Influence of fungal strain, temperature, and wetness duration on infection of grapevine inflorescences and young berry clusters by Botrytis cinerea

The effect of temperature and wetness duration on infection of Vitis vinifera inflorescences and young berry clusters by Botrytis cinerea was investigated. Artificial inoculations were carried out using conidial suspensions of eight B. cinerea strains belonging to the transposon genotypes transposa and vacuma. Infection incidence was significantly affected by strain but not by transposon. Infection incidence was also affected by the interaction between strain and growth stage of the inflorescence or berry cluster. Thus, under our experimental conditions, the ability to cause infection was a strain rather than a transposon genotype attribute. Across all strains, infection incidence was lowest when inflorescences were clearly visible or fully developed, highest at flowering, and intermediate at the post-flowering fruit. The effects of temperature and wetness duration on infection incidence were similar for all fungal strains and grapevine growth stages. Similar results were obtained for mycelial growth and conidial germination.