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Phytophthora forms: A: Sporangia.  B: zoospore.  C: chlamydospore.  D: Oospore.

Phytophthora forms: A:  Sporangia . B:  zoospore . C:  chlamydospore . D:  Oospore .

Sub-kingdom : Stramenopile (Chromista)
Department : Egg mushrooms (Oomycota)
Class : Oomycetes
Order : Peronosporales
Family : Peronosporaceae
Genre : Phytophthora
Scientific name
de Bary
Oak death in California caused by P. ramorum

Phytophthora (from Greek φυτόν phyton, "plant" and φθορά phthora, "destruction, destruction"; "Crushing plants") is a generic phytopathogenic protists from the family of Peronosporaceae . Heinrich Anton de Bary first described it in 1875 .


Phytophthora species are relatively host-specific. They can cause significant damage to crops. In particular Phytophthora infestans , the causative agent of late blight in potatoes , led to the total failure of the potato harvest in Ireland in 1845 and thus to the Great Famine in Ireland . It is still the most important potato disease today.


Each type of Phytophthora secretes its own, individually formed substance, which only overrides the defense mechanisms of certain host plants. Mutations in the molecular structure create new species with the ability to attack another plant species.

Here is a selection of species of the genus Phytophthora and the plant diseases they cause:

Web links

Commons : Phytophthora  - collection of images, videos and audio files

Individual evidence

  1. Aggressive tree disease could cost millions , Copenhagen Post, December 29, 2012, accessed January 3, 2013.
  2. a b New findings in the fight against late blight on February 5, 2014 on
  3. a b c Thomas Jung, LWF aktuell 43, pp. 36–37, April 2, 2011 Phytophthora damages beech stocks throughout Bavaria ( Memento from April 7, 2019 in the Internet Archive )
  4. Phytophthora ramorum in the database of the JKI , Federal Research Institute for Cultivated Plants, see data sheet there