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Yellow Vein Mosaic Virus (YVMV) in okra

Okra Yellow Vein Mosaic Disease (OYVMD) is a viral disease of okra (Okra Crop) caused by a complex of begomoviruses (genus Begomovirus, family Geminiviridae), most prominently Bhendi Yellow Vein Mosaic Virus (BYVMV) and Okra Yellow Vein Mosaic Virus (OYVMV). It is the single most damaging biotic constraint on okra cultivation in India and across South Asia, capable of causing total yield loss in susceptible cultivars when vector pressure is high.

Identification and symptoms

Infected plants show vein-yellowing and chlorosis that progress to a network of bright yellow veins on a green leaf background. Plants become dwarfed, and fruits set on infected plants are short, distorted and yellow-tinged, with no marketable value. Symptoms typically appear 10-15 days after vector inoculation.

Host crops and life cycle

Okra is the primary economic host. The disease is transmitted in a persistent (circulative) manner by the whitefly Bemisia tabaci, the same vector responsible for Tomato Leaf Curl Virus and many other begomovirus diseases. Begomoviruses collectively account for around 90% of whitefly-transmitted plant viruses. High temperatures with moderate rainfall favour rapid vector population build-up.

Damage and economic impact

Yield losses are severe, and the disease has driven near-total replacement of susceptible old open-pollinated varieties with tolerant material. Quality losses on fruit (colour, shape, marketability) compound yield losses.

Management

Integrated management combines roguing of symptomatic plants, whitefly suppression with systemic insecticides, use of reflective mulches and physical barrier nets, and most importantly planting of tolerant cultivars. ICAR-IIHR/IIVR-bred tolerant varieties include Arka Anamika, Arka Abhay, Varsha Uphar and Susthira. Wild relatives A. manihot ssp. manihot, A. callei and A. tuberculatus are documented resistance sources used in breeding programmes.

See also: Okra Crop, Okra Variety Kaveri Shourya, Tomato Leaf Curl Virus.

References

  1. Begomoviruses associated with okra yellow vein mosaic disease. Molecular Horticulture.
  2. Biotechnological Advancements and Begomovirus Management in Okra. Frontiers in Plant Science.