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Sclerotinia minor Jagger

Mycologia, ASCOMYCOTINA, HELOTIALES, SCLEROTINIACEAE .

Crops attacked: lettuce .


[R]Common Names :

Lettuce drop

Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images


[R]Identification
.

[R]Description
Towards the end of the life cycle, "collar drop" or "white drop" symptoms occur.
The outer leaves turn yellow and wither.
At a further stage the infected plant can easily be pulled out of the ground : the leaves come off, the root stays in the soil and a watery black-spotted (sclerotia) white rot can be seen all over the collar.

[R]Biology
S. minor sclerotia can reach 2 mm diameter in a white moderatly thick mycelium.
The fungus survives as sclerotia in the soil for several years.
Apothecia only rarely form.
Contamination is mycelial, through the roots. This infective mycelium is either free in the soil or resulting from sclerotial germination in the proximity of a root.

[R]Epidemiology
High RH favours the spread of the disease.

[R]Treatement
Remove the crop debris.
Drain the soil before planting.
Disinfect the soil regularly.
Avoid tight sowing.
Ventilate the fast crops under glasshouse.

[R]Possible misleading
Sclerotinia sclerotiorum which causes the same damage to the plants but its mycelium is thicker and the sclerotia can reach 1cm diameter. The two fungi may both be present at the same time.

[R] Images

  1. Sclerotinia minor , Lettuce drop (FAIVRE-AMIOT A., INRA)
    Lettuce drop on chirory Collar of chicory infected by sclerotinia disease.

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HYP3 on line : Species (scientific name), Diseases (common names), Glossary, Crops.

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