Rice blast is caused by (Magnaporthe oryzae) fungus.
Rice blast can occur at anytime throughout the plant growth stages.
The disease causes not only on the leaves but also seeds and panicles of rice.
In the tropical and temperate regions, the disease occurs in both summer rice and monsoon rice.
Application of excessive amount of nitrogen fertilizer at once, may challenge to infect this disease.
Occurrence of high humidity in prolong days with idle wind at night time would cause this disease more severe.
Symptom
Diamond shaped lesions with light-colored center and reddish-brown borders appears on leaves.
Dark-brown color lesions can be found on the plant nodes and the necks of panicles.
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Diamond shape lesions on leaves & nodes source: ScienceDirect.com |
Dark lesions on panicle nodes source: Dept of Agriculture & Food |
Disease Cycle
When disease infected, small spots with brown color appear on resistant varieties. In susceptible variety, the lesions coalesce into each other and this may lead to the death of the leaves.
It infects in nodes and panicles, and the nodes are black-brown and breaking.
It infects on neck of panicle with dark-brown lesions and breaking.
Resistant Varieties
CAR 14 (IR 06L164) variety is resistant to rice blast and in Cambodia, it is distributed in 2015 as high yielding variety.
Chemical Control
Seed treatment- fungicide 2.0 g / 1 kg seed -(Captan/ Carbendazim/ Thiram/ Tricyclazole)
Spraying the systemic fungicides such as Pyroqilan at 1g/lit of water (or) Tricyclazole at 1g/lit of water or Edifenphos at 1g/lit of water or Carbendazim at 1g/lit of water
