Looking ahead to the coming autumn, growers should consider the implications of buffer zone restrictions on pyrethroid insecticides used for aphid control in cereal crops.

Controlling aphids early in the cropping cycle prevents spread of the potentially devastating barley yellow dwarf virus (BYDV) in all cereal crops, including wheat, barley, oats, rye and triticale.

Early-drilled crops in high-risk areas such as the West Country will be routinely treated with an insecticide seed treatment such as clothianidin (Deter).

See also: How to calculate pesticide limits in aquatic buffer zones

However, in an open autumn conducive to prolonged aphid flight, foliar sprays may be required once seed treatments begin to wane or to protect untreated later-drilled crops.

In the May issue of Crops, we summarised the rules on approved pesticide labels relating to aquatic buffer zones against watercourses and non-target arthropod buffer zones designed to protect beneficial insects.

With the range of combinations that can appear on an approved pesticide label, the choice of product will affect a proportion of a field’s headland that can or cannot be treated with a foliar insecticide.

Many will focus on Lerap restrictions on pesticide products when choosing which one to use, but on most UK arable farms, watercourses will run adjacent to a very small proportion of field boundaries.

Conversely, almost every field will have a boundary to non-cropped land, so by far the most important consideration is a product’s arthropod buffer zone.

Some products require this buffer zone for all crops, all year, but for others it is only when used in cereal crops. 

For older cypermethrin-containing product labels, the restriction only applies when used in cereal crops after 31 March in the year of harvest, but these are being replaced with newer, more restrictive labels.

In the table, it can be seen that Alert (Mapp 13632), Karate 2.5WG and Toppel (Mapp 15696) are the least restrictive for arthropod buffer zones, while Hallmark Zeon and Major are the least restrictive for Lerap.

Arthropod restrictions apply next to all uncropped land.

Land previously cropped, but now in stewardship schemes such as ELS or HLS are classed as cropped land, but 1m cross-compliance strips next to watercourses or hedges are classed as uncropped land.

Some common sense should apply though, as while it may be legal to apply insecticides right up to a field margin designed to be rich in biodiversity, it is obviously not “best practice”.

Buffer zones for cereal pyrethroid insecticides

This table shows the variety of field margin restrictions for pyrethroid insecticides. This is just a selection of the products available.

Don’t forget to use up methiocarb

Growers are reminded that the use up date for slug killer methiocarb is fast approaching and should check their stores and ensure supplies are gone by 19 September 2015.

EU member states voted to ban the active – contained in products such as Draza Forte and Decoy Wetex slug pellets – early last year.

Peter Stacey, Bayer CropScience’s molluscicide product manager, says that final sales of methiocarb were permitted until 19 September 2014, so some stocks may still be on farm. 

He advises all growers to use up any remaining methiocarb slug control products or have a plan in place to do so before the cut off date, after which it will be illegal to hold any stocks. 

Methiocarb slug pellets withdrawn

Pesticide watch

To help you keep up with key product label changes, Crops is working with Gatekeeper agronomists to highlight key Mapp number changes and the potential implications, keeping you on the right side of the law and aid with on-farm record keeping.

Sentinel is a decision support tool linked to Gatekeeper crop management software, a program that helps arable farmers with record-keeping and legislation issues. For more details visit www.farmplan.co.uk or call 01594 545 011.