Proactively prevent brown spot disease in rice

(Baonghean) -Ranked as the second most serious disease after blast disease among current fungal diseases of rice, sheath blight can cause rice to wither and reduce productivity. The disease also causes rice grains to become empty, milled rice to be crushed, and the quality of rice to be low. The whole province currently has nearly 9,000 hectares of rice infected with sheath blight, including 7,913.3 hectares of summer-autumn rice and 899.6 hectares of winter-spring rice.

Right from the stage when the rice started to form panicles, the brown spot disease appeared sporadically in the summer-autumn rice fields of Yen Thanh district. Ms. Do Thi Hoa (Hamlet 8, Tang Thanh Commune) said: “Currently, my family's 3 sao of rice are concentrating on flowering, seeing dark oval spots appearing on the rice leaf sheaths, I knew that my field had brown spot disease. However, because I was advised that the disease was mild and did not require spraying, I did not spray pesticides but only increased potassium fertilization for the rice.”

Summer-autumn crop - this season, Yen Thanh district planted nearly 13 thousand hectares of rice. Summer-autumn rice has been concentrated from July 26 to August 4, and winter-spring rice is in the final tillering stage. Sheath blight disease appeared when summer-autumn rice began to form panicles, and for about a week now, the disease has developed more strongly. The whole district now has over a thousand hectares of rice infected with the disease, concentrated in the communes of Tang Thanh, Hong Thanh, Hoa Thanh..., especially in the fields with dense planting and high nitrogen fertilization. Currently, the district is directing the Plant Protection Station and communes to focus on monitoring, investigating, and zoning each outbreak and each rice crop to have appropriate treatment measures. It is recommended that people only spray pesticides in areas that are deeply infected to the threshold for spraying, not spraying too early or widely, which is both wasteful and affects the environment and ecosystem. In particular, Yen Thanh focuses on pesticide management, only bringing into the area specific pesticides for each type of disease to increase prevention effectiveness.

Nghi Loc farmers spray pesticides to prevent summer-autumn rice diseases. Photo: PV

In Dien Chau, brown spot disease has appeared in the fields since the rice first started tillering and forming panicles, however, according to Mr. Le The Hieu (Head of the District Plant Protection Station), the rate of new diseases has increased significantly in the past 2 weeks. This summer-autumn crop, Dien Chau planted more than 9,000 hectares of rice, of which about 1/3 of the area planted with Khang Dan 18 and VT-NA2 varieties is forming panicles, 1,000 hectares of BC15 is currently flowering, and the varieties GS9, Nhi Uu 838 and 986 are starting to flower en masse, all of which are susceptible to brown spot disease. The area infected with brown spot disease has now increased to over 835 hectares, of which 50 hectares are heavily infected, concentrated in the communes of Dien Cat, Dien Nguyen, Dien Thai, Dien Dong... Through inspection, the Plant Protection Station has recommended that people spray over 75 hectares that have reached the threshold for spraying. Currently, the infected area continues to increase but not much.

According to the synthesis of the Provincial Plant Protection Department, by early August 2013, the infected area of ​​the whole province had increased to nearly 9,000 hectares. The disease occurred and caused damage in all localities in the province but was concentrated in the districts of Yen Thanh, Thanh Chuong, Dien Chau, Nam Dan... Up to now, the whole province has carried out prevention and control on nearly 6,000 hectares but the disease is still increasing. The common rate of the disease is 3 - 5%, in high places it is 30 - 40% and especially the area infected as well as the level of the disease is increasing quite rapidly.

Sheath blight disease develops strongly and spreads rapidly in conditions of temperature around 24-320C, saturated humidity or high rainfall. Currently, the province has started to have showers, the amount of water in the fields is not lacking, which is a favorable condition for the disease to develop, especially in fields with a lot of water and too dense planting. Meanwhile, the summer-autumn rice is currently in the stage of rice heading to wax ripening, which is the period of severe disease infection. Therefore, localities and people need to focus on monitoring to implement effective prevention measures.

According to Mr. Trinh Thach Lam (Head of Plant Protection Department - Provincial Plant Protection Department), the occurrence and development of brown spot disease is closely related to the water regime in the fields and the fertilizer regime. If farmers apply too much nitrogen fertilizer, apply it many times or apply nitrogen fertilizer late to stimulate panicle formation, the disease will arise and develop more strongly because excess nitrogen fertilizer makes the rice grow densely, the humidity and air inside the rice canopy increase, suitable for fungal diseases to arise and spread.

Therefore, especially in rice fields that have been heavily fertilized with nitrogen, it is necessary to add potassium to balance the amount of fertilizer, help the rice plants become stronger, and reduce the level of disease infection in rice plants. The water level should also not be too high in case the disease is spreading strongly. In addition, rice fields with many weeds such as water hyacinth, watercress, watercress, and betel... are also at risk of serious disease infection because in addition to being an intermediate host of brown spot disease, many weeds also contribute to increasing the humidity in the rice field, creating favorable conditions for the disease to cause more serious damage.

Currently, the weather often has showers, humid air is favorable conditions for the disease to continue to grow and cause damage. It is urgent to take timely preventive measures because if the disease develops strongly, causing damage to leaves and panicles, it will seriously affect productivity.

According to the forecast of the Plant Protection Department, in the coming time, the disease will continue to increase in both severity and scope of damage, especially more severe damage on densely planted rice fields with high nitrogen fertilization. Localities need to pay attention, on rice fields infected with a rate of 10% or more, it is necessary to instruct farmers to prevent and control with one of the following drugs: Valydacin 3-5L, Cavil 50SC, Vida 5WP, Jinggangmeisu 5-10 WP,... For fields with severe disease, spray a second time 5-7 days after the first time.

Phu Huong