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How to prevent rice leaf roller
The rice leaf roller is a serious pest that primarily affects rice crops. The larvae feed on the upper epidermis and mesophyll of the leaves, while rolling them together to form protective shelters. This feeding behavior leaves the leaf surface intact, resulting in white or pale patches on the leaves. In severe infestations, entire rice fields can appear dull and unhealthy, leading to significant yield losses.
Newly hatched larvae typically move to the tip of the rice leaf and begin feeding, creating a "leaf-rolling" stage where the leaf edges are wrapped in silk. By the third instar stage, the larvae roll the leaves lengthwise, forming a distinct white band. As they grow, their feeding increases, and by the fourth and fifth instars, they frequently move between leaves, causing more damage. The affected leaves eventually turn dry and white, and the entire field may be covered with these white patches.
This pest is known for its long-distance migration and exhibits multiple generations depending on the region. In northern areas like Hebei and Shandong, it completes 2–3 generations per year. In central and southern regions such as Hubei, Anhui, Jiangsu, Shanghai, and northern Zhejiang, it has 4–5 generations. In Hunan, Jiangxi, and southern Zhejiang, there are 5–6 generations, while in Fujian, Guangdong, and Guangxi, up to 6–7 generations occur. In Lingshui County, Hainan Province, it can have as many as 10–11 generations annually.
The rice leaf roller mainly targets grassy weeds and moist environments in rice fields. Warm and rainy weather conditions significantly favor its development and spread.
To manage this pest effectively, control measures should be applied during the egg-hatching period. For example, using 1.8% Abamectin (Blueberry) at 75–100 ml per acre, or 2% Abamectin (Triton) at 70–100 ml per acre, or 5% Emamectin Benzoate Soluble Granules at 25 grams per mu, mixed with at least two barrels of water (30 pounds per barrel) for one mu of land. Spraying should be done once every 10 days for optimal results. It's also recommended to spray in the evening, as this tends to improve the effectiveness of the treatment.