- classification : Chromista, Oomycota, Oomycetes, Saprolegniomycetidae, Pythiales, Pythiaceae
- English names: Pythium wilt and leaf blight, Lettuce stunt

 

Pythium tracheiphilum is a vascular oomycete . The origin of the damage it causes has certainly remained undetermined for a long time because of the difficulty in isolating this oomycete, which is often masked by other microorganisms. It was mainly described, initially, in Europe (Italy, France, the Netherlands, Germany, Sweden ...) and subsequently in the USA. It can be the source of significant damage such as that reported in particular in Italy and the United States.

In France , it is affected severely in certain plots which have carried lettuce on several occasions. It is now feared by many producers.

The strains rife in the USA would be different from those coming from Italy or the Netherlands.