Mosaic Virus: how to recognise and treat it

Disease

Symptoms

Yellowish patches or a green-and-yellow mottled mosaic on the leaves; in flowers, white streaks called "breaks".
Leaves curl downward and are distorted and smaller; plants are stunted because the stem sections between leaves stay short.
Lower yields and small, distorted fruit.

Pull out and destroy suspect plants promptly — infected plants cannot be cured.
After touching suspect plants, wash your hands and tools with soapy water before handling healthy ones.
Lay reflective mulch around young vegetable plants to repel the aphids and whiteflies that carry viruses.

There is no chemical control for plant viruses, and spraying insecticides to stop aphids spreading the virus is not practical.

Reference information, not a guarantee. Read and follow the label of any product: dose, safety and the days to wait before harvest.

Grow resistant cultivars where available (e.g. some courgette, cucumber and aubergine varieties resist cucumber mosaic virus).
Keep the garden weed-free — groundsel and chickweed often carry cucumber mosaic virus without symptoms.
Tobacco mosaic virus survives in cigarettes and other tobacco products and is passed on by touch — smokers should wash their hands before handling tomatoes and peppers.
Use healthy seed and transplants; a few mosaic viruses are carried on or in seed.

Figures checked against these sources.