Rule reminder: Key pesticide stewardship guidelines

Plant protection product stewardship campaigns are now at the heart of industry efforts to prevent further losses of under-threat active ingredients.

Here, we give a reminder of the key actives in the spotlight and any stewardship guidelines or information available to help mitigate risk of problems arising from their use.

Nematicides

Granular nematicides play a vital role in controlling soil-borne pests in potatoes and other root crops and the Nematicide Stewardship Programme aims to promote responsible and sustainable use and protect operators, the environment and consumers.

The initiative brings together manufacturers Dupont, Syngenta and Certis and is supported by several industry bodies, including the AHDB, AIC and NFU.

It offers best practice advice for growers using nematicides, summarised as follows:

Seek professional advice from a Basis-qualified agronomist before purchasing and using nematicides and ensuring operators applying the products have the appropriate industry qualifications.

Application machinery should be regularly calibrated and growers should be able to show that applicators have been inspected and certified by the National Sprayer Testing Scheme (NSTS) at least every two years, but ideally every year.

Keep records of daily checks, weekly calibrations and that area treated and product volume used matches for each field.

Protect the environment by preventing granule spills during filling and application processes.

Protect operators by using the correct personal protective equipment (PPE) in line with product labels and Coshh assessments.

Monitor wildlife post-application. Treated fields should be checked 24 hours after application for bird or animal carcasses. Any carcasses found indicate poor incorporation of product. If granules are seen on the surface they should be incorporated immediately and any carcasses removed and covered. The incident should then be reported to the Wildlife Incident and Investigation (WIIS) using the UK free-phone number 0800 321600. Also, the granule manufacturer.

More detail on each aspect of the best practice protocol can be found at www.nspstewardship.co.uk, where there is also a handy video guide to applicator calibration.

Metaldehyde

Late in 2018, Defra secretary Michael Gove announced that metaldehyde would be banned for all outdoor applications from spring 2020, with greenhouse production the only situation where the slug killer will be available.

The decision comes after the UK Expert Committee on Pesticides (ECP) and Health and Safety Executive deemed the active to pose an unacceptable risk to birds and mammals.

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The disappointing news came after more than a decade of the industry battling to prove the active could be used responsibly and in a way that minimised pollution of raw drinking water supplies.

In a last-ditch bid to save the active and gain re-registration, the Metaldehyde Stewardship Group (MSG) introduced enhanced stewardship guidelines for autumn 2017, which increased the protection of watercourses and wildlife such as birds and small mammals.

Despite the active not gaining approval for outdoor use, it is vital growers to continue follow the enhanced guidelines for the remaining period of metaldehyde use.

The Enhanced Metaldehyde Stewardship Group guidelines are:

No pellets to be allowed to fall within a minimum of 10m of any field boundary or watercourse

Use minimum active ingredient per ha to avoid drainage and run-off losses

Maximum application rate 210g metaldehyde/ha. For additional protection of water, suppliers/Basis advisors may recommend rates reduced to 160g/ha or less

Maximum total dose from 1st August to 31st December: 210g/ha. For additional protection of water, suppliers/Basis advisers may recommend rates reduced to 160g/ha or less

Maximum total dose rate: 700g/ha/calendar year

Do not apply when heavy rain is forecast

If drains are flowing do not apply metaldehyde based slug pellets

In addition, three further important steps should be taken before metaldehyde use:

Use metaldehyde slug pellets only as part of a wider Integrated Pest Management (IPM) programme

Consider factors such as soil and stubble management, planting methods, weather, trapping and monitoring

Finally, stop and think “BIRD” before applying. This stands for Buffer, I’m legal, Records, and Dose

Oilseed rape herbicides

There are five oilseed rape herbicide actives that are a vital to keeping crops weed free, but with many post-emergence applications applied late in the autumn, there is an increased risk of contaminating groundwater.

Agrochemical manufacturers BASF and Adama teamed up to implement the “Metazachlor Matters” campaign, which raised awareness of issues relating to metazachlor and quinmerac applications.

Guidance relating to these two actives remains unchanged (see below), but stewardship advice is now included in the Voluntary Initiative’s “OSR Herbicides? Think Water” campaign, along with three other actives – propyzamide, carbetamide and clopyralid.

Metazachlor and quinmerac stewardship guidelines

Maximum dose – 750g/ha metazachlor and 250g/ha quinmerac

Where there are no drains – no timing restrictions

Drained fields (including tempory) – aim for 1 October application, cut-off date 15 October

Applications after 1 October can be made if soil/seed-bed conditions are good and drains not flowing

Drained fields in Drinking Water Safeguard Zones – cut-off 1 October

Of the five actives, propyzamide is most frequently detected, while quinmerac and clopyralid are the most difficult for water companies to remove from raw water supplies.

The Voluntary Initiative is now working with water companies and manufacturers to further raise awareness of the issue, which could see any or all of the actives restricted or lost altogether.

The OSR Herbicides? Think Water campaign outlines five steps that oilseed rape growers can follow to help minimise risk of the five herbicides being detected in water.

Use the Environment Agency’s “What’s in your back yard?” tool at www.wiyby.co.uk to find out if your land is in a Drinking Water Safeguard Zone (DWSgZ) and understand the pesticides which are of specific concern

If you are farming in a DWsgZ, speak to your local water company catchment officer to understand the potential risk on a field-by-field basis, or speak to your agronomist

Further to this, growers should implement best practice agronomy to help protect water by:

Managing tramlines, pathways and gateways to minimise compaction and reduce the risk of surface water run-off

Ensure all surface water adjacent to oilseed rape fields is protected by at least a 6m vegetative buffer strip

Before making applications, always refer to product specific labels and the Voluntary Initiative’s Water Protection Advice Sheets (WPAS)

To apply or not – don’t forget useful smartphone app

Agchem firm Adama’s Water Aware smartphone app provides a useful decision-support tool for use when applying a number of high-risk herbicide actives, plus metaldehyde pellets.

Using soil type, current and forecast weather and soil moisture deficit data, it can provide an indication of potential pollution risk at the time of spraying or pellet application.

It also incorporates the EA’s Wiyby tool to indicate if a field location is in a groundwater or surface water safeguard zone.

The app is free to download and is compatible with both IOS and Android operating systems.

Bentazone

Bentazone is a herbicide familiar to pulse, linseed and potato growers and is an active ingredient frequently found to exceed legal limits in UK groundwater.

This is because the spring-applied weed killer is extremely water-soluble and mobile in soil, so leaching is a ready route to groundwater. Surface water can be affected by run-off and spray drift.

The Voluntary Initiative offer stewardship guidelines to help bring the frequency of exceedances down and the advice was last update in spring 2017.

The advice is as follows:

Avoid use of bentazone on soils vulnerable to groundwater leaching, for example:

soils on chalk/limestone that are shallow (<30-35cm) and stony (>10% of surface area)

shallow (<30-35cm) soils on sandstone

soils with shallow groundwater (<1m below surface)

soils with low organic carbon content (<1% OC)

Do not apply if heavy rainfall is likely within 48 hours

Avoid application when drains are flowing or likely to flow within seven days

Reduce dose rates (≤1000 g ai/ha/year) as far as possible

Use bentazone as late as possible to reduce leaching probability, do not apply in autumn/winter

Follow basic water protection advice

Point pollution sources (farmyard runoff, spillages) must be avoided

Take care when filling and cleaning the sprayer

Use a minimum 6m grass buffer strip or 5m no-spray zone adjacent to watercourses

Do not apply if soils are dry, cracked or saturated

CIPC

CIPC (chlorpropham) has been under regulatory scrutiny for several years, with concerns over maximum residue level (MRL) exceedances when used to control sprouting in stored potato crops.

Subsequently, dose rates of the fumigant have been restricted, with processing potato growers only permitted to use 36g/t, while potatoes destined for the fresh market can only be treated with 24g/t.

The CIPC Stewardship Group launched the “Be CIPC Compliant” campaign back in 2013 and provides up-to-date advice and technical guidance to help store keepers comply with the latest legislation and ensure treatments are effective.

This includes an explanation of “active recirculation” and how to achieve it in both box and bulk stores, with the active and even movement of air through the stored crop now a requirement when using CIPC fog products.

Good airflow has been shown to significantly improve the uniformity of CIPC distribution and reduce the risk of MRL exceedances.