Help for a friend searched-Aide pour la recherche à un ami

I steer a horticultural corporation in France and I had this problem, I looked at my books and Web anything to find of similar your help will be the welcome.
The skin of the stalk of the tomato comes loose, and hundred roots appear.

Mon ami Jean a un problème avec les tomates.
Quelle est la maladie elle?
Je suis reconnaissant pour tout avis