Mal secco disease of Citrus - Phoma tracheiphila

Mal secco disease is a vascular pathogen causing serious damage and death to the host, particularly lemon, in Citrus and related genera, in Mediterranean countries and the Black Sea region. So far, however, it is unknown in Spain, Portugal and Morocco, as well as other major Citrus-growing regions of the world. Symptoms include red strands visible in stem xylem as well as veinal chlorosis, wilt and shedding of leaves, dieback of twigs and branches. Infection us through stomata and wounds. The causal organism, Phoma tracheiphila, is a conidial fungus. Once in the orchard, the fungus can be carried as spores from pycnidia and from hyphae on the plant and on fallen debris by rain, wind and irrigation water, and perhaps by birds and insects. Of concern to many international plant protection organizations, P. tracheiphila must be prevented from being spread in infected propagative material.