Apple stem pitting virus

Capillovirus alphavii, officially recognized as the Apple stem pitting virus (ASPV), is a major viral pathogen affecting pome fruits. Belonging to the Betaflexiviridae family, this virus creates systemic infections that compromise the physiological integrity of the host plant by interfering with the vascular tissue development.

The primary hosts for this virus are apple and pear trees. While many apple cultivars serve as asymptomatic carriers, the virus can cause severe symptoms in sensitive rootstocks or incompatible scion-rootstock combinations, leading to poor tree growth and reduced longevity.

Clinical signs of the infection often remain hidden until the bark is removed. Once exposed, the wood shows distinct pits, grooves, and necrotic depressions. Above-ground symptoms include restricted vegetative growth, leaf chlorosis, poor fruit set, and the production of small, malformed fruits that lack commercial quality.

The virus is primarily transmitted through vegetative propagation. Using infected scion wood during grafting is the most common way it spreads globally. Mechanical transmission via contaminated pruning tools is also a significant factor, especially in high-density orchards where frequent maintenance is required.

Effective management relies entirely on exclusion strategies. Prevention is the best approach to control ASPV:

• Purchase certified virus-tested nursery stock.
• Implement strict sanitation protocols for all pruning equipment.
• Avoid top-working older trees with unknown health status.
• Use molecular diagnostic tools like PCR to screen parent trees for viral load.