Psorosis

Psorosis is a complex and chronic viral disease that severely impacts the cultivation of various citrus species. It is widely recognized in agronomy as one of the most persistent threats to citrus orchards globally, often leading to the gradual decline and eventual death of infected trees.

The causative agent of this condition is the Citrus psorosis virus (CPsV). It functions as a systemic pathogen, meaning that once the virus enters the plant, it travels through the vascular tissues, affecting the metabolic functions and physiological balance of the entire host plant, including the roots, trunk, and canopy.

The symptoms of psorosis are distinctive and vary depending on the stage of the disease. In the initial phases, leaf patterns such as chlorotic flecks or banded spots may appear on young foliage. As the disease advances to the bark, scaling, longitudinal cracking, and gumming (exudation of sap) become clearly visible on the main trunk and primary branches.

Transmission occurs primarily through the use of infected grafting material. Since the virus can remain latent for years, symptomless budwood often serves as the main vehicle for the spread of the pathogen. Additionally, physical contact through non-sterilized pruning tools allows the virus to move between trees within the same orchard.

The impact of psorosis is significant, resulting in reduced fruit yields, stunted growth, and canopy dieback. Because there is no curative treatment for infected trees, preventative strategies are mandatory for growers. These include implementing strict sanitation protocols, using virus-free nursery stock certified by laboratory testing, and immediately removing symptomatic trees to contain the outbreak.