Divisi
Lettuce mosaic virus
Lettuce mosaic virus · Viral
Photo: Roswitha Ulrich, Pflanzenschutzdienst, Hessen · CC BY-SA 4.0
Lettuce mosaic virus is a virus disease of lettuce with no cure once a plant catches it. It arrives two ways: hidden inside a few bad seeds, and carried plant-to-plant by aphids (small soft green sap-sucking insects) that pick it up and pass it on in just a few seconds of feeding. Plants infected while young stay stunted and never form a proper head.
Roswitha Ulrich, Pflanzenschutzdienst, Hessen · CC BY-SA 4.0 
U.S. Department of Agriculture · Public domain
Why it matters
This virus can wipe out well over half a bed of lettuce — up to 60% of your crop — and the plants it hits early are the worst: they stay small, twisted and never form a firm head you can sell. There is no spray that cures a sick plant; once a lettuce has the virus it stays sick for life, and the aphids that carry it move it to healthy plants in seconds, faster than you can kill them. That is why the whole fight is about keeping it OUT — clean seed and pulling sick plants — not curing it after it lands.
When to act
mosaic-symptomatic seedlings appearing, or aphids colonising young lettuce; rogue symptomatic plants at once
This guidance is general, compiled from published agronomic references including FAO and CABI. Thresholds and timing shift with your crop, your variety and the season.
In much of the region a spray is simply called mushonga — medicine. But a chemical group you cannot name is one you cannot rotate, and a product you did not write down has no pre-harvest interval you can observe. Mushonga, and other farming words →
The full lettuce mosaic virus field guide
- Identify it
- Scout for it
- Control it
16 field-guide sections in the app
The full guide to lettuce mosaic virus — every symptom to check, how and when to walk your field looking for it, and the controls that actually work, ranked. Built into your crop plan, so you are told to look before it costs you a harvest.
Crops it affects
Frequently asked questions
How do I identify lettuce mosaic virus?
What you see first: young leaves show a patchy light-green and dark-green mottle (a "mosaic") instead of one even green — hold a leaf up to the light and the pale and dark blotches stand out. This is the clearest early sign.
When should I take action against lettuce mosaic virus?
mosaic-symptomatic seedlings appearing, or aphids colonising young lettuce; rogue symptomatic plants at once
How do I control lettuce mosaic virus?
Prevent — start with clean seed (your strongest guard): sow certified mosaic-tested seed (seed lab-checked to carry zero, or near-zero, virus). Because the virus rides inside a few bad seeds, clean seed stops it before it ever starts. Never save or use untested seed from an old lettuce crop.
Which crops does lettuce mosaic virus affect?
Among the crops covered here: Lettuce.
Catch it before it costs you a harvest
Divisi builds scouting into your crop plan — it tells you when to walk your field, what to look for at that stage, and what to do when you find it. Free for farmers, works offline.
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