Photo Gallery:
The following images are of a commercial corn hybrid planted in central Indiana and afflicted with the systemic wilt phase of Stewart's Disease. This bacterial disease (Erwinia stewartii or Pantoea stewartii) is transmitted by the corn flea beetle (Chaetocnema pulicaria). Flea beetle populations were quite prolific in late April and early May of 2000 throughout many areas of the U.S. Midwest, attacking many fields of early-planted corn.
Typically, this disease manifests itself in corn as wavy leaf lesions that can ultimately coalesce into a true leaf blight that damages extensive portions of a plant. More rarely, the disease becomes systemic in very young corn plants (younger than leaf stage V4) and destroys part of the inner stem tissue. When this damage includes the all-important growing point area, the main stem dies (as evidenced by the wilted, dead whorl). If the growing point area is not mortally wounded, the consequent development of the plant is stunted and often deformed.
The systemic wilt phase of this disease is indeed rare, especially in commercial corn hybrids. Inbred corn lines and popcorn are generally more susceptible to the development of Stewart's Disease.
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1 Pattern of affected plants typical throughout field. |
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2 Affected plant with wilted, dead whorl, typical of many of the affected plants in the field. |
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3 Affected plant that is technically not dead, but so severely stunted that it will likely not produce a harvestable ear. |
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4 Another similarly stunted plant. |
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5 Growing point area damaged by the wilt phase of Stewart's Disease. Example #1 |
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6 Growing point area damaged by the wilt phase of Stewart's Disease. Example #2 |
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7 Growing point area damaged by the wilt phase of Stewart's Disease. Example #3 |
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8 Growing point area damaged by the wilt phase of Stewart's Disease. Example #4 |