Cherry lethal yellows

Cherry lethal yellows is a serious viral disease affecting stone fruit trees, primarily caused by the Cherry lethal yellows virus (CLYV). This pathogen poses a significant threat to cherry orchards worldwide, as it compromises the tree's health leading to progressive decline and eventual death of the affected plant.

The virus acts as a systemic pathogen, colonizing the tree's vascular tissues. It is primarily transmitted through vegetative propagation methods, including budding and grafting using infected scion wood. Because the virus can remain latent for extended periods, nurseries play a critical role in its transmission if strict certification protocols are not followed.

The symptoms of the disease are characterized by systemic chlorosis and the yellowing of foliage, giving the condition its name. Leaves often exhibit curling and malformation. Over time, affected trees show stunted growth, dieback of the terminal shoots, and premature fruit drop, eventually resulting in the total collapse of the tree's canopy.

The spread of the disease is predominantly driven by human activity rather than vector transmission. Conditions that stress the tree, such as poor soil nutrient management or inadequate irrigation, do not cause the virus but can exacerbate the decline of infected trees, making the symptoms more pronounced and visually distinguishable for agronomists.

Since there are no curative treatments for viral infections in woody plants, control strategies must be preventive:

• Sourcing certified virus-free rootstock and scion wood.
• Implementing rigorous quarantine measures in nursery production.
• Prompt removal and destruction of infected trees to eliminate the inoculum source.
• Sanitizing pruning and grafting tools with disinfectants between trees.