How to prevent small leaf roller butterflies from harming rice

It is possible that small leaf roller butterflies in farmers' fields may hatch between August 27 and September 5.

Thus, the rice leafroller disease this year has developed 2-3 weeks later than the same period every year. The main reason is due to weather fluctuations that prolong the pupal stage.

Currently, most of the early and mid-season rice fields of farmers in the province are at the stage from holding the panicle to showing the flower, a few areas are in the stage of bending the fruit. The characteristics of the small leaf roller butterfly are its small body, short wingspan, often flying from one rice clump to another or on the grass banks, a few are also capable of flying far into the house; it is sensitive to light, likes young rice and dense grass banks.

After emergence, they mate and lay eggs; the eggs are small and scattered on the underside of the panicle leaf or two adjacent leaves. After 5-7 days, they hatch into larvae. The larvae are very agile, crawling to the upper surface of the leaf and then spinning silk to sew along the leaf sheath to form a round nest. The larvae have the habit of rolling leaves.
Rice leaf rollers follow the veins of the leaves, hide inside and gnaw at the leaves, making the leaves silvery white. Severely damaged rice is when the rice is stunted and underdeveloped, leading to reduced rice yield. A small leaf roller butterfly can eat and damage 4-5 rice leaves.

Because the eggs of leaf rollers are very small, thin, and difficult to detect, and the rice is in the stage of panicle initiation to flowering, science has set a threshold for spraying pesticides. Accordingly, the most effective time to spray to kill small leaf rollers is 7-8 days after the peak of the butterfly season and the density of larvae is over 20 larvae/1m2 of rice. When spraying, you should spray the pesticide evenly, enough for the pesticide to contact the larvae and achieve the best killing effect.

In fact, the above-mentioned spraying threshold and spraying time are still difficult for farmers. Recalling the last winter-spring rice crop, although there was a bumper crop, some rice fields were still completely white-leafed, the rice could not emerge, due to spraying at the wrong time, not at the prescribed threshold, and spraying the wrong pesticide.

Based on the foundation and goals of crop production, achieving high productivity and efficiency and taking farmers as the center, it is recommended that the relevant agencies continue to direct the People's Committees of communes and towns to coordinate with the Agricultural Service Centers of districts to organize field training for farmers on practical topics to serve promptly.