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Rice Blast

Rice Blast

Magnaporthe grisea


In a Nutshell

    Chlorotic (yellow/light green) lesions with dark necrotic borders and grey to whitish center on leavesStem nodes rotCollar rot

Hosts: %1$s

· Rice


Rice blast affects every part of the plant. The leaves exhibit yellow to light green chlorotic lesions. The borders of the lesions are dark necrotic and the center is grey to white. The size of the lesions depends on several factors like the age of the plant and time of infection. Usually, lesions appear in the form of a spindle or elliptical spots. These lesions grow with the progress of the disease and leaves dry out. If the junctions of leaves and sheaths are infected, collar rot can appear, and the leaves above the junctions die. Nodes can also be affected. This leads to brown nodes and flowed by breaking. This can cause the complete death of the upper stem.


Rice Blast is favored by humid and warm conditions, but also by low soil moisture. A period of high moisture accompanied by leaf wetness is required for an infection, so sites with large day to night temperature differences are prone to a higher infection risk. Also, high nitrogen presence favors the infection risk in rice plants. Young plants are more likely to become infected than older plants.

Biological Control

Destroy all infected plant residues to prevent survival of the fungus in the field.

Chemical Control

Fungicides containing Azoxystrobin, Triazoles or Strobilurins can be applied to control Rice Blast. Carpropamid can be applied to prevent rice blast.

Preventive Measures

    Avoid excessive nitrogen fertilization (split nitrogen fertilization into two or more treatments)Avoid drought stressMaintain continuous flooding and avoid drainage of the rice fieldUse healthy seed materialPlant resistant varietiesPlant early in season (after the onset of the rainy season)Control of weed and alternative hosts