Citrus Tristeza Virus
Citrus tristeza virus (CTV), Closterovirus
Overview
One of the most economically important citrus diseases, transmitted by aphids (especially the brown citrus aphid). Has killed over 100 million citrus trees worldwide on susceptible rootstocks. Citrus Tristeza Virus cannot be cured with sprays. Management means preventing spread through insect vectors, infected seed or sap, and removing sources of inoculum early. Causal agent: Citrus tristeza virus (CTV), Closterovirus. In regenerative gardens, prioritize sanitation, airflow, and unbroken soil cover over calendar spraying, and intervene early when symptoms appear.
Symptoms
Quick decline and death on sour orange rootstock. Stem pitting on grapefruit and sweet orange. Seedling yellows. Inverse pitting of bark. Reduced fruit size and quality. Gradual decline. Compare several plants and note whether symptoms spread after rain, insect feeding, or wet foliage. Photograph undersides of leaves and cut stems when wilt is present to refine the diagnosis. Rule out simple drought, fertilizer burn, and herbicide drift before assuming a pathogen - abiotic injury often mimics disease.
Environmental Conditions
Variable
Prevention
Use tolerant rootstocks (not sour orange). Use certified virus-free budwood. Control brown citrus aphid. Cross-protection with mild strains. Regular testing programs. Mulch to reduce splash, clear season-end debris, and avoid working plants when wet. Design beds for airflow and diverse plantings that support beneficial insects without creating permanent humid pockets around susceptible crops.
Management
No cure. Remove trees on susceptible rootstocks. Replant on tolerant rootstocks (Swingle citrumelo, Carrizo citrange). Control aphid vectors. Cross-protection programs. Prefer drip irrigation, morning watering, and open spacing so leaves dry quickly. Disinfect pruners between cuts on woody plants. Use copper, sulfur, or biological products only as labeled protectants when pressure is high - they rarely reverse advanced infections alone. Destroy (do not casually compost) highly infectious debris.