Sharp Eyespot of Wheat

Sharp Eyespot of Wheat

Sharp eyespot may be found in most temperate wheat growing areas. It is not as damaging as some of the other lower stem diseases but can easily be confused with them. The disease is caused by Rhizoctonia cerealis Van der Hoeven (teleomorph: Ceratobasidium cereale D. Murray & L.L. Burpee). Barley, rye and oats are also susceptible hosts of the pathogen. Oats are less susceptible than the other cereals. Rhizoctonia cerealis overwinters as mycelium or sclerotia in plant debris or sclerotia in the soil. The fungus does not form asexual spores and the perfect stage is rare in nature. Mycelia from infected debris or from germinating sclerotia serve as primary inoculum. Plants may become infected anytime during the growing season. Infection occurs when root or outer leaf sheath tissue is invaded. The pathogen grows into the culm and sclerotia are formed in this structure or between the lower leaf sheath and culm. Infection is favored by cool, wet soils while subsequent disease development is optimum in cool dry soils. Disease incidence tends to be greater in continuously cropped cereals.

Symptoms

Symptoms of sharp eyespot are similar to those of eyespot (also known as foot rot or strawbreaker) but they tend to be more superficial. Lesions are lens or elliptical shaped and appear on the lower leaf sheath. The center of the lesion is tan and the border is dark brown. They may be up to an inch long and multiple infection sites may occur on a given stem. The affected tissue may rot leaving a hole in the sheath. Severe infection in seedlings may cause premature death but most plants survive to maturity. Lesions on the culm are similar to those on sheaths. They are also similar to those of eyespot but may be found higher on the culm (up to 30 cm above the soil line) and do not contain the carbon like structures found with infection by Psedocercosporella herpotricoides. Ash white mycelium may be formed beneath lesions on mature culms. Severe infection may result in premature ripening. White heads are formed and culms may lodge at the second or third internode. Affected plants do not exhibit twisting and lodging at the first internode that is common with eyespot.

Plant Health Management

Pseudocercosporella herpotrichoides

Crop Rotation
Late Fall Seeding.

References

Nyvall, R.F. 1989. Field crop diseases handbook, 2nd ed. Van Nostrand Reinhold, New York, NY. 817 pp.

Wiese, M.V. ed. 1987. Compendium of wheat diseases, 2nd ed. APS Press, St. Paul, MN. 112 pp.

Willis, W.G. 1984. Wheat diseases. Cooperative Extension Service, Kansas State University, Manhattan, KS. Publication S-23. 31 pp.

Useful Links

Texas A&M University

Caveat

This description is presented for information only and no endorsement is intended for products listed, nor criticism meant for products not mentioned. Always consult the product label before purchasing and using any pesticide.

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

This page was researched and 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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