Controlling rice blast disease - Some common mistakes

(Baonghean)In spring rice production, rice blast disease is one of the diseases that causes significant damage to many rice varieties on a wide scale in various localities. However, farmers often make several mistakes in controlling this disease.

First mistake: Overcrowding, especially in direct seeding areas. Fearing early-season frost damage, farmers increased the amount of seed sown by 25-30% compared to the prescribed amount per area, or planted more tillers/clumps, with a density of 48-52 clumps/m2, increasing the rice field population density. In addition, unbalanced fertilization, with excess nitrogen and insufficient potassium, created favorable conditions for rice blast disease to develop. Farmers did not consider the double damage caused by rice blast; once rice has already suffered leaf blight during the tillering stage, it poses a risk of developing neck blast.

Second mistake: Delaying rice blast control; often, pesticides are only applied when the disease is already widespread. The best approach is to regularly inspect the fields and, upon seeing disease spots resembling oil slicks, immediately apply preventative spraying. High-quality rice varieties, in particular, require proactive early prevention spraying.

Farmers in Hamlet 2, Bac Thanh Commune (Yen Thanh District) apply lime to their rice crops to control pests and diseases.
Spring crop of 2013. Photo: Ho Cac

Third mistake: Using pesticides without adhering to the "four correct principles," and especially using non-specific pesticides with excessively low active ingredient content (Tricyclazole and Propiconazole). Farmers are completely dependent on the pesticide seller, buying whatever is offered. Some dealers, driven by profit, sell substandard pesticides. Farmers don't use specific pesticides, only cheap ones.

Fourth mistake: Applying growth-stimulating fertilizers along with spraying, or adding nitrogen fertilizer to rice fields that have turned yellow while rice blast disease is developing. This does more harm than good. The disease continues to spread widely.

Fifth mistake: Seeing a neighboring field infected while your own field is healthy, but the rice is thriving, you cut off some leaves. This action creates mechanical wounds that allow pathogens to spread rapidly, reducing leaf area and affecting photosynthesis. The best approach is to carry out simultaneous preventative spraying on all rice varieties showing signs of infection in the same field.

For the spring crop of 2013, rice blast disease may develop and cause damage early during the tillering stage. In addition, other pests and diseases may also develop during the heading and flowering stages, such as brown planthopper and bacterial blight. Local authorities need to regularly inspect fields and proactively control these pests and diseases, paying particular attention to areas planted with varieties such as AC5, HT1, BC15, and Khai Phong 1.

Hoang An (Department of Agriculture and Rural Development)