Squash vein yellowing virus

Squash vein yellowing virus (SQVYV) is a significant viral pathogen within the genus Ipomovirus, family Potyviridae. It primarily impacts cucurbit crops, such as watermelon, squash, and cucumber, acting as a major limiting factor in high-intensity vegetable production across various agricultural regions.

The disease is characterized by distinct yellowing of the leaf veins, which often progresses into severe chlorosis and leaf mosaic patterns. Infected plants typically exhibit stunted growth, reduced canopy development, and compromised fruit quality. In many cases, the fruits show internal tissue browning or physical malformations, leading to significant economic losses for growers.

The virus is transmitted by the silverleaf whitefly (Bemisia tabaci) in a persistent, semi-circulative manner. The whitefly acquires the pathogen after feeding on infected plant sap and remains infectious for an extended period. Because the virus does not move systemically through the soil or via standard mechanical inoculation in fields, the whitefly is the absolute bottleneck in the disease cycle.

Environmental conditions that favor high whitefly populations, such as warm temperatures and high humidity, significantly correlate with the rapid spread of SQVYV. The presence of weed hosts and abandoned cucurbit fields allows the virus to persist during off-seasons, providing a continuous source of inoculum for newly planted crops.

Management of SQVYV focuses on breaking the transmission chain through integrated pest management (IPM). This includes the aggressive control of whitefly populations using systemic insecticides, the use of reflective mulches to deter vectors, and the physical protection of young crops with insect-proof screening. Timely removal of symptomatic plants and controlling alternative weed hosts are also essential to mitigate the spread.