10 April 1999

TAKING IT CLOSE TO THE MARGIN

Rules on no-spray buffer zones have changed. You can adjust to suit individual fields, as Gilly Johnson reports.

COMPLAINTS about no-spray buffer zones have been heard. After consultation with the industry, the Government has had a change of heart, and adjusted spray policy accordingly.

From this month on, if you are prepared to do a little homework, what was a 6m no-spray buffer zone could in some circumstances shrink to a 1m requirement only, under the new LERAP system.

Thats short for Local Environment Risk Assessments for Pesticides, which in simple language means that growers weigh up the risk of spray drift on each spray occasion themselves, and work out the appropriate buffer zone according to width of watercourse and dose rate.

Thats if they want to; reducing buffer zones via LERAP is not compulsory. You can stick with the original buffer zone if preferred, but still need to record this decision.

Such flexibility makes crop management easier, and no spray zones more sensible, says James Clarke of ADAS, whos been assisting the Pesticides Safety Directorate (PSD) on the implementation of LERAP.

First big change is that the basic no-spray buffer zone – the starting point for adjustment – drops from 6m to 5m. But the unsprayed crop margin hasnt necessarily altered. Its rather because of a new system of measuring distance from the watercourse; instead of using the waters edge as a starting point, the buffer zone width must now be measured from the top of the bank itself out into the field. The 1m gap is an average difference between the waters edge and the bank top, according to the PSD.

Given that water levels in a ditch vary throughout the season, this is a sensible change, says Mr Clarke. By the same code, the no-spray buffer zone for hand-held sprayers drops from 2m to 1m.

For sprayer machinery, the 5m buffer zone is the starting point. And if you cant be bothered to go through the process of a full LERAP assessment, the process can stop there. Map out exactly where all the watercourses and dry ditches are on the farm, and record the fact that a 5m no-spray buffer zone is to be imposed adjoining them, when spraying products with a buffer zone requirement. Ensure that all spray operators are aware.

However, for those who do want to adjust the no-spray buffer zone, the next step is to make an assessment of exactly how wide the watercourses are. There are four categories of watercourse for LERAP purposes:

&#8226 the dry ditch;

&#8226 less than 3m wide;

&#8226 between 3-6m;

&#8226 over 6m wide.

Minimum buffer zones, ranging from 5m to 1m, are attached to each type of watercourse. Most vulnerable is the watercourse of less than 3m, because there is less water available to dilute any spray drift, and this is where the buffer zone must be widest.

Significantly, dry ditches now only attract a 1m buffer zone requirement; growers will welcome this development because the impact of large buffer zones against dry ditches was considered an unnecessary burden and resented by many.

Mr Clarke recommends including the watercourse information as a permanent feature on the farm map. If the water level in ditches varies between two categories through the season, then classify it as that with the greatest buffer requirement attached, he suggests.

"This preliminary planning would make life easier. Although a LERAP should in principle be undertaken before each spray occasion, measuring watercourses each time would be a huge task. So if you record the minimum width that watercourses will ever be, and calculate buffers accordingly, you can be sure you have a buffer that meets with all requirements. And you dont have to assess the watercourse width before each spraying operation."

But err on the side of caution, he says. For example, if some water occasionally runs along otherwise dry ditches at times when spraying might occur, then it should be recorded in the less than 3m wide category, rather than as a dry ditch.

Then all the farms spray operators and advisers need to be made aware of watercourses, and should have maps to hand when spraying decisions are made.

Once the ditches are classified, then the only action that needs to be taken before spraying is to consider: &#8226 what products are being used &#8226 at what rates

A few products will still require a 5m no-spray buffer zone regardless of LERAP. These are Category A products, and include those insecticides containing some synthetic pyrethroids, and organophosphates.

Category B products do attract a buffer zone requirement, but this can be adjusted using LERAP. These products include many fungicides such as Opus (epoxiconazole), Bravo (chlorothalonil) and herbicides such as Debut (triflusulfuron). Other products do not require any buffer zone, in any circumstances. These include Amistar (azoxystrobin).

Growers can check product classifications by contacting the PSD. Quickest route is via the internet; address on the web is: www. maff.gov.uk/aboutmaf/agency/psd/psdhome.htm

Alternatively, an e-mail enquiry from the PSDs information section on p.s.d.information@psd.maff.gov. uk will be answered promptly. Monthly updates are also published in the Pesticides Monitor (formerly known as the Pesticides Register). Crops will also be publishing a list of Category A and B products at regular intervals, starting in our 8 May issue.

Its not a straightforward categorisation, because products can vary with different formulations, although the active ingredient may be the same.

Mixtures of products are classified according to the component with the most stringent buffer zone requirement. That means that any mixtures containing Category A products also have the full 5m buffer zone requirement.

If the product or spray mix comes under category B, then a LERAP is compulsory, and buffer zone may be varied according to dose. At a quarter dose, the buffer zone is just 1m for all watercourses (table 1). Once again, buffer zones for mixtures must be calculated in line with the most demanding component in the mix.

The policing of LERAP comes under the remit of the Health and Safety Executive, so farm records must show that a full LERAP assessment has been carried out.

One element not included for the moment is the effect of different spray equipment. For example, low drift nozzles do play an important role in reducing contamination, and this will be recognised. "Spray equipment will be classified, and we hope this process will produce results in time for the autumn spraying season," says Mr Clarke.

Spray tackle (including nozzles) will be given a one to three star rating, depending on risk of drift. Three stars will be awarded to equipment which is so effective that only a 1m buffer zone would be required for Category B products, even at the highest rates and next to the narrowest watercourses (see table 2).

Contrary to some suggestions by growers, wind speed assessment on the day of spraying is not to be included as part of LERAP. "This is a starting point – other elements may be introduced over time as more information becomes available," says Mr Clarke. "Its an excellent idea anyway to map out the watercourses on your farm. LERAP is a workable system and although it might seem complicated, when you take a closer look it makes sound spray sense."


Dose rate of application

Full rate Three-quarter Half Quarter

rate rate rate

Size of watercourse:

Less than 3m 5m 4m 2m 1m

3-6m 3m 2m 1m 1m

Wider than 6m 2m 1m 1m 1m

Dry ditch 1m 1m 1m 1m


Dose rate of application

Full rate Three-quarter Half Quarter

rate rate rate

Size of watercourse:

Less than 3m 4m 2m 1m 2m 2m 1m 1m 1m

3-6m 2m 1m 1m 1m 1m 1m

Wider than 6m 1m 1m 1m 1m

Dry ditch 1m 1m 1m 1m

Key:

Red – *drift rating Blue – **drift rating

Green – ***drift rating Black – all low drift sprayers