05 Jun 2019
Rising pesticide use is harming wildlife – we need to change direction
Despite repeated claims to the contrary, pesticide use in UK agriculture is rising. Highly toxic active ingredients continue to be used and new equally harmful arrivals threaten to take the place of neonicotinoids, banned due to their impact on bees. In the pursuit of ever higher yields, we’ve developed a farming culture built upon use of chemicals, with pesticides routinely employed as an insurance policy. However, as yields plateau, farmers are struggling to survive with this high-input, high-yield farming model. At the same time the consequences are now becoming clear. Alarm bells are ringing as large numbers of wild species demonstrate steep declines. Intensive agriculture and pesticide use are clearly implicated.
It doesn’t have to be this way. Farming with reduced pesticide use can be more profitable and take advantage of the ecosystem services provided by a range of beneficial organisms which are so often harmed by pesticides. It’s essential that farming shifts urgently to more sustainable methods of pest and disease control.
The government has clearly signalled, through the Agriculture Bill, its intention to reward farmers for providing public goods that will deliver a cleaner, greener countryside. It’s also committed to putting integrated pest management (IPM), which prioritises non-chemical methods of pest and disease control, at the heart of its 25 Year Environment Plan. If it’s serious about halting the decline in wildlife and protecting the building blocks which nature provides for us, the government must honour its commitments, set clear targets for genuine reductions in pesticide use and fully support farmers to adopt IPM as a core practice at the heart of crop protection.
The truth about the growing use of pesticides
It’s commonly claimed by the farming industry
The focus on weight of pesticides masks key growth trends
The focus on weight as a measure of pesticide use gives a false impression. Consideration of three other metrics demonstrates rising overall pesticide use: area treated (measured as ‘spray hectares’); frequency of applications; and the number of active ingredients used (one pesticide product may contain several ‘actives’).
The vast majority of pesticides used are for crop production
Analysis of the figures for different crop classes demonstrates that for cereals the weight of pesticide applied has not decreased, but remained stable, and the number of pesticide applications has risen. In oilseed crops, both the weight of pesticides and the spray hectares have been increasing since 2000.
It is common practice to apply two or more pesticide products in a single spray pass on a field, and individual pesticide products can contain a number of active ingredients. Taking a closer look at individual crops demonstrates that for wheat, all three averaged metrics have been rising from 2000 to 2016. Spray passes have increased from 5.5 to 6.6; products used from 11.4 to 14.5; and active substances from 14.7 to 20.5. Similar growth trends are observed for potatoes: spray passes rising from 12.1 to 15.9; products from 15.2 to 24.4; and actives from 21.6 to 31
Despite a fall in overall weight of pesticide used, when measured by all other available metrics pesticide use is clearly on the rise, amply demonstrating that weight is a wholly inadequate metric for pesticide measurement.
We must end the use of highly toxic pesticides
Analysis of pesticide use must also take into account toxicity, in order to reflect pesticide impact on the environment. Efforts to reduce pesticide use should aim not only to reduce overall pesticide load, but to replace those which are most toxic. This principle lies behind the EU’s list of “candidates for substitution”, which aims for the most toxic pesticides to be substituted with less toxic alternatives
We can use an indicator such as Cornell University’s Environmental Impact Quotient (EIQ) to compare approximate toxicities
The fungicide chlorothalonil has a field rate ecological component of 33.1 (ie, high toxicity). It’s the most widely used pesticide in UK arable production, and its use has increased from less than 0.5 million kg in 2000 to over 2 million kg in 2016. The EU has recently announced a ban on this chemical. Another highly toxic pesticide of concern is the broad-spectrum herbicide pendimethalin, which has an EIQ ecological component of 55.8. Despite being included in the European Commission’s 2015 draft list of candidates for substitution, it was re-approved in 2017 and its use on cereals is rising. Greater emphasis must be placed on reducing the use of these and other highly toxic pesticides – otherwise we will continue with a cycle of allowing widespread use of harmful chemicals until one by one their use is banned.
A new class of pesticides known as neonicotinoids has grown in use substantially since 2000. The most widely used in 2016 was clothianidin, which was applied to 728,000 ha of arable crops. Clothianidin is one of three neonicotinoids that have now been banned by the EU for use on outdoor crops due to their overall impact on bee species. It’s important to note that this decision was made on the basis of sub-lethal impacts such as colony survival, or numbers of queens produced, which are not taken into consideration by EIQ calculations.
The three banned neonicotinoids were chiefly used as seed dressings, a clear example of prophylactic treatment, applied in advance of any pest attack. It’s been demonstrated that only a small proportion of these systemic pesticides remained within the crop plants. Up to 95% contaminated surrounding soil and water, being taken up by subsequent crops or adjacent wildflowers and other vegetation, acting as a route of transmission to affect pollinators
There’s a danger that these banned neonicotinoids will be replaced by new actives with a similar mode of action and toxicity. Sulfoxaflor is one such new insecticide, approved in several EU countries despite a number of studies showing negative impacts on bees. A recent review of data by the European Food Safety Authority (EFSA) identified a high risk to honeybees and bumble bees
A set of more robust tests for assessing impacts on bees – the EFSA Bee Guidance document - which led to the ban on the three neonicotinoids has been under discussion in the EU since 2013 but has not yet been adopted
The indirect impacts of pesticides must be taken into consideration
It’s also becoming clear that pesticide use can have indirect effects that are not due to direct toxicity or sub-lethal effects, but knock-on impacts. This is clearly illustrated in the case of broad-spectrum herbicides, where increasing the amount and range of herbicides used reduces abundance of non-crop plant species, reducing species diversity, habitat and food resources for insects, birds and animals. Herbicide usage (spray hectares) is rising, due to increased uses in cereals and oilseed crops. This is shown by the increase in treatment frequency. In 2001, only 4.0% of the oilseed area and 5% of cereals were being treated more than four times per year with herbicides. By 2016 this had increased to 22% of oilseed crops and 9% of cereals. Concerns about the indirect effects of herbicides have been growing, and there is a clear need for thorough and comprehensive research in this area.
The Cocktail Effect
An as-yet little-studied aspect of pesticide impact is their synergistic effect. Pesticides are often applied in combination, and the increasing number of actives being applied to agricultural soils means they will inevitably be present in the environment as mixtures, creating a synergistic cocktail.
There’s growing evidence that when pesticides are present in combination, this can change or amplify their impact on wildlife, for example changing behaviour and enzyme activity in earthworms
The growth in number and combinations of actives used in UK crop production emphasises the urgency of both adequate monitoring and the introduction of targets for overall pesticide reduction.
Why is our use of pesticides increasing?
Defra chief scientist Ian Boyd and his co-author Alice Milner
As farm sizes have grown, farmers have relied increasingly on agronomists for advice. Agrochemicals have become increasingly complicated, further increasing farmers’ reliance on agronomists to determine pest control strategies. Agronomists themselves are risk averse, and often under pressure to promote pesticide sales because many of them are employed by agrochemical companies. Peer pressure within the farming community also affects farmer behaviour, as does the insistence by supermarkets and consumers for high aesthetic standards. Despite ever-increasing inputs, yields have plateaued and the net result is that farmers are investing more and more in protecting their crops while profits decline.
Undoubtedly there has been a severe shortage of advice, training and research for more sustainable methods of pest and disease contro
Does banning some pesticides lead to increased use of others?
It’s frequently claimed that withdrawal of specific actives leads to greater overall pesticide use. This was particularly notable in the case of the recent ban on neonicotinoids. Industry claimed neonicotinoids were essential for oilseed rape (OSR) production. A partial ban on their use on flowering crops was introduced in 2014, which led to suggestions that farmers were responding by increasing pyrethroid use. While this may have been the case for individual farmers, government figures for the UK as a whole demonstrate that rising pyrethroid use occurred over previous years in parallel with neonic use, and not as a consequence of their withdrawal. Rather than using more pesticides, many farmers adapted to the ban through greater emphasis on IPM, for example using earlier sowing dates, or experimenting with innovative strategies such as overwinter grazing of OSR to remove flea beetle pests.
What needs to change?
The many recent reports of severe declines across a range of different species including bees and hoverflies
The scientific community is calling for a comprehensive revision of pesticide policy to deliver better monitoring and regulation of pesticides
Better regulation and monitoring are needed
The failure to address the cumulative, landscape-scale impacts of widespread pesticide use have been recognised by Defra chief scientist Ian Boyd and co-author Alice Milner
The pervasiveness of pesticides in the environment is highlighted by Professor Boyd, who noted that in the case of neonicotinoids, there was difficulty in performing field experiments on these chemicals because untreated ‘control’ plots were found to be contaminated
Milner and Boyd acknowledge that while the UK has one of the most developed regulatory and monitoring systems for pesticides, it has no systematic monitoring of pesticide residues in the environment, and no consideration of safe pesticide limits at landscape scales. They have called for regulation to be improved, with a much more rigorous authorisation and monitoring process encompassing the full range of toxic effects that could emerge when pesticides are used at scale, including long-term monitoring and assessment of unexpected impacts.
The UK must adopt a meaningful measure of pesticide use, not just a simple measure of weight of pesticide products used
The need for a new, more comprehensive metric for pesticide measurement has never been clearer, or more urgent. Consideration of the issues raised above demonstrates that not only is the current system of pesticide measurement by weight misleading, it’s wholly inadequate when attempting to assess the wide range of complex interactions pesticides have with each other and the natural world.
Defra has for many years acknowledged the inadequacy of our monitoring of pesticides, and that weight of pesticides applied is not a good measure of environmental impact:
“Reductions explained only in volume applied are meaningless with regard to risk as many new active substances are applied at much lower rates per hectare than the older products they are replacing, bringing about significant reductions in the weight applied, without necessarily resulting in any reduction of use or risk
The UK does not currently have a standard system to assess the contribution of individual pesticides to overall toxic load on the environment, or to give clear signals to individual users of the relative toxicities of the products they’re using.
Various attempts have been made to assess the real-world environmental impact of pesticide usage
Productive farming without pesticides
The need for sustained use of high levels of pesticide is far from proven – a recent French analysis
In the UK, a study of conservation agriculture practitioners has demonstrated that lower-input farming, with significant reductions in quantities of pesticide use, can often be more profitable
Cutting pesticide use could actually boost productivity in the long run
Recommendations
A new system of pesticide measurement must be adopted
Despite industry claims to the contrary, pesticide use is continuing to rise, with devastating consequences for wildlife. The UK must commit to a pesticide reduction target in order to reverse these trends and set an adequate level of ambition. Weight is a wholly inadequate measure for pesticide reduction, and a new target must be developed based on alternative metrics. Current data collection and analysis in the UK include measurement of area treated by pesticides and frequency of treatment. These could form the basis of a pesticide reduction target in the short term while a more comprehensive system is developed.
Reduction of the overall toxic load on the environment is imperative.
Pesticides vary widely in their toxicity to humans, toxicity to wildlife, and persistence in the environment. A variety of indicators is currently in use around the world which assess these factors to estimate individual toxicity and overall toxic load. It’s essential that the UK develops and adopts its own risk indicator, which should form the basis of a new system of pesticide measurement for the UK, alongside a reduction target. Such a system would also enable farmers to make the most sustainable choices.
To date there has been no monitoring of the long-term impacts of pesticide use at scale, their synergistic or indirect impacts, or other unexpected effects of their use. In view of the alarming wildlife declines we are witnessing this must be addressed as a matter of urgency.
Integrated Pest Management must be promoted.
Alternative practices to pesticide use must be prioritised. Consultation with farming industry representatives has identified a number of key measures to promote uptake of IPM. It’s essential that the government ensures the necessary support is provided to enable farmers to adopt IPM, including better, independent agronomic advice, farmer training, and more emphasis on farmer-focused research into non-chemical options and low-input farming systems
Clear targets and guidance must be incorporated in national policy
The Agriculture Bill presents a perfect opportunity to reduce pesticide use through adoption of a pesticide reduction target, and a new metric for measuring pesticide use based on toxic load in the environment, alongside measures to support farmers adopting IPM. The new agricultural support scheme which is being developed to replace the Common Agricultural Policy should reward farmers for the public goods resulting from pesticide reduction, such as improved water quality and increases in wildlife.
The 25 Year Environment Plan sets out a commitment to protect crops while reducing the environmental impact of pesticides (and includes this Action in chapter 4:
Putting Integrated Pest Management (IPM) at the heart of a holistic approach, by developing and implementing policies that encourage and support sustainable crop protection with the minimum use of pesticides.
Defra has not set out how it will deliver this target. It reviewed its Pesticides National Action Plan (NAP) in 2018, but failed to include public consultation as stipulated by the EU Sustainable Use Directive. The NAP is clearly the place where measures should be presented for cutting pesticide use and increasing IPM, but has been criticised by the EC for its failure to include clear and measurable targets and indicators for implementing IPM and reducing the risks and impacts from pesticide use. Incredibly, despite these criticisms and failure to consult the public, George Eustice (as Minister) declared that the existing NAP was “fit for purpose”.
As the UK prepares to leave the EU, the government:
- must ensure that we have a robust system of pesticides monitoring and regulation;
- must help farmers to move away from over -reliance on harmful chemicals;
- must find solutions that will boost nature and the long-term resilience of our food production.