First report of Phytophthora acerina, P. pini, and P. plurivora causing root rot and sudden death of olive trees in Italy.
In autumn 2018, severe decline symptoms were observed in four olive (Olea europaea) groves located in the Veneto region, Italy. Declining trees displayed a range of symptoms including partial or complete crown dieback, reddening of drying foliage, loss of rootlets, and collar rot. Disease incidence among sites ranged from 10-40%. The causal pathogens were isolated and identified as Phytophthora acerina, P. pini, and P. plurivora based on morphological characteristics, sequence analysis of the internal transcribed spacer (ITS) and pathogenicity test. This is thought to be the first report of these three Phytophthora species causing root rot and sudden death of olives in Italy.