Coniella granati and Phytophthora palmivora the main pathogens involved in pomegranate dieback and mortality in north-eastern Italy

Severe branch dieback, root rot and sudden death symptoms have recently been observed on pomegranate in several orchards in Veneto (north-eastern Italy). Since there is little information about the aetiology of these diseases and given the growing economic interest in this crop, an in-depth study was conducted. From winter 2017 to autumn 2018, forty-five symptomatic plants in two orchards were monitored and sampled to isolate the associated pathogens. Based on morphology, colony appearance and DNA sequence data, eight species belonging to seven genera and five families were isolated and identified. These included Botryosphaeria dothidea and Neofusicoccum parvum ( Botryosphaeriaceae ), Diaporthe eres ( Diaporthaceae ), Coniella granati ( Schizoparmaceae ), Cytospora punicae ( Valsaceae ), Phytophthrora palmivora , P. pseudocryptogea and Phytopythium vexans ( Peronosporaceae ). Pathogenicity trials conducted on 3-year-old pomegranate seedlings showed that three species, C. granati , N. parvum and P. palmivora are aggressive pathogens on pomegranate. Results obtained have allowed us to establish that the number of pathogens associated with emerging diseases of pomegranate is greater than previously recognised. Further studies are necessary to determine a possible synergistic interaction