Characterization, Phytopathogenicity and Host Range Studies of Neoscytalidium Dimidiatuml. (Botryosphaeraceae) Associated With Dieback of Lebbeck Trees (Albizia Lebbeck L. Benth) in Saudi Arabia

Abstract A survey in 2016 showed that more than 80% lebbeck trees inside the main campus of Qassim University were wilted and dead. Symptoms of dieback, root rot, stem cankers and decline were observed in the trees. The trunks exhibited black masses of spores which soon spread to other, healthy trees. A fungus, having arthroconidial and asexual synanamorph characteristics, and was identified as Neoscytalidiumdimidiatum KSA of the class Coelomycetes within the family Botryosphaeraceae and was subsequently isolated from the infected lebbeck trees. Six-year-old lebbeck seedlings were inoculated with the N. dimidiatum KSA isolate. Symptoms of chloroses followed by dropping leaves appeared four weeks after inoculation. The fungus re-isolated from the infected seedlings expressed the same morphological characteristics on the culture media as the N. dimidiatum KSA isolate. A host range study involving six different tree species were inoculated under growth chamber conditions using the identified isolate of the N. dimidiatum KSA fungus. Four weeks after the inoculation, three of these species exhibited wilting and died. To the best of our knowledge, this study is the first to report on N. dimidiatum in Saudi Arabia.