Instructions for preventing rat damage in paddy fields

Rats destroy rice from the time it is sown to when it is ripe, but it is most severe when the fields are not sown at the same time and the banks have many shelters. Instructions on community-based prevention, cleaning field edges, trapping plants and using baits safely.

Summary: Rats are a pest that is difficult to prevent if only individual fields are worked on. They eat newly sown seeds, bite the stem horizontally to lose the buds, then continue to break the ripening stage until harvest. This article focuses on community-based rat management: clean shelters, kill crop heads, use traps in the right place and absolutely do not use electricity to catch rats.

Applies to: Winter-spring, summer-autumn, fall-winter rice in the Mekong Delta, Central and Northern regions; especially fields near dikes, canals, orchards, and bushes.
Duration: Do before sowing, maintain throughout the season, peak at the beginning of the season and the period of sowing until maturity.
Difficulty level: Basic but needs to be done at the same time.
Estimated additional costs: 150-500 thousand VND per acre if making traps and cleaning fields; higher if you have to hire a centralized rat exterminator.

At what stages do rats damage rice?

Rats can destroy almost the entire crop:

Before and right after sowing: eat newly sown seeds, thin the fields.
Seedling — tillering stage: horizontal biting of stem, loss of buds, empty field in clusters.
Preliminary block statue — making fields: heavy destruction because the tree begins to have good nutrition.
Ripe — harvest: eat seeds, bite flowers, spill rice.

The heaviest damage usually occurs from the initial mass stage onwards, but if not eliminated at the beginning of the crop, by then the rats will have already reproduced and will be very difficult to control.

Signs of harmful mice

The rice plant was bitten across the stem, the bite wound was compact.
The fields are sparse in clusters near banks, near ditches or near high mounds.
There is a small trail on the edge of the field.
There are caves on dikes, canal banks, and high mounds.
In the ripening stage, the flowers are bitten and the seeds fall in streaks.

Rat often destroys a lot at the edge of the field first and then spreads inside if the population is high.

Why are rats breaking out

Mice thrive when three conditions are met:

Food: paddy fields in many different stages, with scattered rice and falling rice.
Drinking water: canals, ponds, trenches, lowlands.
Shelter: wide dikes, bushes, orchards, field roads.

A big reason is that sowing is not done at the same time. When this area has just been sown and the other area is ripe, the mice always have food and a place to move.

Principles of mouse prevention

Must do it at the same time

A household sets good traps but if the next field is left alone, the rats will still return. Effective mouse prevention requires:

Work according to fields, cooperative groups or adjacent household groups.
Kill rats before sowing.
Repeat at shelters such as dikes, canal banks, and bushes.
Integrate trapping, sanitation and crop management.

Killing rats after the rice has been severely damaged is done too late.

Focus on the beginning of the season

Good times:

During soil preparation
Before and immediately after sowing.
Before mice enter their reproductive phase.

Killing at the beginning of the season helps reduce the number of mother rats and the litter of pups in the middle of the season.

Cultivation and hygiene measures

Clean grass on dikes, field edges, and canal banks.
Clean up bushes, piles of straw, and materials left in the field.
Fill rat holes after treatment.
Harvest neatly, don't let too much rice fall.
Plowing and burying rice after harvest.
Sow seeds simultaneously according to the local schedule.

Clean field edges not only reduce rats but also reduce shelter for many other pests.

Traps and mechanical measures

Place traps where mice pass

Priority:

Mouth of the cave.
Shore trail.
Near the canal bank.
The edge of the field was bitten first.
orchard or bushes close to fields.

Traps placed in the field are less effective than traps placed on the right path.

Crop trap

Where rats damage more than 10 percent of the area, crop traps can be used:

Plant or leave a paddy field more attractive to rats.
Surrounded by plastic fence.
Set a trap at the entrance.
Check and collect mice every day.

This method is effective when done on a large enough area and with a group of households participating.

Use safe baits

You should only use baits mixed with chemicals a maximum of 2 times per crop:

First time: when preparing the land or sowing seeds.
Second time: tillering stage if the population is still high.

Principle:

Use treatment according to label and dose.
Place baits in boxes/traps, do not spread them indiscriminately.
Do not place near domestic water sources.
Collect mouse carcasses and excess baits.
Notify surrounding households to avoid being eaten by pets.

Do not use baits of unknown origin. Do not mix drugs arbitrarily based on word of mouth experience.

Absolutely do not use electricity

Do not use electricity to catch rats in paddy fields. This method is very dangerous for:

Person in the field
Children.
Pets.
Wild animals.

Electrical accidents in the field often have very serious consequences. This is not an acceptable mouse prevention measure.

Monitor periodically

[ ] Number of rat holes on the edge of the field.
[ ] New bite marks on rice.
[ ] Proportion of area with sparse buds or flower shedding.
[ ] Number of mice caught per batch.
[ ] Areas where rats reside a lot: dikes, canal banks, orchards.
[ ] Sowing schedule of neighboring fields.

If you see new bites increasing rapidly, it is necessary to immediately treat the field edges and hiding places, without waiting for them to spread into the middle of the field.

Common mistakes

Killing rats alone in one field: short effect, rats return from the next field.

Wait until the rice is bitten a lot before doing it: by then the rats will have bred and dispersed.

Only spread bait, don't clean the banks: the shelter is still there, the rats still come back.

Uncontrolled baiting: dangerous for dogs, cats, ducks, fish and people.

Using electricity to catch mice: extremely dangerous, should not be done under any circumstances.

Take notes

First day of mouse treatment.
Number of traps and locations.
Number of mice caught.
Damaged area
Measures used: traps, cleaning, chemical baits.
Effective after 7-10 days.

Taking notes helps you know hot spots for rats in the field so you can handle them sooner next season.

References

*Instructions for preventing rat infestation in the fields* — Hainong technical document.
*Integrated pest management for rice* — Plant Protection Department.
*Rice IPM Handbook* — FAO Vietnam.