How to prevent rice blast disease

(Baonghean) - Currently, rice blast disease on spring rice in Nghe An has developed quite rapidly, with hundreds of hectares of rice infected.

In Vinh City alone, Hung Hoa commune has 6-7 hectares of rice severely infected, even withered. In Hung Nguyen, according to Mr. Nguyen Thiet Hung - Head of the district's Plant Protection Station, up to now, the whole district has over 300 hectares of rice infected with blast disease. Some varieties with signs of withering are AC5, Xi 23, Xi 30, BT-E1... In Dien Chau, Yen Thanh, Quynh Luu, Nghi Loc districts... blast disease is showing a tendency to develop strongly in the coming days.

Illustration: internet

Farmers’ knowledge of rice blast disease prevention is still limited. Therefore, in one crop, some families spray rice blast disease 2-3 times but still cannot destroy the disease, the rice still burns. Below is some information about rice blast disease that farmers need to know.

Blast disease only develops strongly when the air humidity is high, there is a lot of fog from late afternoon to early morning the next day, weak light, air temperature fluctuates in the range of 20 - 240C. On sandy soil, light loam, hau fields, unbalanced fertilization, especially nitrogen, ... the blast disease has more opportunities to develop strongly. Plant rice varieties that are susceptible to the disease such as: AC5, Xi 23, Xi 30, Xi 33, IR 1820 and some hybrid rice varieties such as: BT- E1, KP1, Nhi uu 986 ...

Rice blast disease develops in two stages: The first stage is the stage when fungal spores penetrate and adhere to the rice leaves to cause disease. At this time, if you visit the field, you will see that the diseased lesions appear individually, are needle-shaped or larger, can be round and slightly round, and are succulent. The diseased lesions are developing in an acute form and have not yet developed spores. Therefore, visiting the field to detect the diseased lesions early at this time will be the most effective prevention. If detected late, the rice blast disease has turned into a chronic stage, then prevention will not be effective. Because the diseased lesions are old and have developed fungal spores. Each chronic diseased lesion can release 2,000 - 6,000 fungal spores into the air and last for 15 days to cause disease throughout the field when they adhere to the rice leaves to parasitize and cause disease. Therefore, in this case, spraying is effective after 5 - 7 days.

Regarding rice blast prevention drugs, up to now there has not been any drug that completely destroys rice blast fungal spores. Even the most effective rice blast fungicides today such as tricyclazole (Filia 525 SC), Azoxystrobin (Amistar top 325 SC, Amistar 250 SC...) only stop at the mechanism of preventing the germination of fungal spores when the sprayed drug comes into contact with the fungal spores.

Therefore, prevention and control of blast disease on rice plants at this time is extremely important. Therefore, it is necessary to use specific drugs such as Filia 525 SC, Amistar Top 321 SC... mix 0.4 - 0.5 liters of drug water with 400 - 500 liters of clean water to spray on the rice hectare (1 sao 20 - 25 liters of mixed drug water) and should only be sprayed when the disease is still young, at the acute stage of the disease is the most effective.

During the rice blast disease period, absolutely do not let the field dry out, temporarily stop fertilizing, especially nitrogen, and it is best to use mixed fertilizer NPK 15.5.20 as the next top dressing.

Doan Tri Tue