According to the National Center for Hydrometeorological Forecasting: due to the MJO phenomenon, it is likely to cause rain in the southern region of Vietnam. Therefore, in the Southern region, there will be a lot of rain in April.
Heavy rain, high humidity, is a very suitable weather pattern for the development of pests and diseases, especially rice blast disease (especially for rice in the tillering stage).
The disease is caused by Pirycularia oryzae. The disease affects leaves, stems, and seeds,… (cổ bông, cổ gié )
- Reason
- The disease depends a lot on external factors, so the disease develops erratically
- Weather conditions: severe disease in cool weather, light wind, high humidity, frequent and prolonged rain, cloudy weather with little sunshine is also favorable for the disease to develop and cause serious harm
- Nutritional conditions (fertilizers): Too much nitrogen fertilizer, lack of phosphorus and potassium often make the disease develop. In fields that have been fertilized with a lot of nitrogen, adding phosphate fertilizers will make the disease worse. If the soil lacks phosphorus, fertilize more phosphorus to limit the disease (acid sulphate soil). To apply more or less potassium, it is necessary to balance the amount of nitrogen applied to the field
Stage of disease development
- On the seedling: the disease is pink rhombus shape, then turns yellow-brown, wilted and dies
- On leaves: initial lesions are small greenish-gray spots. Later, the diseased lesions gradually became rhombic, with two pointed ends along the leaf veins, silvery white in the middle, brown around the edges, narrow yellow at the outermost. When the disease is severe, the lesions connect to form large spots and cause leaf burn
- On the stem, Cổ bông : At first, it was just a small gray spot, then it turned brown and spread around the stems, Cổ bông turned off the conductive circuit, the rice flower was dry and could not enter firmly.
Preventive measures
- Plant disease-resistant rice varieties suitable to local farming conditions.
- Cleaning the field, killing weeds around the bank to eliminate pests, burning remnants after harvest, plowing deeply. For infected varieties, seeds should be treated before soaking by soaking seeds in water with a temperature of 54 0C for 10 minutes or, after soaking, draining.
- Do not fertilize a lot of nitrogen fertilizer, so apply it many times and do not fertilize when the disease is developing.
- When the disease arises, in combination with the use of drugs should add more water to the field and stop fertilizing nitrogen, do not spray fertilizers or growth stimulants.
- People spray Ninja 35EC, with a dose of 0.9 L/ha with a water volume of 400 L/ha, and evenly wet the plants.
