The data related to weed control were gathered and collated by SAC. The data were initially sourced from the participating agrochemical companies: BASF, Bayer CropScience (initially Aventis), Dow Agrochemicals, DuPont (UK) Ltd and Syngenta.
In order to ensure that there were examples of active ingredients not produced by those companies, agreement was obtained from Agrichem Ltd, Headland Agrochemicals Ltd, Makhteshim-Agan (UK) Ltd and Monsanto (UK) Ltd to include certain of their products. In most of these cases, SAC entered the data sets because the companies did not have the staff to undertake such work. SAC also entered data for the key participating companies where required and as requested.
The relevant company audited any data entered by SAC, except where there was an agreement that SAC would audit. A different staff member did this from the person who had done the initial data entry where possible, and was only undertaken for the secondary group of companies: Agrichem, Headland and Makhteshim Agan.
Data on physical and cultural weed control was entered by SAC utilising key literature (notably Davies & Welsh, 2001), and available expertise.
The herbicide data that should be included in the system was agreed during the WMSS project Group Leaders and Herbicide Group meetings. The WMSS Herbicide Group including representative of each of the key funding companies, the UKASTA and AICC representatives of the WMSS Steering Group and members of the WMSS Group Leaders as required. The Herbicide Group not only discussed herbicide data management, but also assisted in responding and advising in system design and in selection of herbicide information for the encyclopaedic modules.
Herbicide data collected - Herbicide X Weed Interactions
Spreadsheets were produced to allow the companies and SAC to enter data (example spreadsheets in Appendix I). The spreadsheets have 256 weed species divided into priority species, key species, other economically important species and other weeds/field major flora. The latter group including many species of biodiversity and rarity value to allow the system to extend to such attributes if required. The weeds with known herbicide resistance problems
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recommended dose against each growth stage of each weed was entered on a scale S (>90% control; 95% for black-grass), MS (75-90%), MR (50-75%), R (<50%) and U unknown. It was agreed the basic selection programme would be based on label dose recommendations (level 1) but that extra information on weeds with those doses would be provided where possible (level 2). Again when available, some companies donated data on lower than recommended rates (level 3) – but this was only included as encyclopaedic data rather than part of the selection programme, because of liability concerns.
Other published data on low doses was entered by SAC onto the encyclopaedic section, as was information on a screening programme of rarer weeds undertaken by ADAS Boxworth and SAC Edinburgh (level 4) (see Appendix A).
To obtain mixtures of herbicides, key mixtures were entered as if single products but the system was designed to be able to mix products using an additive control approach. The companies provided information on recommended mixtures and mixtures to be avoided for various reasons, and further spreadsheets were provided for such data entry.
The need for sequences to be part of the herbicide selection programme entailed the development of a further spreadsheet that indicated the time interval allowed between use of individual herbicide products. To this was added a further spreadsheet which included following crop and cultivation requirements after using specific herbicides or mixtures/sequences of herbicides. This information was to be included in the encyclopaedia. Further information on herbicides collected for the encyclopaedic section included statutory information via LIAISON, a pesticide database programme based at CSL York, and Environmental Information Sheets from the agrochemical companies. Further label information was included, along with lists of weeds and levels of control derived from the spreadsheets described above.
Problems and Solutions
There was considerable discussion regarding allowing reduced dose (below label recommendations) information in the selection process, desired by User Groups. However, the liability problems associated were considered to be too great. Data collection from non- participant companies presented a number of difficulties, which took time and discussion to overcome.
Frequent changes in product approvals and recommendations show the need for regular updating of the database, although once a year, probably in early summer, is probably an acceptable compromise. The basic information/data was collected as required by the Milestones, but updating, detail checking and auditing continued throughout and up to the end of the project.
The lack of information on minor weed species and species with biodiversity and rarity value became very evident as the data was collated. A herbicide screen of less common/rarer weed species of biodiversity value was undertaken at ADAS Boxworth and SAC Edinburgh (Section 1.7and Appendix A). The principle herbicide active ingredients were included in the screen at half recommended and double recommended doses. The work was split between sites because of the large number of treatments involved. However, again due to liability considerations, the data from these screens was included as advisory information in the encyclopaedic section rather than imbedded within the decision process.
This lack of information on most of the more unusual and rarer species, will hinder the use of the system as a tool for species conservation and management. This would require extensive further screening work to provide a comprehensive database. Nevertheless, a reasonably substantial database has been developed for the Weed Manager encyclopaedia, which will assist users in making treatment selections to assist in species conservation.
1.6.1 Herbicide data import
The herbicide data provided by the chemical companies has to be added to the database so that it is available for use in the encyclopaedia and decision support module. These data have to be updated once or twice a year so dialog applications were written to perform the major tasks required:
• import herbicide sensitivity
• import tank mix data
• import product sequence data
• validate herbicide data
These programs are used by a person responsible for updating the system prior to release of the system. Therefore, in this section the term ‘user’ does not refer to the farmer/adviser using Weed Manager.
35 1.6.2 Herbicide sensitivity data
The data were supplied on predefined spreadsheets (Section 1.6 & Appendix I). The header of the spreadsheets contained some basic information about the product so that the data could be linked to the correct statutory product information held in the DSE pesticide database. The header also contains the HRAC groups for the product, which are used in assessing the risk of developing herbicide resistance. The rest of the data on the spreadsheet defined the sensitivity of each weed to the product at each stage.
The herbicide sensitivity importer is a dialog-based program (more detail can be found in Appendix G). The importing of the data is carried out in a worker thread. The program is designed for level 1, 2 (company data) and 4 (glass house trials) data (see section 1.6). In order to check that there are no inconsistencies in the data a herbicide data validation program has been written.
The spreadsheets could contain actual products or generic names. The generic names are converted into actual products, which have the same composition. This is necessary because the module takes the cost of products into account when calculating the efficacy of the treatment.