Can you grow organic potatoes without copper?

Copper has long been used in organic agriculture to control a variety of fungal and bacterial diseases such as potato late blight, apple scab and grape downy mildew. Now concerns over negative environmental impacts have led to restriction on its use. In 2019 there was no authorisation in the UK for its use on potatoes.  This raises the question what are the alternatives?

Ed Moorhouse, Head of Strategy Development with Itaka Crop Solution is to discuss the role of preventative strategies for managing late blight at a workshop on 18th September “Growing organic potatoes without copper’ organised by RBOrganic as part of the Organic-Plus research programme.

Giving up copper for crop protection

The French National Institute for Agricultural (INRA) commissioned a review of the current scientific and technical information to identify research directed at developing alternatives to copper; which is a powerful anti-microbial.

The INRA report “Can organic agriculture give up copper as a crop protection product?” published in June 2018 provides a useful overview of the current status of thinking.

The report looked at:

  1. Solutions – and concluded that there are a range of possible individual technical solutions these include: disease-resistant varieties; natural substances with biocidal effects and/or the capacity to stimulate natural plant defences; antagonistic microbiological agents and the improved management of crop canopies to prevent disease.
  2. Strategies  – how to incorporate these solutions into existing production/pest management systems
  3. Barriers  – what conditions are necessary for the adoption and diffusion of these integrated strategies.

The analysis found that there are numerous methods that have some degree of efficacy against the pathogens, but there has been insufficient exploration of how these approaches can be combined within agricultural systems. This applies particularly to organic agriculture, but also to other forms of agriculture that are seeking to reduce pesticide use.

The late blight workshop “Growing organic potatoes without copper’ will explore potential alternative products and resistant varieties as well as hearing from growers that are growing without copper.

Itaka’s integrated approach

Itaka is evaluating the integration of microorganisms and extracts from natural products to reduce pest and disease pressure within an integrated program. The objective is to build plant health and resilience to adverse environments. The future of control will be in the use of a combination of strategies to support a more balanced agro-ecosystem.

Disrupting pathogen life cycle

The INRA report supports this approach. It stresses that knowledge of the pathogen life cycle provides opportunities to disrupt its development.

For example, the leaf canopy provides conditions that an encourage spore dispersion and germination, so ventilation to reduce moisture can be beneficial.  Spores overwinter in infected tissue so microorganisms that break down plant litter can ‘clean up’ the soil ahead of the next crop. Also natural biocides from plant extracts can prevent colonisation and spore germination.

Selection of varieties resistant to blight can provide an agronomic approach and it reviews the obstacles to the use of the resistant material that is available.

Modes of action  

Biocides – One of the promising developments is the use of natural extracts with biocidal properties, these preparation stimulate the plant defences and under controlled conditions have suggested they are a promising potential substitute for copper. However, more research is required on the impact on the harvested crop.

Competition – Another area of research, identified by the report,  is the use of biological control organisms, which can act against pests by way of antagonism, hyper-parasitism, or ecological competition. Future development of these products would require regulatory approval.

Plant defence stimulators (PDS) – many products and molecules with proven biological activity have been identified, but moving these products from the lab to the field has proved challenging. The product must be able to penetrate the plant and timing of application is crucial, for example defence stimulators must be activated before infection.

Itaka is a leader in the development of bio-rational solutions based on these modes of action and Ed will be discussing some of the paths being evaluated in the workshop.

Workshop: Growing organic potatoes without copper

The workshop will focus on late blight in potatoes and explore potential alternative products and resistant varieties as well as hearing from growers that are growing without copper.

Location: RBOrganic, Great Drove, Yaxley, Peterborough, PE7 3TW

Programme: 10.00 – 14.00

10.00 Coffee and registration

10.30 Welcome and introductions – Ben Raskin, Soil Association

10.40 Where are we on copper? – Sarah Hathway, Soil Association Certification

10.50 Biological preventative strategies – Ed Moorhouse ITAKA

11.10 Growing without copper – Case Study – Joe Rolfe RB Organic

11.30 Tea break

11.40 Organic Plus – the European Picture

12.00 Discussion forum. Creating shared roadmap for the future of Organic UK Potato production

13.00 Lunch

14.00 Depart

To register: click here 

To read the INRA report:Can organic agriculture give up copper as a crop protection product?

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