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Leaf rollers are one of the pests with high impact on rice fields. With the current situation of alternating rain and sunshine, this is a favorable condition for worms to develop.

                              image of worms rolling leaves on rice                              

1.      What is a leaf roller?

The harmful leaf roller on rice has the scientific name of Cnaphalocrocis medinalin . Leaf rollers cause harm by releasing silk, connecting the two edges of the leaves vertically to the tube to live and cause damage inside. They eat the flesh of the leaves, leaving only the epidermis, causing the rice leaves to reduce the photosynthetic area, lose chlorophyll leading to poor growth. The strong attack on a large area will cause the affected fields to become shriveled. Besides, the wound at the edge of the leaf also creates favorable conditions for fungi and bacteria to penetrate, causing more diseases for rice.

2.      The life cycle of leaf rollers

Eggs:  life cycle 6-7 days, oval shape with very small network veins, female leaf rollers lay each fruit on the upper and lower surface of the leaf, newly laid eggs are slightly opaque when near hatching, turning ivory yellow.

Young caterpillars:  life cycle 14-16 days, newly hatched caterpillars are usually milky white, when large worms will be green, the body is divided into many segments and is about 19-20mm long. The young caterpillars, when newly hatched, will begin to eat the leaves, at 2-3 days old, they will begin to roll up the leaves to hide. 

Pupae:  life cycle 6-7 days, yellow or dark brown, usually located in rolled leaves, pupae 7-10mm long.

Adult caterpillars:  life cycle 2 - 6 days, adult rice leaf rollers are a type of moth, the front edge of the forewing is yellow-brown, with two dark brown oblique streaks from the top of the wing down to 2/3 of the wing.

3.      Measures to prevent leaf rollers

Cultivation method

After each season and the preparation period for the new crop, farmers should clean the field, clean weeds and by-products of the previous harvest season.

 Adjust the appropriate transplanting density, so that the rice should not be sown too thickly.

Balanced and reasonable fertilization, especially moderate nitrogen fertilizer.

Besides fertilizing with inorganic fertilizers, farmers should also use organic fertilizers and microbiological fertilizers to help plants improve their overall health and help limit the harmful effects of leaf rollers that damage rice.

Cultivate the fields, plowing the soil thoroughly after each crop to kill and remove the larvae and eggs in the soil.

Chemical measures

When the density of leaf rollers is at a high threshold, it can no longer be controlled by the above measures. Farmers need to use specialized pesticides such as: Gecko 240SC, Tomboy 135WG, ...

Image of leaf rollers dying after 5 days of using GECKO 240SC

People also regularly visit the field regularly to detect the worms early and spray them when they are 1-2 years old, if the worms have grown, they need to break the leaves before spraying the insecticide to be effective.