Southern Leaf Blight

Southern corn leaf blight (SCLB) is favored by warm temperatures (68-90(F) and high humidities.  Thus, it tends to be more of a problem in the southern half of Illinois, although it can be found farther north if weather conditions are favorable.  Frequent rainy periods enhance disease development.
The symptoms of SCLB are leaf lesions ranging from minute specks to spots of one-half inch wide and one and one-half  inches in length.  They are oblong, parallel-sided, and tan to grayish in color.  A purplish to brown border may appear on the lesions depending on the genetic background of the plant. Early and severe infections in susceptible plants predisposes them to stalk rots.