Cyperus rotundus L.*
Authors: CHASE RICHARD L. , APPLEBY ARNOLD P.
Published: July 2006

Research conducted in El Salvador, Central America, demonstrated that an interval of 3 days between application of glyphosate and tillage was sufficient to cause 90% reduction in purple nutsedge (Cyperus rotundus L.) plants, while delays of 11–23 days generally gave slightly less reduction. à second application to the same plots 35 days following tillage resulted in more than 90% reduction with all intervals. Approximately 3 months after the initial treatment, tuber numbers had been reduced to half the original population. Germination of the remaining tubers was reduced by more than 50%.

Glyphosate applied during the dry season caused an average of 79% reduction in plant numbers compared with 88% in the rainy season. However, in the dry season, the remaining plants had no competition from other weeds and after 5 months there was only à 40% reduction in nutsedge population. During the rainy season, 1, 2 and 3 kg/ha were equally effective, but 1 kg/ha was not sufficient in the dry season.
Effects of humidity and moisture stress on glyphosate control of Cyperus rotundus L.*
Authors: CHASE RICHARD L. , APPLEBY ARNOD P.
Published: July 2006

Glyphosate at 2 kg/ha was more effective in reducing regrowth of purple nutsedge (Cyperus rotundus L.) scapes at 90% than at 50% relative humidity (r.h.), and more effective at −2 bars than at −11 bars of plant water potential. Regrowth of treated plants subjected to water potentials of −1 to −8 bars was reduced 54–60% while at −11 bars growth inhibition was only 34%. A time interval of as little as 8 h between application and excision was sufficient to give 47% reduction in regrowth at 90% r.h. None of the treated plants, except those clipped immediately after application, produced new shoots from the basal bulb, while all the untreated control plants produced one or more new shoots. Experiments using 14C‐glyphosate substantiated these results. Three times more 14C‐label was translocated into the underground parts of nutsedge at 90% than at 50% r.h. Twice as much translocated at −2 bars than at −11 bars of water potential.
Über die Beeinflussung der Keimfähigkeit der Samen mancher Grundlandpflanzen beim Durchgang durch den Verdauungstrakt des Schafes und nach Mistgärung
Authors: ÖZER ZEKI
Published: July 2006

Bei den mit 10‐monatigen Schafböcken durchgeführten Versuchen wurden folgende Ergebnisse erhalten:

Die Ausscheidungsrate (Versuehsdauer 96 Stunden nach Verfutterung) der Samen von lOverfutterten Weidepflanzenarten betrug bei Medicago sativa 55,5%, Phteum pratense 53,4%, Coronitta varia 42,8%, Lotus cornicutatus 34,8%, Agrostis alba 32,9%, Trifotium repens 24,5%, Stipaviriduta 16,6%, Vicia sativa 9,3%, Hordeum nodosum 1,4%, Onobrychis sativa 0,8%.

Ausscheidungszeiten: Ohne bestimmte zeitliche Regelmäßigkeiten wurden die Samen von Hordeum nodosum im Verlauf der 96‐stündigen Versuehsdauer ausgeschieden. Bei Medicago sativa wurde ein Ausscheidungsmaximum bei 62 Stunden, bei Phteum pratense bei 86 Stunden festgestellt. Bei den anderen 7 Samenarten lag das Ausscheidungsmaximum zwischen 38–48 Stunden.

Wahrend bei 8 Samenarten eine Verminderung der Keimfähigkeit nach Passieren des Verdauungstrakts im Vergleich zu frischen Samen festgestellt wurde, konnte man eine Erhöhung des Keimwertes bei Agrostis atba und Hordeum nodosum feststellen.

Keimfahig waren die Samen von Vicia sativa bis zu einer Ausscheidungszeit von 38 Stunden, Onobrychis sativa bis 48 Stunden. Samen von Hordeum nodosum waren keimfahig bis zu einer Ausscheidungszeit von 62–96 Stunden, Trifotium repens 24–86 Stunden. Bei den restlichen 6 Arten waren die Samen auch nach 96‐stündiger Verweildauer im Verdauungstrakt zumindest noch teilweise keimfähig.

Nach 3‐monatiger Mistgärung waren die Samen von Vicia sativa, Hordeum nodosum und Onobrychis sativa vollig vernichtet. Bei den restlichen 7 Samenarten betrug die Keimpotenz bei Coronitta varia 6,8%, Lotus cornicutatus 6,1%, Trifotium repens 5,1%, Phteum pratense 4,9%, Medicago sativa 4,6%, Agrostis alba 3,2% und Stipa viridula 1,1%.
Interactions between barban and benzoylprop etbyl, flamprop metbyl or flamprop isopropyl applied at two growtb stages for wild oat control in cereals
Authors: O'SULLIVAN P. A. , BORN W. H. VANDEN
Published: July 2006

Barban was combined with benzoylprop ethyl, flamprop methyl, or flamprop isopropyl, and the eflects of the combinations on wild oat control and crop yield were assessed, tn greenhouse experiments, the interaction in all three combinations was synergistic, following application at the 2‐ or 4‐leaf stage of wild oats. Under field conditions, combinations of barban + benzoylprop ethyl applied at the 2‐ or 4‐leaf stage of wild oats were as eflective for wild oat control and wheat yield response as barban at 028 kg/ha applied at the 2‐leaf or benzoylprop ethyl at 14 kg/ha applied at the 4‐leaf stage of wild oats. Mixtures of barban + flamprop methyl applied at the 2‐ or 4‐leaf stage of wild oats provided excellent wild oat control and wheat yield increases. Mixtures of barban + flamprop isopropyl applied at the 2‐ or 4‐leaf stage of wild oats provided comparable wild oat control and barley yield increases to barban (028 kg/ha) applied at the 2‐leaf or flamprop isopropyl (14 kg/ha) applied at the 4‐leaf stage of wild oats.
The biology of Johnson grass (Sorghum halepense)
Authors: MONAGHAN N.
Published: July 2006

The literature on various aspects of the biology of Johnson grass. Sorghum halepense (L.) Pers. is reviewed. Topics discussed include its distribution, cytology, taxonomy, life cycle, variability and the dormancy and germination of its seeds and rhizomes.
Temperature effects on Eleusine indica and Setana anceps grown in association (I)
Authors: HAWTON D.
Published: July 2006

Studies were made at Kairi on the Atherton Tableland of Queensland, Australia, on the effects of varying lemperature regimes, both controlled and natural, on the germination of seed of Setaria antcept Stapf. cv. Nandi and Eleusine indica (L.) Gaertn. The germination of E. indica seed was found to be much more temperature labile than that of S. ancepts. The temperature required for peak germination was higher for E. indica seed than for S. ancepts seed.

The effects of temperature on competition between E. indica and S. ancepts were studied in the field by varying the time of planting. It was shown that at mean screen temperatures measured throughout the growth period of <23° C, S. ancepts was dominant in mixtures of the two species. At mean temperatures >23° C E. indica was dominant. There was a tendancy for S. aweps yields to decline with increase in E. indica plant density but there was a much closer negative correlation between E indica top dry weight and S. aancepts yield.

From the meteorological data for Kairi for the past 25 years predictions were made on the best times to plant S. ancepts to avoid serious competition from E indica.
Weed control with pre‐sowing herbicides in irrigated cotton (Gossypium barbadense L.) and groundnut (Arachis hypogaea L.) in the Sudan. II. Economic, labour requirement, crop safety and operational aspects of trifluralin and benfluralin
Authors: JENNINGS E. A. , DRENNAN D.S.H.
Published: July 2006

Soil incorporated. pre‐sowing application of trifiuralin in cotton or of benfluralin in gruundnut, each at 1–68 kg a.i., ha, cut labour requirement for handweeding to levels where the tenant could he largely independent of hired labour, Economic returns from a combination of these herbicides plus supportive hand‐ weeding for herbicide‐resistant species compared favourably with those from hand‐ weeding only as presently recommended.

Application and incorporation of trifluralin and benfluralin fited well into existing practices for seedbed preparation and any likely modifications of these. There was no evidence of crop phytoxicity and crop maturity was not affected. Residue analysis indicated no soil residue problems for crops in rotations and no residues were detected in crop seed. Trifluralin applied many months in advance of cotton planting in the dry season, did not start to disappear until the soils were wetted just before couon planting.
The effect of plant‐induced changes of pH upon the adsorption and phytotoxicity of s‐triazlne herbicides
Authors: HARRIS G.R. , HURLE K.
Published: July 2006

The effect of plant‐induced changes of soluiion pH upon the adsorpiion of s‐lriazme herbicides in either K‐monimorillonite or Na ‐ bentonite ciay‐nutrieni suspensions and iheir phyioioxi‐ city in soil was studied. ln clay‐NO3− suspensions (wiih NO3‐ as the nitrogen source) maize planls (Zea may L.) caused a marked rise in solution pH and this resulted in a rapid descrp‐ tion of bound atrazine or simazine. in clay‐NHa + suspensions (with NH4 + as the nitrogen source) the lowering of solution pH through plant aclivity resulted in jnereased adsorption of these herbicides.

In soil, changes of rhizosphere pH were also found when either KNO3 or (NH4) 2SO4 were supplied as fertilizers, bul it was nol established whether ihis had a direct effeci upon the significant increase in weight of (NH4)2SO4 treated wheat (Tri‐ ticum aestivum L.) planls at low herbicide concentrations compared with KNO3 treated wheat plants.
Studies of Salvia reflexa Hornem.: II. Examination of specialized leaf surface structures
Authors: LOVETT J. V. , SPEAK M. D.
Published: July 2006

Scanning electron microscope examination ofadaxial leaf surfaces of Salria reflexa revealed specialized structures from which chemical release was apparently promoted by immersion in water. The significance of ihese slruciures and their contents is discussed in relation to the alletopathic activiiy of this species.
A possible mechanism for the selective herbicidal activity of iodide in relation to thiocyanate content
Authors: STEPHEN N. H. , COOK G. T. , DUNCAN H. J.
Published: July 2006

In an in vivo study, the rate of iodide oxidation by horseradish peroxidase was found to be reduced by the addition of ammonium thiocyanate to the system. The seleetive herbicidal activity of sodium iodide towards dwarf bean, pea, kale and cabbage was tested while the poicnlial ihioeyanale conteni of these platits was measured, A good relationship between inereasmg thiocyanale content and inereasing resistance to iodide was observed.
Differential growth and response to atrazine between and within susceptible and resistant biotypes of Chenopodium album L.
Authors: MARRIAGE P. B. , WARWICK S. I
Published: July 2006

Differential growth and response to atrazine were examined in greenhouse experiment with three populations of Chenopodium album from southwestern Ontario: two known susceptible (SI. SII) and one resistant (R). Germination of the resistant biotype was less than SII but the same as SI. R seedlings were not as mature at 16 days and weighed less at 23 days than seedlings of SI and SII. Within SI. early‐(ESI) and late‐flowering (LSI) variants were recognized. Older plants of R (37 and 44 days) had a greater growth rate than two of the susceptible populations (LSI and SII). In terms of vegetalive, floral, and total biomass. mature individuals of ESI were less productive than the other populations, but devoted a greater percentage of dry weight to floral production.

Young plants (37 days old) were sprayed with atrazine at 00125, 0.25, 0.5, 1.25, 2.5 and 5 kg/ha. Population ESI was most sensitive to at razine; height and weight of stems and production of new leaves showed decreases at 0.25 and 0.125 kg/ha. respectively, compared to the untreated. Populations LSI and SII showed greater tolerance and decreases in these characters occurred at a higher rate of atrazine. Leaf weight per plant decreased at 0.25 kg/ha as a result of decreases in weight per unit area of leaf for all susceptible population. Growth of R as measured by the above criteria was not affected by atrazine treatments but leaf weight per unit area was slightly reduced at 2.5 and 5.0 kg/ha Single leaves of 48 day old plants were infused with at razine concentrations of 0.5, 2.0, 3.0 and 20.0 ppm. Leaf chlorosis increased with concentration and injury was greater in populations LSI and SII than in ESI. A small amount of chlorosis occurred in R.
Interaction between benzoylprop ethyl, flamprop methyl or flamprop isopropyl and herbicides used for broadleaved weed control
Authors: O'SULLIVAN P. A. , VANDEN W. H.
Published: July 2006

A marked antagonism of A. fatua control was found when 2,4‐D, dicamba, 2,4‐D‐dicamba‐mecoprop or bromoxynil were added to benzoylprop ethyl, flamprop methyl or flamprop isopropyl. Because of the much poorer control of A. fatua by these mixtures obtaining broad spectrum weed control with them in one spray operation would not be possible. The A. fatua herbicides did not affect the activity of the added herbicides on Fagopyrum lataricum. In eight out of nine mixtures tested there was no significant antagonism in the field conditions when MCPA or bromoxynil‐MCPA was added to the A. fatua herbicides. There were significant antagonistic effects, however, in six out of nine such mixtures in glasshouse experiments. This suggests that under farm use conditions benzoylprop ethyl, flamprop methyl or fiamprop isopropyl can be mixed with MCPA amine or ester or with bromoxynil‐MCPA to obtain broad spectrum weed control from one spray operation, though slightly poorer A. fatua control may be expected with these mixtures.
Studies on the weed hosts of the rice root nematode, Hirschmanniella spinicaudata Sch. Stek. 1944
Authors: BABATOLA J. O.
Published: July 2006

Weed hosts of the rice root nematode, Hirschmanniella spinicaudata were surveyed in a swamp rice field at Badeggi, Nigeria. Forty‐five weed species, mainly grasses and sedges occurred very frequently and were very good hosts of the nematode. A wild rice, Oryza longistaminata was a preferred host. The importance of the weed hosts is discussed.
Free amino acids of Abutilon theophrasti seed
Authors: ELMORE C. D.
Published: July 2006

The free amino acids of Abutilon theophrasti (velvetleaf) seed were identified and quantified. The content of several amino acids known to inhibit germination of crop seeds was high. No unusual amino acids or other known toxic amino compounds were detected so it is presumed that the natural amino acids present are responsible for the allelopathic effects.
Quantitative estimation of Alectra and Striga seed in soil
Authors: VISSER J.H. , WENTZEL L.F.
Published: July 2006

A physical method is established for determining the population in the soil of viable seeds of the parasitic genera Alectra and Striga. Microscopic observation enables seeds of the two genera to be distinguished but it was not always possible to distinguish species within each genus. Correlation of the seed count with number of plants of these parasites was examined and factors lending to obscure correlation discussed.
Field experiments to investigate long‐term effects of repeated applications of MCPA, tri‐allate, simazine and linuron: II. Crop performance and residues 1969–78
Authors: FRYER J. D. , SMITH P. D. , HANCE R. J.
Published: July 2006

In four field experiments begun in 1963, each of four herbicides was applied to plots planted wilh the same crop each year. The annual treatments were: MCPA at 17 kg/ha to barley (Hordeum sativa Jess) and wheat (Triticum aestivum L.) at growth stage 15. tri‐allate at 17 kg/ha pre‐emergcnce to barley and wheat, simazine at l7kg/ha pre‐emergence to maize (Zea mays L.) and linuron in two applications of 084 kg/ha pre‐ and post‐emergence to carrots (Daucus carota L.).

MCPA did not affect growth or yield of either barley or wheat. In general tri‐allate also did not aftect the crops although wheat yield was depressed in 1978, wheat 1000 grain weight was reduced in 1972 and barley germination percentage was increased in 1973. Simazine did not influence the height, yield or appearance of maize. Linuron normally produced no effect on carrot yield, density and size. However, in 2 years when the post‐emergence application was late, density but not yield was lower than in control plots. There was no accumulation of residues of any of these compounds in the soil. Rates of loss were similar to those predicted on ihe basis of laboratory experiments.

In a fifth experiment these herbicides were applied twice per year (3 times in the case of linuron) at double the rales above on each occasion to bare plots. These applications ceased in 1968 (1969 for MCPA) but residues were monitored until 1972 except in the case of MCPA. Disappearance rates were similar to those in the cropped plots and residues were largely confined to the top 10 cm. The plots treated with MCPA had developed an enhanced ability lo degrade il prior to 1968. This persisted for 5 years after the final application.
Interference of herbicides with photochemical activities of chloroplasts in six shrub species
Authors: RAO I. MADHUSUDANA , SWAMY P. M. , DAS V. S. R.
Published: July 2006

The effects of paraquat and 2,4,5‐T on the photochemical activities of chloroplasts from the leaves of the woody species Carissa spinarum, Maba buxifolia, Flacourtia sepiaria, Chomelia asiatica, Gymnosporia emarginata and Dodonaea viscosa were investigated by comparing the effects on isolated chloroplasts from untreated leaves with those on chloroplasts isolated from herbicide‐sprayed plants. DCPIP and NADP reduction of chloroplasts incubated in paraquat or 2,4,5‐T solution was inhibited, whereas that of chloroplasts isolated from most species sprayed with these herbicides was enhanced after 24 and 48 h. The enhancement was smaller or disappeared after 72 h. The cyclic and noncyclic photophosphorylation rates were suppressed in chloroplasts isolated from herbicide‐treated plants, and also in those from most untreated plants incubated in the herbicide solutions. The differences in reactions of chloroplasts from herbicide‐treated and untreated plants are discussed.
Foliar absorption and translocation of fosamine and 2,4,5‐T in blackberry (Rubus proceras P. J. Muell.)
Authors: RICHARDSON R.G.
Published: July 2006

Fosamine (ammonium ethyl carbamoylphosphonate) formulated as a 1% w/v solution in 0–25%v/v Tween 20 was absorbed slowly by detached leaves of Rubus procerus P.J. Muell., 35% of the applied herbicide being absorbed after 96 h. Fosamine does not appear to be rainfast, as up to 80% of the applied herbicide and 99.9% of the removable herbicide were removed from the leaves by washing for 5 min in distilled water. Translocalion of fosamine was rapid in small R. procerus plants and followed a pattern similar to that taken by assimilates: 2,4,5–T did not translocate to the root system as readily as fosamine or assimilates.
The preferential accumulation of picloram at sites of active growth in gorse (Ulex europaeus L.)
Authors: FIELD ROGER J. , HAI PHUNG HONG
Published: July 2006

Application of 14C‐picloram to single spines of 6 month old, soil grown, vegetative plants of gorse (Ulex europaeus L.) resulted in its translocation to regions of meristematic and metabolic activity, with significant accumulation in the stem apex and root nodules. Dissection of the root system of plants grown in nutrient solution revealed a greater mass of picloram in differentiated root tissue than in root apices, although the concentration of chemical in the latter fraction was greater than in the former. Loss of picloram to the nutrient solution was interpreted as preferential leakage from the root nodules because of the lack of picloram accumulation in this fraction. In reproductive plants bearing flowers and floral buds the picloram was diverted from the root tissue fractions to the floral organs, which constituted the primary sink.
Absorption, translocation and metabolism of 14C‐glyphosate in several weed species*
Authors: SANDBERG C. L. , MEGGITT W. F. , PENNER DONALD
Published: July 2006

The pattern and extent of 14C‐glyphosate [N‐(phosphonomethyl)glycine] translocation from the treated leaf and metabolism of 14C‐glyphosate were studied in field bindweed (Convolvulus arvensis L.), hedge bindweed (Convolvulus sepium L.). Canada thistle [Cirsium arvense (L.) Scop.] tall morning glory [lpomoea purpurea (L.) Roth.] and wild buckwheat (Polygonum convolvulus L.). 14C was translocated throughout the plants within 3 days with accumulation in the meristematic tips of the roots and shoots evident. Cross and longitudinal sections of stems and roots showed that the 14C was localized in the phloem. Field bindweed translocated 3–5% of the applied 14C from the treated leaf, hedge bindweed 21.6%, Canada thistle 7.8%, tall morningglory 6.5%, and wild buckwheat 5%. Field bindweed, Canada thistle, and tall morningglory metabolized the parent glyphosate to aminomethylphosphonic acid to a limited extent. This metabolite made up less than 15% of the total 14C. Of the total 14C applied to excised leaves, 50% had disappeared within 25 days.
Studies on the longevity and germination of seed of Eleusine indica and Crotalaria goreensis
Authors: HAWTON D. , DRENNAN D. S. H.
Published: July 2006

The longevity of seed of Eleusine indica (L.) Gaertn. and Crotalaria goreensis Guill. & Perr. stored at various depths in a krasnozem soil in pots was studied over 3 years under natural climatic conditions on the Atherton Tableland of Queensland. Australia. In the first year the maximum percentage of seed which emerged was 68% for E. indica and 48.3% for C. goreensis. In the second year the percentages were 2.0 and 19.3. respectively and in the third year they were 0.2 and 1.4. In the case of both species emergence was greater from the 0–5 cm depth than from the 5–10 cm depth. Some of the seed buried at the 5–10 cm depth germinated but failed to emerge. Significantly more hard seed of C. goreensis remained at the 5–10 cm depth (25.7%) than at the 0–5 cm depth (9.8%) after 3 years. However, much of this seed was either dead or moribund and the percentage of truly viable seed (c. 5%) was the same at both depths.

In depth of emergence experiments the emergence of seed of both species did not vary significantly in the 0–4 cm depth ranges. At depths greater than 4 cm emergence declined. No E. indica seed emerged from 8 cm or deeper and no C. goreensis seed emerged from 12 cm or deeper.
Effect of herbicides alachlor, metolachlor and oryzalin on soybean (Glycine max) leaf nitrate reductase activity*
Authors: LOLAS P. C.
Published: July 2006

Experiments were conducted in the field, greenhouse, and with leaf disks in test tubes to determine whether the herbicides alachlor, metolachlor, and oryzalin, commonly used for weed control in soybeans [Glycine max (L) Mer.] affect in vivo nitrate reductase activity. Plants in the field, growing in soil treated at the recommended rates were sampled at 30 and 60 days after planting. Plants grown in the greenhouse in pots non‐treated and treated at the recommended area rates and at 1/2 and 3/2 times these rates were sampled at 20 and 40 days for chemical assay. In addition plants were grown in the greenhouse and sampled at 30 days for chemical assay after direct addition of the herbicide dilutions to the reagent solutions. No differences, statistically significant according to Duncan's test at the 5% level were revealed between controls and any treatment.
Einfluß des Applikationsortes auf die Penetration und Translokation von Diclofop‐methyl bei Flughafer (Avena fatua L.)
Authors: WALTER H. , KOCH W. , MÜLLER F.
Published: July 2006

Bei Flughafer wurde der Emfluß verschiedener Applikationsorte zwischen Spitze und Basis des Sprosses auf die Penetration und Translokation von 14C‐Diclofop‐methyl untersucht. Die Penetration liegt an der Basis der Blattspreitc am 1. Blatt um 64% und am 2. Blatt um 95% höher als an der Spitze des jeweiligen Blattes. Die Translokation von 14C‐Diclofop‐mcthyl in basipeitaler Richtung ist begrenzt. Daher ist die Menge an 14C‐Diclofop‐methyl an der Sproßbasis, dem Hauptwirkort, um so höher, je näher das Herbizid zur Sproßhasis appliziert wird. Hinsichtlich einer möglichst optimalen Verteilung von 14C‐Didofop‐methyl in der Pflanze erwies sich die Applikation an die Basis del Blattsprciten als am günstigsten. Dies beruht u.a. darauf daß es bei diesem Applikationsort zu einem Einlaufen der Herbizidlösung in die Blattscheidc und infolgedessen zu einem mechanischen basipetalen Vordringen innerhalb dieser in den Bereich der mcristematischen Gewehe der Sproßbasis kommt. Als Konsequenz daraus ergibt sich die Forderung nach einer möglichst gezielten Deponierung von Diclofop‐methyl in den Bereich der Sproßbasis.
Availability to plants of herbicide residues in soil. Part I: A rapid method for estimating potentially available residues of herbicides
Authors: STALDER LUKAS , PESTEMER WILFRIED
Published: July 2006

A simple extraction method with water is described which allows the quantitative determination, within 1 day of the residues of soil‐applied herbicides which are potentially available to plants. The validity of this method has been examined with a growth test using Brassica rapa in soils containing residues of different ages.
Characteristics of glyphosate inhibition of growth in soybean and tobacco callus cultures
Authors: LEE T. T.
Published: July 2006

Callus cultures or tobacco (Nicotiana tabacum L. cv. While Gold and N. glauca‐langsdorffii, a tumour‐forming amphidiploid hybrid) and soybean Glycine max L., cv. Chippewa) were used lo study the effect of glyphosate [N‐(phosphonnmethyl) glycine) un growth and interactions with growth hormones. Glyphosate inhibited growth both in the dark and light but showed a greater toxicity in the dark. This was contrary to its effect on chlorophyll degradation which was accelerated by light. The inhibition of growth was not reversed by simultaneous addition of aromatic amino acids to the medium. Thus the results suggest a multiple glyphosate action. The tobacco callus tissue was more sensitive to glyphosate than the soybean callus tissue, confirming a difference in tolerance between plant species. Despite the inhibitory effect of glyphosate. the treated tissue revived after being transferred to a glyphosate‐free medium. The glyphosate‐induced growth inhibition in soybean and tumour‐forming tobacco callus cultures also was reversible by high levels of indole‐3‐acetic acid (IAA), which itself was inhibitory Theglyphosate‐IAA interaction in the tissues which were sensitive to IAA suggests that the inhibition of growth by glyphosate was related to auxin levels in these tissues.
Effect of dalapon‐sodium on nitrification and denitrification in a tropical loam soil
Authors: WEERARATNA C. STANLEY
Published: July 2006

Summary: Résumé: Zusammenfassung

A loamy soil treated with dalapon‐sodium was incubated under aerobic or anaerobic conditions with added ammonium or nitrate nitrogen respectively. The incubated dalapon‐sodium treated soil and controls were analysed periodically for NH4+N and NO3‐N. Results indicated that the herbicide retarded nitrification and denitrification by up to 8 and 12 weeks respectively.

Effet du dalapon‐sodium sur la nitrification et la dénitrification dans un sol de limon tropical

Un sol de limon traité avec du dalapon‐sodium a été mis en incubation dans des conditions aérobies ou anaérobies avec addition d'azote ammoniacal ou nitrique respectivement. Le sol traité avec du dalapon‐sodium et mis en incubation a été analysé périodiquement, ainsi que les témoins, pour NH4+N et NO3‐N. Les résultats ont montré que l'herbicide retardait la nitrification et la dénitrification respectivement jusqu’à 8 et 12 semaines.

Wirkung von Dalapon‐Na auf Nitrifikation und Denitrifikation in einem tropischen Lehmboden

Einem mit Dalapon‐Na behandelten Lehmboden wurde Ammon‐ bzw. Nitratstickstoff zugesetzt und unter aeroben bzw. anaeroben Bedingungen gelagert. Der mit Dalapon‐Na behandelte Boden und die entsprechenden Kontrollen wurden periodisch auf NH4+‐ und NO3‐‐Stickstoff untersucht. Die Ergebnisse zeigten, dass das Herbizid die Nitrifikation um bis zu 8 und die Denitrifikation bis zu 12 Wochcn verzögerte.
Yield loss in barley associated with Sinapis arvensis L. (charlock) after continuous routine use of herbicide
Authors: RICHARDSON M. J.
Published: July 2006

Summary: Résumé: Zusammenfassung

Uncontrolled S. arvensis (charlock) in barley, after many years successful control with herbicides, was associated with yield losses of 48‐71%, mostly due to smaller ear populations. Curtailing herbicide use by spraying in alternate years only might not be a suitable strategy for reduction in herbicide usage where charlock is a dominant weed.

Pertes de rendement dans les cultures d'orge, provoqueés par Sinapis arvensis L. aprés l'utilisation routinière et continue d'herbicides

La non destruction de Sinapis arvensis dans l'orge, après de nombreuses années de lutte efficace avec des herbicides, a provoqué des pertes de rendement de 48 à 71%, dues principalement à des populations plus faibles d'épis. La réduction de I'utilisation d'herbicide, par des traitements alternés d'une année à l'autre, ne semble pas constituer une stratégie adéquate pour diminuer l'emploi des herbicides, là où la moutarde est une mauvaise herbe dominante.

Ertragsverluste in Gerste durch Sinapis arvensis L.(Acker‐Sent) nach ständigem Routineeinsatz von Herbiziden

Wurde S. arvensis in Gerste, nachdem es über viele Jahre erfolgreich mit Herbiziden bekämpft worden war, nicht bekämpft, dann war das mit Ertragsverlusten von 48–71% verbunden. Der Ertragsrückgang war hauptsächlich auf eine geringere Ährenrahl zurückzuführen. Eine Beschränkung des Herbizideinsatzes in Form von Spritzungen nur in jedem zweiten Jahr, durfte deshalb auf Standorten, wo der Acker‐Senf als dominierendes Unkraut vorkommt, keine òrauchbare Alternative zur Einsparung von Spritzungen sein.
The influence of reduced cultivations and direct drilling on the long‐term decline of a population of Avena fatua L. in spring barley
Authors: WILSON B. J.
Published: July 2006

Changes in the numbers of Avena fatua seed, incorporated into soil, were monitored in four successive spring barley crops which were harvested early for silage to prevent seed shedding.

In the first year there were four times as many seedlings after tine cultivation compared with ploughing, but this was reversed in the second year as re‐ploughing brought up dormant seeds and gave more seedlings than tine cultivation. Only 11–14% of the sown seeds produced seedlings during the 4 years. When the seeds were first buried to 25 cm by ploughing, and the barley was direct drilled without cultivation, only 0.4% emerged as seedlings.

Few viable seeds remained in the soil after 4 years whether the soil was cultivated annually or not but seed numbers decreased more rapidly with tine cultivation than with ploughing. A few of the deeply buried seeds persisted where the land was direct drilled without cultivation.
Control of Solatium karsensis in grain sorghum
Authors: MONAGHAN N.M. , BROWNLEE H.
Published: July 2006

Solatium karsensis Symon, an Australian native perennial, has become an important weed in irrigated summer crops in far western New South Wales. A screening trial of 14 herbicides showed that atrazine was the most effective treatment, though 2,4‐D also suppressed S. karsensis in grain sorghum (Sorghum bicolor L. cv. Rico) for the duration of the crop. Grain sorghum yields were higher in plots treated with atrazine at 2–5 kg (a.i.) ha−1 than for any other herbicide treatment or the untreated control. Because the root system remained viable annual herbicide application would be necessary for the continued control of 5. karsensis.
Effects of glyphosate on synthesis and degradation of chlorophyll in soybean and tobacco cells
Authors: LEE T. T.
Published: July 2006

The chlorophyll content increased with time in callus cultures of soybean (Glycine max L., cv. Chippewa) and tobacco (Nicotiana tabacum L., cv. White Gold) grown in the light on a standard medium. Addition of 0.5 mmol/1 glyphosate [N‐(phosphonomethyl) glycine] to the medium completely inhibited chlorophyll accumulation in the tobacco callus. Soybean callus required 40 times more glyphosate to initiate inhibitory effects on chlorophyll content. The inhibition was not reversed by simultaneous addition of casein hydrolysate or aromatic amino acids, suggesting that aromatic amino acid levels were not limiting for chlorophyll synthesis. In leaf discs of soybean and tobacco, glyphosate accelerated chlorophyll degradation in the light, but not in the dark; there was little difference in response between the two plant species. Young leaves of tobacco were more sensitive than mature leaves to glyphosate effects with glyphosate‐induced net losses of chlorophyll of 24 and 14% respectively after 5 days. Such rates of loss cannot explain the complete inhibition of chlorophyll accumulation in the callus tissue, suggesting that there was an inhibition of chlorophyll synthesis by glyphosate.
The influence of tillage on the weed flora in a succession of winter cereal crops on a sandy loam soil
Authors: And F. POLLARD , CUSSANS G.W.
Published: July 2006

Weed populations on sandy loam soil were monitored from 1973 to 1976 in a 5‐year experiment comparing different tillage regimes for continuous winter cereal cropping. Tillage treatments were mouldboard ploughing, shallow or deep tine cultivation and direct drilling. The best available chemical weed control which could be universally applied to all treatments was used.

There were marked differences between weed species in their response to tillage. Poa annua L., Matricaria spp., Aphanes arvensis L., Cerastium holosteoides Fr. and Sambucus nigra L. were favoured by reduced cultivation and by direct drilling. Polygonum aviculare L. and Fumaria officinalis L. were discouraged by shallow soil disturbance but Avena fatua L. was favoured by tine cultivation. The remaining twenty‐four species either showed no consistent response to tillage or were present in numbers too low for reliable conclusions to be drawn. The practical implications of the results are discussed.
The comparative behaviour of simazine and terbacil in soils
Authors: JENSEN K. I. N. , KIMBALL E. R.
Published: July 2006

Adsorption of simazine (2‐chloro‐4,6‐bisethyl‐amino‐1,3,5‐triazine) was 2.2–4 times greater than that of terbacil (5‐chloro‐6‐methyl‐3‐t‐butyl‐uracil) in the same soils and adsorption of both herbicides was 2–4 times greater in the topsoils than subsoils. Adsorption was inversely correlated with herbicide movement in a thick‐layer chromatography system. One year after application of 3 kg/ha to field plots, simazine residues were highest near the soil surface, whereas terbacil residues increased with soil depth in the sandy and sandy loam soils. Total residues recovered from the upper 25 cm of soils was 5% or less of the simazine originally applied, and 10% or less of the applied terbacil. In an oat seedling bio‐assay, the GR50 values were generally 1.5–3 times higher for simazine than for terbacil in the same soils.
Effect of salt stress on the structure and carbon flow mechanism in a noxious weed Parthenium hysterophorus L.
Authors: HEGDE B. A. , PATIL T. M.
Published: July 2006

Effect of salt stress on structural changes, ion uptake, rate of photosynthesis and path of carbon in the exotic weed Parthenium hysterophorus have been investigated. Photosynthetic leaf area, chlorophyll and carbon assimilation rates were adversely affected by salt stress. Increased Na+ uptake caused decrease in K+ and Ca2+ absorption. Originally a C3 plant, P. hysterophorus appears to form aspartate as a primary product of photosynthesis when exposed to NaCl. The stimulation of PEP carboxylase activity also occurred due to salt stress. Excessive accumulation of malate during steady state of photosynthesis was possibly due to inhibition of malic enzyme. It appears that although the plant switches over to an ‘aspartate producer’ when exposed to salt, further utilization of photosynthetically assimilated carbon is through malate. Being a weed, the plant appears to be highly adaptive to stress conditions.
Die Verunkrautung neuangelegter mediterraner Weidetypen im Gebiet Mogod/Tunesien
Authors: ZITZEWITZ W. V.
Published: July 2006

Im humiden Nordwesten Tunesiens wurden mit Hilfe von pflanzensoziologischen und bodenkundlichen Untersuchungen unter Einbeziehung von bereits vorliegenden Bewirtschaftungsdaten die Ursachen der Verunkrautung auf neuangelegtem Grünland untersucht. Die Jahr‐zu‐Jahr‐Schwan‐kung der Verunkrautung ist sehr verschieden. Hingegen verandert sich der Jahresgang der Verunkrautung kaum von Jahr zu Jahr.

Die Ursachen fur die Verunkrautung der Klee‐Gras‐Weiden, die auf den sandigen Boden deutlich starker ist, als auf den schweren Boden, ergeben sich aus der Unzuläanglichkeit des Standorts, insbesondere aber aus einer Vielzahl von Bewirtschaftungsfehlern. Gefördert wurde die Verunkrautung u.a. durch: (1) Die ungünstige Niederschlagsverteilung in den Jahren 1970/71, 1972/73 und 1973/74; (2) Weideverfahren mit holier Besatzdichte, kurzer Freβzeit und langerer Ruhezeit; (3) Achtlose Weideführung auf winterlich übernäβten Boden; (4) Unkrautbekämpfungsmaβnahmen mit ungeeigneten Herbiziden; (5) Verschiedene Schädlinge und Krankheiten, die bevorzugt den Klee befallen.

Die Verunkrautung der mehrjährigen Mäh‐weiden mit Festuca arundinacea ist nicht sehr ausgeprägt und nimmt, bedingt durch den jährlichen Schnitt im Frühjahr, über die Jahre merklich ab. Nach dem Schnitt stellt sich kurzzeitig eine sehr spezifische Verunkrautung mit ausdauernden Pflanzen ein. Es werden Vorschläge zur Einschrankung der Verunkrautung durch Haltung von Vieh auf Standweide gemacht.
Control of problem weeds of maize on the Transvaal Highveld (South Africa). III. Crotalaria sphaerocarpa Perr. ex. DC.
Authors: ALAN C. M , VISSER J. H. , GROBBELAAR N.
Published: July 2006

Sixteen different herbicides and herbicide mixtures were evaluated for their efficiency in controlling Crotalaria sphaerocarpa Perr. ex. DC. using percentage mortality and relative plant dry mass as criteria of herbicide efficiency. Paraquat and a mixture of atrazine and Tronic were the only treatments which effectively controlled the weed at all ten leaf stages tested. Atrazine alone and ametryne alone were 100% effective only for the first four leaf stages. Other treatments were relatively ineffective.

The wax coat on the leaves of C. sphaerocarpa possibly impedes the absorption of lethal quantities of some herbicides, resulting in an apparent resistance. This phenomenon, probably accounts for the fact that this plant is considered to be a problem weed.
Factors affecting the activity of GR7 in stimulating germination of Striga hermonthica (Del.) Benth.
Authors: BABIKER A. G. T. , HAMDOUN A. M.
Published: July 2006

Experiments with the alkaline heavy clays of the Sudan Gezira showed that when the strigol analogue GR7 was applied to moist soil prior to subjecting Striga hermonthica seeds to moist conditions (‘conditioning’) for 7–14 days, there was no significant increase in germination. Conditioning of seeds in soils treated with GR7 had an adverse effect on the responsiveness of seeds when GR7 was added again after conditioning. Under ideal conditions, when GR7 was applied to conditioned seeds in moist soil, up to 75% germination could be induced by 2.0 kg/ha incorporated to 2–3 cm depth. Residual activity of GR7 persisted in air‐dry soil, but at 50% moisture there was complete loss within 1 day. However, when conditioned seeds were put into the soil immediately after GR7 application its activity increased with increasing soil moisture.
Chemical weed control in irrigated direct‐seeded rice in the Sudan Gezira
Authors: BABIKER A. G. T.
Published: July 2006

Unrestricted weed growth resulted in serious yield losses (60–75%) in rice (Oryza saliva L.). Hand‐weeding once at 2 weeks after crop emergence was ineffective, but weeding at 2 and 2 weeks after crop emergence brought yield losses down to 20%. Pre‐emergence application of bifenox and oxadiazon (12 l) and post‐emergence application of molinate + propanil gave crop yields comparable to that of the clean weeded control (91–129%). Grain yields obtained with pre‐emergence application of oxadiazon (25 EC) and post‐emergence applications of propanil, bentazone + propanil, and bifenox alone or as a tank mix with propanil or bentazone were considerably less than those obtained from the clean weeded plots. Bifenox, oxadiazon (12 l) and propanil + molinate gave adequate and persistent weed control (72–97%), and did not damage rice. Oxadiazon (25 EC) gave good weed control but resulted in a serious stand reduction. Post‐emergence application of propanil, propanil + bentazone bifenox alone or as a tank mix with propanil or bentazone had no adverse effect on crop stand, but gave poor control of grasses (0–40%).
The influence of tillage on the weed flora in a succession of winter wheat crops on a clay loam soil and a silt loam soil
Authors: POLLARD F. , MOSS S.R. , CUSSANS G.W. , FROUD‐WILLIAMS R.J.
Published: July 2006

Weed populations were monitored for 4 years on two experiments designed to compare the effect of different primary tillage treatments on winter wheat (Triticum aestivum L.) cropping. Ploughing was compared with deep and shallow tine cultivation and with no tillage on both a clay loam and a silt loam over chalk. Soil‐acting residual herbicides were used to control weeds, especially Alopecurus myosuroides Huds. and Avena fatua L.

Dicotyledonous weeds were uncommon on the clay loam but on the silt loam, in a year when no residual herbicide was used, they were most numerous where the soil was disturbed most. In other years there was little difference in the number emerging. Six species were reduced in number by reduced cultivation or no tillage, whilst four species, including two grasses, were increased.

At both sites, A. myosuroides was more numerous on direct drilled and tine cultivated plots than on ploughed. Herbicides gave good control on the silt loam but failed to control the weed on the clay loam. On the clay loam, A. fatua was most numerous on tine cultivated plots and a combination of herbicides and roguing produced a decline in the population.
Comportement de substances analogues du propyzamide dans la plante en fonction de leur structure chimique
Authors: ASPE D. , BASTIDE J.
Published: July 2006

L'absorption, la métabolisation et la migration dans la plante d'orge d'analogues du propyzamide sont étudiées. Sur une plantule développée, l'absorption est parallèle à la pénétration d'eau. alors que pendant la germination, l'absorption est proportionnelle au paramètre hydrophobique π.

Il n'y a pas de différence de migration entre chacun des produits, par contre il y a une différence de métabolisation et le taux de métabolisation est directement lié au paramètre électronique π. Cependant ces variations ne reflètent pas les différences observées sur l'activité biologique globale qui est reliée au paramètre hydrophobique π et au facteur stérique Es.
The uptake of soil‐applied chlorotriazines by seedlings and its prediction
Authors: ROBINSON R. C. , DUNHAM R. J.
Published: July 2006

14C‐labelled atrazine or terbuthylazine was applied to the surface of soil columns 100 mm deep and the uptake by oat seedlings measured for up to 24 days after germination following two contrasting rainfall treatments. Attempts were made to predict measured uptake on the basis of mass flow theory given also measurements of transpiration rates, water, rooting and herbicide distribution profiles in the soil, and soil adsorption characteristics. Predictions over a tenfold range of uptake were close enough to suggest that the assumptions made to predict mass flow uptake were essentially correct. Discrepancies appeared to result principally from (i) shoot‐zone uptake, and (ii) incorrect prediction of long‐term herbicide adsorption in undisturbed soil. Greater attention to the effect of herbicide on transpiration rates and to the patterns of water uptake by roots should improve the accuracy of such predictions. The various factors that influence the mass flow uptake of chlorotriazines in the soil surface by seedlings are discussed as a basis for modelling herbicide uptake.
Etude du polymorphisme des prolamines chez une population d'Avena fatua L.
Authors: DARMENCY H.
Published: July 2006

l'étude par l'électrophorèse du polymorphisme des prolamines (protéines alcoolo‐solubles du grain) a permis de mettre en évidence des modifications de la structure phénotypique d'une population d'Avena fatua L. au cours de trois années successives. Des corrélations avec les facteurs climatiques et culturaux ont été faites, ce qui a conduit l'auteur à proposer des hypothèses sur les mecanismes d'évolution. Ainsi, le caractère de floraison tardive et de vernalisation est étroitement corréléà l'un des quatre phenotypes principaux de la population, et un autre phénotype présente une sensibilité accrue à certains herbicides des céréales. Ces phénomènes entraineraient le maintien d'un polymorphisme non négligeable. L'analyse des prolamines permet donc de reconnaître des plantes qui ont des comportements écologiques différents, et de prévoir l'évolution des populations d'A. fatua vers des types plus ou moins nuisibles.
The contact activity of difenzoquat in two United Kingdom spring wheat cultivars
Authors: PALLETT K. E.
Published: July 2006

The contact action of difenzoquat was investigated on seedlings of spring wheat (Triticum aestivum L.) cultivars tolerant (Maris Butler) and susceptible (Sicco) to the translocated etTect of the herbicide on the apical meristem. Applied as a spray the chemical caused an increase in electrolyte leakage before the development of visible damage. Chlorophyll levels were also reduced and both effects were greater on Maris Butler than Sicco.

Droplets of difenzoquat caused similar ultrastructural effects on the two cultivars. These included swelling of the chloroplasts with subsequent disorganization of the thylakoid system accompanied by disruption of other cellular components. Similar effects have been reported with paraquat and it is suggested that the contact action of difenzoquat is due to a weak paraquat type activity.