Slug Control

Anyone who has tried to grow leafy vegetables, herbs, shrubs, potatoes, or perennials like hostas will know the damage that slugs and snails can cause – both above and below the ground. From leaf shredding to complete plant annihilation, slugs can leave gardeners and growers in despair.

Although there are more than 40 species of slugs found in gardens, only a handful of them are culprits when it comes to plant destruction. These include the common garden slug, the grey field slug, the common keeled slug, the black slug, and largest of them all, the large red slug.

Spotting Slug Damage

Tell-tale signs of slug activity include silvery slime trails, smooth holes in leaves (especially the leaves of succulent new growth) and nibbled cervices in mushrooms and small fruits like strawberries. Slugs are particularly fond of fresh seedling leaves, the newly developed spikes of hostas, and the fully emerged fresh leaves – often feeding between the parallel leaf veins.

If your seedlings have not emerged, you may have a slug problem - the common keeled slug for example is a lover of newly drilled seeds such as potatoes.

Slugs are voracious eaters and can destroy entire patches of seedlings or young veg beds overnight. On a quiet evening, you might hear slugs feasting on crunchy leaves like cabbages!

What is Biological Slug Control?

Biological controls are non-chemical treatments that rely on the natural enemies of pests. In the case of slug and snail control, the enemy is the nematode, specifically, the species Phasmarhabditis sp.

Phasmarhabditis sp. are UK native microscopic worms that actively seek out a variety of slugs, feeding and multiplying inside them, then infecting them with a bacterium. Once infected, the slugs will stop feeding and die. The nematode will then leave the dead slug and go on to seek out more slugs, repeating the cycle. Nematodes also reproduce inside the slug larvae, releasing more nematodes into the surrounding area. 

You are unlikely to notice dead slugs as they will retreat underground to die. Biological slug control is a highly effective, safe treatment that can be used on all edible crops and ornamentals. They are safe for pets and other wildlife and the perfect choice for organic gardeners.

How Many Nematodes Do I Need?

We sell biological slug control in packs that cover the following areas:

• 25m²
• 40m²
• 100m²
• 800m²

There are millions of microscopic nematodes in each pack – carefully worked out to ensure accurate application for each specific area listed. Each application of nematodes will provide at least six weeks control of slugs.

Nematodes are supplied as an easy-to-mix powder which needs to be diluted with water before use. Specific dilution rates are shown in the table below.

How to Apply Biological Slug Control

Apply to moist compost/soil, when the soil temp is above 5ºC using a watering can or sprayer. 

When to Apply Biological Slug Control

You can apply nematodes when the soil temperature is above 5°C between March and October. A second application may be required 6-8 weeks later.

Nematodes will survive occasional frosts so can be used early in the season – though it is best not to apply them when the ground is frozen or frosty. They are particularly effective in damp, wet weather unlike pellets which can become less effective when wet. For best results nematodes need to be re-applied every 6 weeks.

Try and choose a humid or wet day to apply the nematodes. They are UV-sensitive so it is best to avoid applying them on a bright sunny day as they will not survive in these conditions. The best humidity levels are often found first thing in the morning or late afternoon.

Can I Store Nematodes?

Nematodes are perishable and need to be applied quickly after delivery for best results. They can however be stored in the fridge for up to two weeks. Please note that delivery can take up to two weeks.