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The infection of the foliage results in yellow ‘V’ shaped spots arising along the margin which extend in the direction of the midrib.
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These spots are associated with a typical black discoloration of the veins.
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The infection extends through the xylem to the stalk and the vascular bundles turn black. In severe infection, the whole leaf shows discoloration and eventually falls off.
Dept of Agriculture Development 
SFAC Kerala