The document summarizes blast disease, a fungal disease that affects rice plants. It is caused by the fungus Magnaporthe oryzae, which can infect all above ground parts of rice including leaves, stems, and panicles. Symptoms include initial white to gray-green lesions on leaves and nodes that enlarge and merge, potentially killing entire leaves. Control methods include planting resistant varieties, adjusting planting times, splitting nitrogen fertilizer applications, applying silicon fertilizers to soils, and using systemic fungicides.

1. Dr. V. RAMESH
Assistant Professor & Head
Department of Botany
Vivekananda College
Tiruvedakam West – 625 234
ramesh.vnr09@gmail.com
+91 9842629245
BLAST DISEASE IN RICE

2. CAUSAL ORGANISMS: Magnaporthe oryzae or pyricularia oryzae
It causes areas with low soil moisture, frequent and prolonged periods
of rain shower, and cool temperature in the daytime.
INTRODUCTION
Blast is a fungal disease. It can affect all above ground parts of a rice
plant: leaf, collar, node, neck, parts of panicle, and sometimes leaf
sheath.
HOST PLANT: Oryza sativa
Spores of M. grisea

3. SYMPTOMS OF BLAST DISEASE IN RICE
Lesions on NodesLesions on Leaf
Lesions
Affected Rice

4. SYMPTOMS
Initial symptoms appear as white to gray-green lesions or spots, with
dark green borders.
Older lesions on the leaves are spindle-shaped and whitish to gray
centers with red to brownish or necrotic border.
Some resemble diamond shape, wide in the center and pointed
toward either ends.
Lesions can enlarge and growing together to kill the entire leaves.
Leaf blast lesions are usually elongated and pointed at each end

5. CONTROL MEASURES
The primary control option for blast is to plant resistant varieties.
Adjust planting time. Sow seeds early, when possible, after the onset
of the rainy season.
Apply nitrogen fertilizer application in two or more treatments.
Silicon fertilizers (e.g., calcium silicate) can be applied to soils that
are silicon deficient to reduce blast.
Systemic fungicides like Triazoles and Strobilurins can be used for
control to control blast.

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