bluuebunny/crossref_metadata_2025_split huggingface dataset:
Response of weeds to the method of fertilizer application on low‐fertility acid soils in Suriname
Authors: EVERAARTS A. P. 
Published: July 2006

Summary: Résumé: ZusammenfassungThe effect of broadcast or band‐placed application of fertilizer on the growth of weeds was studied at two locations on low‐fertility acid soils in Suriname. Band placement of fertilizers considerably reduced weed growth compared to fertilizer‐applied broadcast. With band‐placed fertilizer the increased weed growth due to fertilizer application was concentrated on the fertilized bands. Weed growth was also stimulated in planter wheel‐tracks. The spatial distribution of the weed growth is discussed in relation to the crops groundnut, sorghum and soybean, grown at the same location. Réponse des adventices au mode d'application des engrais sur des sols acides de faible fertilité au Surinam L'effet d'application d'engrais sur le rang ou en plein sur la croissance des mauvaises herbes a étéétudiée en deux lieux du Surinam sur sols acides pauvres. Le traitement sur le rang des engrais a considérablement réduit la croissance des adventices comparéà l'application en plein. Avec l'application de l'engrais en ligne l'augmentation de croissance due à la fertilisation était concentrée sur les bandes fertilisées. La croissance des adventices étaient également stimulée dans les traces de roues de tracteurs. La distribution spatiale de la croissance des adventices est discutée en relations avec la distribution spatiale de la croissance des adventices trouvé chez le sorgho, le soja, l'arachide cultivés dans les mêmes lieux. Wirkung der Düngungsmethode auf die Verunkrautung ertragarmer, saurer Böden in Surinam An 2 Ortem mit ertragarmen, sauren Böden in Surinam wurde die Wirkung der Düngungs‐methode auf das Wachstum von Unkräutern untersucht. Banddüngung reduzierte das Unkrautwachstum im Vergleich zur breitwürfigen Düngung erheblich. Ein gefördertes Unkrautwachstum zeigte sich nur auf dem Döngungsband und auch auf den Fahrspuren. Die unterschiedliche Verunkrautung in Erdnuß, Sorghum und Sojabohne wird diskutiert.
Effects of herbicide mixtures and additives on Rhododendron ponticum
Authors: LAWRIE J. , CLAY V. 
Published: July 2006

Summary: Résumé: ZusammenfassungThe possibility of increasing the activity of glyphosate, imazapyr, sulfonylurea herbicides and triclopyr against Rhododendron ponticum L. was investigated using container‐grown plants. Glyphosate, imazapyr and triclopyr alone and metsulfuron‐methyl with added surfactant were all phytotoxic, imazapyr and triclopyr being the most effective at the doses used. Thifensulfuron‐methyl and tribenuron‐methyl with ‘Mixture B’ were ineffective. The surfactants ‘Mixture B’ and ‘Silwet L77’ consistently increased the activity of imazapyr and metsulfuron‐methyl. Mixtures of the herbicides did not lead to synergistic activity, and mixing imazapyr and triclopyr depressed the activity of each component. There was some enhancement of activity on R. ponticum when imazapyr and metsulfuron‐methyl were applied sequentially, 48 h apart. Effets de mélanges d'herbicides et d'adjuvants au Rhododendron ponticumLa possibilité d'accroître l'activité du glyphosate, de l'imazapyr, des sulfonylurées et du triclopyr contre Rhododendron ponticum a étéétudiée en utilisant des plantes cultivées en containers. Le glyphosate, l'imazapyr et le triclopyr seuls et le metsulfuron‐methyl additionné d'un surfactant ont tous été phytotoxiques: l'imazapyr et le triclopyr étant les plus efficaces aux doses utilisées. Le thifensulfuron‐méthyl et le tribenuron‐methyl avec ‘Mixture B’ ont été inefficaces. Les surfactants ‘Mixture B’ et‘Silwet L 77’ ont considérablement augmenté l'activité de l'imazapyr et metsulfuron‐methyl. Les mélanges des herbicides n'a pas abouti à une activité synergistique et les mélanges avec l'imazapyr et le triclopyr ont diminué l'activité de chaque composé. Il y a eu un certain renforcement de l'activité sur R. ponticum quand l'imazapyr et le métsulfuron‐méthyl étaient appliqués de façon séquentielle, à 48 heures d'intervalle. Wirkung von Herbizidmischungen und Additiven auf Rhododendron ponticumAn Container‐Pflanzen von Rhododendron ponticum L. wurden versucht, die Wirksamkeit von Glyphosat, Imazapyr und Sulfonylharn‐stoff‐Herbiziden zu verstärken. Glyphosat, Imazapyr und Triclopyr allein und Metsulfuron‐methyl nach Zugabe von Netzmitteln waren phytotoxisch, besonders Imazapyr und Triclopyr. Thifensulfuronmethyl und Tribenuron‐methyl waren mit dem Netzmittel ‘Mixture B’ wirkungslos. Die Netzmittel ‘Mixture B’ und ‘Silwet L77’ erhöhten die Wirksamkeit von Imazapyr und Metsulfuron‐methyl durchweg. Mischungen der Herbizide ließen keinen Synergismus erkennen, und die Mischung von Imazapyr mit Triclopyr verringerte die Wirksamkeit der Einzelkomponenten. Die Wirkung auf R. ponticum ließ sich erhöhen, wenn Imazapyr und Metsulfuron‐methyl 48 h nacheinander angewandt wurden.
Soil moisture relations and critical period of Cynodon dactylon (L.) Pers. (coastal bermudagrass) competition in conservation‐tillage cotton (Gossypium hirsutum L.)
Authors: VENCILL W. K. , GIRAUDO L. J. , LANGDALE G. W. 
Published: July 2006

Summary: Résumé: ZusammenfassungField experiments were established at the Southern Piedmont Research facility near Watkinsville, GA during 1989 and 1990 to assess the critical period of interspecific interference between different Cynodon dactylon (coastal bermudagrass) densities and cotton (Gossypium hirsutum) in a conservation‐tillage system. Cotton was exposed to coastal bermudagrass for 0, 4, 7, 10 and 25 weeks. Cotton height, yield, and soil volumetric water content were examined. Volumetric water content was determined by time domain reflectometry. Cotton height and yields were significantly reduced by exposure to coastal bermudagrass and reduction in cotton productivity increased with increasing coastal bermudagrass density. Soil volumetric water content decreased in the upper 30 cm of soil with increasing coastal bermudagrass density. The critical period of coastal bermudagrass in cotton was determined to be 4 to 7 weeks after planting. Relations entre l'humidite su sol et la periode critique de competition de Cynodon dactylon (L.) dans du coton en systeme de labour (Gossypium hirsutum L.)Des essais de plein champ ont été mis en place sur le centre de recherche du Sud‐Piémont près Watkinsville, GA pendant 1989 et 1990 pour évaluer la période critique d'interférence interspécifique entre différentes densités de Cynodon dactylon et de coton (Gossypium hirsutum) dans un système de labour. Le coton a été exposé au cynodon pendant 0, 4, 7, 19 et 25 semaines. La hauteur du coton, le rendement et la teneur en haut du sol ont été examinés. Le volume d'eau du sol a été déterminée par reflectométrie. La hauteur du coton, et les rendements ont été réduits significativement par l'exposition au cynodon et la réduction de productivité du coton a augmenté avec l'augmentation de la densité du cynodon. Le volume d'eau du sol dans les 30 premiers centimètres a diminué avec l'augmentation de la densité du cynodon. La période critique du cynodon pour le coton a été déterminée comme se situant 4 à 7 semaines après la plantation. Konkurrenz von Cynodon dactylon (L.) Pers. mit Baumwolle (Gossypium hirsutum L.) bei konservierender Bodenbearbeitung — Kritische Periode und Bezug zur BodenfeuchteZur Ermittlung der kritischen Periode der Konkurrenz von Cynodon dactylon (L.) Pers. mit Baumwolle (Gossypium hirsutum L.) bei konservierender Bodenbearbeitung wurde die Kultur in Feldversuchen 1989 und 1990 auf der Piedmont‐Versuchsstation für 0, 4, 7, 10 und 25 Wochen mit dem Unkraut in unterschiedlicher Dichte wachsen gelassen. Höhe und Ertrag der Baumwoll‐Pflanzen wurden durch die Verunkrautung signifikant reduziert, und mit steigender Unkrautdichte nahm die Produktivität genauso wie die Bodenfeuchte in den obersten 30 cm ab. Die kritische Periode der Konkurrenz zwischen dem Unkraut und der Kulturpflanze lag zwischen der 4. und der 7. Woche.
Rapid seed extraction from soils by a flotation method
Authors: TSUYUZAKI S. 
Published: July 2006

Summary: Résumé: ZusammenfassungIn this study a flotation method is described which enables the rapid extraction of seeds from soil. Essentially, soil is mixed with 11.0 M K2CO3 and thoroughly dispersed by mechanical stirring for 3–6 min. The dispersed soil samples were delivered to plastic tubes, then centrifuged at more than 4000 g for about 5 min. Buried seeds and lighter organic materials floated in the supernatant and could be removed by filtration, washed and subsequently identified. This method performed reliably using soil samples artificially loaded with white clover and a range of cultivated grass species. In addition, a wide range of weed seeds which differed in size and density were also effectively recovered from a range of soil types from loam to gravel. Extraction rapide de graines à partir du sol par une méthode de flotation Cet article décrit une méthode de flotation qui permet l'extraction rapide de graines à partir du sol. Pour l'essentiel, le sol est mélangé avec du K2CO3 11,0 M et complètement dispersé par agitation mécanique pendant 3 à 6 min. Les échantillons de sol dispersé sont placés dans des tubes en matière plastique et contrifugés à plus d 4000Xg pendant environ 5 min. Les graines enfouies et le matériel organique plus léger flottent dans le surnageant, sont récupérées par filtration, lavées et identifiées. Cette méthode s'est révélée fiable avec des échantillons de sol portant artificiellement de fortes densités de trèfle blanc et une série de graminées cultivées. De plus, de nombreuses graines de mauvaises herbes qui différaient par leur taille et leur densité ont été efficacement récupérées de plusieurs types de sol (limons à graviers). Schnellmethode zur Bestimmung des Samengehalts im Boden durch Abschwemmen Es wird eine Methode beschrieben, mit der Samen aus Boden schnell ausgelesen werden konnen. Bazu wird dem Boden 11,0 M K2CO3 zugesetzt und der Boden 3 bis 6 Min. lang grundlich gemischt. Danach wird das Bodenmaterial in Plastikzylindern bei mehr als 4.000 g 5 Min. lang zentrifugiert. Die im Boden enthaltenen Samen und organisches Material sammeln sich im Uberstand und konnen durch Filtration abgetrennt und nach dem Waschen identifiziert werden. In einem Modellversuch, bei dem Samen von Weiß‐Klee und einer Reihe Graser dem Boden beigemischt worden waren, erwieß sich diese Methode als zuverlassig. Auch andere Samen unterschiedlicher Große und Dichte wurden in verschiedenen Bodenarten von Lehm bis grobem Sand vollstandig wieder aufgefunden.
Using phenology prediction in weed management: a review
Authors: GHERSA C. M. , HOLT J. S. 
Published: July 2006

SummaryThe success of weed management based on ecological principles and weed biology will depend on a better understanding of the effect of environment on lift history strategies, growth, and competition of weeds; and crops, and particularly upon the ability to predict weed and crop phenology, This paper reviews the importance of phenotypic plasticity to weed and crop competition and other biological interactions. We also discuss the utility of phenological predictions in weed management and review current weed phenology models that are based on thermal time. By understanding the variables that drive plant phenotypic responses, new approaches and more long‐term solutions for weed problems can be developed.
Seed dynamics in populations of A vena sterilis ssp. ludoviciana
Authors: DEL ARCO M. J. SANCHEZ , TORNER C. , QUINTANILLA C. FERNANDEZ 
Published: July 2006

SummarySeed populations of Avena sterilis ssp. ludoviciana (Durieu) Nyman were monitored in a naturally occurring infestation throughout its life cycle. Considering the large weed population present (298panicles m−2), total seed production was relatively low: 3838 seeds m−2. Only 68% of these seeds were recovered from the soil surface and a further 3% were removed with wheat grain and straw during harvest operations. The numbers of seeds from the stubble between mid‐July and mid‐September were relatively low (10%). Ploughing the stubble in October buried most of the recently produced seed rain and resulted in a relatively uniform vertical distribution of the seedbank. Maximum seed persistence in the soil ranged from 27 to 43 months (depending on the experimental technique used to do the study). Seed decline followed an exponential pattern on a yearly basis, with the greatest decline taking place between October and April (57–90% in year 1 and 10–40% in year 2), Between May and September the buried seed populations remained practically constant. Seedbank depletion was primarily due to seedling production (25%) and ‘lethal’ germination (24%). Although the depth of burial had very little effect on seed survival, the mode of seed disappearance was closely related to their depth in the soil. Seed depletion through ‘lethal’ germination increased with increasing depth in the soil, whereas depletion through seedling emergence decreased with increasing depth.
The effect of pre‐germination chilling on subsequent growth and flowering in three arable weeds
Authors: FENNER M. 
Published: July 2006

SummaryThis experiment investigated the effect of pre‐germination moist chilling of seeds (for 3 weeks at 2^C) of 10 common arable weeds on the subsequent growth and flowering of the plants. In only three of the species (Alopecurus myosuroides Huds., Veronica persica Poir. and Trifolium dubium Sibth.) was flowering markedly increased by the seed chilling treatments. At 3 months, the mean number of flowers and seed heads per plant on the treated plants was greater than that on the controls by factors of 13.9, 2.02 and 1.74 respectively. Shoot lengths of the seed‐chilled plants were also significantly greater in all three species, though dry weights did not differ significantly from those of the controls. Thus, the plants showed morphological changes associated with reproduction but no significant alteration in total dry weight. The ecological implications of the data are discussed in relation to possible effects of climatic change on species which require seed vernalization.
The allelopathic effect of three Amaranthus spp. (pigweeds) on wheat (Triticum durum)
Authors: QASEM J. R. 
Published: July 2006

SummaryThe allelopathic effect of Amaranthus retroflexus L., Amaranthus blitoides S. Wats, and Amaranthus gracilis Desf. on wheat Triticum durum L. was investigated under laboratory, glasshouse and field conditions. Laboratory experiments showed that fresh shoot or root extract of the three weed species reduced germination, coleoptile length, root length and root dry weight of wheat seedlings. The inhibitory effects were rate dependent, with low concentrations of shoot extract promoting shoot growth of wheat. Fresh plant extracts were more phytotoxic than dried plant extracts and shoot extracts had higher detrimental effects than root extracts. In pot experiments, dried shoot extract of A. gracilis increased shoot and root dry weights of wheat seedlings. For A retroflexus and A. blitoides the extracts of these and dried shoots (8 g kg−1), which had been added to soil mixtures significantly reduced ger‐mination and growth of wheat seedlings. Addition of up to 16 g kg−1 of A. gracilis residues promoted shoot growth of wheat and had no significant harmful effect on root growth. Roots appeared more sensitive to allelopathic effect than shoots. Under field conditions, incorporation of A. retroflexus or A. blitoides residues in the soil reduced height, grain and straw yield of wheat, whereas A. gracilis residues stimulated plant height and increased yield.
Interaction between timings and doses of quindorac in rice
Authors: STREET J. E. , TERESIAK HOLGER , BOYKIN D. L. , ALLEN R. L. 
Published: July 2006

SummaryQuinclorac (3,7‐dichloro‐8‐quinolinecarboxylic acid) is a new herbicide in United States rice production. Field studies were conducted in 1990 and 1991 in Mississippi to determine the influence of application timings and rates on weed control efficacy and rice yield. Control of Echinochloa crus‐galli (L.) Beauv. (barnyard‐grass), Sesbania exaltata (Raf.) Rydb. ex A. W. Hill (hemp sesbania) and Ipomoea wrightii Gray (palmleaf morning glory) were greatest with early post‐emergence application. Efficacy of pre‐emergence application depends strongly on soil moisture, with significantly reduced weed control resulting when applied to dry soil. Weed control with pre‐emergence application to moist soil was comparable with early post‐emergence application at higher rates of quinclorac. Pre‐plant and incorporated quinclorac controlled weeds effectively. Control of E. crus‐galli, S. exaltata and I. wrightii ranged from 73 to 99%, 75 to 99%, and 92 to 99% at 28 days after treatment, respectively. Rice yield generally reflected weed control. No rice injury was observed for any treatment. Results indicate that early post‐emergence application of quinclorac is the best time for using reduced rates and field conditions at application should be considered with these rates pre‐emergence.
Degradation of primisulfuron‐methyl and metsulfuron‐methyl in soil
Authors: JAMES T.K. , KLAFFENBACH P. , HOLLAND P.T. , RAHMAN A. 
Published: July 2006

SummaryA newly developed chemical assay was used to determine the degradation in soil of two sulfonylurea herbicides, primisulfuron‐methyl and metsulfuron‐methyl, under both controlled and field conditions. The results from the chemical assay were compared with those from traditional bio‐assays for determination of persistence in the field. Phytotoxic effects of these herbicides were not observed after 6 weeks following application to an acidic (pH 5.7) soil with high organic matter content (7.3% o.c). Half‐lives of 13 to 29 days were measured for primisulfuron‐methyl at different soil‐water contents and temperatures while those for metsulfuron‐methyl ranged from 8 to 36 days. The rate of degradation of metsulfuron‐methyl was more sensitive to temperature than that of primisulfuron‐methyl. Persistence in the field was shorter than expected considering the results from the controlled environment studies. However, determination of the persistence by both chemical assay and bioassay methods produced very similar results.
Physiological mechanisms for the rapid growth of Pennisetum clandestinum in Mediterranean climates
Authors: WILEN C. A. , HOLT* J. S. 
Published: July 2006

Summary Pennisetum clandestinum Hochst ex Chiov. (kikuyugrass) is a C4 grass that has become an invasive weed in temperate climates. We examined ecophysiological mechanisms that have allowed it to become a successful weed in these locations by comparing P. clandestinum and two other common turigrass species, Festuca arundinacea Schreb. (tall fescue cv. Mojave), a C3 cool‐season grass, and Stenotaphrum secundatum (Walt.) Kuntze (St. Augustinegrass), a C4 warm‐season grass, grown in a warm or cool growth regime. We measured rates of photosynthesis over a range of leaf temperatures and also measured growth rate parameters of these species. At leaf temperatures between 25^C and 40^C P. clandestinum maintained the highest rates of photosynthesis in both temperature regimes. Under warm temperatures, this species rapidly increased biomass and leaf area to a greater extent than either of the other two grasses. Theoretical whole plant photosynthesis (mean leaf area × mean photosynthetic rate) was higher for P. clandestinum than for the other two species in both growth regimes and over most leaf temperatures. Our results suggest that P. clandestinum is a successful weed in Mediterranean climates as a result of its capacity to photosynthesize over the full range of temperatures found in those climates, its rapid growth during warm weather and its apparent tolerance to moderately cool temperatures.
Surfactant and salt affect glyphosate retention and absorption
Authors: NALEWAJA J. D. , DEVILLIERS B. , MATYSIAK R. 
Published: July 2006

SummaryThe influence of nonylphenoxy surfactants and glyphosate salt formulation on spray retention, phytotoxicity and [14C]glyphosate uptake was investigated in wheat (Triticum aestivum L). and Kochia scoparia L. The amount of spray retained, and uptake of [14C]glyphosate increased with increasing hydrophilic‐lipophilic balance (HLB) value of surfactants. The volume of spray delivered to the plant treatment area and retained by wheat and K. scoparia plants increased with increasing surfactant HLB values, but this only partly accounted for the higher spray retention. Spray retention by leaves of plants was not affected by calcium chloride, either alone or with ammonium sulphate in the glyphosate spray solution. [14C]Glyphosate absorption by wheat and K. scoparia was reduced by calcium chloride alone, but not in mixtures with ammonium sulphate, regardless of surfactant. Phytotoxicity and uptake of glyphosate salt formulations for wheat was: isopropylamine > ammonium > sodium > calcium; these results indicate that the surfactant selected is important to maintain glyphosate efficacy and that sodium and calcium cations antagonize glyphosate by forming salts that are absorbed less than commercial isopropylamine formulations.
Resistance to paraquat in Hordeum glaucum is temperature dependent and not associated with enhanced apoplasmic binding
Authors: LASAT M. M. , DITOMASO J. M. , HART J. J. , KOCHIAN L. V. 
Published: July 2006

SummaryResponse to paraquat was investigated in two Hordeum glaucum Steud. (wall barley) biotypes grown at warm (30^C) and cool (15^C) temperatures. Paraquat‐resistant (R) plants were nearly seven‐fold more tolerant when grown at 15^C than when grown at 3CPC. In contrast, there was a tendency for susceptible (S) plants to be more tolerant when grown at the higher temperature. The difference in response between the two biotypes grown at 30^ and 15^C increased from 3‐ to >40‐fold. Forty‐eight hours after foliar application, 62% less radiolabelled paraquat had translocated basipetally in the R compared with the S biotype. In addition, 26% more herbicide was retained within the treated zone of R compared with S plants. Thus, paraquat movement was restricted in the R biotype. It has been postulated that reduced mobility of the herbicide in the R plants is due to enhanced apoplasmic binding. In this study, paraquat binding to the cell walls and its release into the external solution was investigated in roots of R and S biotypes of H. glaucum grown under warm or cool conditions. No significant differences between the two biotypes were measured at either growth temperature. We propose that the mechanism of resistance to paraquat may involve a temperature‐dependent alteration in symplasmic transport of the herbicide.
Weeds in the traditional slash/mulch practice of frijol tapado: indigenous characterization and ecological implications
Authors: KETTLER J. S. 
Published: July 2006

SummaryWeeds in the secondary vegetation of the fallow in slash/mulch or shifting cultivation systems have been identified as important components of the system. Weeds found in the traditional slash/mulch or frijol tapado bean (Phaseolus vulgaris L.) production system in southern Costa Rica were identified and given preliminary rankings based on fanner surveys. The variance of these rankings was used as a measure of farmer uncertainty. Weed rankings were further characterized by key informant interviews. This study also investigated the ecological implications of the vegetative dynamics in the system. Biomass estimates of individual weed species, nutrient dynamics and crop yield response are considered in conjunction with the farmers' rankings of weeds. A negative correlation was found between weed rankings and bean yield, and between weed rankings and C:N ratios.