Phytophthora infestans is a water mould, that causes the serious disease of the potato, late blight or potato blight. (Early blight, caused by Alternaria solani, is also often called potato blight). This disease was a major culprit in the causation of the 1847 Irish potato famine and also the Highland potato famine. The organism can also infect tomatoes and some other members of the Solanaceae. Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms (as opposed to folk taxonomy). ... Typical phyla Protists (IPA: ) are a heterogeneous group of living things, comprising those eukaryotes that are not animals, plants, or fungi. ... Typical classes Colored groups Chrysophyceae (golden algae) Synurophyceae Actinochrysophyceae (axodines) Pelagophyceae Phaeothamniophyceae Bacillariophyceae (diatoms) Raphidophyceae Eustigmatophyceae Xanthophyceae (yellow-green algae) Phaeophyceae (brown algae) Colorless groups Oomycetes (water moulds) Hypochytridiomycetes Bicosoecea Labyrinthulomycetes (slime nets) Opalinea Proteromonadea The heterokonts or stramenopiles are a major line of eukaryotes. ... Orders Lagenidiales Leptomitales Peronosporales Pythiales Rhipidiales Saprolegniales Sclerosporales Water moulds or Oomycetes are a group of filamentous protists, physically resembling fungi. ... Species Phytophthora cactorum Phytophthora cinnamomi Phytophthora infestans Phytophthora lateralis Phytophthora ramorum Phytophthora is a genus of water mould, and a pathogen of considerable economic importance. ... In biology, binomial nomenclature is the formal method of naming species. ... Anton de Bary Heinrich Anton de Bary (January 26, 1831 - January 19, 1888) was a German surgeon, botanist, microbiologist, and mycologist (fungal systematics and physiology). ... Orders Lagenidiales Leptomitales Peronosporales Pythiales Rhipidiales Saprolegniales Sclerosporales Water moulds or Oomycetes are a group of filamentous protists, physically resembling fungi. ... Binomial name Solanum tuberosum L. The potato (Solanum tuberosum) is a perennial plant of the Solanaceae, or nightshade, family, commonly grown for its starchy tuber. ... 1847 was a common year starting on Friday (see link for calendar). ... Bridget ODonnell and her two children during the famine The Great Famine or the Great Hunger (Irish: An Gorta Mór or An Drochshaol), known more commonly outside of Ireland as the Irish Potato Famine, is the name given to a famine in Ireland between 1845 and 1849. ... In the Highlands of Scotland, in the mid 19th century, most croftters were very dependent on potatoes as a source of food. ... Binomial name Solanum lycopersicum L. The tomato (Solanum lycopersicum, formerly Lycopersicon lycopersicum) is a plant in the Solanaceae or nightshade family, native to Central and South America, from Mexico to Peru. ... Genera Acnistus Atropa (deadly nightshade) Brugmansia (angels trumpet) Calibrachoa Capsicum (chile peppers) Cestrum Chamaesaracha Combera Crenidium Cuatresia Cyphanthera Cyphomandra Datura (jimsonweed) Hyoscyamus (henbane) Iochroma Lycium (boxthorn) Lycopersicon (tomato) Mandragora (mandrake) Nicandra Nicotiana (tobacco) Petunia Physalis (tomatillo) Solandra Solanum (potato, eggplant) Streptosolen For more genera see Solanaceae in The Families...

The spores of this water mould overwinter on infected tubers, particularly those that are left in the ground after the previous year's harvest, and are spread rapidly in warm wet conditions when blight can have devastating effects, destroying entire crops. Spores produced in a sporic life cycle. ... Orders Lagenidiales Leptomitales Peronosporales Pythiales Rhipidiales Saprolegniales Sclerosporales Water moulds or Oomycetes are a group of filamentous protists, physically resembling fungi. ...

Spores develop on the leaves, spreading through the crop when temperatures are above 10°C and humidity is over 75% for 2 days or more. Rain can wash spores into the soil where they infect young tubers, or else spores can be blown in from distances of up to miles by the wind. Rain falling For other uses see Rain (disambiguation). ... Soil is the material on the surface of a lithosphere subject to weathering, and especially the earthy portion of that material. ...

The early stages of blight are easily missed, and not all plants are affected at once. Symptoms include the appearance of dark blotches on leaf tips and plant stems. White mould will appear under the leaves in humid conditions and the whole plant may quickly collapse. Infected tubers develop grey or dark patches that are reddish brown beneath the skin, and quickly decay to a foul-smelling mush caused by the infestation of secondary soft bacterial rots. Seemingly healthy tubers may rot later when in store.

Potatoes infected with late blight are shrunken on the outside, corky and rotted inside.

Up until the 1970s, there was only one type of blight (A1) in the UK, and this was unable to produce resistant spores that could survive the winter. There are now two types (A1 and A2) which can mate and after that produce resistant spores, although the indications so far are that this rarely, if ever, happens in the UK. Mating can occur only between moulds of different mating-types and is required for the production of resistant spores. Image File history File links Potatoes infected with late blight are shrunken on the outside, corky and rotted inside. ... Image File history File links Potatoes infected with late blight are shrunken on the outside, corky and rotted inside. ... The 1970s decade refers to the years from 1970 to 1979, inclusive. ...

Prevention and control of potato blight can be achieved by planting only good quality seeds obtained from certified suppliers. Do not save your own seed for replanting, and try to ensure that no ‘volunteer’ tubers are left in the soil after harvest. Potato varieties vary in their susceptibility to blight. Most early varieties are very prone; so that the crop matures before blight starts (usually in July) plant them early. Maincrop varieties which are very slow to develop blight include Cara, Stirling, Teena, Torridon, Remarka and Romano. Some so-called resistant varieties can resist some strains of the blight and not others, so their performance may vary depending on which are around.

Growing potatoes should be earthed up regularly in order to minimise the risks of spores being washed down into the soil reaching the tubers. If blight symptoms appear, remove all affected leaves immediately. Cut off and burn all foliage in bad cases to help prevent spread to the tubers. Don't harvest the crop for at least 3 weeks. By then, tubers will have thicker skins and blight spores on the surface will have died. A hot compost heap should destroy the spores on the leaves, but it is probably not worth the risk. Any infected tubers should definitely be burned.

The potato blight caused the Irish Potato Famine in 1845-49 which, it is estimated, caused over 1,000,000 to starve death and forced a further 2,000,000 to emigrate. Starvation during the famine The Irish Potato Famine, also called The Great Famine or The Great Hunger (Irish: An Gorta Mór), is the name given to a famine which struck Ireland between 1846 and 1849. ...

References

• Erwin, Donald C. and Olaf K. Ribeiro. Phytophthora Diseases Worldwide, American Phytopathological Society (1996).
• Lucas, J.A. (editor), R. C. Shattock (editor), D. S. Shaw (editor), Louise Cooke (editor). Phytophthora (British Mycological Society Symposia), Cambridge University Press (1991)

• Online Phytophtora bibliography
• USDA-BARC Phytophthora infestans page
• Phytophthora infestans Genome Project