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Mycologia, FUNGI IMPERFECTI, HYPHOMYCETALES, DEMATIACEAE .
Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images
[R]Description
The first spots occur on the sheaths 10 to 20 cm above the ground as early as february. They are elongated, oval, dark brown on the edges, with a diffuse margin, sometimes as large as the sheath itself.
Grey marks (stromas) are visible on the underface of the sheath or the second sheath.
The lesions can cause lodging at the end of the life cycle.
Even when lodging does not occur, the disease leads to more or less severe shrivelling of the grains.
[R]Biology
The fungus survives in the haulms of previous crops.
Primary infection is promoted by the conidia which spread from autumn to may-june.
After the first sheath has been infected, the fungus progresses through all the succesive sheaths before attacking the stem.
[R]Epidemiology
Eyespot sporulation requires high RH close to saturation and 2 - 15 °C. temperature (7 °C. optimum).
Airborne conidial dissemination.
Over 85% RH for at least 15 hours is necessary for the conidia to germinate on the sheaths.
Contamination can occur from late autumn on.
The progress through the sheaths stops if temperature rises above 25 °C.
[R]Treatement
Avoid planting winter cereals after crops with large nitrogenous residues (legumes, potatoes, rape, fodder plants).
Avoid too frequent occurence of susceptible cereals in the rotation (wheat, oat, barley).
Burry the straw deep in the soil.
[R]Possible misleading
Foot-rot caused by Fusarium but in pseudocercosporella infected hosts the roots are healthy and the fungus forms stromas as the disease progresses from one sheath to another.
HYP3 on line : Species (scientific name), Diseases (common names), Glossary, Crops.
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