How should snails in orchards and vegetable plots be controlled and what pesticides should be used?

The snail, also known as the slug snail or water buffalo, is a common harmful mollusk in vegetable plots and orchards. Anywhere moist and shady is a snail's favorite, and it is distributed nationwide. So how should snails be controlled? With what pesticide?

Snails are mollusks and are one of the important pests on fruit trees in high-temperature, high-humidity regions. They damage leaves, branches and fruit, and also carry pathogens. They mostly harm weak trees, leaving a long white trail as they crawl, and where conditions are suitable they can cause rot disease.

Snails generally become highly active and cause damage in April to May and September to October, and autumn damage is more severe than spring damage. Snails are hermaphroditic animals that mate with other individuals; mating usually takes place at dusk, at night or on rainy days. About 15 days after mating they begin to lay eggs, laying 4 to 6 times a year, with 150 to 200 eggs each time, and the eggs hatch after 10 to 18 days. Newly hatched larvae only feed on the leaf mesophyll, leaving the epidermis; after growing larger they often eat crop leaves into holes or notches.

They have a varied diet and can harm many vegetables and other crops of the cruciferous, legume and nightshade families. Snails hide by day and come out at night, mostly starting activity and feeding after 6 p.m., reaching a peak from 8 p.m. to 11 p.m., gradually reducing their feeding after midnight, and stopping feeding one after another by early morning, then burrowing into the soil or hiding places. Snails like dark, damp environments, and on rainy days or after watering they can be active and feed day and night.

Control methods for snails in orchards

1. Agricultural control

① Clean the field regularly, carry out timely intertillage, and remove weeds and crop residues from the field and bed surfaces. Destroy the snail's habitat and egg-laying sites.

② Deep plow the soil in autumn and winter.

③ Do not apply undecomposed organic fertilizer.

④ Strengthen tree vigor, reduce the occurrence of rot disease, and leave snails with no conditions in which to survive.

2. Physical control

① Hand capture and killing, and raising chickens and ducks in the orchard.

② Spread a band of quicklime. Spread quicklime between crop rows or around them, taking care not to spread it on the leaf surface.

③ Spread plant ash: in the evening, spread dry, pure plant ash on the stems at the base. If the stems and leaves are dry, first spray some clean water so the branches and stems are moist before spreading, and snails will no longer climb up the stems and leaves to bite them.

3. Chemical control

① Mix metaldehyde with flour into a paste and smear it on the tree trunks, and there will be no snails all year;

② Poisoned soil barrier: use a metaldehyde and carbaryl bait, and spread it on the orchard ground in March to April and August to September, before snails emerge from dormancy and climb the trees, to stop snails from climbing the trees.

Control methods for snails in vegetable plots

Living habits

The pest causing similar damage to vegetables is mainly one kind of snail, and there is also a shell-less one called the slug (kuoyu), commonly known as the “snail without a shell”. These two pests have similar living habits and control methods. They mainly like high temperature, high humidity and weed-covered environments, hide by day and come out at night, and are afraid of light; under strong light they can die in 2—3 hours. Therefore they are all active at night, starting to emerge in the evening, reaching a peak at 10—11 p.m., and then one after another burrowing into the soil or into hidden places with lots of weeds before dawn. Experts remind everyone that these two pests mainly inhabit the soil wall at the front face of the greenhouse, and this is the key area for control.

Methods for controlling snails

1. Spread poisoned soil or granules

Generally speaking, the active ingredient of the pesticides used to control these two pests is metaldehyde, usually in granule form. The finished metaldehyde preparation is light blue in appearance, has a special fragrance, and is strongly attractive. When a slug is attracted and feeds on or comes into contact with the pesticide, it causes a large release of acetylcholinesterase in the snail's body, destroys the special mucus in the snail's body, and rapidly dehydrates the snail's body, paralyzing the nerves. Due to the massive loss of body fluids and destruction of cells, the slug and similar pests die of poisoning within a short time. You can also use a powder containing metaldehyde mixed with 5 kg of fine sand and spread it evenly on the ground, which can also produce a contact-killing effect. Experts from Caiyi.com remind everyone that it should be noted that metaldehyde granules can only work when dry; if they soften on contact with water their effect is greatly reduced and they need to be spread again.

This is the chemical method everyone often uses. If the pest infestation is severe, experts suggest choosing this method.

2. Spread quicklime, plant ash and salt

The body fluids of snails and slugs are important substances for maintaining life. If body fluids are consumed too much, the pests will die of dehydration. Therefore the purpose of spreading quicklime, plant ash or salt in the greenhouse is to absorb their body fluids and cause death by dehydration.

Key protection can be carried out against the front face of the greenhouse, where humidity is high and weeds are abundant. Of course, it can also be spread alone near the base of the plants to prevent slugs from climbing the plants and causing damage. The amount of lime is about 7 kg per mu, depending on the degree of slug occurrence. Plant ash can not only kill slugs but also, after entering the soil, is a good potassium fertilizer. Spreading salt can create a concentration difference on the surface of the slug's body, causing water to move from low concentration to high concentration, making the slug's internal water flow outward and leading to death.

3. Killing with bait

Slugs are even more fond of some leafy vegetables, so lettuce, cabbage and Chinese cabbage leaves can be used as bait for capture and killing. Place the leaves where slugs appear, and spread contact-killing pesticides around the leaves to kill the slugs. Alternatively, crush the leaves, mix in beer, add an appropriate amount of imidacloprid, and spread it where slugs are often active, which can also achieve a very good killing effect.