Agronomist's notebook: Dealing with snails and slugs once and for all

Friday February 15 2019
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A snail. Maintenance of farm hygiene is key to curbing snails and slugs. Remove all weeds or plant waste to reduce their hiding places, therefore, decreasing their population. FILE PHOTO | NMG


A few weeks ago, I received an email from a farmer seeking ways to control snails that were feasting on her cabbages.

The snails were punching holes on the leaves of the crops and leaving a mucous trail, making them unsaleable. While other insects cause such damage, for snails it is easier to know they are the culprit due to the mucous trail.

Symptoms vary from one crop to the other but all affected plants have a degree of leaf shredding and leafing.

Mostly, they cause damage to ground crops such as brassicas, lettuces, potato tubers and ripening strawberries.

Snails and slugs are in the class Gastropoda, and they cause similar damage to crops. They are hermaphrodites, which means they possess both male and female sex organs.

Therefore, they can mate and reproduce or a single snail can self-fertilise increasing their population rapidly.


The morphological difference between them is that snails carry a spiral shell, which is absent in slugs. Snails usually feed above and below the soil surface causing damage to seeds, shoots, and roots.

They are likely to be found outdoors, but they can as well thrive in greenhouses. Snails most common habitats are near the fence lines and tree stumps and they are found in all types of soils.

Slugs can squeeze themselves into hiding places with little space due to lack of shells, which gives them environmental survival advantage. When facing danger, snails normally retreat in their shells for protection.

To control the two, a farmer should use integrated pest management methods. The pests are mainly nocturnal, therefore, one should eliminate all places that they can hide during the day to curb crops’ infestation.

Maintenance of farm hygiene is key to curbing them. Remove all weeds or plant waste to reduce their hiding places, therefore, decreasing their population.


Growing crops that have grid leaves makes it difficult for the snails to feed on them since the plants cause injuries.

Also, the farmer may practice trap cropping, a valuable organic technique.

A trap crop, which is also known as a sacrificial crop, is a plant one grows on the garden to attract pests away from the main crops. Parsley can be a good trap crop for snails.
It is advisable to prepare your land well by doing the primary and secondary cultivation. Studies have shown that pest population, sometimes, increases when the farmer practices minimum tillage, which requires little or no disturbance of the soil.

Snail and slugs like moist places and lay their eggs in clusters beneath the leaves or other areas where the soil is damp.

This means if one is using overhead irrigation, consider shifting to drip irrigation system since it reduces humidity making the environment less conducive for the pest.

Sprinkling copper pellets around the farm helps to control the snail since copper acts as a repellent.

Snails and slugs can also be controlled by handpicking though it’s tedious and inconveniencing, especially on large-scale farms.

In small-scale farming, this is reasonably effective but should be done regularly to reduce their population.

Ground beetles feed on snails, therefore, they can help to control the pest. Use of diatomaceous earth, a natural powder made from fossils, kills the insects when they walk over them by making them dehydrated.

The product is best used on large-scale plantations. Lastly, spraying snails and slugs with hot pepper aids to curb attacks.