PISTACHIO DISEASES IN GREECE
Several diseases have been identified on this crop, some of which cause considerable damage. The data presented in this paper were obtained from diagnostic work carried out at the Department of Plant Pathology of the Benaki Phytopathological Institute over a period of more than fifty years. The large number of samples examined over this rather long period compensates for the lack of a typical survey. As the study indicates, the relative importance of diseases has changed during this period, mainly because of new knowledge about the causal agents of pistachio diseases, new farming practices, and also the cultivation of pistachios in new areas with different environmental conditions resulting in changes in the epidemiology of the different diseases. The diseases that have been observed are discussed in the remainder of this report.
Root rots. Pistachios growing mostly in dry areas are rarely infected by root-rotting fungi. In the few cases observed the damage was caused by unidentified Basidiomycetes, which produced the typical symptoms and mycelial mats on infected roots. No special control measures were applied except for removal of infected trees.
Phytophthora foot rot. Foot rot caused by Phytophthora spp. is one of the most important phytopathological problems of pistachio industry. The species commonly isolated are P. parasitica Dastur and P. citrophthora Smith and Smith. Phytophthora foot rots observed in Greece are usually confined to the scion (P. vera) while the rootstock (P. terebinthus L.) is considered immune. In two cases, however, the disease was observed affecting the scion and rootstock as well (Kouyeas, 1973). The species identified in those two cases were P. citricola Savada and an unidentified species of Phytophthora which showed taxonomic characters different from the known species. Though these two species were isolated only once, the fact that they can also infect P. terebinthus is of considerable significance since control of the disease in Greece is based mainly on the resistance of this rootstock to Phytophthora spp.