Work Package 2.1 - Crop and grassland production and disease control
Sustainable crop protection minimises yield and quality losses from pests, weeds and diseases whilst reducing current reliance on pesticides. This is driven by the need to maintain, or increase, crop yields and quality for priority Scottish crops (barley, potato, soft fruit) whilst diversifying crop protection options, such that Scottish crop production systems will be greener and wealthier. Integrated management of pests, weed and diseases by maximising the beneficial effects of varietal resistance, crop agronomy, action thresholds and alternative control measures are key strategies. Pesticide losses as a result of legislative changes and the development of resistance provide a further driver for research into alternatives.
Aim of Research
The aim of this research is to understand the importance of factors that modify reliance on pesticides and integrate these into Integrated Pest Management (IPM) toolboxes tailored to key Scottish horticultural and arable crops. Novel control options, which reduce reliance on pesticides, are required because of reduced availability of plant protection products. IPM tools are being developed and evaluated in optimised combinations to suppress key pest and disease threats for each cropping system. This work integrates contributions from other areas of research e.g. new varietal resistance, pest monitoring and forecasting tools, and works closely with stakeholders to prioritise IPM research and promote uptake of best practice.
A programme of events promoting IPM, including four Agronomy roadshows, the inaugural Arable Scotland event and IPM@Hutton/CSC stakeholder event and the Royal Highland Show was undertaken in 2019. Several presentations based on this research were given at The Crop Production in Northern Britain meeting. These events reached a wide ranging audience of policymakers, growers and industry. Discussions demonstrated a renewed appetite for implementation of the broad principles of IPM, particularly considering the reduction in available pesticides.
In-depth analysis of survey data from 225 arable farms across the UK and Ireland revealed positive relationships between farm area and IPM adoption reflecting an increased capacity to take risks, rotate crops between fields and monitor pest levels intensively. Good working relationships with agronomists, farmer familiarity with IPM and seeking information from IPM experts at open days/crop walks/discussion groups were also key to IPM adoption. These findings highlight the need to focus on delivering current, evidence based IPM advice to growers through robust trialling and knowledge exchange.
Elicitors were found to reduce disease levels and protect yield in potatoes (powdery scab and root galling), oilseed rape (clubroot) and winter barley (rhynchosporium and powdery mildew). In winter barley the effect of the elicitor seed treatments was greatest when supported by an early foliar fungicide application and a combination of elicitors and fungicides significantly improved the control of potato foliar blight when compared with fungicides alone. Two independent inhibitors of a biochemical pathway and an inhibitor of protein lipidation which lead to reduced growth of the late blight pathogen P. infestans were identified, fluorescently labelled strains have been successfully developed and are being used to aid in agrochemical mode of action determination.
The proximity of crop debris to plant shoots and roots may influence levels of infection of barley by Ramularia leaf spot disease of barley; preliminary results showed that the fungus can be transmitted to the crop from debris in controlled conditions, thereby confirming anecdotal evidence from growers and having implications for no-tillage systems.
Cereal Toolbox: Advice on tailored approaches to crop protection programmes for Ramularia leaf spot was given at various events. Potato Toolbox: Over-irrigation led to an increase in tuber contamination from environmental Pectobacterium the cause of potato blackleg. Soft Fruit Toolbox: A technical report documented the main insect pests of blueberry and natural enemies suitable for pest biocontrol.
Uptake of Integrated Pest Management measures: Factors affecting IPM adoption on arable farms were identified through applying a universal metric, developed to facilitate the practical monitoring and measuring of IPM adoption in the UK and Ireland. High IPM adopters preferred to receive IPM advice from independent agronomists, crop walks/open days and discussion groups. Incentives to promote IPM adoption must therefore consider the importance actively engaging with IPM experts.
Late Blight IPM: Potato growers understandably, but wrongly, associate the reduced fungicide inputs and reliance on host resistance used in IPM approaches with an increased risk of tuber blight, a disease of very high economic impact. Field experiments showed that cultivars with moderate disease resistance reduced the risk of tuber blight to between 2.5-8% of a susceptible cultivar. Field trials using an IPM approach to fungicide application based on disease forecasting again showed effective disease control with reduced inputs. These data are crucial in modifying growers’ understanding of blight risk and facilitating the uptake of late blight IPM tools.
Elicitors of plant defence: The potential role of elicitors in reducing fungicide inputs if the elicitor is applied prophylactically was demonstrated in barley, oilseed rape and potatoes. This elicitor effect is often best demonstrated when the elicitor is applied in combination with synthetic fungicides to offer protection later in the season.
The Mains of Loriston Trust (£54K) to investigate the scope for adjusting fungicide inputs based on a combined effects of tillage regime and crop variety in winter barley crops. The results will inform future IPM strategies and recommendations.
- EU Horizon-2020 (£220k) for “IPMWORKS An EU-wide farm network demonstrating and promoting cost-effective IPM strategies” The project aims to promote the adoption of IPM strategies, allowing a low reliance on pesticides with better pest control, reduced costs and enhanced profitability.
- UKRI (£914k) ‘A Decision Support tool for Potato Blackleg Disease’ This project aims to improve disease control by focusing on irrigation regimes, monitoring and management of free-living nematode (putative Pba vectors), changes in crop rotations and the use of cover crops, and the use of physical protection to reduce aerial transmission. This is supported by environmental data subjected to novel machine learning methods to develop a series of integrated decision support tools for industry use.
Eight IPM themed events across Scotland were used to communicate key messages relating to the need to modify fungicide and insecticide programmes according to season, soil conditions, rotation and variety. The need for a holistic approach to pest management, from soils to fungicide usage was stressed. IPM practitioners were informed of the current and anticipated regulatory changes regarding pesticide availability. Key findings and issues were discussed with government policy makers and key stakeholders such as Scottish Quality Crops Ltd and the Voluntary Initiative.
A method for assessing uptake of IPM practices on arable farms was devised through collaboration with research institutes in England, Ireland and Northern Ireland. This ‘IPM metric’ was based on the expert opinion of c. 50 stakeholders and was tested in farmer survey for which over 200 responses were collected. The survey results showed that level of adoption of IPM practices varied over the sample. All had adopted IPM to some extent but only 6% of farmers had adopted more than 85% of what is theoretically possible, as measured by the new metric. This metric could be a viable and cost‐effective method to facilitate the benchmarking and monitoring of national IPM programmes, including National Action Plans for the Sustainable Use Directive, in temperate arable farming systems.
Research on risk modifiers in wheat and barley this year demonstrated the significant role of weather in disease development: the harsh winter and dry spring curtailed disease development. Research on risk modifiers for late blight in potatoes led to recommendations being made based on varietal resistance for both leaf and tuber blight. Workshops and surveys supported the notion that there is a perceived risk associated with high levels of IPM adoption. Unless this risk is shared amongst others in the supply chain then high levels adoption may not be economically feasible for the farmer.
The influence of different environmental factors on the barley disease Ramularia leaf spot was analysed and increased rainfall and temperature were significant drivers of disease progression and will be studied in more detail in controlled environment work. Work on the importance of other stages in the life cycle on epidemic progression are under way. A guide and video to identifying symptoms in the field was produced in conjunction with AHDB and articles on Ramularia were published in the farming press.
Products which elicit plant defence pathways (i.e. elicitors) and therefore have the potential to protect plants against disease development, were tested in cereal and potato crops. In barley the value of these elicitors, particularly in a reduced rate fungicide programme, to manage diseases such as ramularia and powdery mildew was demonstrated. In potatoes, elicitors were shown to have potential to control powdery scab and to reduce root galling. Working with manufacturers has granted access to novel biological alternatives to synthetic pesticides that are currently approaching, the market.
Potato Toolbox: The “Hutton criteria” for forecasting risk of late blight was validated through field trials and comparison with other available models. The Decision Support System (DSS) was promoted through various industry focused events. Oilseed rape toolbox: IPM solutions for the control of clubroot showed that the clubroot population in the UK is very diverse so it's not sensible to rely solely on current varietal resistance for control. A recommendation to only use resistant varieties in fields known to have clubroot issues was made as overuse of these varieties will hasten the breakdown of resistance. The need to test soil and monitor the situation on farm was communicated to stakeholders. Cereal Toolbox: Factors such as sow date, seed rate and variety were shown to influence the need for fungicide in wheat and barley. Advice on tailored approaches to crop protection programmes has been amended and there has been an uplift in the varietal disease ratings deployed by growers.
- Late Blight IPM: research has tested late blight management components including host resistance, disease forecasting, spore detection, inoculum sources and fungicide programmes in consultation with stakeholders. Reduced fungicide input applied to cultivars with high foliar blight resistance ratings gave good control of late blight under high disease pressure. Susceptibility to tuber blight has been recognised as a potential barrier to late blight IPM uptake and industry alerted. Recent work on tuber blight achieved a reduction in fungicide costs of 28% through use of host resistance in commercial practice.
- Potato Blackleg IPM: The use of bacteriophages as an option for potato blackleg disease control, where chemical use is not available gained traction. Field trials provided underpinning science to support a successful £800K Innovate UK application, in collaboration with biocontrol, agronomy and potato industry partners to move the research to commercial application with a potential estimated EU market size of £37M.
- IPM toolboxes for important Scottish crops are being assembled. There is evidence of on-farm pesticide reductions and uptake of alternative control methods in soft fruit. Over-reliance on pesticides in oilseed rape has led to declines in efficacy and therefore guidance on fungicide efficacy and resistance management has been developed. Building on results, targeted treatments through field mapping of disease has been supported by industry funding. Agrochemical companies are interested in developing seed treatments based on evidence generated from field trials for elicitors to reduce clubroot and therefore decrease fungicide applications.
- Based on information showing the continued presence of a metalaxyl-M resistant lineage of P. infestans in Scotland, application of the fungicide reduced from 25,000Ha of treated potato in 2006 to 73Ha in 2016 (Scottish Pesticide Surveys Database, SCOPES). Similarly, we have reported evidence of insensitivity to the key fungicide Fluazinam, currently used to treat >90% of Scottish ware and 76% of Scottish seed crops (SCOPES) resulting in rapid changes to industry advice on use (e.g.Farmers Guide, Syngenta, Crop Protection Magazine, Farmers Weekly). These interventions prevented the use of ineffective products and the consequent crop losses and environmental impacts in the UK and internationally. Results are incorporated into updated 2018 FRAG-UK guidelines for optimising fungicide use.
Four summer field trial events showing themed trials were linked with four workshops, delivered around Scotland, covering IPM findings. Key themes featured tailoring inputs to seasonal risk and the use of sustainable solutions. Links were made to soil health talks and to presentations on pollinators. Barriers to uptake of IPM were explored and three key findings emerged. 33% of growers were unaware of IPM. Industry is divided as to the best:best and worst:worst options; they over-estimate responses to fungicides and over-estimate grower uptake of resistant varieties.
Historic trial databases and a long-term database of Scottish crop disease surveillance in commercial crops (known as the 'adopt-a-crop' database) were mined for detail on barley diseases. The effects of wet weather, varietal resistance and sow date were identified as the most significant drivers of disease. Analysis shows that there is scope for greater uptake of IPM in Scotland as key risks are not reflected in farmer uptake of IPM measures such as resistant varieties despite the willingness expressed in co-construction workshops to the adoption of such measures.
Ramularia leaf spot in barley causes large yield losses in Scottish barley crops and affects the quality for markets such as malting. Risk factors are not well understood so an annotated life cycle diagram was prepared which highlights where knowledge is based on peer reviewed evidence and identifies areas where there is still uncertainty over the life cycle and the key drivers of disease risk. A ramularia field guide and a technical note were prepared and a series of press articles raising awareness and promoting accurate identification were published in the farming technical press.
Novel products based on natural plant compounds such as sugars and starches were tested in combination with full and reduced rates fungicide programmes for disease control and results showed that they offer potential to reduce fungicide inputs in barley and potatoes. Discussions were held with manufacturers of these products to determine the potential and timescale for bringing such products to market.
Oilseed rape toolbox: Field mapping was added to the suite of varietal, fungicide and defence elicitor treatments previously evaluated against clubroot affecting oilseed rape were carried to test if targeted approaches to treating this patchy disease would be viable. Cereal Toolbox: In wheat, delayed drilling, varietal resistance and crop density were evaluated alongside low moderate and high fungicide inputs. Results show that reduced inputs are possible in low risk scenarios. Potato Toolbox: The use of the “Hutton criteria” for predicting blight risk was incorporated into IPM trials and was promoted in commercial practice.
- Integrated pest management: Using evidence from recent research on cropping and pest management issues, an online planning tool was developed and delivered. In 2017 its use was recommended by Scottish Quality Crops Ltd, a scheme which assures >90% of Scottish combinable crops and this will become a requirement in 2018. Of the available IPM options, growers were shown to be most willing to use more resistant varieties. Varietal disease resistance ratings have been discussed at industry forums and greater uptake of disease resistant spring barley varieties (e.g. Laureate) is evident while Concerto, an older variety of spring barley has declined. Similarly, wheat varieties with poor untreated yields (e.g. Viscount and Myriad) are declining, while new varieties with improved disease resistance (e.g. LG Motown, LG Sundance, Revelation), have increased.
- Information on new resistant variants of endemic pathogens linked to fungicide anti-resistance strategies produced by the Fungicide Resistance Action Committee (FRAG-UK) and AHDB led to improved stewardship, with increased use of mixed chemistry and low-risk multisite fungicides with the Scottish Pesticide Surveys Database (SCOPES) data showing a 67% increase in the use of the low risk multisite fungicide chlorothalonil in 2016 compared with 2014.
- Cereals Knowledge Exchange: A stakeholder workshop was held to develop best practice interventions in cereals and to identify potential barriers to uptake amongst end users, complementing research on adoption of IPM practices amongst arable farmers. Resulting information on improved targeting of fungicides was incorporated in AHDB barley growth guides and FRAG-UK fungicide stewardship guides.
- Fighting pest and pathogen resistance in agriculture: Additional funding (£33K) was secured from the Mains of Loirston Trust to investigate the scope for omitting early applications of fungicides to spring barley crops where the risk of Rhynchosporium commune epidemics developing prior to flag leaf emergence are low. The results will help inform future strategies for Integrated Pest Management (IPM) and the stewardship of fungicides.
- From research to outcomes. An event was held on 7th December 2017 to showcase outcomes of crop science research and their benefits to Scotland and beyond. In attendance were Scottish Government policy makers and key stakeholders including industry representatives (50 in total). A feedback survey demonstrated that participants appreciated the enhanced lines of communication and so the event will be held annually, developing the format according to the feedback.
- Uptake of Integrated Pest Management measures: A greater capacity to use sustainable disease control measures in Scotland and a willingness amongst farmers to do so was identified. Information regarding the overestimation of yield responses to fungicides and failure to moderate inputs according to seasonal risk was shared with industry and SG colleagues concerned with the implementation of National Action Plans for the Sustainable Use Directive.
Field demonstrations, trial events, articles in the farming press, podcasts, winter workshops on integrated pest management (IPM) and a cross-sector IPM science workshop were delivered. Practical IPM workshops collected evidence on farmer's and agronomist's attitudes to pest management, priority diseases and current management practice. Analysis showed that there was greater potential to take up resistant varieties to reduce fungicide use. Contributions were made to stakeholder groups and forums such as the Fungicide Resistance Action Group which has given rise to specific industry guidelines and updates on pesticide stewardship.
A review of disease management decision making was carried out and provides information that allows an overall risk assessment to be made when evidence from several concurrent risks, which may have been measured using different scales, needs to be quantified. Database mining has quantified the key disease risk for Scottish barley crops and shown that yield benefits from pesticides are often smaller that growers think. This long-term analysis ruled out the direct influence of environment on Ramularia epidemics and showed that spore movement 100 days before harvest is important in disease development. This will be used to develop a risk warning system to allow Scottish farmers to tailor their fungicide inputs to risk and to select more resistant varieties.
Two IPM publications delivered the 8 principles of IPM. Alternatives to pesticides e.g. biological control agents and elicitor products which prime host plant's own defences were tested in potato, barley and oilseed rape trials and a paper was published on the brassica results. Work will now focus on integrating the most effective products into fungicide programmes. Cereal and oilseed rape variety testing trials contributed resistance data to industry committees that list new varieties suitable for growing in Scotland. Genes involved in encoding potential new disease control targets have been validated for Potato Cyst Nematode, P. infestans and R. commune and are being tested. Spore trapping methodology for the barley pathogen Ramularia has been developed to inform risk surveillance.
- Delivering to the UK national action plan and the sustainable use directive: SEFARI scientists worked with the Scottish Government, the Voluntary Initiative in Scotland and National Farmers’ Union of Scotland on the development of a web tool for Integrated Pest Management (IPM). The new approach will discourage the development of weed, pest and disease populations and so minimise the use of pesticides and enable pesticide usage that is more cost effective and ecologically justified. IPM is a vital part of delivering the UK National Action Plan (Sustainable Use of Pesticides) and SEFARI’s expertise in IPM is helping Scottish Government meet its obligations under the EU sustainable use directive.
- Reduced environmental inputs: Ramularia leaf spot (RLS) reduces barley yield and quality and influences malt quality. Annual yield losses have been estimated at ca. £9M. SRP research led to the suspension of the current Ramularia resistance ratings on the AHDB recommended list. A Ramularia technical note and identification guide were published including guidelines for growers (>23,000 UK levy payers, >2,000 in Scotland) on avoidance of Ramularia infection in barley crops. SRP scientists revealed a shift in fungicide sensitivity of Ramularia and advice was given to farmers of the importance of incorporating chlorothalonil into their spray programme. In Scotland between 2014-2016, winter and spring barley area treated with chlorothalonil increased (8% & 21%, respectively).
- The genome sequence of the barley pathogen Ramularia collo-cygni has been annotated offering insights into the biology and infection strategy of the fungus, the potential to examine the interaction between the pathogen and the host and informing effective crop protection programmes.
With evidence of fungicide insensitivity, research using targeted approaches to design new crop protection products is timely. SRP developments in pathogen genomics and life cycle biology have allowed a re-evaluation of target-based screening approaches for identification of new agrochemicals in consultation with four international agrochemical companies. Incremental steps to accelerate the pesticide discovery process can have a multi-million-dollar impact and based on our information, screening within lead discovery programmes has been re-evaluated.
IPM research will continue to bring together management components within IPM toolboxes, including host resistance, disease forecasting, spore detection, inoculum sources and fungicide programmes in consultation with stakeholders and in alignment with policy makers’ considerations. Future research will, in collaboration with industry and through involvement in international consortia, improve, develop and deliver components of best practice.