Biology, epidemiology

• Conservation and source of inoculum : are maintained in the soil, in particular on plant debris, or on various organic substrates. Their dormant mycelium or even stromatic masses represent forms of conservation on mummified berries, pedicels, dead bark, etc.

• Penetration into the plant and invasion of the host : the spores (ascospores or conidia) germinate in the presence of a film of water on the surface of polluted berries, and directly penetrate the tissues. Subsequently, mainly intracellular mycelium invades the latter. Contaminations seem to be able to take place early after flowering and remain latent until the berries are ripe.

• Sporulation, dissemination of fungi : fairly rapid production of acervuli on lesions present on berries. Conidia grouped together in the form of mucus are dispersed by water and splashing water, by the wind carrying fine water droplets, by workers and farm tools, and by some insects. They provide secondary contamination at the end of summer. Ascospores produced in perithecia are dispersed by the wind during humid climatic periods.

• Factors favoring the development of fungi : humidity and temperatures of around 25-30 ° C influence ripe rot epidemics on grape berries. Contaminations often take place following wet periods, thanks to the rains.