Thanh Chuong: Nearly 5,000 hectares of summer-autumn rice crops infested with rice leaf roller.

(Baonghean.vn) - This year, Thanh Chuong district planted 5,500 hectares of rice during the summer-autumn crop season. At this time, some early varieties have already started to develop panicles; currently, the small leaf-rolling caterpillar is developing and causing severe damage to nearly 2,000 hectares.

According to inspections by the District's Crop Production and Plant Protection Station, as of July 10, 2017, the fourth generation of adult rice leaf rollers is beginning to emerge in large numbers, producing fifth generation larvae at high densities over a wide area, causing damage to summer-autumn rice crops during the tillering and heading stages.

Rice leaf rollers feed on chlorophyll, causing rice leaves to curl and affecting the plant's growth. Photo: Dinh Ha

According to Mr. Nguyen Nhu Quan, Deputy Head of the Thanh Chuong Plant Protection Station, the affected area is approximately 5,000 hectares, spread across most localities in the district. The leaf-rolling caterpillar is very difficult to detect; if not detected early and controlled promptly, by the time the rice leaves curl and turn white, it's too late. Particularly in the fifth generation, there is overlapping of generations, therefore the period of damage caused by the young caterpillars will be longer than in the fourth generation.

To proactively detect and effectively control the fifth generation of rice leaf roller, the district has directed the Plant Cultivation and Protection Station to act as the focal point to coordinate with communes and towns in inspecting, classifying, and zoning areas to closely monitor the development and damage caused by rice leaf rollers in the fields; disseminating information, providing guidance, and directing effective control measures in areas with high pest density. This is to prevent farmers from neglecting control measures due to complacency or lack of information.

Mr. Nguyen Nhu Quan (center) - Deputy Head of the Plant Protection Station of Thanh Chuong district, is instructing people in Thanh Dong commune on how to detect pests on rice leaves. Photo: Dinh Ha

The District's Crop Production and Plant Protection Station also advises farmers to spray insecticides in areas where the density of young larvae reaches 50 or more per square meter.²For rice in the tillering stage, the density should be 30 or more per square meter.²For rice in the heading stage, spray with specific pesticides containing the following active ingredients: Indoxacarb (Ammate 150SC, Clever 150 SC, 300 WG, Sunset 300 WG, Opulent 150SC, Obaone 95WG,…), Chlorantraniliprole (Prevathon 5SC, Voliam targo 063SC, Virtako 40WG,…), Flubendiamide (Takumi 20WG,…).

The most effective time to spray is when most of the insects are in their 1st-3rd instar; when spraying, ensure that the amount of water and pesticide are as recommended and that the correct technique is used.

Residents of Thanh Linh commune (Thanh Chuong district) are actively spraying pesticides to control the fifth generation of rice leaf rollers. Photo: Dinh Ha

In addition, the district has also assigned the Plant Protection Station, communes, and relevant agencies to strengthen inspections of the business and use of pesticides in the area. They are tasked with promptly detecting and preventing the sale of substandard pesticides, pesticides not on the approved list, and expired pesticides, which negatively impact pest control results.

Dinh Ha