The UK’s approach to weed management investment needs to be overhauled, if the needs of industry are to be met.

This was a key conclusion of the first ever major cross-sector review of weed management, commissioned by AHDB and BBRO.

According to the review, essential weed management information could be lost to the industry unless key sources of reference material are identified and archived.

Coordinated programmes of research and knowledge exchange (KE) across cropping sectors were also deemed necessary to make the best use of depleted funds.

Drawing upon national and international information sources, the review covered cereals, oilseeds, horticulture, potatoes, sugar beet, legumes and grassland systems.

Joe Martin, AHDB senior crop protection scientist for weeds, said: “The UK has been at the forefront of weed research in the post-war era, laying the foundation for management, including the provision of essential data on weed biology. However, the legacy of this research is being eroded. Key reference sources, such as those published by Defra and its predecessor, MAFF, are gradually being lost.”

In addition to identifying, protecting and translating weed management information, the ADAS-led review team highlighted that information can become trapped within high-science, peer-reviewed journals. As a result, it recommended that a mechanism be identified to get essential information out to farmers and growers faster.

Non-chemical control methods were also reviewed. Many showed promise and the authors recommended effort be placed on trialling such approaches in the UK. However, the review states that the industry needs to be more unified and strategic to maximise the chance of such methods making an economic difference to farmers and growers.

Joe said: “Chasing management of a specific weed with chemistry is a luxury in current times. The review suggests we should look at ‘broad-spectrum’ alternatives that tackle weeds across entire cropping systems.”

Cross-sector conclusions

In addition to recommending that the industry be provided with robust and up-to-date weed management information and tools, the review also detailed how research investment needs to be directed over the short, medium and longer term.

Information on ‘whole-systems’ approaches is required, in particular. This includes investigating the role that cover crops, minimum cultivation systems, inter-row management and inter-cropping can play.

Investment in monitoring is also needed, from basic research on how weeds spread (e.g. via organic materials), to how herbicide-resistant populations can be identified and managed.

The fast-tracking of suitable technologies was also deemed essential. This covers the use of drones, weed maps and non-chemical control approaches (e.g. based on mechanical, electrical and thermal techniques). Genomic approaches, to disrupt weeds and to develop herbicide-tolerant crops, were also earmarked as avenues of exploration.

As chemistry will continue to play an essential role, it was also recommended that substances to support it be developed, such as adjuvants and soil stabilisers. Improved targeting of herbicides was also cited as key, including the development of weed thresholds for patch spraying.

New direction

The review has provided its funders and the wider industry with the comprehensive information needed to coordinate investment through a targeted programme of research and knowledge exchange. AHDB has recently committed to support a coordinated programme of activity on the integrated management of weeds over the next five years.

Joe said: “AHDB has to balance many priorities. Due to the strategic importance of weeds, the green light has been given to develop the next phase of weed research and KE. This will involve working in partnership with industry to develop cross-sector programmes of work.”

The full review can be accessed via ahdb.org.uk/weedreview

Notes to editors

The full review includes a list of knowledge gaps and recommended actions across cropping sectors, as well as for specific sectors (see appendix 1). The timescale and potential funding routes are also described. A brief statement for each sector is provided below.

The high-value nature of horticultural produce often puts this sector at the cutting edge of weed management solutions. Cross-sector funding could be used to establish proof of concept of alternative approaches in horticultural systems. With a strong focus on the intra-row environment, there is great potential to develop spot and mechanical weeding technologies, as well as novel mulches and inter-cropping techniques. Alternative chemistry, including biopesticides, is also a strong focus for this sector.

For cereals and oilseeds, quantification of the benefit of alternative weed control approaches is a priority. More robust information on the ability of varieties to compete with weeds is in particular demand. The efficacy/value of all main alternative weed-control approaches is required, from simple hand rogueing, to harvest weed seed control opportunities.

In potatoes, key herbicides have been lost recently. For this sector, mechanical weeding approaches need to be fast-tracked. Improved information on canopy development and guidance technology is also urgently required. Herbicide evaluations also need to be improved and should include assessments of variety sensitivity.

In sugar beet, broad-leaved weed control strategies are crucial. Spray programmes need to make the most of remaining chemistry, including the use of adjuvants and safeners. Several herbicide active ingredients are available in other cropping systems and the industry needs to work closely together to ensure the most promising are authorised for use in this major crop.

In the grassland sector, there is a requirement for KE and basic research, including how weed populations respond under various grazing systems. The economic viability of non-chemical weed control of specific weeds (e.g. ferns, rushes, bracken and docks) in grassland systems also needs to be established.

In legumes, getting the crop off to a strong start is essential. The influence of cultivation, competitive ability of varieties, as well as optimum seed rates and row widths, all need to be investigated.

The ‘Weed control options and future opportunities for UK crops’ (project number CP 182 / 1807258) was led by ADAS. The work was funded by a contract from AHDB (£26,000), BBRO (£10,000) and cash and in-kind contributions from other partners. The project had wide industry support and involved five manufacturers, three distributors, technology providers, key crop experts and CRD.