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Cucumber mosaic virus
Cucumber mosaic virus · Viral
Photo: DieterO · Public domain
Cucumber mosaic virus (CMV) is one of the most widespread plant viruses, attacking a very broad range of vegetables — cucumber, pumpkin, squash, melon, tomato and pepper — as well as many weeds that keep it alive between seasons. It is carried plant-to-plant by aphids (tiny sap-sucking insects) that pass it on in seconds of feeding, and it also travels on sap left on hands and tools, and inside some seed. Once a plant is infected there is no cure — the virus lives in the whole plant's sap.
William M. Brown Jr. · CC BY 3.0 us 
Dr. Parthasarathy Seethapathy, Amrita School of Agricultural Sciences, Bugwood.org · CC BY 3.0
Why it matters
Cucumber mosaic virus can take up to half your crop (50%) — infected plants stay small, and the fruit comes out warty, blotchy and twisted, so buyers won't touch it. It is a virus: it lives inside the whole plant's sap, so there is no spray that can cure a plant once it is sick. That is why it is so hard to fix — your only real power is to stop it reaching healthy plants and to pull out the sick ones fast.
When to act
Rogue at first sight of mosaic; treat aphid colonies before they establish on young plants.
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 cucumber mosaic virus field guide
- Identify it
- Scout for it
- Control it
16 field-guide sections in the app
The full guide to cucumber 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 cucumber mosaic virus?
The first sign — the leaves: young leaves show a yellow-and-green patchwork (mosaic) — irregular light-green and dark-green blotches mixed together, like a badly dyed cloth. The newest leaves at the growing tip are always the worst hit.
When should I take action against cucumber mosaic virus?
Rogue at first sight of mosaic; treat aphid colonies before they establish on young plants.
How do I control cucumber mosaic virus?
Prevent first — plant resistant and clean (your strongest tools): where you can, choose CMV-tolerant or resistant varieties of cucumber, squash, melon and tomato, and always start from virus-free (clean) seed. Resistant varieties are the single most reliable defence against this virus.
Which crops does cucumber mosaic virus affect?
Among the crops covered here: Cucumber, Tomato.
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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