Photo Gallery:
he Great Flood of '03 will be remembered for the crop
devastation caused by the flooding of the Wabash River and many of its
tributaries. As the flood waters recede, the totality of crop death is
immediately evident in those areas where crops were totally submerged for a
period of days.
Less obvious is the damage to plants on the higher elevations within the flood plain that were only partially submerged, particularly those fields where pollination was in progress or that were in the early grain filling period following pollination. These plants withstood the onslaught of flood waters that rose to heights above the ear but quickly receded with little to no major structural damage to the plants. Unfortunately, these survivors along the fringes of the major flooding may have won the battle, but may lose the war because of the potential for the development of bacterial ear rot as a consequence of the exposure of the immature ears to the muddy flood waters.
The following images illustrate the occurrence of bacterial ear rot in a corn field along the Wabash River in Vermillion County, Indiana. The field was adjacent to one that was totally destroyed by flood waters, but which itself had been briefly immersed up to and just beyond the ear shoots.
The corn plants themselves were still green and technically alive, but the husk leaves were a discolored, slimy, soft, and smelly mess; especially at their basal ends near the point of attachment to the stalk node. The immature ears also exhibited varying degrees of gray, slimy, and soft rotting tissue. The odor associated with this slimy mess of rotting plant tissue reminded me of fermenting corn silage.
Bacterial stalk rots in corn are more commonly reported than are bacterial ear rots; often developing under warm & humid conditions or in conjunction with pivot/sprinker irrigation systems (Shaner, 1998; Stack, 2002). While less common, bacterial ear rots have been reported before in Indiana following similar flooding conditions (Nielsen & Ruhl, 1998).
Bacterial ear rot is caused by one of several species of soft rot bacteria that live as saprophytes on plant debris in the soil. During periods of high rainfall, flooding, overhead irrigation, or poor drainage; bacteria are splashed onto plants and infect susceptible tissue. The bacteria normally enter the plant through leaf stomates or wounds on leaves or stalks.
While there is no remedy for this flood-related problem, growers should nonetheless scout areas of field that were partially immersed by the outer reaches of flooding rivers and creeks to more accurately assess the full extent of the flood damage to their corn crops.
 Flood waters briefly rose to above the ears, but quickly receded with little structural damage to the stalks. |
 Mud-covered ears already destroyed by bacterial ear rot. |
 Mud-covered ear shoot. |
 Bacterial ear rot following immersion of ear shoot by flood waters. |
 Rotting husk leaf tissue near connection of ear shank to stalk node. |
 Rotting husk leaf tissue near connection of ear shank to stalk node. |
 Rotting ear shank tissue at point of connection to stalk node. |
 Entire rotting ear shoot. |
 Rotting kernel/cob tissue. |