Squash leaf curl virus

Causal agent and disease type: Squash leaf curl virus (SLCV) is a plant-pathogenic virus belonging to the genus Begomovirus within the Geminiviridae family. It is a persistent circulative virus, meaning it does not multiply within the insect vector but is moved from infected plant tissues to healthy ones during the feeding process.

Susceptible crops: This virus primarily affects members of the Cucurbitaceae family. It poses a significant threat to commercial production of squash, pumpkins, cucumbers, melons, and gourds. Several weed species within the cucurbit family can act as alternate hosts, allowing the virus to survive between planting cycles.

Symptoms and signs: Infected plants exhibit severe leaf curling, wrinkling, and prominent swelling of the leaf veins. A typical yellow mosaic pattern or interveinal chlorosis develops on the foliage. Infected plants show stunted growth, shortened internodes, and a bushy, rosetted appearance. Fruit quality is severely compromised, often resulting in misshapen and discolored harvests.

Conditions for development and spread: The virus is transmitted exclusively by the sweetpotato whitefly (Bemisia tabaci). Warm and arid environmental conditions favor the rapid proliferation of whitefly populations, leading to explosive outbreaks of the virus in fields. Once a whitefly acquires the virus, it can remain infectious for the rest of its lifespan, facilitating long-distance dispersal.

Harmfulness and control measures: The disease causes massive reductions in yield and marketability of produce. Management strategies focus on vector suppression: applying systemic insecticides, using fine-mesh netting in greenhouse production, and practicing strict weed control. Roguing of symptomatic plants is critical in early stages to prevent further spread within the crop plantation.