Slugging it Out
So, the government has withdrawn the ban on metaldehyde slug pellets.
After legal action brought about by Chiltern Farm Chemicals, a major manufacturer of slug pellets, the December 2018 Defra ruling that withdrew all products containing metaldehyde, with immediate effect, (with their use on farms banned from 2020) has been overturned by the High Court.
Apparently, the legal challenge was based on how the decision-making process was conducted. So, based on technicalities, this poison is back on the market despite the fact that studies show that metaldehyde poses an unacceptable risk to birds, fish and mammals.
A Defra spokesman said that: ‘We will retake the decision as swiftly as possible, taking account of the procedural points raised. Our priority is to protect people and the environment, and all decisions on pesticides are always based on the best available science,” the spokesman said. So perhaps all is not lost.
In the meantime, gardeners as well as commercial growers and farmers have a choice.
In my opinion, pellets containing metaldehyde should be avoided at all costs.
There are alternative slug pellets available based on Ferric phosphate, or Iron III phosphate. These kill slugs, and as long as they are used sensibly and sparingly (read the instructions on the label, in other words), have been shown to cause no ill effects to other creatures. Any uneaten pellets eventually break down into phosphate and iron which occur naturally in the soil. These kinds of pellets are allowed under EU regulation 2092/91 which outlines the minimum legal standards for organic production, so, if absolutely necessary, I am quite happy to use them in my garden.
There are a few non-chemical tricks that a gardener can have up his/her sleeve to try and deal with this ghastly gastropod, though – here are some of the ruses that I have tucked up mine.
Slugs prefer soil that is poorly maintained. Well-structured soil will help to deter slugs and it is good for your plants, so keep up with the mulching and weeding!
This is an awkward one. If you are too particular with tidying and keeping everything ship-shape and Bristol fashion, not only will you make slugs homeless, you won't be providing anywhere for the good bugs to live either. You somehow have to strike a happy medium. I find the easiest way of achieving this is to use a corner of the garden, away from my edibles and ornamentals, to stack my flowerpots and old paving slabs, at the same time leaving some nettles and other weeds to grow there. I can go on ‘slug patrol’ periodically and still have a place in the garden for the good guys.
Grow Your Plants ‘Hard’
Slugs love tender, young leaves, so I grow my plants ‘hard'. The trick is to get them to a decent size before you plant them out in the garden, don’t overfeed them so you have growth which is robust and not ‘leggy’ or floppy, and make sure they have been hardened off adequately before you do plant them. The idea is that the bigger and ‘tougher’ the plant is before it has to fend off attack, the more likely it is to survive. Even if some of the leaves have been munched, it may well keep going. This is not a fool-proof method, obviously, but it gives your crop a fighting chance. It will really only work effectively if you grow your own plants or buy in young plants from the garden centre or nursery.
If you have the time, alongside getting breakfast, feeding the cat, hanging out the washing and all the other myriad things to do before you start work in the morning, try to fit in any watering you might need to do. If you water in the evening any moisture left on the ground will create an ideal slug-route.
GROW SLUG-RESISTANT PLANTS
Another approach worth trying is to grow slug-resistant plants. Please note that I don’t call them slug-proof! I know that if I say a plant is slug-proof, the little blighters will prove me wrong with the first planting and reduce it to a twig.
Unfortunately, there are quite a number of vegetables, salad leaves and fruit, that slugs like to eat as much as we do. Cabbage and lettuce seem to make it on to the slug food chart, along with a host of other plants with tender, delicate leaves, and soft fruit. There are edible plants they will avoid, however. Plants with tough, hairy, glossy, waxy or bitter leaves, like kale or rocket, remain, for the most part, untouched, as do those with pungent or fragrant leaves, like many herbs and members of the onion family.
Some research and development has been done on breeding varieties of susceptible vegetables that have some degree of slug resistance. The most notable is the potato, which is often attacked by keel slugs: many of the ‘Pentland’ varieties have good slug resistance, for example.
As with the edible plants, there are some ornamental species which attract slugs like a jam pot attracts wasps. Perhaps the most oft-quoted slug attractant is the Hosta: some varieties look like a filigree lace cloth after only a few days of emerging. But there are others, notably larger varieties with tough, often blue, leaves, which are less prone to attack.
Unless you really, really want to grow a particular plant despite its notoriety for being a magnet for slugs, my advice is to choose plants which have proven to be less attractive to our uninvited gastropod guests. Trees and shrubs aren’t on the Michelin guide for slugs, but for a list of relatively slug resistant herbaceous plants, click here.
ATTRACT NATURAL PREDATORS
A good way of keeping the slug population down is to attract as many natural predators into your garden as possible. There are a number of insects, reptiles, birds and mammals that look on slugs as a tasty treat so the more we can encourage them the better for us, and the worse for the slugs!
One of the most important groups of insects as far as slug eradication is concerned is the ground beetle, or carabid. These are the fast-running black beetles which are fairly common in gardens. They will happily feast on both slugs and aphids. Devil’s coach horse beetles (the black beetles that will arch their abdomens like a scorpion if they feel under threat) will also feed on slugs and other invertebrates.
Flies belonging to the family Sciomyzidae, also known as marsh flies, are one of the most important parasites of slugs. The larvae feed on slugs and have a particular penchant for field slugs – lucky for us.
Most slug-destroying insects will find their way into the garden: as long as some suitable habitats, such as small piles of logs tucked away in a corner, are made available for them, they will stay.
Amphibians and Reptiles
The top three slug-eating creatures in this group are frogs, toads and slow worms. If you have a pond you will undoubtedly have frogs and toads in your garden. Of the two, frogs are the master-sluggers: as much as a quarter of their diet can be made up of slugs. Like the insects we have looked at, slow worms (which are really legless lizards) like piles of logs or heaps of stones to hide in. They are also partial to long grass, so don’t mow everything in sight – leave a patch for the slow worms.
There are many garden birds which will eat slugs, including blackbirds, thrushes, robins, starlings, rooks and crows. These are primarily ground-feeders so if you are used to hanging up containers of seed and peanuts, put a little food on the ground to encourage the slug-eaters to visit your garden. (Don’t leave too much food on the ground, though, as vermin will see it as a free meal too.)
Top of the mammal charts for dealing with slugs is the hedgehog. We had a hedgehog that came every night to our garden – we heard him (I should say it, as we have no idea of its gender) snuffling around and we took to supplementing his diet with a little cat food. Last autumn we set up a hedgehog des. res. in an undisturbed corner of the garden in the hope that he might hibernate there, but no joy. Hopefully he'll find his way back to us later this spring.
There is a down-side of encouraging some of the slug predators I have mentioned into your garden, and that is many will also eat beneficial creatures – even the ones that you want to actively encourage, such as earthworms. The chances are, however, that the odds are in favour of the good guys.
Grow Some Sacrificial Plants
One of a number of the measures a friend of mine takes to prevent slugs ruining her delphiniums (which slugs find irresistible) is to surround them with plants that slugs like even more. The idea is that they will happily chomp away at some succulent lettuce or hostas and leave the delphiniums alone. My friend concedes that this strategy doesn’t always work on its own, but coupled with other cunning measures (see below) she says it’s reasonably successful. Worth a try, I would say.
Put Down Some Barriers
Another method of keeping slugs from getting to your plants in the first place is to protect them (the plants, that is!) with a barrier which slugs find repellent. There are a number which appear to produce reasonable results, but I do think some are a bit hit-and-miss: my advice is to try them and see which works best for you.
I use the term ‘home-made’ very loosely. This group includes things like scrunched up egg shells and grit: in fact anything that has sharp edges. Encircle your plants with this slug version of barbed-wire and they will find it difficult to negotiate. On the other hand, you can enclose your plants with a circle of bran which slugs love to eat: the idea here is that they will gorge themselves on the bran and leave the plants alone, although I have never found this to be the case!
Copper gives off a natural electric charge. Slugs have a moist ‘undercarriage’ which successfully conducts the charge. Consequently slugs will be reluctant to cross the copper tape because of the uncomfortable electric shock. To protect the whole garden with copper tape is unfeasible, but it can be used effectively on pots. Impregnated mats can be used around plants or you can cut slits in it and plant through it.
Commercial Granules and Gels
There are some commercial products which either absorb moisture or create a sticky gel-like barrier: both make it very uncomfortable for slugs to make their way across. I have heard mixed comments about their efficacy, especially when the cost is taken into account, but I think it’s another example of trying them out for yourself.
There sometimes comes a point when all your best preventative measures have failed and there are more holes in your plants than vegetative matter. Now there is no choice but to resort to eradicating the slimy pests completely. There are two methods open to the gardener: natural and chemical – the latter has already been discussed, above.
The most effective method of natural control that I have employed is the use of nematodes (microscopic, parasitic worms), and more specifically, Phasmarhabditis hermaphrodita. These slug-eating nematodes occur naturally in the soil, although the numbers aren’t sufficient to control an average slug population. Modern developments have made it possible to breed large numbers of the nematodes and make them available to gardeners. They come in a pack of moist clay which you mix with water, and then water on the soil with a can.
There are some points to remember if you use this method, however: the slugs will only be controlled to up to 6 weeks; the soil must be kept moist for 2 to 3 weeks after you apply it; the soil temperature must be above 5°C; and once you open the packet you must apply the nematodes immediately. In addition, this is a relatively expensive way of controlling your slug population – you may like to use it in conjunction with one or other of the methods below.
I find that one of the most effective methods of culling my slugs is to set out a beer trap. This involves setting a shallow bowl or jar in the ground so that the top edge is about 2cm proud of the soil level. (This is to prevent beetles from falling in.) Fill the bowl with beer or lager (the slugs don’t seem to mind which – I use the cheapest I can find) and wait for the slugs to fall to a drunken death.
This involves setting out a suitable shelter, such as a roof tile or even skins from half an orange or grapefruit, under which slugs can hide during the day. What you do with them thereafter is best described as ‘dispose of them as you see fit’.
Torch, Bucket and a Pair of Gloves!
This is my ‘last resort’ natural method! It’s very simple. You grab a torch and bucket, don a pair of gloves and go hunting at nightfall! Again, you can ‘dispose of them as you see fit’.