Tomato Yellow Leaf Curl Virus
Tomato yellow leaf curl virus (TYLCV), Begomovirus
Overview
Tomato yellow leaf curl virus (TYLCV) is a begomovirus transmitted by the silverleaf whitefly (Bemisia tabaci). It is a major constraint on tomato production in warm regions and protected culture worldwide. The virus is not seedborne in tomato; whiteflies acquire it from infected plants and move it as they feed. Once introduced into a greenhouse or garden, secondary spread can be rapid when whitefly numbers are high. Yield loss is severe when plants are infected young, with little recovery for fruit set.
Symptoms
Infected tomatoes show upward leaf curling, yellowing of leaf margins, and shortened internodes that give plants a bushy, stunted look. New growth is small and chlorotic. Flower drop is common, and fruit set collapses on plants infected before flowering. Older leaves may thicken and become leathery. Pepper and bean can show related symptoms when infected by related begomoviruses. Whitefly adults and nymphs are often visible on leaf undersides in outbreak conditions.
Environmental Conditions
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Prevention
Exclude whiteflies with fine mesh on greenhouse vents and doors. Source transplants from whitefly-free nurseries and inspect leaf undersides before planting. Avoid overlapping tomato plantings that keep whiteflies and virus circulating year-round. Control weeds that serve as alternate hosts near production beds. Use resistant cultivars as the backbone of prevention in endemic areas. Maintain plant health with steady water and fertility so stress does not amplify symptom severity.
Management
Roguing infected plants early reduces local virus sources for whiteflies. Use reflective mulches, insect screens, and sticky traps to lower whitefly pressure in gardens and tunnels. Encourage predators such as lacewings and parasitic wasps by providing floral diversity and avoiding broad-spectrum insecticides. In greenhouses, combine exclusion screens with careful monitoring. Plant TYLCV-resistant tomato cultivars where the virus is established. After severe outbreaks, remove crop residue and allow a host-free period before the next planting.