Causal Agent, Hosts, and Infection

This disease is caused by the fungus Fusarium moniliforme J. Sheld. (teleomorph: Gibberella fujikuroi (Sawada) Ito in Ito & K. Kimura). This species and other Fusarium species also incite ear, kernel and root rot and seedling blight. Corn and sorghum are the most economically important hosts of F. moniliforme in Nebraska. Its important to note that the fungus has a very broad host range influencing crop production in many areas of the world. The fungus overwinters as chlamydospore-like structures and mycelium on plant debris and mycelium on seed. Stalk rot is generally thought of as a problem of senescing plants. A higher incidence of stalk rot is common when conditions that tend to encourage early senescence occur. Two such conditions are water stress and foliar diseases. Insect or hail injury may also result in more stalk rot as will high plant populations and imbalanced fertility ( high N to K ratio). Timing of infection has been debated for quite some time. Most researches feel that infection occurs early in the season (possibly at the seedling stage as a result of planting infected seed) and the fungus grows systemically, producing symptoms during the later stages of plant development. Others maintain that infection occurs later in the growing season. The infection process occurs when the fungus invades host tissue directly or through wounds. Mycelium and conidia serve as primary inoculum. Common points of entry are roots and stalks at the base of leaf sheaths. Weather conditions that favor stalk rot development are dry weather before silking and warm wet weather after silking.

Symptoms

The earliest symptoms of stalk rot are wilted plants in the field. Infected plants take on a grayish green hue then turn tan. Outward symptoms of the disease are indefinite discolored patches on the lower internodes. The pith disintegrates, leaving vascular strands in tact. Stalks feel spongy when squeezed. A pink growth is evident on vascular strands when spores are produced. There is also a reddish-pink discoloration of the roots. These symptoms are best observed by splitting stalks longitudinally. As with many stalk rots, lodging is another common symptoms.

Plant Health Management

Resistant or Tolerant Hybrid Selection

Hybrids that have good stalk strength are often characterized as "resistant"; however, the phenotypic"resistance" is due to the hybrid's rind strength and not the resistance to the organism.

Proper fertility levels.

Avoid too much nitrogen and a high N to K ratio.


Proper population.

References

Christensen, J.J., and R.D. Wilcoxson. 1966. Stalk Rot of Corn. Monograph No.3. American Phytopathological Society. St. Paul, MN.

Jardine, D.J. 1986. Stalk Rots of Corn and Sorghum. KansasState University Cooperative Extension Service. L-741.

Nyvall, R.F. 1989. Field Crop Diseases Handbook (2nd. ed.) Van Nostrand Reinhold, New York. pp 114-115.

Schurtleff,M.C.(ed.). 1980. Compendium of Corn Diseases (2nd. ed.). American Phytopathological Society, St. Paul, MN, pp. 45-46.

Useful Links

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Caveat

Material contained on the Links from the page are the responsibility of the linked page's author(s).

This page was drafted by: Jane Christensen, Department of Plant Pathology, University of Nebraska-Lincoln

Disease images were provided by: Dr. David Wysong, Department of Plant Pathology, University of Nebraska-Lincoln

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This page is authored and maintained by:
Dr. J.E. Partridge, Department of Plant Pathology, University of Nebraska-Lincoln

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