back to HYPP Pathologyhome page
back to HYPP Pathology
Mycologia, MASTIGOMYCOTINA, PERONOSPORALES, PERONOSPORACEAE .
Identification, Description, Biology, Epidemiology, Treatement, Possible misleading, Images
[R]Description
Pale yellow translucent spots that developed in undersurface of the leaves which become covered with downy growth (sporangia) turning necrotic later; deformations, dark colour and death of young shoots; bending of the fruit stalks and death of the flowering clusters; in later infections the grapes become greyish and covered with a downy growth, or a brownish green colour when developed.
[R]Biology
The fungus overwinters as sexual fructification (oospores), resisting to adverse conditions; they are formed inside the tissues, in the debris of the plants, in autumn.
The infection results from the oospore germination which gives origin to sporangia that liberates zoopores that cause primary infections ; from these, asexual fructifications are formed which lead to secondary infections.
[R]Epidemiology
The favourable conditions for the disease are temperatures between 15 and 20 °C., with a rainfall of 10mm, at least; the oospores are carried by the raindrops to the leaves and green organs and germinate in the water film at the surface.
[R]Treatement
For best control, preventive chemical measures according to the forecasting services. Systemic fungicides are also available.
[R]Possible misleading
At the first stages of the infection the symptoms (translucent spots) resemble, under particular circumstances, with those caused by Uncinula necator .
HYP3 on line : Species (scientific name), Diseases (common names), Glossary, Crops.
back to HYPP Pathology home page
