Citrus concave gum

Citrus concave gum is a chronic viral disease caused by the Concave gum virus, which affects the structural integrity of various citrus species. This pathogen is particularly dangerous because it interferes with the cambial activity, leading to permanent malformations in the woody tissues of the tree.

The disease primarily affects sweet oranges, mandarins, and grapefruits. Once a tree is infected, the virus becomes systemic, spreading through the vascular system and hindering the plant's ability to transport water and essential nutrients effectively, which eventually leads to a significant decline in fruit production.

The most distinctive symptoms are concave depressions or pit-like formations on the trunk and primary branches. In these areas, the bark may crack, and gumming (exudation of sap) is often observed during periods of active growth. Over time, these lesions can compromise the mechanical strength of the tree branches.

Transmission occurs almost exclusively through infected scion wood used in grafting and budding processes. Because the symptoms can remain latent for several years, growers often unintentionally introduce the virus into their orchards by using propagation material from asymptomatic but infected parent trees.

There is no known cure for infected trees, making prevention the only viable management strategy. Growers should strictly adhere to using certified, virus-indexed nursery stock, implement rigorous disinfection protocols for all pruning and grafting tools, and promptly remove and destroy any symptomatic trees to prevent further spread.