Slugs. We all hate them and just like the story with rats, we have been brought up to despise and almost fear them. But just like the rats, they too have in important role to play within biological systems in clearing up mess and converting it into available nutrients for plants. It is official this past year it has been the worst ever for slug problems on farms and gardens, the mild wet winter has seen an explosion of them.
Understandably growers are looking for quick fix to deal with the problem, as it affects almost all crops that are grown. Farmers apply vast amounts of metaldehyde slug pellets to thousands of hectares of cereal every year to control the slugs. These poisons, like rat poison, go up through the food chain and have a devastating effect on wildlife. Organic growers are not allowed to use metaldehyde, but are allowed to use ferrous sulphate – a naturally occurring element which will have a controlling effect on slugs. It does not have any negative effects on other species, it is claimed. But it actually does, as if the slug population declines, then so do all the various fauna that live on slugs, the beetles, nematodes, birds, reptiles – all potentially could be negatively affected by the loss of the slug population. Growers love the idea of a quick fix result, put something on and the problem goes away. But its’ not that simple, because the problem does not go away, it just moves somewhere else.
The chemicals that have traditionally been used to control slugs are coming under closer scrutiny and are gradually becoming more restricted in their use, a good thing of course. So, the race is on to find safe alternatives, and this is what all the big chemical companies are working towards – a biological control. Biotech is big business worth billions, if you can sell a safe product to a grower, who feels that the pest is being controlled then surely this is a good thing? Well yes and no. It is certainly hugely better than the indiscriminate use of poisonous chemical destroying biodiversity and leaving residues, as the biotech approach only targets the actual pest.
Nemaslug is the industry answer to slug control – a naturally occurring soil inhabiting nematode that lives on slugs. Spray it on your land and all slugs die. What can be bad about that? The natural slug predators also die, as their food source has gone. Slugs are amazingly resilient. You need to be if you are this low down in the food chain. They will soon return to the sterile and, in their opinion, safe site. The natural predators will eventually recover, but in the meantime the slug population is now able to recolonise the site with no fear of predators and so they can multiply even faster. The grower needs to reach for the Nemaslug again and apply a bit more this time. And so, starts a culture of dependency on the control materials, just what the Big Company wants, they need to be continually selling you something. If the slugs problem was delt with in one application, they are not going to be making any more sales.
We have developed a complex systems approach to slugs on our farm and for the most part it works very well. Soil health, good soil drainage, plenty of ground cover with green manures to encourage predators especially beetles, appropriate cropping, choice of varieties, diverse habitats, and many other aspects of a natural system are in place on the farm. We see the farm as a whole organism with everything being close to balance. We still get occasional slug problems early in the spring and have to drill some crops like carrot several times to get a decent stand in the crop, but we accept this as sometimes inevitable. If there is a massive slug problem, then the natural system is broken and it needs to be fixed. There are no safe quick fixes for any pest problem, it is dependent on developing a system.
The Good
The Ugly