The Phytophthora is one of Champignon Oomycète concerning the plants, crop plants the such Potato and trees, of which for example Châtaignier or the Pommier. It also touches the Cactus (Mildiou of cactées the). The taxonomic confusion of the oomycètes with the mushrooms phytopathogenes involved a delay in the acquisition of knowledge on this major phytopathogene.

Biology

The stocks are not, little or very pathogenic and more or less virulent according to the conditions of the environment, the stock and the infected species.

It can grow without plant-host, but it needs Stérol S to finish its biological cycle, to manufacture Oospore S. Without these sterols it cannot reproduce.

It is a group of species which Co-evolves/moves probably for a very long time with the plants, while adapting by multiple strategies to their defense systems. It is possible that the human activities (exchanges and transport of agricultural produce, forestry and horticultural) could contribute to propagate certain pathogenic stocks in the world (Mildiou of the vine or potato for example) or to support them by degrading the grounds and the immunity and the diversity of the cultivated plants. Introduced stocks can tackle native species. For example, a conference indicated that in Australia in 2001 Phytophthora cinnamomi directly affected 2000 of the 9000 native species of the continent.

A species of Phytophthora , P. alni , is responsible for massive deteriorations of Aulne S in edge of rivers these last years.

It was believed main cause of deteriorations almost striking down of Marronnier S observed in the years 2000, but it could be only one opportunist secondary agent, because not systematically found. The chestnut tree would be rather victim of the bacterium Pseudomonas syringae.

Species of Phytophthora

One knows some more than 60 species (with the beginning of the year 2000, in France, INRA had approximately 600 different stocks).

• Phytophtora cactorum , person in charge of a disease of the Apple tree commonly called Canker of the collet

Treatment

A treatment the Trichoderma harzianum can be effective under certain conditions.

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