A new citrus decline disease in Iran is associated with ‘Candidatus Liberibacter asiaticus’ and ‘Candidatus Phytoplasma aurantifolia’
Since 2010, a new emerging citrus decline disease has been observed in Iran. This disease is currently widespread in the Southern part of Kerman province where it is causing the death of approximately 10% of cultivated citrus trees. The disease has been observed on sweet orange (Citrus sinensis), grapefruit (C. paradisi), and mandarin (C. reticulata) plants grafted on Bakraee, a local citrus variety frequently used as a rootstock. Early symptoms include pale green leaves, no production of new sprouts, and general retardation of growth. Late symptoms include evident tree decline along with reduction and decay of the root system. To determine the possible causes of this new decline disease, leaf and root samples were collected in March 2017 in Southern Kerman, from 9 symptomatic and 3 asymptomatic citrus trees. Molecular tests revealed the presence of mixed infections with phytoplasmas and liberibacter species in symptomatic samples. Liberibacter species were identified exclusively in roots, while phytoplasmas were found in both roots and leaves. Further tests showed that liberibacter strains could be attributed to ‘Candidatus Liberibacter asiaticus’ (EPPO A1 List) and that phytoplasma strains could be attributed to ‘Candidatus Phytoplasma aurantifolia’ (EU Annexes). It is noted that further investigations are needed to better understand the etiology and epidemiology of this new citrus decline, as well as to determine its potential impact on citrus production.
Alizadeh H, Quaglino F, Azadvar M, Kumar S, Alizadeh A, Bolboli F, Casati P, Bianco PA (2017) First report of a new citrus decline disease (CDD) in association with double and single infection by ‘Candidatus Liberibacter asiaticus’ and ‘Candidatus Phytoplasma aurantifolia’ related strains in Iran. Plant Disease 101(12), p 2145.