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Getting Rid of Gastropods

It is spring, and people everywhere are getting busy in their gardens. Unfortunately, so are slugs and snails. These pesky gastropods are a nuisance all year round, but in the warm, damp climate of spring, they thrive, and young spring shoots in your ornamental beds and pottagers are particularly vulnerable.

These molluscs are partial to many plants, especially beans, celery, lettuce, peas and potatoes in the veggie garden, and dahlias, delphiniums, hostas, sweet peas and tulips in the ornamental garden. They eat many parts of the plant: buds, flowers, fruit, leaves, stems, roots, corms, bulbs and tubers, and are especially fond of, and inflict catastrophic damage upon, fresh young seedlings and new, soft growth.

Signs of slug and snail infestation include slime trails, holes throughout plants, and entire seedlings being completely devoured. Most damage occurs at night, especially during warm humid periods.

It’s virtually impossible to eradicate these ubiquitous creatures, so the best course of action is to target your efforts around your most vulnerable plants, and to consider employing a number of pest control techniques. Delay transplanting fragile seedlings until they have grown bigger and sturdier, growing them on in pots instead, and utilise any or all of the following methods.

Prevention, of course, is better than cure. Hopefully you have been raking up fallen leaves throughout autumn and winter, for a tidy garden and to create leaf mould; as well as cultivating your soil ready for the spring season. This also has the benefit of exposing slugs’ eggs so that birds and other predators can easily eat them, thus reducing your future slug population.

One of the easiest but most effective things you can do is time your watering schedule so that it is beneficial for your plants but not for molluscs. They thrive in damp conditions, so avoid watering late in the day, which creates an optimum environment for their nocturnal activities. Instead, irrigate in the early morning. The water has time to soak down to the plants’ roots and the heat of the day will dry out the surface level of the soil by the evening. 

A basic and time-consuming, but effective, method is to manually remove these voracious pests. Go into your garden (preferably in the evening) and remove them by hand, relocating them far away from any gardens, killing them with salt, or feeding them to your chickens or ducks. Similarly, you can encourage other predators into your garden to pick them off for you: hedgehogs love to eat them, as do various birds, ground beetles, frogs and toads. Creating a pond or boggy area will attract these beneficial creatures.

Gastropods, either dead or alive, make a good addition to your compost heap. Dead ones rot down and add to the compost, while live ones will love that environment, and stay there, and do a good job breaking down the compost.

You can put spent kitchen products to good use. Coffee is a repellent, and you can sprinkle coffee grounds around vulnerable plants, to both form a mulch and to dissuade slugs and snails. A coffee solution is even more effective, so that leftover coffee that's gone cold in the bottom of the pot - don’t tip it down the sink, pour it onto the soil in your garden, or spray directly onto your plants.

Any craft beer fans out there?  I'm rather partial to Domaine du Merchien beer from a local producer in the Lot, and I like to use the dregs of each bottle, with the yeasty sediment, to make slug and snail traps. Sink a steep-sided pot into the ground, leaving it slightly protruding so beetles don't fall in (you want them alive and munching on the molluscs) and half fill it with beer. The slugs and snails will be attracted to the beer (can't blame them for that!) and will fall in and drown. Surely the classiest control method around - almost too good for the slimeballs!

Fruit rinds also make a good lure. Place empty halves of orange, lemon, melon or grapefruit in your garden. The gastropods love them and will gather underneath these fragrant domes, in search of food and shelter, ready for you to collect and dispose of in the morning. Similarly, wooden planks will attract slugs, as they seek shelter from the sun.

Copper gives slugs and snails an electric shock. You can buy ready-made strips, rings, tapes and barriers in different sizes, or create your own with coppers from your small change. Ensure that no leaves cross over the copper barrier to form a bridge. Alternatively, you can buy, or make, a battery powered electric slug and snail fence. You can also use companion planting to repel them, forming a barrier with fragrant plants that gastropods dislike. Chives, garlic, geraniums, lavender, mint, sage, rosemary and thyme can all be planted around the edge of the garden to help keep them out.

Diatomaceous earth is a chalky powder that looks like flour but is very sharp at a microscopic level. It consists of the fossilized remains of diatoms and can be sprinkled on the garden to kill slugs and snails. Other sharp textures can be used to create barriers: sand, gravel and broken eggshells are all worth considering.

Phasmarhabditis hermaphrodita nematodes are another excellent natural solution. These microscopic parasitic worms live in the soil and they infect and kill slugs and snails but do not harm humans and animals. They occur naturally in your soil, but for them to provide an effective pest control, you need to increase their numbers. You can buy them online and they arrive in packets which you add to water and then water into the soil. This is best done from spring to autumn, as a moist, warm soil, with temperatures of 5-20ºC/ 41-68ºF, creates an optimum environment.

While all of the preceding methods have been natural, you can, of course, use chemical slug pellets. There are two different active ingredients used in slug pellets: metaldehyde or ferric phosphate. Metaldehyde is highly toxic and should be kept away from animals and young children, while ferric phosphate is a safer choice. Slug pellets, if used, should be applied sparingly.

Gastropods lay up to 100 eggs after each mating, several times a year. They can live for up to 6 years, and it is estimated that each cubic metre of garden generally contains up to 200 of them. Reproductive activity is most prolific and productive during warm, damp conditions, and while you will never eliminate the entire population, ongoing preventative measures are advisable, especially at this time of year. 

John and Debbie Wilson www.lejardindesespiemonts.fr

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