Severe Diseases Induced by Viruses and Phytoplasmas in Hydrangea in Italy

Epidemiological surveys were carried out in Liguria and Lazio regions to detect virus and phytoplasma infections in Hydrangea machrophylla. Plants showing stunting, flower virescence and phyllody, yellowing, necrosis and redness of the leaf edge, collected in "Piana di Albenga" (Liguria region), were infected by Hydrangea ringspot virus. One of these hydrangea plants, showing also flower virescence and red edges of leaves, was infected by phytoplasmas belonging to subgroup 16SrI-B, GroELI subgroup III. Almost all hydrangea plants growing in Bolsena city (Lazio region) showed severe leaf and flower symptoms. Cucumber mosaic virus was detected in three plants characterized by stunting, leaf mosaic of malformed leaves and flower colour-breaking; Elm mottle virus was detected in two plants with mosaic symptoms on the leaves. One plant showing growth reduction, flower virescence and phyllody was found to be infected by phytoplasmas belonging to ribosomal subgroup 16SrXII-A. Leafhoppers pres...