Sharp Eyespot

Ceratobasidium cerealis D. Murray & L.L. Burpee [teleomorph]
Rhizoctonia cerealis van der Hoeven [anamorph]

  1. Symptoms: The primary symptoms of sharp eyespot are the oval-shaped lesions that develop on basal leaf sheaths; these lesions are similar to those caused by eyespot (Tapesia yallundae and T. acuformis), however sharp eyespot lesions are more superficial and more sharply outlined than those typical of eyespot. The margins are dark brown with pale, straw-colored centers (pictureat left). The mycelia often present in the centers of lesions are easily removed by rubbing. Roots can also be affected, usually becoming brown in color and reduced in number. The disease can cause stunting and a reduction in the number of tillers. Sharp eyespot also will produce whiteheads and shriveled kernels, as well as lodging.
  2. Development: Infection is highly dependent upon environmental conditions. Disease development is favored by light and well-drained soils, cool temperatures, and high humidity. The fungus persists in soil and in crop debris, and invades root and crown tissues.
  3. Hosts/Distribution: The hosts of R. cerealis include wheat, rye, oats, barley, corn, rice, and a number of grasses, though wheat is more susceptible than barley, oats, or rice. Winter cereals are affected more severely than spring cereals. Sharp eyespot is found widely distributed through wheat growing areas, including China, USA, Canada, UK, France, Turkey, and New Zealand, though serious problems only occur in local areas.
  4. Importance: Sharp eyespot is not a major yield-limiting disease in most countries, but it can considerably reduce yields under favorable environments, with losses up to 20%. The disease is usually more severe in fields that are continuously sown to cereals, especially winter wheat. However, no major or widespread epidemics have been reported.

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  • Professor Li-Honglian- Senior Plant Pathologist, College of Plant Protection, Henan Agricultural University, Zhengzhou, China.
  • Dr. Matthew B. Cromey- Plant Pathologist, New Zealand Institute of Crop and Food Research, Christchurch, New Zealand.