Abstract: | Pathogenic microorganisms on medicinal and aromatic plant species cultivated on plantation in Serbia were studied during the last ten years. The seeds of majority of these plants were contaminated with fungi from the genus Fusarium, Alternaria, Verticilium, Colletotrichum, Penicillium, Aspergillus, Rhizopus and Phoma, which significantly reduced seed germination and caused seedlings decay. On the stem and leaves the symptoms of powdery mildew rust, fleckening and wilting were manifested. The fungi from the genus Oidium, Puccinia, Coleosporium, Phragmidium, Alternaria, Fusarium, Phoma, Septoria, Sclerotinia, Verticilium and Botrytis were isolated as the causative agents. The most intensive changes were recorded on St. John’s wort and coneflower, where percentage of the diseased plants was very high. In the tissue of the diseased Echinacea species with the symptoms of yellowing (witches brooms, virescence), the presence of the phytoplasma (Stolbur type) was established. In the xylem vessels of the St.John’s wort diseased plants, with the symptoms of redness and remature decay, the presence of fastidious bacteria (rickettsia – like organisms – RLO) was recorded. The symptoms of redness were also registered in the cultivated oregano and lovage, as well as in the wildgrowing dandelion. |