Patti sukh jana or patti rog

patti sukh rahi he isko kese bachaya ja sakta he upay bataiye

its symptoms of leaf blight diseases. After cob development, the symptoms of the disease take a lead to increases.
No need to spray after cob development.
if you want to break the further spread of spore within the field then Spray carbendazim 50%WP@30g/10 liters of water.