Watermelon potexvirus

Watermelon potexvirus (Potexvirus citrindicum) is a viral pathogen belonging to the Potexvirus genus, known for causing significant damage to various cucurbit crops. The virus is identified as a positive-sense single-stranded RNA virus that disrupts normal plant physiology, leading to systemic infection and physiological decline.

The primary host for this virus is the watermelon (Citrullus lanatus), but its host range also includes other members of the Cucurbitaceae family, such as cucumbers, melons, and squash. Because the virus is highly systemic, it spreads through the vascular system of the plant, affecting both the vegetative growth and the reproductive development of the crop.

Symptoms of the infection typically manifest as mosaic patterns on the foliage, including interveinal chlorosis and mottling. Affected plants often exhibit stunted growth, leaf curling, and distortion. In addition to leaf symptoms, the fruits may develop severe deformation, spotting, or reduced sugar content, which renders them unmarketable and significantly reduces the overall yield.

The transmission of this virus is primarily mechanical. It spreads rapidly through contaminated pruning tools, contact between neighboring plants, and human activity within the field. Environmental factors like high humidity and moderate temperatures can favor the metabolic activity of the virus, allowing it to colonize new plant tissue quickly after the initial mechanical injury or contact.

Managing the watermelon potexvirus requires strict adherence to phytosanitary protocols, as there is no chemical cure for the viral infection. Recommended management practices include:

• Sourcing high-quality, virus-free seeds and transplants.
• Rigorous sterilization of pruning shears and other tools using disinfectants.
• Immediate removal and destruction of symptomatic plants to prevent field-wide spread.
• Implementing weed control to eliminate alternative hosts that may harbor the virus.