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Cereals:
Eyespot (Strawbreaker)
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| Author: | OMAFRA Staff |
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| Creation Date: | 01 March 2002 |
| Last Reviewed: | 01 March 2002 |
| Agronomy Guide > Pub 811: Cereals > Eyespot (Strawbreaker), Rhizoctonia Sharp Eyespot |
The fungi that cause these diseases can be found in most of Ontario soils and have the ability to cause disease in many crops. These diseases become a problem in fields or regions that predominantly grow cereal crops under cool, moist conditions.
Eyespot and sharp eyespot produce lesions on the lower sheaths and stems of most cereals. Winter wheat is more susceptible than spring cereals. In the spring, both diseases produce elliptical, eye-shaped lesions on the lower internodes near the soil line. Lesions have a dark brown border with a tan or straw-coloured centre.
Plate 110. Eyespot produces elliptical, eye-shaped lesions on the lower internode near the soil line.
Distinguishing between the two diseases is difficult. Rhizoctonia sharp eyespot lesions are more superficial and their margins are sharply defined; plants infected with eyespot (strawbreaker) have a white fungal growth in the lower stem cavity. In severe cases, plants infected with these diseases may lodge, bend or break at the soil line from a weakening of the stem at the lesion areas. Other symptoms include reduced yields, whiteheads and death of tillers.
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The eyespot fungus survives in the residue of infected plants for 3 or more years and is most severe under cool, wet conditions. The sharp eyespot fungus survives in the soil and on infected crop residues. Sharp eyespot is most severe in light, dry, acidic soils during cool springs. Dry conditions in the fall and spring favour development of sharp eyespot.
Avoid planting cereals 2 years in a row, preferably leaving at least 2 years between cereal crops. Practices that bury stubble in the soil are effective in reducing eyespot severity. Eyespot can be severe when the stubble remains on the surface. Sharp eyespot can be severe when crops are planted early and deep. Fungicide seed treatments may reduce losses (refer to OMAFRA Publication 812, Field Crop Protection Guide). (Order OMAFRA Publication 812)
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