Instructions for preventing rice thrips

Thrips are very harmful from the seedling to tillering stage, especially 10-15 days after sowing when the field is dry, lacks water, and the weather is dry. Instructions for identifying dry yellow leaf tips, retaining water, fertilizing and limiting chemical spraying.

Summary: Thrips are pests at the beginning of the season, often causing severe damage when rice is young, fields lack water and the weather is dry. Thrips gather at the leaf tips, sucking sap, causing the leaf tips to turn yellow, dry, and curl the leaves. Many fields just need to keep water and fertilize properly and the plants will overcome, it is not necessary to spray chemicals immediately.

Applies to: Rice from seedling to tillering stage, heaviest 10-15 days after sowing.

Duration: Monitor closely during the first 3 weeks after sowing.

Difficulty level: Basic. It is necessary to distinguish thrips from water deficiency, alum poisoning and physiological leaf blight.

Estimated additional costs: Low if treated with water and nutrients; Spray only when population is high, according to local recommendations.

What are thrips that damage rice

Thrips are very small insects:

• Young thrips are about 1 millimeter long, light yellow.
• Adult color is black, body is 1.5-2 millimeters long.
• Both juveniles and adults suck sap.
• They often live concentrated in rice tops and young leaf tips.

Because of its small size, people often only see symptoms on the leaves and cannot see the bugs clearly.

Identification signs

Observing young rice:

• The tips of the leaves turn yellow, then dry.
• Young leaves curl up at the tip.
• Rice plants grow slowly.
• The fields look gray and yellow in patches.
• When you separate the leaf tips, you can see small bugs moving.

Thrips cause severe damage 10-15 days after sowing. If the rice has produced strong branches, the plant will usually endure better.

Conditions that cause thrips to grow

Thrips often increase strongly when:

• Dry weather.
• The field lacks water.
• The rice is still small.
• Soil lacks nutrients, plants are weak.
• The fields are sown unevenly, the high places are dry.

Simply put: the drier the field and the weaker the plants, the more likely thrips will cause serious damage.

Distinguish from other causes

Dry yellow leaf tips are not always caused by thrips.

Before spraying, you should carefully check the field for lack of water or alum.

Main management measures

Stay properly hydrated

This is the most important measure:

• Keep the field moist enough after sowing.
• Do not let the field surface dry and crack.
• For high fields, it is necessary to check the water every day for 10-15 days after sowing.
• When you see yellow leaf tips due to thrips, add water to the field at a level appropriate to the age of the rice.

Sufficient water in the fields helps rice recover quickly and makes conditions more unfavorable for thrips.

Fertilize early and in balance

• Fertilize according to the recommended schedule.
• Do not let the plants lack nutrients during the seedling stage.
• Add foliar fertilizer to restore the plant if it is slightly yellow and dry.
• Do not fertilize too much nitrogen as this will cause the plant to become weak later.

The goal is to help the tree get through the initial stages, without making it too soft.

Limit chemical spraying

Thrips on young rice in many cases decrease when the field has enough water and the plants recover. Therefore:

• Do not spray immediately if you only see a slight yellow color.
• Do not mix multiple drugs.
• Do not spray broad-spectrum crop-protection products when the field has many natural enemies.
• Only spray when the population is high, symptoms spread quickly and water/nutrition adjustments have not decreased.

When spraying is necessary, choose the crop-protection product according to local recommendations and the correct label.

Procedure for treating fields infected with thrips

Step 1: check the water. If the field is dry, add water first.

Step 2: check 5 points in the field to see if there are any bugs in the leaf tips.

Step 3: fertilize or spray nutrients to recover if the tree is weak.

Step 4: follow up after 2-3 days.

Step 5: if symptoms spread quickly and bug population is high, consider spraying as recommended.

This procedure helps avoid spraying when the main cause is lack of water.

Follow up the first 3 weeks

• [ ] Field water level every day.
• [ ] Are the leaf tips dry yellow?
• [ ] Are the tips of young leaves curled?
• [ ] Are there small bugs in the leaf tips?
• [ ] Is there a higher place in the field that is drier?
• [ ] Did the plant recover after adding water?

Thrips are an early-season pest, so close monitoring during the first 21 days after sowing is enough to reduce major risks.

Common mistakes

Spraying when the field is dry: plants are still stressed, low efficiency.

Confused with alum poisoning: spraying does not cure roots and alum water.

Using too much nitrogen to save the tree: the tree grows green quickly but easily attracts other pests.

Not checking high fields: thrips are often heavy in areas that lack water first.

Multiple crop-protection product application at the beginning of the season: harms natural enemies and increases unnecessary costs.

Take notes

• Sowing date.
• The day I saw the first yellow leaf tip.
• Field water level.
• Measures taken: watering, fertilizing, spraying if any.
• Results after 2-3 days.
• Proportion of tree recovery.

If the field is affected by thrips every year at the beginning of the season, you need to review the field surface and water retention capacity.

References

• *Instructions for preventing rice thrips* — Hainong technical document.
• *Integrated pest management for rice* — Plant Protection Department.
• *Rice IPM Handbook* — FAO Vietnam.

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