Corn is susceptible to diseases such as leaf wilts, blights, and even rotting. The best way to control disease is to rotate your crops each year, keep the area weed-free and remove any plant debris/residue from the growing area. The plants can also attract pests which will minimize your yields. Using a fungicide solution of Bacillus thuringiensis kurstaki (Btk) and mineral oil on the corn after the silk has formed will help prevent pests.