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An appraisal of diseases and pathogens of olive

Martelli, G.P., Salerno, M., Savino, V., Prota, U.
Acta horticulturae 2002 no.586 pp. 701-708
Fusicladium, Glomerella cingulata, Mycocentrospora, Phytophthora, Pseudomonas syringae pv. savastanoi, Verticillium dahliae, Verticillium wilt, anthracnose, bacteria, certification, double-stranded RNA, fruits, fungi, leaf spot, leaves, olives, pathogens, surveys, trees, viruses, wilting, Middle East
An account is given of major olive diseases caused by bacteria (Pseudomonas savastanoi) fungi, leaf spot (Spilocaea oleagina), cercosporiosis (Mycocentrospora cladosporioides), anthracnose (Colletotrichum gloeosporioides), verticillium wilt (Verticillium dahliae), Phytophthora-induced rots, and intracellular pathogens (viruses and phytoplasmas). Whereas recent advances in the knowledge of biology and control of defoliating diseases (leaf spot and cercosporiosis), anthracnose, and Phytophthora rots, are discussed, for verticillium wilt and olive knot the attention is mainly focused on the serological and molecular diagnostic tools, recently developed for certification of propagative material. Virus infections are surprisingly widespread as judged by the presence of double-stranded RNAs (dsRNAs) in trees analyzed in the course of surveys conducted primarily in Mediterranean and Near East countries. Infection rates in the range of 50-60% or higher are commonly recorded, and the number of viruses detected in, or isolated from olives has grown to 14, belonging to no less than seven different genera. Most of these viruses are found in apparently symptomless plants, and also those viruses that have been found associated with distinct diseases (e.g., bumpy fruits and leaf yellowing) often incite latent infections. A new threat is represented by phytoplasma infections. Four different such pathogens have been identified in variously diseased olives but their incidence and distribution is still largely unknown. Remarkable progresses have been made in the identification of viruses and phytoplasma, primarily using nucleic acid-based detection techniques, which is expediting certification procedures.