Tobacco mosaic virus

Tobacco mosaic virus (TMV)

also called TMV, ToMV, tomato mosaic virus

Light-and-dark mosaic mottling with distorted, fern-like leaves; notoriously tough, it lingers on hands, tools, and dried debris and has no cure.

Virus Serious Spread by contactSpread on tools & handsSeed-borne Spreads to neighbors

What you'll see

Leaves carry a mosaic of light and dark green, sometimes with yellow flecking.
Foliage is puckered, curled, or narrowed into a fern-like shape.
Growth is stunted and cropping falls away.
Fruit may ripen unevenly with bronzed or mottled patches inside.
Symptoms often show worst on the youngest leaves.

Why it happens

Tobacco mosaic virus and its close relative tomato mosaic virus are exceptionally stable, mechanically transmitted viruses. They spread by touch, on tools and hands, and can survive for months or years in dried plant debris, on stakes, and even in cured tobacco, so smokers can carry it on their fingers.

Any handling, pinching out, or tying in during the growing season can move it, and crowded glasshouse conditions with frequent contact make outbreaks worse.

Treating it

There is no cure; remove and bin or burn affected plants rather than nursing them on.
Wash hands with soap and disinfect tools, stakes, and ties thoroughly.
Do not compost debris and clear all fallen leaves from the area.
Handle healthy plants first and leave suspect ones until last.

Keeping it away

Buy in resistant tomato varieties, which carry good protection against the strain.
Wash hands before handling plants, especially if you smoke or have handled tobacco.
Disinfect canes, ties, and tools between plants and between seasons.
Rotate crops and clear all old debris from beds and greenhouses at the end of the year.

Who gets it

Tomato above all, along with pepper, aubergine, potato, and many ornamentals in the same family, plus tobacco itself.