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  • Artikel  (5)
  • Blackwell Science Ltd  (5)
  • American Association for the Advancement of Science (AAAS)
  • Canadian Society of Petroleum Geologists (CSPG)
  • Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft  (5)
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  • Artikel  (5)
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  • 1
    Digitale Medien
    Digitale Medien
    A decision algorithm for patch spraying (2003)
    Oxford, UK : Blackwell Science Ltd
    Weed research 43 (2003), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: It has been established that weeds are spatially aggregated with a spatially varying composition of weed species within agricultural fields. Site-specific spraying therefore requires a decision method that includes the spatial variation of the weed composition and density. A computerized decision method that estimates an economic optimal herbicide dose according to site-specific weed composition and density is presented in this paper. The method was termed a ‘decision algorithm for patch spraying’ (DAPS) and was evaluated in a 5-year experiment, in Denmark. DAPS consists of a competition model, a herbicide dose–response model and an algorithm that estimates the economically optimal doses. The experiment was designed to compare herbicide treatments with DAPS recommendations and the Danish decision support system PC-Plant Protection. The results did not show any significant grain yield difference between DAPS and PC-Plant Protection; however, the recommended herbicide doses were significantly lower when using DAPS than PC-Plant Protection in all years. The main difference between the two decision models is that DAPS integrates crop–weed competition and estimates the net return as a continuous function of herbicide dose. The hypothesis tested is that the benefit of using lower herbicide doses recommended by DAPS would disappear after a few years because weed density will increase and thus require higher doses. However, the results of weed counting every year did not confirm this hypothesis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3180.2003.00344.x
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 2
    Digitale Medien
    Digitale Medien
    Using laser to measure stem thickness and cut weed stems (2002)
    Oxford, UK : Blackwell Science Ltd
    Weed research 42 (2002), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Stem thickness of the weed Solanum nigrum and the crop sugarbeet was determined with a He–Ne laser using a novel non-destructive technique measuring stem shadow. Thereafter, the stems were cut close to the soil surface with a CO2 laser. Treatments were carried out on pot plants, grown in the greenhouse, at two different growth stages, and plant dry matter was measured 2–5 weeks after treatment. The relationship between plant dry weight and laser energy was analysed using two different non-linear dose–response regression models; one model included stem thickness as a variable, the other did not. A binary model was also tested. The non-linear model incorporating stem thickness described the data best, indicating that it would be possible to optimize laser cutting by measuring stem thickness before cutting. The general tendency was that more energy was needed the thicker the stem. Energy uses on a field scale are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3180.2002.00282.x
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 3
    Digitale Medien
    Digitale Medien
    Cutting weeds with a CO2 laser (2001)
    Oxford UK : Blackwell Science Ltd
    Weed research 41 (2001), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Stems of Chenopodium album. and Sinapis arvensis. and leaves of Lolium perenne. were cut with a CO2 laser or with a pair of scissors. Treatments were carried out on greenhouse-grown pot plants at three different growth stages and at two heights. Plant dry matter was measured 2 to 5 weeks after treatment. The relationship between dry weight and laser energy was analysed using a non-linear dose–response regression model. The regression parameters differed significantly between the weed species. At all growth stages and heights S. arvensis was more difficult to cut with a CO2 laser than C. album. When stems were cut below the meristems, 0.9 and 2.3 J mm−1 of CO2 laser energy dose was sufficient to reduce by 90% the biomass of C. album and S. arvensis respectively. Regrowth appeared when dicotyledonous plant stems were cut above meristems, indicating that it is important to cut close to the soil surface to obtain a significant effect. When cutting L. perenne plants with 2-true leaves at a height of 2 cm from the soil surface with a laser, the biomass decreased significantly compared with plants cut by scissors, indicating a delay in regrowth. This delay was not observed for the dicotyledonous plants nor for the other growth stages of L. perenne.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3180.2001.00212.x
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 4
    Digitale Medien
    Digitale Medien
    Real-time weed detection, decision making and patch spraying in maize, sugarbeet, winter wheat and winter barley (2003)
    Oxford, UK : Blackwell Science Ltd
    Weed research 43 (2003), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Information on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Most of all, it allows a potential reduction in herbicide use, when post-emergence herbicides are only applied to field sections with weed infestation levels higher than the economic weed threshold; a review of such work is provided. This paper presents a system for site-specific weed control in sugarbeet (Beta vulgaris L.), maize (Zea mays L.), winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.), including online weed detection using digital image analysis, computer-based decision making and global positioning systems (GPS)-controlled patch spraying. In a 4-year study, herbicide use with this map-based approach was reduced in winter cereals by 60% for herbicides against broad-leaved weeds and 90% for grass weed herbicides. In sugarbeet and maize, average savings for grass weed herbicides were 78% in maize and 36% in sugarbeet. For herbicides against broad-leaved weeds, 11% were saved in maize and 41% in sugarbeet.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3180.2003.00349.x
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
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  • 5
    Digitale Medien
    Digitale Medien
    Sugarbeet yield response to competition from Sinapis arvensis or Lolium perenne growing at three different distances from the beet and removed at various times during early growth (2002)
    Oxford, UK : Blackwell Science Ltd
    Weed research 42 (2002), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: A sugarbeet field experiment was conducted in 1999 and 2000 to measure beet yield where Sinapis arvensis or Lolium perenne were growing in the crop row at 2, 4 or 8 cm from the beet plants. The weeds were removed by cutting once in the growing season in either late May, mid-June or early July. The number of neighbouring beet plants to every target beet plant was recorded. Projected leaf cover of a subset of the data with non-cut weeds was analysed by using image analysis to investigate whether this could be used to predict beet yield loss early in the growing season. Increasing the distance between beet and weed from 2 to 8 cm increased the beet yield significantly by an average of 20%, regardless of weed species. The dry weight of non-cut and re-growing weeds at harvest time decreased when cutting was postponed to the period between mid-June and early July. The number of neighbours described a sigmoidal yield decline of the single beet plants. Results from image analysis showed that approximately 33 g of beet yield was lost in October/November for each per cent relative projected leaf cover of the weeds in May, despite variation in growing conditions. The results are discussed in relation to potentials for robotic in-row weed control.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1365-3180.2002.00301.x
    Standort Signatur Erwartet Verfügbarkeit
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    Artikel (Nationallizenzen)
    Volltext
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