back to HYPP Pathology
home page

Mycologia, MASTIGOMYCOTINA, PERONOSPORALES, PERONOSPORACEAE .

Crops attacked: artichoke .

Mildiou

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

[R]Description
On the adaxial surface of leaves discoloured yellowish spots appear and dry out early, on the abaxial surface the fungus causes downy mildew. The head is rarely attacked.

[R]Biology
The fungus has several physiological species and exhibits considerable host specialization (eg. the pathogenic species on artichoke do not affect lettuce and viceversa ).
Conidial infection : conidia germinate on the epidermis producing hyphae which enter the stomata and colonize the leaf tissues. After a variable incubation period depending on the temperature and the RH, the cottony white spots appear on the abaxial surface ; they are made of conidiophores (or sporangiophores) which are thin branched filaments ending with vesicles (sporangia) that carry the conidia responsible for the spreading of the infection.
Inoculum persists as mycelium on infected crop debris and other cultivated or spontaneous Compositae. Oospore formation rarely occurs inside the contaminated tissues.

[R]Epidemiology
The epidemic settles in relatively humid and cold weather (optimum temperature 10 -15 °C.). Nevertheless, the attacks are sporadic and are likely to occur at the end of winter when the cycle of the crop is over.

[R]Treatement
Destroy potentially infected residual foliage and previous crop debris.
Specific treatment is necessary in rare cases.

[R]Possible misleading
The mildew symptoms caused by Leveillula taurica .

[R] Images

To read this page in French

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

back to HYPP Pathology home page