Review of Weed Control options and future opportunities for UK crops

Review of weed control options and future opportunities for UK crops

Purpose/Primary Objective

Weed control is a key priority for crop production in many UK crop production systems. The aim of the project is to review weed control research being conducted nationally and internationally on a global scale that would be of benefit to UK crop production in the short, medium and long term.

The review output will be used by AHDB and BBRO to help shape future Research and Knowledge Exchange activities on weed management.


The review should cover all crops for which AHDB collect a levy across Agriculture and Horticulture (including Field Vegetables, Protected Edibles, Soft Fruit, Tree Fruit, Hardy Nursery Stock and Protected Ornamentals, Bulbs and Outdoor Flowers) Cereals & Oilseeds and Potatoes. This review is a joint funded piece of work for AHDB and BBRO and should also cover sugar beet. Consideration should also be given to weed control in grassland including grassland renewal and upland management.

Weed control in production including seed, propagation, glasshouse, pot grown, field and storage should be included.

The review should be a horizon scanning piece including review of current and future weed control solutions (past, present and future) in order to gain an idea of emerging technologies in terms of timeliness, economics and feasibility.

It should help to show where the gaps in research currently are which AHDB and BBRO may want to fund and will also help to prevent duplication of existing work and direct activities linking with other funding bodies or areas of relevant research.

Identifying priority areas where AHDB and/or BBRO should consider investigating in new weed control strategies for the future will be a key output from the project.

Areas of interest for Research and/or Knowledge Exchange will be developed following on from this horizon work including control by non-chemical / cultural control, application technology and novel technology including robotics for example with the aim of providing growers and farmers with other tools / options for weed control which can complement existing synthetic chemistry in the short term and provide longer term weed control options as availability of synthetic chemistry diminishes.


Growers rely almost entirely on synthetic herbicides in order to grow quality produce in a cost-effective manner.  Yet the availability and scope for use of pesticides to control weeds in agriculture and horticulture are under pressure from legislation, climate change, the development of resistance in target organisms and market requirements (e.g. reduced pesticide inputs and maximum residue levels).

Historic and current regulatory changes and additions such as the review of Approval for Active Substances, Maximum Residue Limits (MRLs), Definition of Endocrine Disruptors, Sustainable Use Directive (SUD), Water Framework Directive (WFD) and Candidates for Substitution, continue to erode the number of available herbicidal active substances for use in Horticulture and Agriculture. Combined with pesticide resistance this is acutely felt in Horticulture and is also impacting Potatoes, Grassland, Cereals & Oilseeds and Sugar beet.  Resistance being of particular issue for blackgrass control in cereal production.


With a decreasing number of herbicides available to the horticultural industry, weed control has become critical. Withdrawal of key herbicide products across many horticultural crops has left many gaps in herbicides available to growers (for example, the loss of glufosinate ammonium and the loss of the residual herbicide linuron). Under current production methods broad-leaved and grass weeds have the potential to cause the largest impact on yield and quality of about £110 million per year (Andersons (2014) - The Effect of Loss of Plant Protection Products on Agriculture and Horticulture and the Wider Economy). The gap analysis conducted for Horticulture in 2016 identified weed control as a high priority in 38 crop or crop groups.

In untreated situations, the loss of herbicide control for weeds would increase costs due to hand weeding. Growers can pay around £600/ha for hand weeding and one grower spends up to £10K/week hand weeding brassicas (A. Richardson – Allium and Brassica Centre). Labour is likely to become increasingly difficult to find if Brexit has the expected impacts and therefore more expensive.

Difficulties in harvest could result in crop losses due to outcompeting crops and/or contamination of produce with seeds could affect marketability. For example control of common groundsel in some outdoor lettuce.  The financial impact to outdoor lettuce production without having suitable control measures for weed control is estimated at £70 million per year with a 50% loss in marketable yield (CP 132 – Gap analysis). 

Cereals & Oilseeds

Loss of herbicide active ingredients in cereals and oilseeds crops due to changes in legislation, e.g. IPU has been compounded by resistance to remaining herbicides in a range of grass and broad leaved weeds. Although resistance in black-grass dominates thinking, wild oats, ryegrass, poppy and chickweed populations in the UK, are all locally resistant to a range of herbicides and resistance issues are emerging in bromes and mayweed. Although not nationally significant all are increasing in frequency and for individual farmers can present serious problems, with associated business costs. While cultural control using for instance changed drilling dates are effective control options for some weeds (e.g. black-grass) for others (e.g. poppies), long lived seedbanks, extended germination periods or other biological or agronomic features make cultural options very limited.

The cost of weeds to cereal and oilseed production is significant, with £89-125/ha average herbicide spend in winter wheat (Monsanto, 2017). The potential impact that resistance has was demonstrated at the BCPC Weeds Review in 2015. Strutt and Parker presented results from a Bedfordshire farm where black-grass had developed herbicide resistance. Prior to resistance herbicide spend on wheat was £65/ha once resistance had become established this cost had risen to £134/ha.


The approximate area of potatoes grown in the UK is estimated at 120,000ha.  Around 30% of the potato area is grown for processing whilst the fresh market accounts for 54%. The remaining area of potatoes is grown for seed (GB Potatoes: Market Intelligence 2016/17). 

Yield losses in potatoes in the absence of any weed control can vary from 14% to 80% and losses could equate to £228 million a year. The most competitive weeds could cause losses of £55 million each (Pesticide availability Report R415).

Weed control options in potatoes have become more limited with the loss of linuron, further losses could occur due to the water framework directive.  Therefore cultivation will become more important but economically more expensive.  The seed sector is at particular risk due to losing post emergence actives.

Crop desiccation is also of relevance with the potential loss of diquat.

Sugar beet

In 2017, sugar beet was grown on 110,000 ha in the UK by over 3,000 growers. The sugar beet crop has a significant role in the crop rotation regarding Integrated Pest Management, biodiversity and soil protection. Additionally, sugar beet weed control plays an important role concerning weed management in the crop rotation and is an environmentally important spring-sown crop. In the near future there are some major changes that will affect weed control in UK sugar beet. These are the potential loss of phenmedipham and desmedipham, the loss of chloridazon, potential loss of a range of graminicides and triflusulfuron-methyl. Sugar beet is very susceptible to weed competition in its early stages of growth and, if uncontrolled, weeds can lead to crop failure.

Phenmedipham and desmedipham are crucial for weed control in sugar beet and their removal could make the crop uneconomic to grow. These actives are the backbone of weed control systems in the UK (and the rest of the EU). Without them it is likely that growers will need to be extremely vigilant about the mixes and timings of application that they use. Phenmedipham and desmedipham are used in low dose mixtures with other herbicides to control a spectrum of weeds. Desmedipham is important for use in dry conditions and has also become more important with the loss of and/or reduction of permitted doses of residual herbicides for use in beet. Timing of treatments will also be more critical for those who currently rely on pre-emergence chloridazon to sensitise weeds to post-emergence sprays. The loss of phenmedipham and desmedipham would not only adversely affect sugar production, but also animal feed and bio-energy from sugar beet. Phenmedipham is also used in other crops such as red beet, fodder beet, spinach, chard and strawberries.

ALS tolerant sugar beet is expected to be introduced in the near future but the system’s potential effectiveness in sugar beet without phenmedipham and the longer-term implications for rotational weed control also need examining.

Undoubtedly, non-chemical weed control will have a more important role to play in the future and integrating combinations of mechanical and chemical weed control is advisable where and when possible and is also key for resistance management, but currently mechanical weed control is not a viable alternative. There is a wide range of potential systems being launched at present (heat, lasers, electricity, hot water and foam, steam, mechanical hoeing coupled with weed ID, etc.) and apart from hoeing, all of these have yet to show an ability to work economically in arable crops; hoeing has limitations on wind prone soils, in wet conditions and to control weeds close to the crop.

The BBRO Stakeholder Board has agreed this is a high priority and would like the applicant to undertake a review of possible future scenarios in order to identify short and long-term strategies that need to be developed to ensure weed control in sugar beet remains viable in the future.

As the loss of phenmedipham and desmedipham is so critical for sugar beet production this review should cover the key objectives below, alongside the specific objectives detailed later in this call;

  1. The decision-making processes and guidance required in the absence of phenmedipham and desmedipham.

  2. Review of the implications and robustness of the ALS tolerant varieties, especially in the absence of phenmedipham. It should be noted that not all growers will want to adopt this new technology.

  3. Identify which weeds will be of particular concern if phenmedipham and desmedipham are not re-registered for use in sugar beet to allow alternative weed control strategies to be developed based on where the big challenges could arise.


Current issues in grassland are mainly centred on establishing new grass leys or grassland rejuvenation.  Although there are a number of reasonable products for controlling weeds during establishment they can have impact on clover mixes and on other species such as chicory and plantain.  Grassland renewal in the UK is on average 7% of total UK land and therefore having relevant weed control measures is an important step in the grassland renewal process.

Other areas of concern may also include weed control in upland areas such as bracken control where there is currently limited synthetic available chemistry with Asulam being one of the only available products.

From the detail above it is clear that options are needed for growers both short, medium and long term and this review should help to identify the technologies in development as well as gaps in current research that need addressing to help crop production. Consideration on how the control options would fit into an integrated crop management programme should be given.

The review should cover but not be limited to new and existing chemistry, biopesticides, non-chemical / cultural control, application technology and novel technology including robots as well as drawing relevant information from other industries.

Specific objectives

As well as information detailed in the Scope and Background the proposed work should include but not be limited too;

  1. Novel physical / mechanical weed control (including Robotics and automation, Drone technology and electric weeding, precision application)

  2. Sensing, modelling and genetic tools

  3. New weed species and changes to weed flora, allelopathy

  4. Seed return control, volunteer control, yield impacts, varietal sensitivity and competiveness, crop desiccation, drift and cross contamination between crops

  5. New synthetic chemistry, biopesticides, biological control, glyphosate alternatives and likelihood for UK use

  6. Cultural control, rotations, tillage and cultivation systems, cover cropping

  7. The economics of the above solutions should be included to allow growers and farmers to compare with existing cost of weed control in production

  8. Identifying the role of mechanical and/or non-chemical weed control as substitutes for herbicides, including real case studies with proven cost benefit scenarios and rotational management.

  9. The environmental impact including carbon footprint should also be covered within this review.

  10. The potential for market share and ability for investment

  11. Potential timelines for when the technologies above may become available for use with consideration to regulatory and/or Health and Safety legislation considered.

  12. The development of technology in one sector such as horticulture and the potential benefit to arable production

The above list is indicative and is not meant to be exhaustive. Contractors should seek to identify additional areas of interest and relevance for inclusion in the review.

Knowledge Exchange and Knowledge Transfer is a key part of the project to disseminate results and improvements to the growers and wider industry with potential to link with BCPC Weeds Expert Group.

We look forward to receiving proposals for the work detailed below by 12th August 2018 and decisions on which contractors are appointed to conduct the work will be made by 27th August 2018.

Applicants should specify the timescale for completion of the review with relevant milestones for the duration of the project.


Knowledge Exchange and Knowledge Transfer will be a key part of the project including collating the information from relevant organisations and levy payers and then disseminating key messages to the industry. Defining practical take-home messages that growers could adopt in the short-term until new weed control strategies are developed, should be included in the proposal as well as long term messages. The work plan should detail the number and format of events.

Applicants should specify the timescale for completion of the review. Key outputs from the review should include but not be limited to:

  • a review report detailing the findings

  • a prioritized list of future research (strategic and applied) recommendations for each crop

  • a prioritized list of control options which are used successfully elsewhere and should be evaluated/validated under UK conditions

  • At least 5 presentations at relevant events on the outcomes of the project and creation of materials suitable for dissemination to growers and available on the AHDB website

Previously funded AHDB work on Weed control

This list is not exclusive or exhaustive and includes examples of previous and ongoing AHDB funded work. 

Project Number


CP 077

Sustainable Crop and Environment Protection – Targeted Research for Edibles (SCEPTRE)

CP 132

AHDB Horticulture’s Gap Analysis

CP 134

Eye Spot – Leaf specific herbicide applicator for weed control in field vegetables

CP 165


FV 346

Desk Study for electrical weed control in Field Vegetables

FV 266

Mechanical weed control for integrated and organic salad brassica production

HNS/PO 192

Herbicides screening for ornamental plant production (nursery stock, cut flowers and wallflowers)

HNS 198

Improving weed control in hardy nursery stock

SF 154a

Blackcurrant herbicide screening

SF 161

Rhubarb: Evaluation of herbicides for problem weeds - 2015


Weed control in potatoes – coping without paraquat


Reducing herbicide use in row crops with targeted application methods detected weeds in small patches or spots


Potential impacts of loss of pesticides on the GB potato Industry


BBSRC-HGCA Blackgrass project


Investigating the distribution and presence, and potential for herbicide resistance of UK brome species in arable farming


Preventing a widescale increase in ALS resistant broad-leaved weeds through effective management in a cereal-oilseed rape rotation


BBRO Pest, Weed and Disease Charts 2018 (


Annex 1: International Institute of Sugar Beet Research (IIRB) Weed Control Group Paper (2018) - The importance of phenmedipham and desmedipham for weed control in sugar beet. This paper was prepared by the IIRB Weed Control Group for consideration by SCOPAFF at its meeting in May 2018.


  • These reports and publications are available from the AHDB websites or the BBRO website
  • Applicants are expected to review the AHDB back catalogue.
  • Other relevant international and national research should be considered

All proposals submitted should have detail on the financial costs associated with the work.

Project duration

It is envisaged that a decision on the successful project will be communicated by 27th August 2018 and project outcomes should be presented to relevant groups by the end of December 2018. To allow for recommendations from the review to be implemented in 2019 this is a fast turn-around piece of work. A staged approach to the project and reporting may be required to fit with early planting of different cropping systems. 


The budget for this project is capped at £36,000.  Value for money to levy payers is a selection criteria.  The intention is to fund a single project but joint proposals are acceptable as are bids with subcontractors awarded to key industry consultants. Additional in-kind contributions and collaborations providing added value to the proposal will be considered favourably. If deemed productive, applicants may be requested to form a consortium and work together.    

Deadlines for the application procedure and project delivery

Full Proposal deadline

12:00 on 12/08/2018

There is no Concept or Expressions of Interest phase.

Make an electronic submission in line with the instructions below.

Receipt will be the time of receiving email.

Applications reviewed

Submissions will be evaluated internally by AHDB, BBRO and with Industry Representatives By 26/08/2018

Applicants informed of outcome

By 27/08/2018

Project commences

By 01/09/2018

Project completion

By 30/12/2018 (or later depending on start date)

To allow for recommendations to be implemented in 2019 it may require a staged completion particularly for early planting crops in the spring of 2019


If you have a specific question related to this call, please email As part of the open tender process, AHDB cannot discuss specific project details with you before submitting your proposal. View the Questions & Answers for this Research Call.

Completion and submission of the application form

Please refer to the guidance notes for completion of application forms. Applicants should complete the AHDB Research and KE Application Form - Full Proposal Large, completed forms must be emailed to no later than 12:00 noon on 12 August 2018.

Evaluation of submissions

A number of criteria will used to judge the quality of the submissions (value in brackets indicates weight in assessment process). Please click here to access the Standard Assessment Criteria.