Phytoplasmas in declining cherry plants.

In several growing areas of Northern Italy cherry is affected by a severe decline that leads plants to die in two-weeks/one month maximum. From the beginning of the summer the affected plants show leaves of smaller size, with chlorosis, reddening, curling aspect and premature fall; young branches also show some lack of lignifications. Preliminary tests excluded presence of several biotic or abiotic agents; to verify the possible phytoplasma association with the disease nucleic acid extraction was performed from leaf midribs as well as from phloem scrapes of trunks from declining trees. Molecular analyses carried out on samples from declining cherry plants collected in different orchards from 2002 to 2004 allowed identification of phytoplasmas belonging to different ribosomal subgroups such as 16SrV-B; 16SrIII-B and 16SrXII-A (stolbur). Since the area monitored was limited and phytoplasma detection was achieved in both hilly and sandy soil locations on plants usually older than 5–6 years, it appears possible that infection was related to the health status of propagation material employed for plantations.