Crown Rot in Corn

Early-season seedling diseases have caused some stalk rot issues in area corn fields. Fields that endured wet growing conditions this spring may have been infected by Fusarium species. This infection may have developed into crown rot, which is currently being observed as stalk lodging.
 

 

Disease Development & Symptoms

 

Crown rot infections are usually caused by Fusarium species, but the fungus that causes anthracnose (Colletotrichum) may also be a factor1. While the crown of a healthy plant should be a fleshy, white-green color, a tan-to-brown crown is observed with a Fusarium infection. The discoloration is affected by the level of infection. More severe infections are darker brown, and the crown tissue becomes quite rotted. This extensive infection disrupts the “plumbing” of the plant and may cause stunting, leaf yellowing, wilting, and even death. Stalk cannibalization occurs when the corn plant is not able to complete ear fill without remobilizing nutrients and energy from lower leaves and stalks to meet the demand from the developing kernels.

 

The stress of wet soils this spring were conducive for disease infection. Other stresses may include cold temperatures, soil compaction, fertility issues, or herbicide injury2. In previous years, the stress combination of a wet spring followed by an extended dry period led to crown rot infection.

 

While crown rot infections have their beginnings in early-season plant infections, they can persist much longer, eventually resulting in stalk rot and potential yield loss.

Harvest Concerns & Yield Impact

 

A crown rot infection that results in stalk rot may also lead to lodging. Typical symptoms of Fusarium stalk rot include whitish-pink to salmon discoloration of tissue at the nodes, while plants infected with anthracnose tend to have shiny black blotches or streaks on the outer stalk. Monitor fields closely to schedule harvest while there is still enough stalk strength left to help facilitate harvest. Fields with considerable lodging should be harvested early to minimize the risk of increased lodging. Although drying cost is a concern when harvesting wet grain, this expense will likely be a better option compared to potential yield loss from lodging.

 

Test weights may be lighter due to the impact from crown rot and/or lodging on the ability of corn to finish transporting carbohydrates to the kernel.

 

Fusarium Stalk Rot and Stalk Rot in the Root CrownDisease Management

 
 
 
 
Fusarium is a pathogen commonly found in crop residue and soil. Resistance to Fusarium crown rot is not available in current corn products. While fungicide seed treatments do protect against Fusarium, the treatment does not persist long enough to protect corn from crown rot. Because crown rot is associated with various stresses in addition to a fungal infection, identifying and alleviating any stresses may help reduce loss from Fusarium crown rot. For example, early in the season stunted plants with crowns that are not completely discolored and rotted may benefit from cultivation. Bringing the soil up around the crown may promote nodal root development and help the plants recover.
 
 
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