Article: Utilise the potential herbicide savings using weed maps, when the sprayers have limited capabilities. Somerville, G.J. et al., 2019. In J. Stafford, ed. ECPA 2019. The 12th European Conference on Precision Agriculture. p. 8.

Article: Spatial variability of optimized herbicide mixtures and dosages. Rydahl, P. et al., 2018. In International Conference on Precision Agriculture. 14th International Conference on Precision Agriculture (ISPA). International Society of Precision Agriculture, pp. 1–14.

Article: Marrying futuristic weed mapping with current herbicide sprayer capacities. Somerville, G.J. et al., 2019. In Precision agriculture ?19. 28. Wageningen Academic Publishers, pp. 231–237.


Article: DSSHerbicide: Weed control in winter wheat with a decision support system in three South Baltic regions – Field experimental results

M. Sønderskov · R. Fritzsche · F. de Mol · [...] · P. Rydahl

ABSTRACT: DSSHerbicide Germany and DSSHerbicide Poland are two decision support systems (DSS) developed for weed control in winter wheat in Northern regions of Germany and Poland. DSSHerbicide is based upon an existing Danish DSS, Crop Protection Online (CPO). Herbicide recommendations from DSSHerbicide are based on efficacy estimates from a dose–response model and required weed control levels defined by expert evaluations and practical experience. DSSHerbicide was parameterised for 22 commonly occurring weed species and 48 herbicides in Poland and for 23 weed species and 32 herbicides in Germany. Validation trials were conducted in Poland, Germany and Denmark primarily in private farmer"s winter wheat fields. This enabled a comparison between the herbicide use with standard recommendations and with the existing Danish CPO and the German and Polish DSSHerbicide. Differences among herbicide applications were analysed based on the treatment frequency index (TFI, relation of actually applied dose to label rate) and the costs of herbicide treatments. Full-text Article · Oct 2015 · Crop Protection

Article: Four years validation of decision support optimising herbicide dose in cereals under Spanish conditions

J. M. Montull · M. Soenderskov · P. Rydahl · [...] · A. Taberner

ABSTRACT: The Danish decision support system Crop Protection Online (CPO) optimises herbicide weed control. CPO recommends specific herbicide solutions to achieve a required level of control. The aim is to apply herbicides as little as possible but as much as necessary. CPOWeeds is a version of CPO adjusted to conditions in North-eastern Spain. The predicted efficacies and the yield obtained with CPOWeeds were validated in winter cereal field trials from 2010 to 2013. All CPOWeeds treatments were related to the efficacies obtained with standard herbicide treatments decided upon by local advisors. The predictions from CPOWeeds were compared to the actually achieved efficacies in the field trials for the nine weed species at different developmental stages and for 84.2% of the comparisons the obtained efficacies were equal to or higher than predicted. The average difference between predicted and observed efficacies was 2.35 percentage points. Yield was measured in three trials and the recommendations from CPOWeeds were maintaining yield. There were two situations where CPOWeeds were performing suboptimal. One is in the early weed growth stages, as the model is not yet prepared to account for water stress on root action herbicides applied at 10-11 BBCH. The second situation was in fields with a prior unidentified population of resistant Alopecurus myosuroides. For key species in winter cereals in Spain, such as Avena sterilis, Lolium rigidum and Papaver rhoeas, CPOWeeds achieved a satisfactory control level. It was concluded that the use of CPOWeeds allowed optimisation of the herbicide application with a very high robustness. The recommendations were satisfactorily for the conditions of the Northeast of Spain and have the potential to decrease the amount of applied herbicides by at least 30%. Therefore, it can be an important tool in Integrated Weed Management. Article · Oct 2014 · Crop Protection

Article: Decision Support System for Optimized Herbicide Dose in Spring Barley

Mette Sønderskov · Per Kudsk · Solvejg K. Mathiassen · [...] · Per Rydahl

ABSTRACT: Crop Protection Online (CPO) is a decision support system, which integrates decision algorithms quantifying the requirement for weed control and a herbicide dose model. CPO was designed to be used by advisors and farmers to optimize the choice of herbicide and dose. The recommendations from CPO for herbicide application in spring barley in Denmark were validated through field experiments targeting three levels of weed control requirement. Satisfactory weed control levels at harvest were achieved by a medium control level requirement generating substantial herbicide reductions (~ 60% measured as the Treatment Frequency Index (TFI)) compared to a high level of required weed control. The observations indicated that the current level of weed control required is robust for a range of weed scenarios. Weed plant numbers 3 wk after spraying indicated that the growth of the weed species were inhibited by the applied doses, but not necessarily killed, and that an adequate level of control was reached later in the season through crop competition. Article · Jan 2014 · Weed Technology

Article: PC‐Plant Protection: optimizing chemical weed control1


ABSTRACT: In Denmark, a political decision was taken to achieve, before 1997, a 50% reduction in the bulk of active ingredients in pesticides consumed, compared with average consumption in the period 1981/1985. To meet this requirement, a computer-based decision support system has been developed. In order to minimize doses, the system combines the concept of factor adjusted doses and expert knowledge. Herbicide doses are adjusted on the basis of the sensitivity of different weed species and their growth stages. Based on actual field observations, the system suggests suitable herbicides, the normal dose, the actual dose, prices per ha, etc. In future, doses will probably also be factor-adjusted according to climatic conditions, competitive ability of cereal cultivars and soil type. The need for control of individual weed species (thresholds) is based on expert knowledge. Ongoing long-term studies on seed production by weeds, competition studies etc. will hopefully help to establish more exact models for economic thresholds. After satisfactory validation through field trials, the system will be continuously updated with new findings in weed research. The system has been on the market in Denmark since spring 1991. Article · Apr 2008 · Bulletin OEPP/EPPO Bulletin

Article: O. 24-Decision support systems (DSS) for weed control in Europe–state-of-the-art and identification ofbest partsfor unification on a European level

P Rydahl

ABSTRACT: A survey has been conducted of decisions support systems (DSS"s) for weed control in Europe. 9 DSS"s representing 7 countries were studied. These were all targeted at farmers, but they differed in decisions supported, in number of crops covered and in demonstrated impact. At a workshop in Denmark in March 2008, a set ofbest parts/building blocksfrom these DSS"s suitable for unification of a European level was identified. These could form the basis for building and validating DSS"s on a European level that meets requirements for robustness in production lines and which hold some potential for reducing dependency and / or use of herbicides. When some robust and potent DSS concepts have been identified, the production and exchange of data that support integrated decision algorithms and calculation models of such DSS should be co-ordinated on a European level. Full-text Article · Jan 2008

Article: Decision support systems: Barriers and farmersneed for support

L. N. Jørgensen · E. Noe · A. M. Langvad · [...] · P. Rydahl

ABSTRACT: The highly complex knowledge of scientific disciplines makes nuanced analysis and modelling possible. However, the information produced often does not reach farmers because it is presented in a way that does not correspond to the way their work is carried out in practice. The decision support system Crop Protection Online is widely used by advisors and as a learning tool for students. Although the system has been validated in many field trials over the years and has shown reliable results, the number of end-users among farmers has been relatively low during the last 10 years (approximately 1000 farmers). A sociological investigation of farmers’ decision-making styles in the area of crop protection has shown that arable farmers can be divided into three major groups: (a) system-orientated farmers, (b) experience-based farmers and (c) advisory-orientated farmers. The information required by these three groups to make their decisions varies and therefore different ways of using decision support systems need to be provided. Decision support systems need to be developed in close dialogue and collaboration with user groups. Full-text Article · Sep 2007 · Bulletin OEPP/EPPO Bulletin

Article: A web‐based decision support system for integrated management of weeds in cereals and sugarbeet*

P. Rydahl

ABSTRACT: A Danish decision support system (DSS) named Crop Protection Online (CPO) for integrated management of weeds in cereals and beet has been developed during the past 20 years. CPO is based on a model that runs in three main steps: model step 1 quantifies the level of weed control needed on a field level, model step 2 selects candidate herbicides and calculates dose rates to meet the need, and model step 3 calculates tank mixtures of herbicides with two to four mixing components, if advantageous. CPO has been developed in cereals and beet, and various prototype versions have been validated in 1679 field tests. CPO secured yield potentials, and the level of residual weeds was not increased when compared with reference treatments. The potential of CPO to reduce herbicide use has been observed in all model crops, but the potential was greatest in cereals. In spring cereal field trials highly infested with weeds, the present version of CPO suggested 35% of one full herbicide dose on average and in winter cereals CPO suggested 44% on average of one full dose. The results from validation trials demonstrate that CPO is capable of suggesting robust treatment options with a low input of herbicides. The system architecture of CPO has been exported to Poland and the Baltic countries, and the system is expected to be suitable for export to other countries too. Article · Mar 2004 · Bulletin OEPP/EPPO Bulletin

Article: User interfaces and system architecture of a web-based decision support system for integrated pest management in cereals

P. Rydahl · L. Hagelskjaer · Pedersen LH · O. Q. Bojer

ABSTRACT: A Danish decision support system (DSS) on integrated pest management (including pathogens and weeds) has been developed during the past 20 years. This DSS is distributed as an integrated part of the ‘Danish Integrated Farm Management System’, which is a PC program, of which the plant protection module presently has about 2500 subscribers in Denmark. This program has been designed to propose relevant options for treatment with plant protection products according to observations from a field inspection. The new object-oriented web-based system architecture of this DSS was developed in 2001. This allows local (national) adaptation of the DSS in terms of language, crops, pests, products and features. Model complexity and DSS algorithms can also be adjusted to local conditions. The system has been implemented in a relational database structure (Microsoft SQL Server) and a dynamic web application (Java and Jscript in Active Server Pages on an Internet Information Server). The system architecture has been designed with emphasis on a high level of flexibility for future adjustments due to agronomic and legal requirements. The DSS models have been linked to a pest identification module and to a comprehensive database on label information on plant protection products. Article · Dec 2003 · Bulletin OEPP/EPPO Bulletin

Article: Application of information technology in plant protection in Denmark: from vision to reality 


N.S Murali · Bo J.M Secher · Per Rydahl · Finn M Andreasen


ABSTRACT: With 2051 licences sold to farmers, ‘PC-Plant Protection’ is the most widely used PC-based farm level decision support system for control of weeds, pests and diseases in Denmark and in Europe. The system is distributed by the Danish Agricultural Advisory Centre and marketed by the local advisory centres. In order to help the local advisors promote sales at farmers meetings or agricultural exhibitions, they are provided with a video film of the field assessment methods, overhead transparencies outlining the structure of recommendation models, and sales brochures. More than 30 non-technical articles have been published in the national agricultural newspapers and magazines. National and regional TV stations have broadcast interviews with farmers on their experience with the system. A farm survey of 488 farmers who used the system in 1995 shows that the system has been well accepted by the farmers not only because of the reliable recommendations but also because of increased profits. A similar survey among crop production advisors also showed that the system has been very useful both for the direct and indirect advisory services. Article · Apr 1999 · Computers and Electronics in Agriculture

Article: A Danish decision support system for integrated management of weeds

P. Rydahl

Article: Availability and comparison of data on efficacy of reduced doses of herbicides in seven European countries

Weide · R.Y · L.A.P. Lotz · P. Rydahl

Article: Tørresen, K.S., J. Netland & P. Rydahl. 2004. Norsk utgave av det danske beslutningsstøttesystemet Plantevern Online for ugrassprøyting i korn. Grønn kunnskap 8 (2): 100-109

Article: Netland, J., Tørresen, K.S. & Rydahl, P. 2006. Resultat frå forsøk med beslutningsstøttesystemet VIPS -Ugras for ugrassprøyting i haustkorn. Bioforsk FOKUS 1(3): 50-51

Article: Netland, J., K.S. Tørresen & P. Rydahl. 2005. Evaluation of the weed module in the Danish decision support system "Crop Protection Online" adapted to Norwegian conditions. Bari, Italy, 19-23 June 2005. Proceedings 13th EWRS Symposium. 2 pp.