Peach latent mosaic viroid

Peach latent mosaic viroid (PLMVd) is a significant plant pathogen affecting stone fruit trees, belonging to the Pelamoviroid genus. It consists of a single-stranded circular RNA molecule that lacks protein coding, making it highly dependent on the host cell's machinery to replicate and cause systematic disease throughout the tree.

This viroid primarily attacks Prunus persica (peach) and its varieties, including nectarines, though it can also infect other stone fruits. Because the disease is often latent, meaning trees may carry the infection without showing immediate symptoms, it poses a severe threat to commercial nurseries and international plant trade.

Symptoms of the infection can be subtle but damaging. They include:

• chlorotic or necrotic mosaic patterns on leaves;
• deformities in fruit texture and color;
• cracking or scarring on the fruit surface;
• reduced tree vigor and branch dieback;
• significant reduction in overall yield quantity and quality.

The transmission of PLMVd is almost entirely anthropogenic. The viroid spreads through the use of infected grafting scions and rootstocks. Furthermore, pruning practices play a critical role in its spread, as the viroid is easily transmitted by pruning tools if they are not properly sterilized between individual trees during the maintenance season.

Effective management relies on exclusion and sanitation strategies. There is no chemical cure for PLMVd; therefore, the most effective approach is to maintain high-quality germplasm in certified pathogen-free programs. Growers should enforce strict sanitation protocols for tools, monitor orchard health consistently, and eradicate any infected trees to minimize the risk of horizontal spread.