Farming Oilseed Rape without Neonicotinoids

In 2013, following a thorough scientific review by the European Food Safety Authority (EFSA) and a vote by Member States, the European Commission restricted the use of three neonicotinoid pesticides which posed a “high acute risk” to honey bees. The current restrictions are unlikely to be changed before 2017, at which time they could be extended or made permanent. Friends of the Earth believes that, due to the mounting evidence of harm to bees since the restrictions were introduced the ban should be made permanent and applied to all crops in order to protect bees and other wildlife.

Farmers need effective alternatives to neonicotinoids that do not harm bees or other beneficial insects. This report looks at evidence and farmer practice in using non-chemical methods of pest control in oilseed rape (OSR).

Our research found that combining a range of alternative techniques in a genuine Integrated Pest Management (IPM) approach should enable farmers to significantly improve control of OSR pests without neonicotinoids.

The need for an alternative approach

There is a clear need to develop an alternative approach to pest control in OSR. Evidence is mounting that insecticides are harming the very ecosystem services – such as pollination and natural pest control – that farming relies upon. Added to this is the increasing development of resistance of key pests to the chemicals used to control them, making these controls ineffective in the long term. Under EU law (EU Directive 2009/128/EC), farmers are already expected to practice Integrated Pest Management. But it is increasingly clear from surveys that much of the OSR in the UK has not been grown according to IPM principles. For example, crop rotations have been shortened, and pest thresholds and monitoring protocols are available but not widely used. Instead insect pest management in OSR has hinged around the use of both pyrethroids and neonicotinoids. Many of the commercial neonicotinoid seed dressings, such as Modesto, also contain a pyrethroid, so neonicotinoids did not replace pyrethroids. Over-use of pyrethroids has led to widespread resistance in key pests, despite which they continue to be widely used, and resistance to neonicotinoids is also becoming apparent. Using insecticide treated seed is not compatible with IPM because it involves treating the crop before any assessment of pest threat is undertaken, it is basically an insurance treatment against possible pest attack.

Surveys show that there was not a widespread take up of IPM measures following the restrictions on neonicotinoids. However there are farmers (some who are featured in this report) who are farming successfully without neonicotinoid and reducing their overall reliance on chemicals.

Towards non-chemical pest control in OSR

Our research concluded that there is plenty that farmers can do now to reduce pest pressure using a variety of non-chemical approaches in line with a genuine IPM approach. Doing so will bring additional benefits including control of other pests and nitrogen retention.

From available evidence and existing practice it is clear that the following measures are effective and should be more widely employed in OSR production:

  • Wider use of current advice on pest monitoring and thresholds. The first step of IPM should be to assess the threat to the crop (including for weeds and diseases, as well as insects) so that pesticides are only used when the thresholds are exceeded.
  • Use of natural enemies of key OSR pests. Natural enemies can be encouraged via a network of habitats around the farm, including hedgerows, beetle banks and flower-rich margins. Encouraging natural enemies into the cropped area to maximise pest control will require reduced spraying of insecticides, fungicides and broad spectrum herbicides.
  • Follow current agronomic advice for crop establishment:

›› Establish the crop early

›› Avoid sowing into bare earth

›› Use a method that minimises soil disturbance.

›› Minimum tillage has also been found to help conserve natural enemies. These are all current good practice guidance but recognising that particular local conditions of each farm could sometimes require a different approach.

  • Disease resistant OSR varieties.

›› Can reduce the need to completely control aphids – an OSR variety resistant to turnip yellows virus (TuYV) is now available to farmers.

The following measures also show considerable potential, and deliver other benefits to farmers:

  • Trap crops e.g. of turnip rape around fields of OSR. Good results in reducing pest attack on OSR have been obtained in some but not all trials.
  • Companion crops can provide a range of agronomic benefits (e.g. improving nitrogen retention and out-competing weeds) and in some trials has shown potential to reduce pest pressure.
  • Introducing new crops to the rotation to increase the interval between OSR crops, reduce the financial risk should the OSR crop fail, and diversify sources of farm income.

Some methods have stronger evidence of effective pest control than others, partly due to non-chemical controls not being given priority for research. But all these methods show benefits to farmers and the environment. The same cannot be said of chemical controls.

Are neonicotinoids effective?

In 2015 the NFU successfully applied for an emergency authorisation for the use of two of the restricted neonicotinoid seed treatments (Modesto and Cruiser). Part of its case was that non-chemical controls for cabbage stem flea beetle (CSFB) are not proven. Yet there is no consistent evidence of the effectiveness of neonicotinoid seed treatments as has been noted by the Defra Chief Scientist and a review of evidence relating to neonicotinoids published by the Royal Society (Godfray el at).

In 2014/2015, the first year that the restricted neonicotinoids were unavailable, OSR yields were above the 10 year average. In the following growing year, AHDB surveys show that early crop losses attributed to CSFB in December 2015 from OSR that was mostly grown from untreated seed were similar to, but slightly lower than, crop losses at the same stage in 2014. Loss due to CSFB was at similar levels to losses recorded from other causes. Some farmers (including one featured in this report) who used treated seeds under the 2015 emergency authorisation are reporting seeing little difference in CSFB damage between treated and untreated fields.

Increasingly evidence suggests limitations to the use of neonicotinoids including:

  • Most of the pesticide (up to 90%) is not absorbed by the crop and is released intothe environment
  • Susceptibility to the pesticide leaching into soil in heavy rainfall
  • Potential to harm beneficial insects that are important for controlling other pests of OSR such as slugs
  • Pests developing resistance to neonicotinoids.

There has been a focus on the challenges farmers will face in controlling CSFB,for which neonicotinoids have been marketed to farmers as an effective means of control, but in 2015 damage from slugs was at least equivalent to damage from CSFB. Neonicotinoids do not control slugs and could harm natural predators relied upon for slug control such as carabid beetles. This, combined with evidence of harm to pollinators, suggests that neonicotinoids could be doing more harm to food security than good.

Neonicotinoid seed dressings are often used prophylactically without reference to the level of actual pest risk. The emerging picture from research and monitoring is that in many cases their use was not economically justified.

It would not be reasonable or scientific to set a higher bar for proof of efficacy for non-chemical controls over pesticides such as neonicotinoids.

There needs to be a more balanced consideration in decisions regarding applications for emergency authorisation of neonicotinoids, and in advice that the NFU, AHDB, and other industry bodies give to farmers about pest control.

The way forward – sustainable Oilseed Rape

At the time of writing this report OSR prices are rising and so it seems likely that farmers may decide to plant more OSR in Autumn 2016, than last year, since surveys show that generally price is a stronger factor in decisions about what to plant than pest pressure.

Our research shows that non-chemical controls are a valid alternative to neonicotinoids for farmers choosing to grow OSR. There are methods that should certainly be used more widely now and a longer list of options that should continue to be trialled over the longer term as the basis for developing a more sustainable system of OSR production.

Continued research to improve our understanding of, and maximise the effectiveness of, non-chemical techniques will benefit farmers.

Despite the emerging problems with efficacy and resistance, the past availability of chemical control for key OSR pests has meant that research into pest monitoring and thresholds, natural pest control,

cultural approaches and resistant crop varieties has been treated as a low priority by industry an Government. This needs to change. Sharing information and knowledge among farmers will also be key to ensuring that nonchemical methods are adopted more widely. The restrictions on neonicotinoids must stay in place to protect bees and other beneficial insects.

As our knowledge develops about the damage to ecosystems caused by pesticides, and about our dependence on natural systems it is increasingly clear that farming needs to reduce its use of chemical pesticides.

Our future food production and the protection of much of our best loved and most valuable nature including bees requires a new approach based on non-chemical control as the main means of pest control with pesticides only used as a last resort.

source: Friends Of the Earth, UK

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