Characterization and pathogenicity of fungal pathogens associated with root diseases of citrus in Oman

A study was conducted to characterize fungal and oomycete pathogens associated with root diseases of acid lime and sweet lime in Oman. A survey which covered 17 administrative districts and 166 farms showed prevalence of dieback symptoms in 8.8% of acid limes and in 15.9% of sweet limes. Some of the acid limes (3.0%) and sweet limes (3.5%) were also found to suffer from gummosis at the trunk base. Isolations from bark and root samples obtained from diseased acid lime and sweet lime trees showed association of 19 fungal species with these plants, with Lasiodiplodia hormozganensis, L. theobromae and Fusarium solani being the most common. When the most common fungi were inoculated on acid lime and sweet lime seedlings, L. hormozganensis, L. theobromae, Neoscytalidium dimidiatum and F. solani reproduced wilt, decline or gummosis symptoms on the inoculated plants. Isolations from 14 nursery seedlings of acid lime and sweet lime showed association of 12 fungal species, which implies that nurseries act as a main source for some citrus pathogens in Oman. The study reports for the first time sweet lime as a host for L. hormozganensis and N. dimidiatum. It also reports for the first time the presence of six new fungi to Oman.