DISEASES OF CORN - GIBBERELLA STALK ROT

Another common stalk rot is Gibberella stalk rot, caused by the fungus Gibberella zeae. This fungus is the sexual stage of the fungus Fusarium graminearum, which causes scab of wheat and other small grains. External symptoms of Gibberella stalk rot include a dulling of leaves to a gray-green color, softening and discoloration (tan to dark brown) of stalk internodes, and ultimately lodging. The most characteristic symptoms of the disease however occur internally. These symptoms include a shredding of the pith and a pink to red coloring of internal stalk tissues.

The fungus that causes Gibberella stalk rot readily survives in corn debris. Thus this disease may be more prevalent in fields where continuous corn is grown. Deep plowing, or a suitable rotation strategy helps control the disease. An appropriate choice of rotation crops is critical however. Use of soybeans in rotation with corn is likely to provide better disease control than use of small grains. Remember that Gibberella zeae/Fusarium graminearum attacks both corn and small grains, and thus corn may serve as an inoculum source for small grains and vice versa. Also, as is generally true for stalk rots, proper soil fertility is critical in controlling Gibberella stalk rot. A high soil N/K ratio favors disease development. Finally, use of resistant varieties can aid in disease control.