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Mycologia, DEUTEROMYCOTINA, HYPHOMYCETALES, DEMATIACEAE .
Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images
[R]Description
All the above-ground parts of the plants can show symptoms at any stage of growth.
Brown, elongated spots (1-2 mm) may appear on the hypocotyl and the cotyledons starting from autumn.
On the rosette leaves spots can grow to 12 mm. They show circular zones of alternate light brown and dark brown colour and are often surrounded by a halo of chlorotic tissue.
On the pods black irregular spots (2-5 mm) occur.
Severe attacks cause shrivelling of the grains and premature splitting of the pods.
[R]Biology
In autumn and spring the primary infections occur through conidia surviving on crop debris or wild crucifers.
The first symptoms (black dots) appear within three days after penetration of the leaf tissue.
The disease is also transmitted through the seeds.
[R]Epidemiology
Free water is needed for conidial germination on the leaves.
The optimum temperature (17 -24 °C.) allows for spore germination, mycelial growth and the contamination of rape.
The sporulation of the spots is favoured by low RH(dry sunny weather.).
Conidia are wind-borne.
[R]Treatement
Burry the crop debris deep in the soil.
Use treated seeds.
Preventive chemical treatment of the high risk-plots in the G4 stage of the rape.
Curative treatment as soon as the symptoms occur on the pods.
[R]Possible misleading
The Pseudocercosporella capsellae attacks on the stem and the pods.
HYP3 on line : Species (scientific name), Diseases (common names), Glossary, Crops.
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