Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

The control of perennial weeds in organic stockless and pasture systems - OF0367

The overall objective is to improve the management of difficult-to-control perennial weeds in organic farming systems. The project was initiated by Defra in response to the research recommendations developed by the Advisory Committee on Organic Standards (ACOS) R&D committee informed by the Defra project OF0350: "Stakeholders issues and aspirations to inform future public funded research in organic farming" ( ACOS identified research into the control of perennial weeds in organic stockless and pasture systems as a research need. Control of perennial weeds (principally docks) was also overwhelmingly the main issue coming from stakeholders in "Participatory investigation of the management of weeds in organic production systems" (OF0315). Perennial weeds (predominantly creeping thistle) were identified as the main biological constraint in project OF0318 "Assessing the sustainability of a stockless arable organic rotation".

A large number of individual weed reviews were done in project OF0315. These will be collated and updated with the conclusions of other recent reviews. We will include couch grass, bracken, creeping thistle, rush and docks. From our experience, and the outcomes of various consultation exercises, these are the most widespread, and difficult-to-control, perennial weeds in pasture and stockless systems. Gaps in knowledge required to better manage these weeds will be identified. An expert group will be convened in summer 2006. It will debate the outcome of the review and advise the project steering group on priority weeds for further study taking account of those: a) causing the greatest economic, environmental, social and landscape impact, and b) with the best opportunity for progress from further research within the timescale of this project. A maximum of three weeds will be selected for further study. We will aim to maximise the value to stakeholders of the money invested in this project. Invitations will be extended to key staff from ADAS, HDRA, Defra, farm advisers and researchers from other organisation in the UK and further afield.

There are likely to be two types of experiment – to research basic weed biology, and to research control methods. The biology experiments may cover issues such as the relative importance of seed versus vegetative and mechanical spread of couch grass, or the survival of weed seeds in silage or slurry. These experiments would be relative short term and may be in the field or in the glasshouse at ADAS Boxworth. The locations, treatments and design of the experiments to research control methods would follow from the deliberations of the expert group. Sites would be on established research locations with a known and recorded problem, or on suitable commercial farms. For example, ADAS Terrington would provide an ideal site for creeping thistle studies, if that were a selected weed. We know from reviews already done in OF0315 and from results of studies done within OF0318, that in stockless systems, the nature, management and duration of the fertility building phase of the rotation has a major impact on weed population. Therefore, these are probable treatments in experiments. Crop durations of up to two years are likely to be compared and then followed by a test cash crop. Therefore, field experimental work is likely to run through 2007, 2008 and 2009.

The effect of fertility practices on the management of perennial weeds and the effect of weeds on fertility building will be assessed in collaboration with project OF0363, Fertility building in stockless systems, and would be done on common sites or in integrated experiments. A suitable monitored site would be the core study of OF0318, Assessing the sustainability of a stockless arable organic rotation, which has a high and (importantly) even population of creeping thistle. The economic impact over the whole rotation, to gross margin level, of adopting the treatments successful in controlling perennial weeds in the experiments would be modelled. Data on crop performance from OF0318 and OF0332, Organic field vegetable production - baseline monitoring of systems with different fertility building strategies, would be used in the models.

Regular communication events will be arranged in conjunction with project OF0363. These would be mainly field-based events on the experiment sites. The aim will be to communicate best practice as outlined from the review process, and to receive feedback, particularly from farmers and growers, that could influence the direction of the studies. We will offer the review and the results of field experiments, if suitable, for publication in peer-reviewed journals. Brief details will be placed on an existing web site. This will contain details of the project, communication events, publications and the outcomes of the review and experiments.

The project will directly benefit farmers and growers by leading to improved control of perennial weeds in organic stockless and pasture systems. Better control options should reduce costs and improve yields. This will help sustain existing producers and help encourage more conversion to stockless arable and vegtetable systems. This will help increase the supply of UK-grown arable and horticultural products which will help Defra meet Organic Action Plan targets, and benefit consumers by increasing choice.
The overall objective is to improve the management of difficult-to-control perennial weeds in organic farming systems.

1) Review the literature on the management of the principal perennial weeds affecting organic farming systems. There will be emphasis on already identified areas of particular concern: pasture and stockless systems.
2) Agree priority weeds for further study through the use of an expert group. Weeds will be selected where further research could make progress in the timescale of the project, and which give best value for money.
3) Design and conduct experiments in both pasture and stockless systems to develop methods to control the three highest-priority weeds.
4) Assess the effect of fertility practices on the management of perennial weeds and the effect of weeds on fertility building.
5) Analyse the environmental and economic impacts of the control of perennial of weeds.
6) Communicate results of the work to stakeholders.
Project Documents
• FRP - Final Report : OF0367 The control of perennial weeds in organic and low input farming systems Finalreport   (2395k)
Time-Scale and Cost
From: 2007

To: 2011

Cost: £340,281
Contractor / Funded Organisations
Farm Management              
Organic Farming              
Fields of Study
Organic Farming