Role of propagation material in dissemination of grapevine and European fruit tree phytoplasma diseases

Grapevine yellows are widespread diseases of grapevine associated with molecularly distinguishable phytoplasmas and the most important in Europe are “flavescence dorée” and “bois noir”. While the phytoplasmas associated with the latter disease has wide host range, however, host range of “Flavescence dorée” is more restricted. These phytoplasma along with the eggs of the vector can be spread with symptomless planting material. The three economically important phytoplasmas disorders of temperate fruit trees present in Europe are apple proliferation, pear decline and European stone fruit yellows. These diseases are all psyllid vectored. Together with insect vectors, propagation material plays a main role in phytoplasma disease dissemination in woody host plants, especially for long-distance transmission and introduction of diseases in new geographic areas. Although the importance of planting material for long-distance transmission is clear, its relevance for some diseases, when planting in areas with high infection pressure is still controversially discussed.