On-farm field trials, carried out to raise awareness of pesticides in water, have highlighted the efficacy of ferric phosphate as a viable alternative to managing slug populations.

Kelly Hewson-Fisher, catchment advisor at Anglian Water, began the trials in the Louth Canal area in Lincolnshire – an important drinking water source for the county - just over one year ago, and she has since been raising awareness of the trial results.

“When I started with Anglian Water 18 months ago, there were no surface water catchment management trials being carried out in Lincolnshire.

“Awareness of sustainable metaldehyde usage was growing, but farmers still had concerns about the available alternatives,” explains Mrs Hewson-Fisher.

It was soon established that a major barrier to using ferric phosphate pellets, was the lack of knowledge surrounding efficacy.

This triggered the decision to undertake a very simple trial that would investigate overall slug control strategies, and close the knowledge gap.

“Over the past year at numerous collaborative events, I’ve been able to stand up in front of farmers and say with confidence that I was involved in the trial and monitored slug levels myself. I know how and why ferric phosphate works, and have seen first-hand the results in the field,” she says.

Three farms took part in the trials and all had similar soil types, which were under-drained. This was a key factor, given 90% of the metaldehyde can be lost through field drainage systems.

Three fields of winter oilseed rape, across the three farms, were put to the test. In field one, half of the field was treated with metaldehyde pellets, and the other with Derrex, ferric phosphate pellets.

Field two was treated with the same 50:50 split, but with metaldehyde and Sluxx, ferric phosphate pellets.

The third field was not treated with pellets, but cultural controls such as drilling and rolling were used to consolidate the seedbed and reduce slug movements.

“The farmers each made their own decision about timing and frequency of application,” explains Mrs Hewson-Fisher.

“Slug activity was then monitored using slug traps and we presented our findings back to the farmers.

“I also looked at ten, 1m2 plots to assess plant damage. This was a useful way to gather data on the differences between ferric phosphate pellets and metaldehyde. The results provided valuable evidence of the efficacy of ferric phosphate for Anglian Water’s own knowledge, and for us to be able to share with the wider agricultural community.

“We saw for ourselves that plant numbers were comparable in both treated fields, and there was no considerable variation in efficacy. Through this we’ve driven a huge amount of awareness.

“It’s rewarding to be able to work with the farming community in this way, and share valuable information that will help them to make informed decisions in the future.”