bluuebunny/crossref_metadata_2025_split huggingface dataset:
An emerging system management approach for biological weed control in crops: Senecio vulgaris as a research model
Authors: And H. MÜLLER‐SCHÄRER , FRANTZEN J. 
Published: July 2006

SummaryA ‘system management’ approach of biological weed control in crops is proposed and compared with other method's of biological weed control. It is based on the management of a weed pathosystem in order to maximize the natural spread and disease severity of a native or naturalized pathogen. This approach may be well‐suited to situations where it is necessary to control single weed species in crops, and where no immediate and complete control is required, the production of large amounts of the agent is rather limiting (e.g. when using biotrophic fungi), and/or the importation of an exotic agent is not possible. This strategy provides fundamental knowledge of underlying mechanisms of crop production systems and is aligned with the view of modern agro‐ecology, in which complete eradication of weeds is not desirable. The fundamental research required for a successful application of the ‘system management’ approach will be illustrated with the biological control project of Senecio vulgaris L. using the naturalized rust fungus Puccinia lagenophorae Cooke. A five‐step procedure, together with selected results, will be presented. Main emphasis is given to the infection window, the study of the genetic structure of the plant and pathogen population, and the management of the infection conditions (a) to maximize the spread of the disease and the impact on the plants, and (b) to minimize the development of resistant plant populations. Joint application of herbicides at low doses, additional necrotrophic pathogens, and of biochemicals interfering with the weed's defence also will be envisaged, as well as their integration into general pest control practices. In this regard, biological weed control agents have to be seen as stress factors, not as weedkillers, and biological weed control as an integral part of a well‐designed pest management strategy, not as a sole cure.
Movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil in soil
Authors: MILANOVA S. , GRIGOROV P. 
Published: July 2006

SummaryThe movement and persistence of imazaquin, oxyfluorfen, flurochloridone and terbacil residues were studied using a bioassay based on the shoot growth of Raphanus sativus L. var, radicula DC (radish) in a sandy loam soil under field conditions in 1992 and 1993. Imazaquin (0.3 kg a.i. ha‐1) was more mobile in the soil than the other three compounds. In 1992, under heavy rainfall conditions, the herbicide was distributed down to 60 cm in amounts of about 0.01 mg kg‐1. Conversely, in the dry year of 1993, the maximum depth of penetration was 20 cm and persistence in the surface soil layer (0‐5 cm) was greater. After the first month in 1992, residues of terbacil were distributed in the 0‐20 cm layer, and after 2, 3 and 5 months the herbicide had penetrated to a depth of 40 cm. In 1993, terbacil residues were distributed in the 0‐10 cm layer only. In both years, residues of flurochloridone (1.0 kg a.i. ha‐1) were located mainly in the 0‐5 cm layer, but there was some penetration to 10 cm. Oxy‐fluorfen (1.2 kg a.i, ha‐1) showed least mobility in the soil profile. It was retained in the 0‐5 cm layer throughout the experimental period in both. years.
Evaluation of three pesticide leaching models with experimental data for alachlor, atrazine and metribuzin
Authors: WALKER A. , WELCH S. J. , MELACINI A. , MOON Y.‐H. 
Published: July 2006

SummaryThe persistence and movement of residues of alachlor, alrazine and metribuzin were measured in a mini‐lysimeter system in the field. This comprised a number of soil columns (11 cm diametert; 30 cm long), and permitted the vertical distribution of residues to be determined at. intervals alter application and the collection and analysis of leaehale water. Laboratory experiments were also performed to determine the degradation rates of the three herbicides and their strengths of adsorption by the test soil. The results showed an order of degradation rate of metribuzin> alachlor>atrazine and an order of adsorption of alacblor>atrazine>melribuzin. Movement of residues in the soil columns and concentrations in the leachate were inversely related to the strength of adsorption. Parameters derived from the laboratory data were used in conjunction with weather data for the period of the field experiment in three mathematical models of pesticide leaching: VARLEACH, LEACHP and PRZM2. In most instances, the models gave acceptable predictions of the distribution of residues in soil. This was particularly so for the less mobile compound alachlor. With the most mobile compound, metribuzin, residues were not well predicted at the later sampling dates. All three models gave accurate predictions of the volumes of drainage water, but none of them predicted the concentrations of herbicide in the leachate, presumably because they do not take account of preferential flow pathways of water and solute in the soil.
Influence of water stress on absorption, translocation and phytotoxicity of fenoxaprop‐ethyl and imazamethabenz‐methyl in Avena fatua
Authors: XIE H. S. , HSIAO A. I. , QUlCK W. A. , HUME J. A. 
Published: July 2006

SummaryThe influence of water stress on the absorption and translocation of 14C‐labelled fenoxapropethyl and imazamthabenz‐methyl in Avena fatua L. (wild oat) was studied. The phytoioxicity to A. fatua of both herbicides with a droplet application was also examined under water stress conditions. The absorption of both fenoxaproethyl and imazamethabenz‐methyl was reduced by waler stress when the plants were harvested within 24 h after herbicide application. Up to 48 h after the application, the translocation out of the treated lamina of both herbicides, based on percentage of applied 14C. was reduced under water stress conditions. When havested 96 h after herbicide application, however, water stress no longer significantly affeaed the absorption and translocation of either herbicide. When the herbicides were applied as individual droplets, water stress reduced the phytotoxicity of fenoxaprop‐ethyl but not that of imazamethabenz‐methyl. It is concluded that the changes in herbieide absorption and translocation may not be the major physiological processes associated with differential whole‐plant response oi A faiua to fenoxaprop‐ethyl and imazamefhabenz‐methyl under water stress.
Effects of depth of seed burial and soil aggregate size on seedling emergence of Alopecurus myosuroides, Galium aparine, Stellaria media and wheat
Authors: CUSSANS G.W. , RAUDONIUS S. , BRAIN P. , CUMBERWORTH S. 
Published: July 2006

SummarySeedling emergence of Alopecurus myosuroides Huds., Stellaria media L. (Vill.), Galium aparine L. and wheat (Triticum aestivum L.) was compared at a range of depths of soil cover from 2 to 11 cm. The covering soil was a fertile agricultural soil with 60% clay content which had been sieved into four aggregate sizes. The aggregate sizes used were 26‐50 mm. 14‐25 mm. 6‐13 mm and below 6 mm. Total emergence of all species was reduced with increased depth of sou cover. With A. myosuroides and S. media, total emergence was lowest in fine soil conditions. Alopecurus myosuroides showed a marked interaction whereby response to depth of sowing was least with fine tilth. The time to 50% emergence showed a similar response. With all four species, seedling emergence was slowest at greater depths of sowing and with the finest tilth, the differences tending to increase with increasing depth of sowing. A vert high proportion of the time to 50% emergence was accounted for by the lag time between sowing and the first recorded emergence.
Competition between winter wheat and Veronica hederifolia: influence of weed density and the amount and timing of nitrogen application
Authors: ANGONIN C. , CAUSSANEL J.‐P. , MEYNARD J.‐M. 
Published: July 2006

SummaryThe effects at Veronica hederifolia. densities on the yield of winter wheat (Triticum aestivum L.) were studied in field trials conducted at the same location in 1992 and 1993. In 1992, nitrogen at 60 kg ha‐1 was applied at tillening followed by a further 80 kg ha‐1 at the first node of stem elongation. In 1993. four regimes of nitrogen applications were compared: a total of 140 kg ha‐1 supplied at three dales. 60 kg ha‐1 supplied at tillering, 60 kg ha‐1 Supplied al the first node of stem elongation and no nitrogen as the control. Competitive effects from V. hederifolia (ranging from 17 to 192 plants m‐22), were greatest in 1993, the year with the best early growth development of this weed. In 1993, yield losses, as described with a non‐linear model changed for each regime of fertilization. In both years, V. hederifolia decreased wheat ear number per unit area for each nitrogen treatment. This is explained hy an increase in tiller mortality and a nitrogen deficiency in wheat at the stem elongation and flowering stages. Nevertheless, with late application of nitrogen, individual grain weight increased and the effect of V. hederifolia on wheat yield loss was lowest. The results are discussed in relation to the effects on all yield components, and show the importance of choosing the rieht nitrogen fertilization for specific yield targets of wheat production when infested by weeds.
Variation in total phenols and condensed tannins in Eucalyptus: leaf phenology and insect grazing
Authors: MACAULEY BARRY J. , FOX LAUREL R. 
Published: July 2006

AbstractTotal phenols and condensed tannins in leaves of seven species of Eucalyptus ranged from 4–40% and 0–27% respectively of the leaf dry weight. The concentrations of these compounds were variable but usually high in young and older leaves throughout the growing season, and typically increased during winter, but no other trends with season or leafage were apparent. This pattern of seasonal variation in concentrations of total phenols and condensed tannins is different to that studied for other plant species. This difference may be related to repeated production of new leaves by Eucalyptus during the growing season, and the probability that these leaves will be attacked by herbivorous insects.
The effects of temperature and moisture on the inception of diapause in eggs of the Australian plague locust, Chortoicetes terminifera Walker (Orthoptera: Acrididae)
Authors: WARDHAUGH K. G. 
Published: July 2006

Abstract Chortoicetes terminifera lays a mixture of diapause and non‐diapause eggs during the autumn months of March and April. Diapause eggs cease development in late anatrepsis when kept in moist soil at 32.5°C. These conditions favour rapid embryogenesis and hatching in non‐diapause eggs.Significant reductions in the incidence of diapause were obtained when newly‐laid eggs were kept for 40 days at either 15.5°C or 32.5°C in conditions that prevented the uptake of water. In eggs held for a similar period in moist soil at 15.5°C, diapause was virtually eliminated. These eggs did not develop to the stage at which water uptake occurs. It is suggested that the inception of diapause is dependent upon the occurrence of warm, moist conditions at the time of laying and that these requirements are an integral part of the overall inductive process, which also involves the temperature and photoperiod at which the parent insects are reared.A flow‐diagram illustrating the development of diapause eggs in relation to temperature and moisture is discussed in relation to the survival of the species.
The distribution and abundance of species of Danthonia DC on the New England Tablelands (Australia)
Authors: SCOTT A. W. , WHALLEY R. D. B. 
Published: July 2006

AbstractThe distribution and percent frequency of the 13 species and one variety of Danthonia recorded on the New England Tablelands were examined in a survey of 110 predominantly pastoral sites. The relationships between site factors and the presence and percent frequency of the different Danthonia species were subjected to canonical correlation analysis. Individual species were found to have particular sets of environmental factors associated with their distribution and percent frequency; a fact not well recognized in the past.The most common factor associated with the abundance of Danthonia was either a long time since the last cultivation or no cultivation at all. Other factors such as altitude, drainage, soil parent material, soil texture and total soil phosphorus status were also of some importance.The six species most commonly recorded throughout the New England Tablelands were D. racemosa RBr, D. pilosa RBr, D. laevis J. Vickery, D. linkii Kunth., D. richardsonii Cashmore and D. tenuior (Steud.) Conert. Of these the first three are ecologically wide species. The first two can coexist with other naturalized species under grazing while D. laevis tends to disappear with disturbance. D. linkii and D. richardsonii require fairly narrow habitat conditions but these conditions and consequently these species are common. Both species respond positively to disturbance. Danthonia linkii increases with cultivation and D. richardsonii colonizes eroded soil surfaces. Danthonia tenuior has more restricted requirements and is not so frequentThe other seven species and one variety did not occur often enough for detailed study and the occurrence of two of these species, D. carphoides and D. caespitosa must be considered as rare.
Above‐ and below‐ground litter decomposition in an Australian salt marsh
Authors: VAN DER VALK A. G. , ATTIWILL P. M. 
Published: July 2006

Abstract Decomposition of litter and the release of nutrients during decomposition were studied both above‐ and below‐ground in a salt marsh in southern Australia. Above‐ground litter of two species, Sclerostegia arbuscula and Sarcocomia quinqueflora, placed in a salt marsh bordering Westernport Bay, Victoria lost significantly different amounts of weight (61% and 50%, respectively) after 272 days in the field. Below‐ground litter buried at depths of 10, 20 and 30 cm lost only 35‐43% of its initial weight during the same period. Above‐ground litter lost more N than below‐ground litter (ca. 50% versus 30%, respectively), more P (ca. 80% versus 45%), more K (ca. 90% versus 65%), more Ca (ca. 50% versus 10%), and more Mg (ca. 40% versus 25%). Significant differences in the rate at which elements (N, P, Ca, and Mg) were lost occurred at different depths in below‐ground litter. Above‐ground litter of the two species examined also differed in the rates and amount of most elements (N, P, Ca, and Mg) lost.
Mean annual population density of Collembola and Acari in the soil and litter of three indigenous South Australian forests
Authors: HUTSON BARRY R. , VEITCH L. G. 
Published: July 2006

AbstractA quantitative study of the soil and litter fauna of three South Australian low open forests was made for two years. The soil and vegetation of the sites were similar but the mean annual rainfall of the areas differed; 635, 690 and 1050 mm/y, respectively for the ‘dry’, ‘medium’ and ‘wet’ sites. Monthly samples were taken of litter, and the upper 0–4 cm and lower 4–8 cm soil layers, and the method used to estimate the numbers of active animals is also described.Mean annual population densities of Collembola and Acari were greatest at the medium site (9.5 and 48.6 × 103/m2, respectively) and least at the dry site (4.9 and 35.1 × 103/m2, respectively) and values are discussed in relation to site organic carbon content. Over all the sites, between 11–21, 67–75 and 10–15% of the collembolan populations, and 10–13, 66–72 and 16–21% of the acarine populations inhabited the litter layer and upper and lower soil layers respectively. Isotomidae were the most abundant collembolan family in each level at each site, but the overall proportion of Entomobryidae increased from the dry to wet site. Prostigmata were the most abundant acarine order in each level at two sites. Cryptostigmata were dominant in the litter layer of the wet site, and their overall proportion increased from the dry to wet site. Seasonal density changes were similar on all sites with minima in the summer and maxima in the winter months.The results obtained here combined with those from other published investigations indicate a trend of faunal population change over various ecosystems in Australia. Prostigmatid mites and iso‐tomid Collembola dominate at arid sites. As sites become less arid and the amount of soil organic matter increases, the proportion of cryptostigmatid and mesostigmatid mites increases, and other groups of Collembola, particularly Entomobryidae, become more frequent.
Comparison of distance based density estimates for some arid rangeland vegetation
Authors: LAMACRAFT ROBIN R. , FRIEDEL MARGARET H. , CHEWINGS VANESSA H. 
Published: July 2006

AbstractA method was required for determining the effect of management on extensive populations of trees and shrubs in central Australian rangelands. One useful indicator of change in these populations is the density of individuals, and there are several methods available based on distance measurement for density estimation. This study compared those procedures.Samples were drawn by computer from ground maps of actual plant distributions for Acacia aneura, Cassia nemophila and Atalaya hemiglauca and from a map generated at random. These samples were drawn to examine the properties of the nearest neighbour, point centred quarter, conditioned distance and compound T‐square estimates of density. Samples were drawn by two methods: simple random sampling and semisystematic sampling.In general, there was a tendency for all estimators of density to underestimate the true density of naturally occurring populations with the compound T‐square method (Byth 1982) being most robust. The compound T‐square method was least biased but its variance increased for more aggregated spatial distributions. Estimates of density were not altered by the use of semisystematic sampling, when compared to simple random sampling.The spatial distributions examined in this study have not previously been studied as theoretical models. Acacia aneura and Cassia nemophila showed some aggregation of clusters, while the Atalaya hemiglauca showed a more extreme form of clustering due to its root suckering propagation.
A floristic framework of Australian rainforests
Authors: WEBB L. J. , TRACEY J. G. , WILLIAMS W. T. 
Published: July 2006

AbstractIn the first comprehensive floristic classification of Australian rainforests and monsoon forests, fresh insights made possible by the use of floristic as distinct from structural data are outlined. A set of 561 individual communities, on sites ranging from North Queensland westwards to the Kimberley region and southwards to Tasmania, is defined by the presence or absence of 1316 tree species, or 406 genera. The data have been subjected to numerical classification, first with respect to species, then to genera.The species classification first divides into three ‘ecofloristic regions’: A, temperate (microtherm) and subtropical (mesotherm) humid evergreen rainforests; B, tropical (megatherm) humid evergreen grading into highly seasonal raingreen (monsoon) forests; and C, subtropical (mesotherm) moderately seasonal humid/subhumid raingreen forests. The sites are further divided into eight ‘ecofloristic provinces’, for each of which a core area is identified and the ten most common diagnostic tree species listed for selected floristic elements, whose ecological relationships are briefly described.Gradients of quantitative thermal‐moisture indices are added to standard climatic typology to provide a more flexible identification of local climates that characterize community‐types of each province across a wide latitudinal/altitudinal range. Community disjuncts and outliers of a particular province are interpreted as the results of past environmental sifting (in which ecological factors are not entirely determinate), of previously more continuous rainforest vegetation.The genera classification first divides into humid eastern coastal and subhumid western and subcoastal sites, then four thermal types, and finally nine groups of floristic ‘paleo‐provinces’. Where the species and genera classifications are not in substantial agreement, a wide‐ranging generic element across the provinces in northern and northeastern Australia is interpreted in paleogeographic terms.The relict distribution of existing community types, as the result of climatic sifting of ancient floral stocks, is discussed in support of emerging ideas about the autochthony of Australian rainforests, especially those tropical types that are not intrusive.It is argued that the unique ecological relationships of Australian rainforests justify the most conservative uses of the relatively small remaining areas.
Distribution of invertebrates on foliage in forests of south‐eastern Australia
Authors: WOINARSKI J. C. Z. , CULLEN J. M. 
Published: July 2006

AbstractNearly 1500 foliage samples were collected from a total of 156 plant species, distributed at 16 study sites representing a wide range of forests and woodlands in south‐eastern Australia. Samples were collected in all months. Invertebrates present in samples were counted, sorted into 13 categories, and the number present (> 3 mm in length) converted into density estimates. Densities of all invertebrates combined and invertebrate diversity were also calculated.Despite high variability there were some obvious distributional patterns for most categories. Three major dichotomies affected abundance and distribution of invertebrates: these were presence or absence of flowers, whether the plant species was Eucalyptus or other, and if Eucalyptus, whether the plant species was Symphyomyrtus or Monocalyptus. The presence of flowers in foliage samples increased the abundance of most invertebrate taxa. Compared to foliage of non‐Eucalyptus species, Eucalyptus foliage had more lerp‐forming psyllids and miscellaneous larvae, but fewer Arachnida, Coleoptera, Psocoptera, Hemiptera (other), Thysanoptera, Diptera, and total arthropods. Foliage of Symphyomyrtus species had higher densities of most categories (and particularly lerp‐forming psyllids) than that of Monocalyptus.There were seasonal variations in abundance in most invertebrate taxa, but these patterns were different for Eucalyptus and non‐Eucalyptus species. For most sites abundance of all arthropods combined was lowest in winter, but this decline was not especially pronounced, and was reversed at more xeric sites.For most categories there were significant differences between study sites in abundance and for some this was related to position of sites on a moisture gradient. In general total arthropod densities were highest at intermediate and xeric sites. There were some significant differences in arthropod communities for the same plant species at different study sites.Sample height, plant height, and the ratio of these were relatively unimportant variables. Likewise, the ratio of leaf width: leaf length was not significantly correlated with abundance for any invertebrate category across 128 plant species, but mean leaf size was negatively correlated with densities of Arachnida and total invertebrates. The distributions of some invertebrate categories were inter‐correlated.