Grapevine red blotch disease

Grapevine red blotch disease is a serious viral infection caused by the Grapevine red blotch virus (GRBV). This pathogen colonizes the phloem of the grapevine, disrupting the transport of photosynthates from the leaves to the clusters, which impairs berry ripening and negatively impacts the production of high-quality wines.

The disease primarily affects Vitis vinifera (cultivated grapevine) and can occur in all major viticultural regions. Because it is a systemic virus, once a vine is infected, there is no curative treatment available, making preventive measures the only viable way to manage the impact of the disease in the vineyard.

Symptoms typically become visible in mid-to-late summer. Affected vines show irregular reddish blotches on leaf blades, while the veins often turn red. In white grape varieties, these areas appear yellowish. Additionally, the leaves may curl downwards, and the shoots show reduced lignification (hardening), which often leads to poor cold tolerance during winter dormancy.

The virus is primarily spread through contaminated propagation material and by insect vectors. The most documented vector is the three-cornered alfalfa hopper (Spissistilus festinus). The spread of the disease is highly dependent on the presence of these insect populations and alternative plant hosts that can harbor the virus near the vineyards.

Integrated management is essential for controlling the disease. Key practices include:

• Sourcing certified, virus-tested planting material.
• Regular scouting and rouging (removal) of symptomatic vines to limit inoculum spread.
• Controlling insect vector populations through well-timed insecticide applications.
• Maintaining clean vineyard borders to remove secondary host plants.