Pelamoviroid

Pelamoviroid is a genus of viroids that includes the Chrysanthemum stunt viroid (CSVd), one of the most destructive pathogens for commercial floriculture. These infectious agents are characterized by a small, circular, single-stranded RNA molecule that lacks protein coding capacity, relying entirely on the host plant for replication.

The primary host for this pathogen is the chrysanthemum. It affects various cultivars used in pot culture and cut flower production. While less common, other ornamental plants may act as asymptomatic carriers, making the pathogen difficult to track within complex nursery environments.

Symptoms of an infection often include severe stunting of the entire plant, which is where the common name "stunt viroid" originates. Other signs include smaller, chlorotic leaves, significantly reduced flower size, and premature or off-season blooming. In many infected plants, the flowers may appear pale or bleached, reducing their aesthetic value.

Transmission of the viroid occurs primarily through mechanical means. Pruning tools, knives, and even human hands that have touched an infected plant can easily transfer the viroid to healthy ones. The high stability of the viroid RNA allows it to survive on contaminated tools for extended periods, facilitating rapid spread across greenhouse benches.

Effective management relies heavily on preventative measures. Growers should source plant material only from certified, viroid-free programs. Sanitation protocols are critical; tools must be sterilized between every plant, and any symptomatic specimens should be immediately removed and destroyed to prevent the pathogen from spreading further.

• Use certified virus-free cuttings.
• Disinfect pruning tools using appropriate chemical agents.
• Perform regular sanitation of greenhouse facilities.
• Monitor crops for symptoms such as stunted growth.
• Implement molecular diagnostic tests (RT-PCR) for stock plants.