Slug killer leaves no direct trace
The future for UK slug control will demand a change of mindset in how the success of a treatment is judged. That was the view of Certis technical officer Alan Horgan speaking at last week’s AAB Crop Protection in Southern Britain conference.
Delivering the findings from his recent paper entitled ’Challenges associated with controlling slugs in UK arable crops,’ he explained that while new chemistry was being embraced, differences in how the latest slug pellet solutions work and resulting slug behaviour are important to understand.
"For the past sixty years or so, UK agriculture has depended upon molluscicides that contain either metaldehyde or methiocarb. Both of these active ingredients (AIs) leave clear evidence of their action, with dead slugs a testament to their efficacy. But with the introduction of a third option, that’s now changing."
Alan explained that water and other environmental concerns are leading growers to seek new alternatives to the two traditional slug pellet choices, particularly in vulnerable catchments. "Since its launch in 2009 a new 3% formulation of ferric phosphate, in the form of Sluxx, has really shaken up the market," he said. "It’s got an excellent environmental profile and is far more economical for commercial agriculture than its predecessor products containing the same AI. And importantly, trials show it’s delivering on a par with both metaldehyde and methiocarb when it comes to efficacy.
"But the key difference is that crop health must be taken as the ultimate measure of control because dead slugs are often not visible due to the mode of action of the active ingredient, ferric phosphate.
"That’s because the first symptom of ingesting ferric phosphate is an anti-feeding effect. This delivers immediate protection of the crop from the pest, but death takes a bit longer. As a result, slugs often retreat underground leaving little visible evidence of their presence to symbolise control."
Alan concluded that the lack of crop damage is the standard to use in assessing effective slug control. "A thriving crop with minimal symptoms of damage or a crop where damage has been stopped and reversed with new growth will be the telling factors that show successful control has been achieved."
