Tomato query

[Canny Grower]

Does anyone have an idea of what's causing these white blotches on my tomato plants?

[WendyC]

Could it be scorching from the sun? Has the leaf been in full sun and had water on it?

[Kleftiwallah]

It could be a mineral deficiency. Google the phrase and compare.

Cheers, Tony.

[wbmkk]

Could it be scorching from the sun? Has the leaf been in full sun and had water on it?

Yes, I agree that this is the likely cause

[george356]

Tobacco mosaic virus?



Tomato viruses / Royal Horticultural Society

If it is TMV there is no cure except destroy the plants and disinfect thoroughly.

"What are tomato viruses?

More than 20 viruses affect tomatoes worldwide, causing a wide variety of mosaic patterns and distortions to the leaves, stunted growth and marbling patterns on the fruit, whenever the plants are growing from late winter until early autumn.

The most common tomato viruses are:

Tobacco mosaic virus (TMV)
Tomato spotted wilt virus (TSWV)
Pepino mosaic virus (PepMV)
Cucumber mosaic virus (CMV)

Pepino mosaic virus, has quarantine status in the UK.

For more on how these viruses are transmitted, see the Biology section below.
Symptoms Back to top

You may see the following symptoms:

Stunted growth is a common symptom, especially when several viruses are present
Mosaic patterns of lighter green on the leaves (TMV, CMV, PepMV)
Fern leaf, where the leaf blade is reduced in size to give a fern-like appearance (TMV, CMV, PepMV)
Brown streaked leaves (TMV)
Young leaves curl downwards and become bronzed (TSWV)
The leaf surface appears distorted and bubbly (PepMV)
Dry set, when fruit fail to set (TMV)
Fruit develop a bronzed, patchy appearance (TMV)
Fruit ripens unevenly with pale patches or marbling (TSWV, PepMV)

Stunting, distortion and fern leaf may also be caused by exposure to hormone weedkillers, to which tomatoes are very sensitive. These are volatile and can act from a distance, without direct contact. Providing the source is removed, plants usually recover, but they do not usually recover from virus infection.
Control Back to top
Non-chemical control

Remove plants with symptoms promptly
After handling infected plants, wash hands and tools in hot soapy water. As an additional precaution, sterilise tools in the disinfectant Virkon S, obtainable from farm suppliers
Avoid growing other susceptible plants in close proximity
Varieties with claimed resistance to TMV include ‘Cherry Wonder’, ‘Cumulus’, ‘Dombito’, ‘Dona’, ‘Estrella’, ‘Ida’, ‘Nimbus’, ‘Piranto’, ‘Shirley’ and ‘Sonatine’

Chemical control

There are no chemical controls. The use of insecticides to reduce aphid transmission is not practical."

[Mr Bones]

Looks like sun scorch to me. Go with it, new leaves will be darker green and more resistant to burning

[solway cropper]

Not TMV. My greenhouse potatoes have exactly the same marks where the wet leaves have touched the glass and got burned.

[Canny Grower]

Thanks to all of you. You are very reassuring. I'm usually very careful with watering but I think I may have put some dripping pots on the shelf above these on a sunny day. I'll just leave them alone and see what the new growth is like.

[Tomatoking]

It is not a virus but a scorch, either from the sun when too dry, but unlikely at this time of the year. I would say it is cased by too strong a concentration of feed either watered in too strongly or a residue in th e compost you are using. The plants will grow out of it so do not worry too much.