Date of this Version
Extension Circular 1898 (EC1898)
Stalk rot diseases of corn are common, occurring in every field to some extent. Each year stalk rot diseases cause about 5 percent yield loss. Under some conditions, losses can exceed 10–20 percent, and in isolated areas losses have been as high as 100 percent. Stalk rot diseases reduce yield both directly and indirectly. Plants with prematurely rotted stalks produce lightweight, poorly filled ears because of the plant’s limited access to carbohydrates during grain fill. Infected stalks are converted from sturdy, solid rods to hollow tubes as the stalk pith pulls away from the outer rind, compromising stalk strength. Rotted, weakened stalks are prone to lodging, particularly if decay occurs below the ear.
Stalk rot diseases tend to be more common in higher yielding hybrids that produce large, heavy ears. During times of stress, such as when foliar diseases cause substantial loss of leaf area, these large ears may cannibalize carbohydrates from the stalk and weaken it. Large, heavy ears also can predispose the stalk to lodging with the added weight supported above weakened lower stalk tissue. Lodging indirectly reduces yield through harvest complications and ear loss.
Stalk rot diseases can be caused by many fungi and bacteria. Most of these pathogens occur commonly in the field and behave opportunistically by primarily infecting senescing, injured, or stressed plants. A single plant often may be infected by multiple stalk rot pathogens which cause other diseases of corn and other crops. Each pathogen is favored by particular environmental conditions.