DETECTION OF THE GERMAN GRAPEVINE YELLOWS (VERGILBUNGSKRANKHEIT) MLO IN GRAPEVINE, ALTERNATIVE HOSTS AND A VECTOR BY A SPECIFIC PCR PROCEDURE

A polymerase chain reaction procedure was developed which enables spec ific amplification of a ribosomal sequence from the mycoplasmalike org anism (MLO) associated with German grapevine yellows (Vergilbungskrank heit, VK) and stolbur-related diseases of solanaceous plants. Successf ul amplification from all samples prepared from various cultivars coll ected in different viticultural areas indicates that the causal agent is a relatively homogeneous organism. Amplification was also achieved with template DNA prepared from naturally infected weeds in vineyards such as Convolvolus arvensis and Solanum nigrum, and from the planthop per Hyalesthes obsoletus that was collected in the vineyards. Feeding of insects of this species on grapevine seedlings resulted in the deve lopment of typical yellows symptoms by the grapes. H. obsoletus could therefore be identified as a vector of Vergilbungskrankheit.