PHYTOPATHOGENIC FUNGI CAUSATIVE AGENTS OF OLIVE (Olea europaea L.) DECLINE IN THE AREA OF ISTRIA

Sa？etak The appearance of decline of olive trees in Istria during the years 2016 and 2017 was investigated. To determine the possible causative agents that could be related to that phenomenon, visual examinations of trees and collection of samples of plant material were carried out. Samples of plant material were collected on 23 locations, within four olive growing areas: Buje-Umag, Pore？-Vrsar, Rovinj and Vodnjan-Pula. Surveyes olive growing areas differed by microclimatic features, varieties, age of trees and soil properties. Identification of particular causative agents of diseases was performed in a specialized mycological laboratory. Several species, genera and families of phytopathogenic fungi has been identified in symptomatic samples. For the identification of species, classical (cultivation and analysis of isolate morphology) and molecular methods (PCR and sequencing) has been used. A total of 78 isolates were collected. The most common isolated species of phytopathogenic fungi, which could be the causative agent of partial or total decline, weaker growth and lower vigor of olives was the species Verticillium dahliae Kleb. Beside that, in symptomatic samples, Diplodia seriata, fungal species of the family Botryosphaeriaceae and Armillaria mellea, the causative agent of white root rot, were found. The oresence of Verticillium dahliae (on 57% of locations) and Armillaria mellea (on 17%) have been determined in all olive growing areas covered by this work, while the presence of D. seriata (on 13% of locations) have been determined only in olive groves in the area of Rovinj and Bale