Almost nine out of 10 growers don’t know the rate of slug pellets they are applying and they are not being spread accurately, according to the Metaldehyde Stewardship Group (MSG).

The difficulties stem from the range of products that were available and the variability with which they spread, said agronomist Colin Myram. “Applicator operators don’t recognise what the 210g/ha limit actually means.”

This is the maximum amount of active ingredient that can safely be applied between 1 August and 31 December without the risk of polluting a watercourse; just one pellet could trigger an exceedence of the 0.1 parts per billion drinking water limit.

The MSG has produced an easy-reference table (see below) to help operators calibrate spreaders correctly. Work had also been carried out to improve spreader accuracy. “Not all machines will spread all the pellets to the width you want,” pointed out Rob Foxall of Spreader and Sprayer Testing.

The advice is to limit bout width to 12m – a table showing recommended settings for various spreaders to achieve a good distribution of pellets is available on the MSG website (www.getpelletwise.co.uk).

There had been a significant decline in the number of incidences where metaldehyde had been detected in drinking water, according to MSG’s Paul Fogg. “This is partly due to weather, partly reduced inclusion rates and partly restrictions the industry has implemented. But there are still some isolated incidences.”

Training and greater awareness would reduce these and improve spreading accuracy, noted Steve Hewitt from City and Guilds NPTC. Operators need a PA4s certificate to spread pellets, a specialised version of the PA4 granular certificate.

About 3,000 had upgraded since it was introduced in June 2010 – noted as a great achievement – but potentially there were 40,000 operators who are still relying on their old PA2 certificate. “I am saddened that more growers who completed training have not taken the test,” says Mr Hewitt.

From July 2011, anyone wishing to upgrade to a PA4s must complete the full test. The option to take a quick test after attending a slug-pelleting seminar had nearly expired.