1,721,132 research outputs found
Herbicide use in sugar beets - weed infestations, costs and control efficiency infield experiments of the Landwirtschaftskammer Hannover from 1990-1999
No full textField experiments of the Landwirtschaftskammer Hannover on chemical weed control in sugar beets of 10 years (1990-1999) were comprehended and analysed. Information on the level of the weed infestation and the species composition were collected for each treatment, as well as the weed control applied in the treatments. The analyses focuses the species Galium aparine and Viola arvensis. A method was derived to ex-ante and species specific compare control strategies. Costs of herbicides and applications were calculated for all treatments. Chemical weed control in sugar beets is characterised by several applications of various mixtures of active ingredients. If herbicides were applied more often, higher costs for herbicides appeared. The relation between original and residual weed infestation (after finishing all control) was significant for the two weed species, but no relation to the costs of control appeared. It was not possible to derive conditions for higher cost of control connected with higher original weed infestations of the two species. For G. aparine it can be stated based on the presented data, that more than 5.5 % relative cover of G. aparine in the original weed infestation resulted in significantly higher residual weed infestations
Development and control of weeds in arable farming systems
No full textIt is investigated, whether the arable weed vegetation can perform as a characteristic to stimulate sustainable development of agriculture in Central Europe. The concept of sustainable development represents a dynamic process, influenced by ecological, economic and social aspects. Characteristics are required to integrate desired ecological aspects into farming concepts, in order to stimulate production systems which add to a sustainable development of the sector. The investigations rely on data of an arable farming system experiment (INTEX). Three farming systems called good-farming-practice (GFP), integrated-flexible and integrated-non-inversion were established from 1994 to 1998 on two sites. The systems differed in crop rotation, soil tillage, fertilisation and pesticide use. Thus, weed management comprised Cultural or indirect control by plant husbandry and direct mechanical and chemical control. A residual weed vegetation after terminating all direct control in the arable crops was ex-ante intended in the integrated systems. The spring weed densities were observed in winter wheat previous to any direct control treatments. The residual weed vegetation was investigated in all crops by monitoring species numbers and total ground cover after terminating all direct control. The direct chemical control intensity was considerably lower in the integrated farming system, in which the crop rotation was extended and the soil was ploughed annually. Spring densities of problematic weeds like annual grass weeds and Galium aparine in the winter wheat crop were not higher in these systems. Higher covers of the residual weed vegetation Occurred more often in the productive arable crops of the two integrated farming systems, which additionally hosted higher number of species after terminating direct control. The different system strategies, including a higher input of herbicides in the system integrated-non-inversion, averted severe problems, including those arising from the dominating species being generally problematic in arable land use. (C) 2003 Elsevier Science B.V. All rights reserved
Herbicide use in sugar beets - weed infestations, costs and control efficiency infield experiments of the Landwirtschaftskammer Hannover from 1990-1999
No full textField experiments of the Landwirtschaftskammer Hannover on chemical weed control in sugar beets of 10 years (1990-1999) were comprehended and analysed. Information on the level of the weed infestation and the species composition were collected for each treatment, as well as the weed control applied in the treatments. The analyses focuses the species Galium aparine and Viola arvensis. A method was derived to ex-ante and species specific compare control strategies. Costs of herbicides and applications were calculated for all treatments. Chemical weed control in sugar beets is characterised by several applications of various mixtures of active ingredients. If herbicides were applied more often, higher costs for herbicides appeared. The relation between original and residual weed infestation (after finishing all control) was significant for the two weed species, but no relation to the costs of control appeared. It was not possible to derive conditions for higher cost of control connected with higher original weed infestations of the two species. For G. aparine it can be stated based on the presented data, that more than 5.5 % relative cover of G. aparine in the original weed infestation resulted in significantly higher residual weed infestations
Long-term cultural control of Cirsium arvense (L.) Scop. in cereal crops
No full textThe N-fertilisation of the cereal crops was varied in two treatments of a rotational experiment (beets-winter wheat-winter barley). The cereal crops were not fertilised with mineral N in one treatments, while cereals were moderately N-fertilised in the other. The beet crop was N-fertilised in both treatments The treatments were investigated in two project periods: Between 1988-96 no weed control was undertaken in cereals in both treatments, while weed were controlled in the beet crop. Between 1997-99 weeds were controlled with herbicides in all crops. While hardly any sprouts of Cirsium arvense appeared in the fertilised treatment, although no weed control was undertaken, sprout densities continuously increased in the unfertilised one. Success of the chemical control of Cirsium arvense in the beet crop 1997-99 could be observed in the cereal crops. Annual investigations of the seed bank indicated the existence of viable seeds, although no seedlings appeared in the field observations. No further relations exist between sprout densities in the field and the seed bank in the soil
Long-term cultural control of Cirsium arvense (L.) Scop. in cereal crops
No full textThe N-fertilisation of the cereal crops was varied in two treatments of a rotational experiment (beets-winter wheat-winter barley). The cereal crops were not fertilised with mineral N in one treatments, while cereals were moderately N-fertilised in the other. The beet crop was N-fertilised in both treatments The treatments were investigated in two project periods: Between 1988-96 no weed control was undertaken in cereals in both treatments, while weed were controlled in the beet crop. Between 1997-99 weeds were controlled with herbicides in all crops. While hardly any sprouts of Cirsium arvense appeared in the fertilised treatment, although no weed control was undertaken, sprout densities continuously increased in the unfertilised one. Success of the chemical control of Cirsium arvense in the beet crop 1997-99 could be observed in the cereal crops. Annual investigations of the seed bank indicated the existence of viable seeds, although no seedlings appeared in the field observations. No further relations exist between sprout densities in the field and the seed bank in the soil
Cultural control of Cirsium arvense in a cereal-based crop rotation
No full textThe influence of mineral nitrogen fertilisation and mowing frequency on a Cirsium arvense population was investigated in a 3-year grass-clover/winter wheat rotation. The field experiment was carried out from 2000 to 2003, following a long-term study (1988-1999) on the same field. In the unfertilised treatment, sprout numbers increased, while in the moderately fertilised treatment sprout numbers remained stable. Fertiliser application in established thistle stands led to a rapid decrease in sprout density as well as patch area within two years. Sprout numbers were reduced in the grass-clover mixture in both fertiliser treatments, but one year of grass-clover was not enough for a sustainable limitation of thistle spread in the unfertilised treatment
Long-term population development of Viola arvensis Murray in a crop rotation. II. Modelling population development
No full textIn this paper, a model is outlined and parameterized for Viola arvensis using data from a long-term experiment (1982-1996) an population development described previously by GEROWITT and BODEN-DORFER (1998). Simulation exercises on population development were done using this model. It was found that re-parameterization was necessary for a satisfactory simulation of the population development for a treatment without N fertilisation in cereals, The simulation results of HOLZMANN (1987) were repeated and improved by fitting them to the investigated data. Variations in the data could be accounted for by modifying the parameters using the annual data for the investigated variables, when the variables within a Year were related to one another. The significance of the simulations is discussed with respect to investigations on the long-term risk associated with various control strategies
An investigation of genetic variation in Cirsium arvense field patches
No full textThe genetic structure of typical Cirsium arvense patch populations in two arable fields was examined. Patches were mapped and plant samples were taken in these patches. Plants of a central patch and four surrounding patches were sampled in I year to investigate the influence of root fragment dispersal. Plants of another patch were sampled in three subsequent years to investigate the patch development. The genotypes of the plants were examined using repetitive enterogenic primer (REP) and inter simple sequence repeat (ISSR) analysis. The mean proportion of distinguishable genotypes ranged from 0.13 to 0.67 and the evenness index ranged from 0.58 to 1.00. Differences in genotypes between neighbouring patches indicated that root fragment dispersal via soil cultivation was of minor importance. Three years sampling within a patch showed that the patch mainly 'grew' via the establishment of new clones rather than by clonal growth of one genotype. The influence of various factors caused by population demography or arable practice on patch development in an arable field is discussed. Although various factors can help to maintain genetic diversity, there is strong evidence for regular seedling establishment in arable fields
Cultural control of Cirsium arvense in a cereal-based crop rotation
No full textThe influence of mineral nitrogen fertilisation and mowing frequency on a Cirsium arvense population was investigated in a 3-year grass-clover/winter wheat rotation. The field experiment was carried out from 2000 to 2003, following a long-term study (1988-1999) on the same field. In the unfertilised treatment, sprout numbers increased, while in the moderately fertilised treatment sprout numbers remained stable. Fertiliser application in established thistle stands led to a rapid decrease in sprout density as well as patch area within two years. Sprout numbers were reduced in the grass-clover mixture in both fertiliser treatments, but one year of grass-clover was not enough for a sustainable limitation of thistle spread in the unfertilised treatment
Long-term population development of Viola arvensis Murray in a crop rotation. II. Modelling population development
No full textIn this paper, a model is outlined and parameterized for Viola arvensis using data from a long-term experiment (1982-1996) an population development described previously by GEROWITT and BODEN-DORFER (1998). Simulation exercises on population development were done using this model. It was found that re-parameterization was necessary for a satisfactory simulation of the population development for a treatment without N fertilisation in cereals, The simulation results of HOLZMANN (1987) were repeated and improved by fitting them to the investigated data. Variations in the data could be accounted for by modifying the parameters using the annual data for the investigated variables, when the variables within a Year were related to one another. The significance of the simulations is discussed with respect to investigations on the long-term risk associated with various control strategies
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