Citrus leprosis

Citrus leprosis is a serious viral disease caused by viruses belonging to the genus Dichorhavirus. These viruses are characterized by a bipartite genome and are known for causing significant economic losses in citrus-producing regions worldwide. The disease affects the productivity of trees and significantly reduces the quality of the fruit, making them unmarketable.

The transmission of the virus is exclusively mediated by false spider mites of the genus Brevipalpus (such as B. yothersi and B. phoenicis). The mites acquire the virus while feeding on infected plant tissues and subsequently transmit it to healthy plants. Unlike many other plant viruses, leprosis is not known to be transmitted through mechanical inoculation, seed, or pollen, which highlights the vector as the critical link in the infection cycle.

Symptoms of the disease are characterized by the development of localized chlorotic or necrotic spots on leaves, stems, and fruits. On the fruit skin, these lesions appear as circular rings or blotches that eventually turn necrotic and brown. As the disease progresses, the plant experiences defoliation, twig dieback, and massive premature fruit drop, severely compromising the tree's health and structural integrity.

The development and spread of citrus leprosis are heavily dependent on the population dynamics of the mite vectors. Favorable environmental conditions, such as warm and humid weather, facilitate rapid mite reproduction and movement. The spread of the disease is also often accelerated by the movement of contaminated nursery stock, which can introduce the virus into new, previously unaffected areas.

Management and prevention of citrus leprosis require an integrated pest management (IPM) approach. The primary strategy involves the rigorous control of mite populations using acaricides and biological agents. Additionally, the use of certified virus-free planting material, routine monitoring for mite presence, and the timely pruning and destruction of heavily infected branches are essential to mitigate the impact of the disease in commercial orchards.

• Use of certified pathogen-free citrus cultivars.
• Regular monitoring of Brevipalpus mite populations.
• Application of strategic acaricide rotations.
• Removal and burning of symptomatic plant debris.