Spraying process for rice at sowing stage

The sowing stage requires priority in managing soil, water, grass, golden apple snails and thrips rather than early spraying. Checklist guide to decide when to spray, what to spray, and how to spray to avoid losing natural enemies at the beginning of the season.

Summary: Sowing is the easiest stage to "spray for sure", but it is also the time when spraying incorrectly can have long-term consequences for the entire season. During 0-40 days after sowing, the field needs to keep natural enemies, control snails, grass, thrips, onion mosquitoes and migrating leafhoppers according to the threshold. This article does not provide a rigid spray schedule, but rather guides the decision-making process before putting chemicals into the field.

Applies to: Rice sowing in the Mekong Delta and intensive rice growing areas.
Duration: From before sowing to 40 days after sowing.
Difficulty level: Basic. Need to visit fields and check water/grass/worms before spraying.
Estimated additional costs: Can be significantly reduced if pest control is not sprayed early; Cost depends on the object that really needs to be treated.

Objectives of the sowing stage

From sowing to 40 days, the main goal is:

Rice grows evenly.
Strong root system.
Appropriate tree density.
Grass and snails are controlled.
Natural enemies at the beginning of the season are protected.
Do not create pressure for hoppers/worms to break out later.

At this stage, treatment should not be considered the main measure. Soil preparation, water, seed and density are the foundation.

Objects that need attention

Golden apple snail

Most important in the first 7-25 days:

Bite young rice.
Strong in low-lying fields and deep water.
Priority is to collect, withdraw water, and block water gates.
Use medication only at high concentrations and according to the label.

Weed

The grass competes strongly in the first 20-40 days:

Manage by careful soil preparation, leveling, water.
You can use pre-emergence or post-emergence treatment for the right type of grass.
Do not use herbicides when the field is too dry, too flooded or the rice is weak.

Thrips, onion mosquitoes

These two subjects are closely related to water, weak plants and secondary hosts:

Thrips are heavy when the field is dry and the rice is small.
Onion mosquitoes are related to rice fleas, host grasses and humid weather.
Before spraying, check the water and clean the field.

Brown planthoppers migrate

Do not spray hoppers according to schedule. Need:

Monitor warnings for hopper migration.
Counting leafhoppers at the rice base.
Only spray when the threshold is exceeded or there is a clear risk of virus.

Checklist before spraying

Before any spraying, check:

[ ] What is the harmful object?
[ ] Has the password exceeded the threshold?
[ ] How many days after sowing of rice?
[ ] Is the field dry, has enough water or is it flooded?
[ ] Are there many natural enemies?
[ ] Can it be treated with water, collected, and weeded first?
[ ] Is the treatment right for the right target and the right stage of rice?

If you can't answer, don't spray yet.

Procedures for handling situations

The field has golden apple snails

Step 1: drain water for 24-48 hours.

Step 2: collect snails and eggs by hand, set bait if necessary.

Step 3: check snail density.

Step 4: only use local snail insecticide when density is high, avoid affecting aquatic life.

The field has thrips

Step 1: check the field for lack of water.

Step 2: bring the water to the appropriate level.

Step 3: add nutrients to recover if the tree is weak.

Step 4: After 2-3 days the infection is still strong, consider medication.

The field has weeds

Step 1: identify grass groups.

Step 2: check the age of the grass and the age of the rice.

Step 3: choose the appropriate pre-emergence or post-emergence treatment.

Step 4: keep the water level according to label instructions.

The field has brown planthoppers

Step 1: count leafhoppers at the base.

Step 2: determine the age of the leafhopper.

Step 3: see if there is a dwarf/dwarf yellow tree with twisted leaves.

Step 4: if the threshold is exceeded, spray the roots with the correct drug group.

Spraying technique at the beginning of the season

Spray early in the morning when the dew has dried or in the late afternoon.
Do not spray in the hot midday sun.
Do not spray before rain.
Use enough water, do not mix thicker than labeled.
Spray in the right location: base for leafhoppers, water surface/nest for snails, young leaves for thrips.
Do not mix multiple drugs if you are not sure they are compatible.

The rice plants are still young at the beginning of the season, so they are susceptible to chemical shock if mixed incorrectly or sprayed in unfavorable weather.

Things to do instead of treatment

Clean the soil thoroughly and dry it.
Leveling the field surface.
Block the water gate screen.
Sow sparsely, sow simultaneously.
Stay properly hydrated.
Early weeding.
Clean rice and weeds.

These reduce pest pressure longer than one spray.

Post-injection monitoring

[ ] Will symptoms decrease after 2-5 days?
[ ] Is the rice leaves burned, buds shrunken or unusually yellow?
[ ] Are the natural enemies still in the field?
[ ] Does the harmed object recur?
[ ] Does it need to be reprocessed or just monitored.

Do not repeat spraying just because "it's on schedule". Must rely on real fields.

Common mistakes

Spray crop-protection products early for general prevention: kills natural enemies, easily breaks out later.

Combining herbicides with crop-protection products arbitrarily: young rice plants are susceptible to shock.

Spraying when the field is dry, cracked or deeply flooded: low efficiency, easy to damage rice.

Not properly identifying the target: thrips, lack of water and alum can together make rice yellow.

Mix thicker than longan: does not increase effectiveness, only increases the risk of rice burning.

Take notes

Sowing date.
First spray: date, subject, active ingredient.
Reason for injection: code/threshold.
Field water level at spraying time.
Results after 3-5 days.

Clearly stating the reason for spraying will help you know which times you really need it and which times you can skip.

References

*Spraying process for rice at sowing stage* — Hainong technical document.
*IPM Integrated Pest Management Guide* — Hainong technical document.
*Rice IPM Handbook* — FAO Vietnam.