By Cornishsally
Cornwall,
United Kingdom 
For the last three years I've grown white Nicotiana in troughs outside my kitchen window. This year I bought new larger troughs & put a mixture of new topsoil & good quality potting compost in. I also put in some verbena bonariensis. The tobacco plants took a while to get going & then produced enormous leaves which have become mottled & very unhealthy looking. There are now flower spikes coming. I also potted up some spare seedlings in a pot in the garden, & they look fine. Any advice please on what's gone wrong & what I can do? I've included a picture of last years plants for comparison.
9 Jul, 2014
Answers
Thank you. You may be right! It's frustrating: I bought new bigger troughs & put better soil in with the aim of not having to replace it every year. You can't win!
Would the soil account for the mottling though? The plants in the pot have the same soil, and although the leaves are bigger than normal they look healthy.
10 Jul, 2014
tobacco mosaic virus would be my suggestion. if so then the plants need burning and then the soil [as its in a trough] replaced for next season.
10 Jul, 2014
Oh no! That's very depressing. It was all new soil and they're big troughs. Would you have any idea how it's contracted? The troughs are on the road, with only a few weeds in the cracks about. I wondered if it was a kind of powdery mildew - there's a bit on the verbena - but realistically I fear you're right! But thank you for the information!
13 Jul, 2014
the virus spreads due to the aphids that feed on it. think of it like being bitten by a mosquito.
14 Jul, 2014
Just a thought - new topsoil - could it have been fertilised? The 'mix' could be too rich for your plants. As to a solution, the drastic one would be to take the plants out, replace the compost and try again...that's a lot of hassle, though.
10 Jul, 2014