Features
Gardening Tips - Slug Control
It's the time of year again to sow your first polytunnel crops. Apart from carrots and early potatoes which we sow directly into the soil, all other crops are sown in blocks for transplanting at a later stage. Ground will be tilled and composted in advance and this is the best time to apply the latest in slug control Phasmarhabditis herma phrodita or 'Nemaslug' the trade name - a little easier to remember.
Night Patrols
There is little doubt that slug control is one of the biggest challenges facing the organic grower in our damp climate. Shredded salad leaves are set to become a thing of the past. After years of nightly slug patrols in the springtime its high time to kick some slug-ass the 'easy way' - bring in the swat team. This is a slug parasite, a soil organism natural to north European soils that is now being bred and introduced into the soil in large numbers. Once introduced, 'parasitised' slugs stop feeding after seven days and die. The microscopic worms (nematodes) continue to work for at least six weeks according to the manufacturers Micro Bio, Cambridge, UK. This ensures that the crop will be well on if not fully grown by then. They can be used all year round in polytunnels and greenhouses and out of doors from March through to October. The guide temperature given for outdoor use is when soil temperatures exceed 5ºC /41ºF
Big slugs
The nematodes are harmless to people, pets and wildlife it is claimed they will exterminate small to medium sized slugs up to 8cms. This may leave some of the monster molluscs still active but these are easily spotted and dealt with - anyway it's usually the lesser slugs that do most of the damage. One is advised not to use the product in water-logged areas and on very heavy wet clay soils because in these conditions the nematodes will not thrive. You are also advised to keep six inches away from ponds to avoid harming water snails.
Application
The product is applied with a watering can fitted with a coarse rose. It comes in a plastic tub that should be stored in the fridge until use but do not freeze. The pack is added to two gallons of water and stirred to break up any lumps. Four pints of the mixture is then put into a two-gallon watering can and topped up with clean water. This is watered onto the soil and then watered in with a further can of clean water. Used like this one pack will cover approximately 50 square yards/40 square metres.
Experiment
The only time I used Nemaslug last season was in tunnels already full of plants. This made it impossible to apply properly with a lot of the mix falling on leaves to dry out and perish. In other words I am reserving my judgement on the control achieved for a few months yet. I would be very interested in how other growers have got on or will get on in the future. I did read one favourable report in an English gardening magazine. Should temperatures drop after application the nematodes are capable of surviving an odd frost - control will just slow down. Nemaslug also continues to work well during wet weather when slugs are most active. Once opened the whole pack should be used at once as the nematodes are not distributed evenly in the carrier medium.
Cost
So what's the catch? The cost is quite expensive. At present €29-80 to treat 40 square metres - enough for a good-sized polytunnel. For widespread use at this price it would need to be very effective. Increased crop quality, less waste and prep time plus the peace of mind that comes with knowing your crop is safe is not to be sniffed at. I know some people who just apply a strip along the tunnel plastic and in doorways and this may be enough in tunnels where slug numbers are regularly controlled.
So it looks set to become easier to be a successful 'slugger' - time will tell!
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