Yellow mosaic virus (YMV)
Bright yellow-and-green mottling that spreads to whole-plant yellowing — a whitefly-spread virus that is stopped by stopping the whitefly.
- Pathogen
- Virus (begomovirus, YMV)
- Spreads by
- Whitefly (Bemisia tabaci)
- Favoured by
- High whitefly numbers; nearby infected crops
- Main risk
- Stunting, poor podding, severe yield loss
Overview
Yellow mosaic virus (YMV) is one of the most damaging diseases of mung (green gram), urd (black gram), soybean and several other legumes. It is a begomovirus spread by the whitefly (Bemisia tabaci), not by seed or contact. Early leaves show scattered bright yellow spots that spread into a striking yellow-and-green mosaic; as it worsens the leaves turn almost fully yellow, become thin and small, and the whole plant is affected.
The earlier a plant is infected, the worse the damage: early-infected plants are badly stunted, flower and pod poorly, and the pods that form are small with shrivelled seed, so a heavy early attack can cause very high yield loss. Because the virus itself cannot be sprayed out, control is aimed at the whitefly vector and at reducing the virus source — resistant varieties, early whitefly management, roguing infected plants, and removing weed and volunteer hosts.
How to identify it
- Scattered bright yellow spots on young leaves that spread into a yellow-and-green mosaic or mottle.
- Leaves turning almost fully yellow, becoming thin, small and puckered as it worsens.
- Early-infected plants badly stunted, flowering and podding poorly.
- Small pods with shrivelled seed; the earlier the infection, the greater the loss.
What causes it and when
- A begomovirus spread only by the whitefly (Bemisia tabaci) — not by seed or by touch.
- Whiteflies pick up the virus from infected plants and carry it to healthy ones, so spread tracks whitefly numbers.
- Favoured by high whitefly populations and by nearby infected pulse crops, volunteers and weed hosts.
- Early-season infection is the most damaging; late infection near maturity matters far less.
Cultural & organic control
- Grow YMV-resistant/tolerant varieties — the single most effective and economical control.
- Sow at the recommended time to escape peak whitefly, and avoid overlapping/staggered susceptible crops nearby.
- Rogue out and destroy infected plants early, and remove weed and volunteer hosts that carry the virus.
- Use yellow sticky traps and encourage natural enemies as part of whitefly management.
Chemical (vector) control
- Because the virus cannot be sprayed, target the whitefly vector — manage it early, before the virus spreads through the crop.
- Use CIB&RC-registered insecticides for whitefly judiciously (rotating groups) when populations build, alongside traps and natural enemies.
- A seed treatment/early systemic against whitefly can delay early spread where recommended.
- Confirm the current whitefly-management schedule for your crop with your local KVK.
Prevent it coming back
- Make resistant varieties, timely sowing and early whitefly management the routine in YMV-prone areas.
- Remove volunteer legumes and weed hosts between seasons to cut the virus reservoir.
- Rogue infected plants as soon as seen, and avoid a continuous overlap of susceptible pulse crops.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My mung/urd leaves have bright yellow and green patches. What is it?
That bright yellow-and-green mottling, spreading until the leaves are almost fully yellow, is yellow mosaic virus (YMV), spread by the whitefly. It badly stunts early-infected plants and cuts podding. The virus cannot be cured or sprayed out, so grow a resistant variety, manage the whitefly early with traps and judicious insecticide, rogue out infected plants, and remove weed and volunteer hosts.
If I cannot spray the virus, how do I control YMV?
By attacking the two things you can reach: the whitefly that carries it and the source plants it carries it from. Grow a resistant variety, sow on time to dodge peak whitefly, manage the whitefly early with yellow sticky traps, natural enemies and judicious registered insecticides, and rogue out infected plants and weed/volunteer hosts. Stopping early spread — before the virus runs through the crop — is what protects yield.
Why does early infection matter so much with YMV?
Because a plant infected early spends most of its life diseased — it is badly stunted, flowers and pods poorly, and fills only small, shrivelled seed, so its yield loss is severe. A plant infected late, near maturity, has already set most of its pods and loses far less. That is why YMV control focuses on preventing early-season spread with resistant varieties and early whitefly management, rather than reacting once mottling is widespread.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.