Psorosis

Psorosis is a serious viral disease that primarily affects citrus crops (Citrus). The disease belongs to a group of systemic infections caused by the Citrus psorosis virus (CPsV). It is considered one of the most insidious plant diseases because it can remain latent in a tree for many years, gradually weakening the host without showing immediate symptoms.

The primary pathogen is the psorosis virus, which belongs to the genus Ophiovirus. The nature of the disease is a viral infection that disrupts the plant's phloem and cortical tissues. This damage interferes with the translocation of nutrients, leading to the degeneration of vascular pathways and, eventually, the decline and death of the infected tree.

The most characteristic symptom is the scaling of the bark on the trunk and primary branches, where the outer layers of the epidermis flake off, resembling scales. Gum exudation is frequently observed in the affected areas. Additionally, young leaves often display characteristic chlorotic patterns or flecking, which are best seen when the leaves are backlit against the light.

The transmission of psorosis is primarily associated with the use of infected grafting material. Under field conditions, the virus can spread through root grafting between adjacent trees or through the use of non-disinfected pruning tools. The progression of the disease is highly dependent on the susceptibility of the scion and rootstock combination, as well as the overall vigor of the trees.

The economic impact of this disease is severe, as infected trees show reduced yields, stunted growth, and poor fruit quality. Since there is no cure for an infected tree, management relies entirely on prevention. This includes the exclusive use of certified virus-free budwood and the systematic roguing of any trees showing symptoms to prevent further spread within the orchard.