Brown Spot

Symptom

It is caused by seed-borne fungal pathogen and occurs from seedling stage to milk stage. On seedlings, the fungus produces small, circular, brown lesions, which may girdle the coleoptile and cause distortion of the primary and secondary leaves. In some cases, the fungus may also infect and cause a black discoloration of the roots. Infected seedlings are stunted or killed. 
On the leaves of older plants, the fungus produces circular to oval lesions that  have a light brown to gray center, surrounded by a reddish brown margin. When infection is severe, the lesions may coalesce, killing large areas of affected leaves. The fungus  may also infect the glumes, causing dark brown to black oval spots, or the grain, causing a black discoloration. The disease can adversely affect the yield and milling quality of the grain.
Severely infected leaves can die before maturity, which will produce lightweight or chalky kernels. Therefore, brown spot infection reduces the number of grains per panicle and the kernel weight.