''Pythium'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...

oomycetes. They were formerly classified as

fungi A fungus (plural, : fungi or funguses) is any member of the group of Eukaryote, eukaryotic organisms that includes microorganisms such as yeasts and Mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified ...

. Most species are

plant Plants are predominantly Photosynthesis, photosynthetic eukaryotes of the Kingdom (biology), kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all curr ...

parasites, but '' Pythium insidiosum'' is an important

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a ger ...

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

s, causing pythiosis. The feet of the fungus gnat are frequently a vector for their transmission.

Morphology

;Hyphae: ''Pythium'' species, like others in the family Pythiaceae, are usually characterized by their production of

coenocytic A coenocyte () is a multinucleate cell which can result from multiple nuclear divisions without their accompanying cytokinesis, in contrast to a syncytium, which results from cellular aggregation followed by dissolution of the cell membranes insid ...

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one o ...

e without septations. ;Oogonia: Generally contain a single

oospore An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae, fungi, and oomycetes. They are believed to have evolved either through the Somatic fusion, fusion of two species or the chemically-induced stimulat ...

. ;Antheridia: Contain an elongated and club-shaped

antheridium An antheridium is a haploid structure or organ producing and containing male gametes (called ''antherozoids'' or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. Androecium is also ...

Ecological importance

''Pythium''-induced root rot is a common crop disease. When the organism kills newly emerged or emerging seedlings, it is known as

damping off Damping off (or damping-off) is a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in wet and cool conditions. Symptoms There a ...

, and is a very common problem in fields and greenhouses. Thus there is tremendous interest in genetic host resistance, but no crop has ever developed adequate

resistance Resistance may refer to: Arts, entertainment, and media Comics * Either of two similarly named but otherwise unrelated comic book series, both published by Wildstorm: ** ''Resistance'' (comics), based on the video game of the same title ** ''T ...

to ''Pythium''. This disease complex usually involves other pathogens such as ''

Phytophthora ''Phytophthora'' (from Greek (''phytón''), "plant" and (), "destruction"; "the plant-destroyer") is a genus of plant-damaging oomycetes (water molds), whose member species are capable of causing enormous economic losses on crops worldwide, a ...

'' and '' Rhizoctonia''. Pythium wilt is caused by

zoospore A zoospore is a motile asexual spore that uses a flagellum for locomotion. Also called a swarm spore, these spores are created by some protists, bacteria, and fungi to propagate themselves. Diversity Flagella types Zoospores may possess one or m ...

infection of older plants, leading to biotrophic infections that become necrotrophic in response to colonization/reinfection pressures or environmental stress, leading to minor or severe wilting caused by impeded root functioning. Many ''Pythium'' species, along with their close relatives ''

'', are plant pathogens of economic importance in agriculture. ''Pythium'' spp. tend to be very generalistic and unspecific in their large range of hosts, while ''Phytophthora'' spp. are generally more host-specific. For this reason, ''Pythium'' spp. are more devastating in the root rot they cause in crops, because

crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant ...

alone often does not eradicate the pathogen as ''Pythium'' spp. are also good

saprotrophs Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi (f ...

, and survive for a long time on decaying plant matter. In field crops, damage by ''Pythium'' spp. is often limited to the area affected, as the motile zoospores require ample surface water to travel long distances. Additionally, the capillaries formed by soil particles act as a natural filter and effectively trap many zoospores. However, in hydroponic systems inside

greenhouse A greenhouse (also called a glasshouse, or, if with sufficient heating, a hothouse) is a structure with walls and roof made chiefly of transparent material, such as glass, in which plants requiring regulated climatic conditions are grown.These ...

s, where extensive

monoculture In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monoculture is widely used in intensive farming and in organic farming: both a 1,000-hectare/acre cornfield and a 10-ha/acre field of organic kale a ...

s of plants are maintained in plant nutrient solution (containing

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...

potassium Potassium is the chemical element with the symbol K (from Neo-Latin '' kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosp ...

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

, and

micronutrient Micronutrients are essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for example, huma ...

s) that is continuously recirculated to the crop, ''Pythium'' spp. cause extensive and devastating root rot and is often difficult to prevent or control. The root rot affects entire operations (tens of thousands of plants, in many instances) within two to four days due to the inherent nature of hydroponic systems where roots are nakedly exposed to the water medium, in which the zoospores can move freely. Various ''Pythium'' populations have been known to have resistance to mefenoxam since the 1980s and metalaxyl since 1984. Several ''Pythium'' species, including '' P. oligandrum'', '' P. nunn'', '' P. periplocum'', and '' P. acanthicum'', are mycoparasites of plant pathogenic fungi and oomycetes, and have received interest as potential biocontrol agents.

Species

*''

Pythium acanthicum ''Pythium acanthicum'' is a plant pathogen infecting strawberries The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown hybrid species of the genus '' Fragaria'', collectively known as the strawberries, w ...

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Pythium acanthophoron ''Pythium'' is a genus of parasitism, parasitic oomycetes. They were formerly classified as fungus, fungi. Most species are plant parasitism, parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet ...

'' *''

Pythium acrogynum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *'' Pythium adhaerens'' *''

Pythium amasculinum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *''

Pythium anandrum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium angustatum'' *'' Pythium aphanidermatum'' *''

Pythium apleroticum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequen ...

'' *''

Pythium aquatile ''Pythium'' is a genus of parasitism, parasitic oomycetes. They were formerly classified as fungus, fungi. Most species are plant parasitism, parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet ...

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Pythium aristosporum ''Pythium aristosporum'' is a species of pythium under the class oomycota (often referred to as water molds) that causes root dysfunction in creeping bentgrass. Hosts and symptoms ''Pythium aristosporum'' causes root dysfunction in creeping b ...

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Pythium arrhenomanes ''Pythium arrhenomanes'' is a plant pathogen. References External links Index FungorumUSDA ARS Fungal Database
Water mould plant pathogens and diseases Pythium, arrhenomanes {{plant-disease-stub ...

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Pythium attrantheridium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium bifurcatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium boreale ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *''

Pythium buismaniae ''Pythium buismaniae'' is a plant pathogen Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that ...

'' *''

Pythium butleri ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *''

Pythium camurandrum ''Pythium camurandrum'' is a plant pathogen, first isolated in Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Oc ...

'' *''

Pythium campanulatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *''

Pythium canariense ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *''

Pythium capillosum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium carbonicum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium carolinianum'' *''

Pythium catenulatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium chamaehyphon'' *''

Pythium chondricola ''Pythium porphyrae'', is a parasitic species of oomycete in the family Pythiaceae. It is the cause of red rot disease or red wasting disease, also called ' () in Japanese. The specific epithet ''porphyrae'' () stems from the genus of one ...

'' *''

Pythium citrinum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium coloratum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *''

Pythium conidiophorum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *''

Pythium contiguanum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *''

Pythium cryptoirregulare ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *''

Pythium cucurbitacearum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *''

Pythium cylindrosporum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium cystogenes ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium debaryanum'' *''

Pythium deliense ''Pythium deliense'' is a plant pathogen infecting potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanac ...

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Pythium destruens ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium diclinum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium dimorphum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium dissimile ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium dissotocum ''Pythium dissotocum'' is a plant pathogen infecting strawberry and rice. Disease cycle ''Pythium dissotocum'' is a polycyclic oomycete root rot capable of both sexual reproduction, sexual and asexual reproduction. In its mid-season asexual phas ...

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Pythium echinulatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium emineosum ''Pythium emineosum'' is a plant pathogen, first isolated in Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocea ...

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Pythium erinaceum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium flevoense ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium folliculosum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *'' Pythium glomeratum'' *'' Pythium graminicola'' *''

Pythium grandisporangium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium guiyangense'' *'' Pythium helicandrum'' *''

Pythium helicoides ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium heterothallicum ''Pythium heterothallicum'' is a plant pathogen infecting spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to central and western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenop ...

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Pythium hydnosporum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *'' Pythium hypogynum'' *''

Pythium indigoferae ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium inflatum'' *'' Pythium insidiosum'' *''

Pythium intermedium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium irregulare'' *''

Pythium iwayamae ''Pythium iwayamae'' is a plant pathogen infecting barley and wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the ...

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Pythium jasmonium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium kunmingense ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium litorale ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium longandrum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium longisporangium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium lutarium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium macrosporum ''Pythium'' is a genus of parasitism, parasitic oomycetes. They were formerly classified as fungus, fungi. Most species are plant parasitism, parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet ...

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Pythium mamillatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium marinum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium marsipium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *'' Pythium mastophorum'' *''

Pythium megacarpum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *'' Pythium middletonii'' *'' Pythium minus'' *''

Pythium monospermum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

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Pythium montanum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium multisporum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *'' Pythium myriotylum'' *''

Pythium nagaii ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

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Pythium nodosum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium nunn'' *''

Pythium oedochilum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium okanoganense ''Pythium okanoganense'' is a plant pathogen Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms th ...

'' *'' Pythium oligandrum'' *'' Pythium oopapillum'' *''

Pythium ornacarpum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium orthogonon ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *'' Pythium ostracodes'' *''

Pythium pachycaule ''Pythium'' is a genus of parasitism, parasitic oomycetes. They were formerly classified as fungus, fungi. Most species are plant parasitism, parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet ...

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Pythium paddicum ''Pythium paddicum'' is a plant pathogen infecting barley Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in ...

'' *'' Pythium paroecandrum'' *''

Pythium parvum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium pectinolyticum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium periilum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium periplocum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium perniciosum'' *''

Pythium perplexum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium phragmitis ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

'' *''

Pythium pleroticum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

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Pythium plurisporium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium polare'' *''

Pythium polymastum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *'' Pythium porphyrae'' *''

Pythium prolatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium proliferatum'' *''

Pythium pulchrum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium pyrilobum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium quercum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium radiosum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but '' Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are ...

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Pythium ramificatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium regulare ''Pythium'' is a genus of parasitism, parasitic oomycetes. They were formerly classified as fungus, fungi. Most species are plant parasitism, parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet ...

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Pythium rhizo-oryzae ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium rhizosaccharum'' *''

Pythium rostratifingens ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium rostratum ''Pythium rostratum'' is a plant pathogen infecting strawberries, fuchsias, and citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops s ...

'' *'' Pythium salpingophorum'' *''

Pythium scleroteichum ''Pythium scleroteichum'' is a plant pathogen infecting sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant that belongs to the Convolvulus, bindweed or morning glory family (biology), family, Convolvu ...

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Pythium segnitium ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequentl ...

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Pythium spiculum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium spinosum ''Pythium spinosum'' is a plant pathogen infecting a wide variety of crops. Hosts observed to by infected include rice in Taiwan, ''Primula'', '' Impatiens'', soil in Florida, ''Cucumis melo'' in South Korea (as damping off), and soybeans in Ark ...

'' *'' Pythium splendens'' *''

Pythium sterilum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium stipitatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium sulcatum'' *''

Pythium tardicrescens ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium terrestris ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium torulosum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

'' *'' Pythium tracheiphilum'' *''

Pythium ultimum ''Pythium ultimum'' is a plant pathogen. It causes the damping off and root rot diseases of hundreds of diverse plant hosts including corn, soybean, potato, wheat, fir, and many ornamental species. ''P. ultimum'' belongs to the peronospora ...

'' ** ''Pythium ultimum'' var. ''ultimum'' *''

Pythium uncinulatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Pythium undulatum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium vanterpoolii ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are freque ...

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Pythium viniferum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

'' *'' Pythium violae'' *''

Pythium volutum ''Pythium volutum'' is a plant pathogen infecting wheat, barley, and turfgrass.Kerns, James P.; Tredway, Lane P. (2010). "''Pythium'' Root Dysfunction of Creeping Bentgrass". ''Plant Health Progress'', 11(1), 40. It is known to be sensitive to ...

'' *'' Pythium zingiberis'' *''

Pythium zingiberum ''Pythium'' is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but ''Pythium insidiosum'' is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequent ...

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Globisporangium sylvaticum ''Globisporangium sylvaticum'' is a plant pathogen, an oomycete known to cause root rot and damping off in a multitude of species. These species include apples, carrot, cherry laurel, garden cress, cress, cucumber, garlic, lettuce, pea, rhododend ...

'' was formerly placed here as ''Pythium sylvaticum''

Morphology

Ecological importance

Species

See also

References

Further reading