On the factors that may have influenced the esca epidemic in Tuscany in the eighties

Tuscany is one of the viticultural regions in Italy most severely affected by esca. The epidemic started in 1986, and at the time it was explained as being caused by the great frost that hit Tuscany and many other parts of Italy the year before. Now, several years later, with a clearer understanding of the disease in the light of more recent research, we re-examined the cause of the epidemic and ask which factors could have been more likely explanations of that epidemic - factors such as the chemicals then used to control other vine diseases in Italy (active ingredients, dosages, times of application), or, contemporary, methods to produce propagation material, changes in cultural practices, or the rootstock that were then used in new vineyards and so on. We found little evidence that there was a direct correlation between the cold damage suffered in 1985 and the increase in esca disease later. We suggest that contributing factors causing the epidemic included the selective activity of fungicides used in the vineyard, which may have led to a build-up of inoculum of the fungi causing esca, and poor quality planting material arising from large scale propagation, resulting in vines more susceptible to weak pathogens such as Phaeomoniella chlamydospora.