Mosaic virus
Light-and-dark-green mottled, distorted, blistered leaves and a stunted plant — mostly aphid-spread viruses managed through the vector and clean material.
- Pathogen
- Plant viruses (mosaic group)
- Spreads by
- Mostly aphids; some sap/seed/setts
- Favoured by
- High aphid activity; infected sources
- Main risk
- Mottling, distortion, stunting, poor yield
Overview
Mosaic is the common name for a large family of plant viruses that produce a characteristic mottle — patches of light and dark green, and often yellow, giving leaves a "mosaic" pattern. Depending on the virus and crop (cucumber/cucurbit mosaic, papaya ringspot/mosaic, sugarcane mosaic, tobacco/tomato mosaic and many others), the leaves may also be distorted, blistered, narrowed (shoestring) or puckered, and the plant is stunted with reduced, poor-quality yield.
Most mosaic viruses are spread by aphids (usually in a quick, non-persistent way as the aphid probes plants); some are also spread by mechanical sap contact (handling, tools) and a few through seed. They cannot be cured or sprayed out. Control therefore aims at the vector and the virus source: resistant/tolerant varieties, clean and (for vegetatively propagated crops) virus-free planting material, roguing infected plants, managing aphids early, and good field hygiene.
How to identify it
- A mottle of light and dark green (and often yellow) patches giving leaves a mosaic pattern.
- Leaves distorted, blistered, narrowed (shoestring) or puckered depending on the virus and crop.
- Stunting and reduced, poor-quality yield, worse the earlier the plant is infected.
- Ringspots or fruit mottling in some (e.g. papaya ringspot), and streaks on the leaves in others (e.g. sugarcane mosaic).
What causes it and when
- A family of plant viruses, most spread by aphids as they probe plants, some by mechanical sap contact and a few through seed or planting setts.
- Aphid-spread mosaics track aphid activity — worse when aphids are active and infected source plants are nearby.
- Sap-spread mosaics (e.g. tobacco/tomato mosaic) move on hands, tools and by plant-to-plant contact.
- Early infection is the most damaging; the virus persists in infected crops, volunteers and weed hosts.
Cultural & organic control
- Grow resistant/tolerant varieties where available and use clean, healthy (virus-free) seed or planting material.
- For vegetatively propagated crops (e.g. sugarcane), take setts only from a healthy, virus-free crop/seed nursery.
- Rogue out and destroy infected plants early, and remove weed and volunteer hosts that hold the virus.
- Wash hands and disinfect tools for sap-spread mosaics, and avoid working through the crop when wet.
Chemical (vector) control
- The virus cannot be sprayed — target the aphid vector and reduce the virus source instead.
- Manage aphids early with yellow sticky traps, natural enemies and judicious CIB&RC-registered insecticides where needed.
- For non-persistent aphid-spread viruses, insecticide alone is limited — barrier/border crops and roguing matter as much.
- Confirm the current vector-management approach for your crop with your local KVK.
Prevent it coming back
- Base the crop on resistant varieties and clean/virus-free seed or setts.
- Remove weed and volunteer hosts and rogue infected plants to cut the virus reservoir.
- Manage aphids and practise tool/hand hygiene for sap-spread mosaics.
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 plant’s leaves have a light-and-dark-green mottled pattern and look distorted. What is it?
That light-and-dark-green mottle, often with distortion, blistering or narrowing of the leaves and a stunted plant, is a mosaic virus. Most mosaics are spread by aphids, some by sap on hands and tools. The virus cannot be cured, so grow a resistant variety, use clean/virus-free seed or setts, rogue infected plants, manage aphids early, and remove weed hosts. Wash hands and tools for sap-spread types.
How is mosaic different from a nutrient deficiency that also yellows leaves?
A nutrient deficiency usually gives a fairly even or patterned yellowing (for example between the veins, or on old vs new leaves) and improves when you correct the nutrient. Mosaic gives an irregular light-and-dark-green (and yellow) mottle, often with leaf distortion, blistering or narrowing and stunting, and it does not improve with fertiliser. If mottled plants appear in spreading patches and are linked to aphids, suspect mosaic virus.
Can I cure a mosaic-infected plant by spraying?
No — there is no spray that cures a virus-infected plant, and an infected plant stays a source for spread, so it is best rogued out. Insecticide is worthwhile only to manage the aphid vector and protect still-healthy plants, and even then it is limited for the quick, non-persistent aphid spread of many mosaics. The real control is resistant varieties, clean planting material, roguing and vector/hygiene management.
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.