Olive branches blight in Jordan

Abstract

This disease of olive trees was noticed throughout field surveys in the north of Jordan. Olive branches show necrosis and eventual blight starting at the old pruning points, damaged branches ends and broken branches by the end of the growing season. Disease symptoms are characterized by reddish discoloration starting on one side of the affected branch and then moves downward in the cortex and the phloem making long red strip of sunken tissue. At the advanced stages the xylem underneath form that growing red discoloration becomes brown. The affected xylem tissue at first appears as a sector in the cross section and then the whole xylem inside of the branch become affected. Those symptoms were previously attributed to improper pruning practices. However this case becomes rather a phenomenon affecting large population of olive trees in the olive plantations in the north of Jordan. It is suspected that one or more pathogenic fungi prevailed throughout past seasons becoming significant on predisposed olive branches and trees. This investigation aimed to evaluate the magnitude of the disease incidence and severity and also to confirm the pathogenic agents associated with such symptoms and test there pathogenecity. At the end to evaluate all possible control methods and management measures against this disease.