Then it might be too late. As was already posted, many viral 
infections are asymptomatic but still the host is a source of 
infection for other plants. If I were you I'd really avoid such 
treatments, which are only a risk. Why do you not use conventional 
cures?
To be honest I would not trade plants with a grower who treats his 
plants with a TMV-suspension;-) I really would fear the risk of 
introducing this virus into my own collection and there are no 
working treatments to cure a plant from a viral infection. The only 
thing you can do is destroying your plants.
To wait for symptoms certainly is the wrong strategy. You should be 
aware that you not only have a responsibility for your own collection 
but also for the collection of everybody you ever trade plants with. 
Aphids or scale insects are just nasty and easily cured but viral 
infections are a desaster.
Every grower should try to keep his collection and others virus free!
Bye,
Andreas
 
Andreas Wistuba; Mudauer Ring 227; 68259 Mannheim; Germany
Phone: +49-621-705471 / +49-621-7152027
Fax: +49-621-7152028
E-Mail: andreas.wistuba@rhein-neckar.de
WWW: http://www.rhein-neckar.de/~carnivor/index.html