Occurrence of European Stone Fruit Yellows Phytoplasma (ESFYP) Infection in Peach Orchards in Northern-Central Italy

During ®eld surveys in 1999 and 2000 of peach orchards in Northern-Central Italy, plants of di€erent cultivars were observed with symptoms of early leaf reddening, abnormal thickening of midribs and primary veins, autumnal growth of latent buds which produce tiny chlorotic leaves and sometimes ¯owers, and early phylloptosis; such symptoms, rarely seen previously on peach, are associated with European stone fruit yellows phytoplasma (ESFYP). In the orchards inspected, 1±4% of trees were a€ected and most were grafted on cv. G.F. 677. In most of the symptomatic samples (130 of 157 tested), only ESFYP was detected using di€erent diagnostic methods [4¢,6¢-diamidino-2-phenilindole, 2HCl (DAPI), polymerase chain reaction (PCR) with ribosomal and non-ribosomal primer pairs, PCR- enzyme-linked immunosorbent assay, nested-PCR]. The immunoenzymatic detection of PCR products with a pathogen-speci®c probe ensured fast, sensitive and speci®c detection of ESFYP. This is the ®rst survey to assess the occurrence of phytoplasmas in peach orchards in Northern-Central Italy.