SUMMARY Following the discovery and description by the mid- dle of the past century in France of an epidemic grapevine disease called Flavescence dorèe (FD), com- parable disorders known with the general name of Grapevine Yellows (GY) were reported from all major grape-growing countries of the world, where they con- stitute a serious threat to viticulture. In Italy, FD and Bois noir (BN), the two most important diseases of the GY group, have been recorded since the 1970’s, both representing a major concern for grapevine growers. FD is caused by phytoplasmas of the ‘elm yellows’ or 16Sr- V taxonomic group and is transmitted by the leafhop- per Scaphoideus titanus in the persistent-propagative manner. Severe FD epidemics started about two decades ago and are still in progress in the main viticul- tural districts of northern Italy, i.e. Liguria (Italian Riv- iera), Lombardy, Piedmont and Veneto. The disease in- cidence may exceed 50% and the economic losses can be very high. BN is caused by phytoplasmas of the ‘Stol- bur’ or 16S-XIIA group transmitted in the persistent- propagative manner by the planthopper Hyalesthes ob- soletus. Other hopper species may also act as vectors since the disease has been observed to spread actively in geographic areas where H. obsoletus does not occur. Currently, the presence of FD seems limited to northern Italy, i.e. the Po Valley and a few regions south to it, like Marche, Tuscany and Umbria (central Italy). Its vector, however, has occasionally been found also in regions further south. BN occurs throughout the country and its incidence, initially believed to be negligible by com- parison with that of FD, has recently attained economi- cally important levels in some districts. FD and BN are symptomatologically undistinguishable from one anoth- er, molecular diagnosis is therefore necessary for the proper identification of the agent. Since 2000, compul- sory control measures against FD are enforced in Italy by a govermental decree. These consist mainly in the elimination of infected vines, the use of healthy material Corresponding author: G. Belli Fax: +39.02.50316781 E-mail: giuseppe.belli@unimi.it for new plantations, and insecticide sprays against S. ti- tanus. Thanks to these measures, a sharp decrease of FD incidence has been registered in the last few years in all affected areas of the country. Research on GY in Italy is now focusing mostly on epidemiological aspects (e.g. new potential insect vectors), new control practices such as genetic resistance to either FD or BN, or both, use of thermotherapy on propagation material, and in- vestigation of the possible role of symbiotic micro-or- ganisms present in host plants and insect vectors as an- tagonists of the phytoplasma agents of GY. INTRODUCTION Grapevine yellows (GY), a group of diseases that were originally thought to be caused by viruses, are now known to have a phytoplasma aetiology. The first such disorder to be reported from Vitis vinifera, and the most widely known of the GY group, is certainly Flavescence dorée (FD), which appeared in south-west France in the 1950’s, from where it spread to other viticultural districts of France, northern Italy and neighbouring European coun- tries. Bois noir (BN), whose symptoms are indistinguish- able from those of FD, was also first reported from France, then from the most important viticultural areas of Europe. During the last forty years or so, other diseases re- sembling FD and BN have been observed and studied in many countries all over the world. All these diseases are associated with the presence of phytoplasmas, which are now regarded as their effective aetiological agents, and closely resemble each other in symptomatology. In fact, affected vines show downward rolling of the leaves accompanied by yellow or bright red discoloration of veins and blades, berry withering and uneven or total lack of cane lignification. GY, however, have different phytoplasma species as causal agent, as well as different insect vectors, which are either leafhoppers or plan- thoppers (Homoptera:Auchenorrhyncha) that feed ei- ther specifically or occasionally on the vines. It is worth noting that two or more different phytoplasma species may infect simultaneously individual grapevines, thus causing mixed infections. The symptoms, however, do not differ from those outlined above. Journal of Plant Pathology (2010), 92 (2), 301-324 Edizioni ETS Pisa, 2010 301 INVITED REVIEW GRAPEVINE YELLOWS IN ITALY: PAST, PRESENT AND FUTURE G. Belli 1 , P.A. Bianco 1 and M. Conti 2 1 Dipartimento di Produzione Vegetale, Sezione Patologia Vegetale, Università degli Studi, Via Celoria 2, 20133 Milano, Italy 2 Istituto di Virologia Vegetale del CNR, Strada delle Cacce 73, 10135 Torino, Italy