''Pythium'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of parasitic oomycetes. They were formerly classified as

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

. Most species are

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

parasites, but ''

Pythium insidiosum ''Pythium insidiosum'' is a species of ''Pythium'' and a member of the class oomycota. ''Pythium insidiosum'' is mainly found in standing water and occasionally soil. Unlike most ''Pythium'' species, which are generally pathogens of terrestrial ...

'' 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 germ ...

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 Pythiosis is a rare and deadly tropical disease caused by the oomycete ''Pythium insidiosum''. Long regarded as being caused by a fungus, the causative agent was not discovered until 1987. It occurs most commonly in horses, dogs, and humans, with ...

. The feet of the

fungus gnat Fungus gnats are small, dark, short-lived gnats, of the families Sciaridae, Diadocidiidae, Ditomyiidae, Keroplatidae, Bolitophilidae, and Mycetophilidae (order Diptera); they comprise six of the seven families placed in the superfamily Sciaroide ...

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 or ...

e without septations. ;Oogonia: Generally contain a single oospore. ;Antheridia: Contain an elongated and club-shaped antheridium.

Ecological importance

''Pythium''-induced

root rot Root rot is a condition in which anoxic conditions in the soil or potting media around the roots of a plant cause them to rot. This occurs due to excessive standing water around the roots. It is found in both indoor and outdoor plants, although ...

is a common crop disease. When the organism kills newly emerged or emerging seedlings, it is known as damping off, 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'' 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 mo ...

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 '' Phytophthora'', are

plant pathogens Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...

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 ceramics, transparent material, such as glass, in which plants requiring regulated climatic condit ...

s, where extensive monocultures 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 se ...

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 atmosphe ...

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 phospho ...

, and

micronutrient Micronutrients are nutrient, 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 exam ...

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 Metalaxyl is an acylalanine fungicide with systemic function. Its chemical name is methyl N-(methoxyacetyl)-N-(2,6-xylyl)-DL-alaninate. It can be used to control ''Pythium'' in a number of vegetable crops, and ''Phytophthora'' in peas. Metalaxy ...

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 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'' 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 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'' 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 aphanidermatum ''Pythium aphanidermatum'' is a soil borne plant pathogen. ''Pythium'' is a genus in the class Oomycetes, which are also known as water molds. Oomycetes are not true fungi, as their cell walls are made of cellulose instead of chitin, they are d ...

'' *''

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 ...

'' *'' Pythium aristosporum'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 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 ...

'' *''

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'' 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 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'' 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 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 ...

'' *''

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 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 debaryanum'' is a species of water mould in the family Pythiaceae. It is known as a plant pathogen on many kinds of wild and cultivated plants, including peanut, beet, eucalyptus, tobacco, and pine trees. The plants develop damping off ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *'' Pythium dissotocum'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *'' Pythium flevoense'' *''

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'' 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 graminicola ''Pythium graminicola'' is a plant pathogen infecting cereals. Host and symptoms ''Pythium graminicola'' infects a wide range of hosts, including: bent grass, turmeric, cotton, barley, wheat, rice, beans, peas, and sugarcane. In particular ' ...

'' *''

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'' 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 helicandrum ''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 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 ...

'' *'' Pythium heterothallicum'' *'' Pythium hydnosporum'' *''

Pythium hypogynum ''Pythium hypogynum'' is a plant pathogen infecting Strawberry, strawberries. References External links Index FungorumUSDA ARS Fungal Database
Water mould strawberry diseases Pythium, hypogynum Species described in 1941 {{plant-disea ...

'' *''

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'' 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 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 irregulare'' is a soil borne oomycete plant pathogen. Oomycetes, also known as "water molds", are fungal-like protists. They are fungal-like because of their similar life cycles, but differ in that the resting stage is diploid, they h ...

'' *'' Pythium iwayamae'' *'' Pythium jasmonium'' *'' Pythium kunmingense'' *''

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 ...

'' *'' Pythium longandrum'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 mastophorum'' is a plant pathogen infecting pocketbook plants (''Calceolaria crenatiflora ''Calceolaria crenatiflora'' is a species of flowering plant in the pocketbook plant genus ''Calceolaria'', family Calceolariaceae. It is nat ...

'' *''

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

'' *''

Pythium minus ''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 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 ...

'' *''

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 ...

'' *''

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 myriotylum'' is a soil-borne oomycete necrotroph that has a broad host range, this means that it can infect a wide range of plants. Hosts and symptoms ''Pythium myriotylum'' is a causal agent of soft root rot in economically important ...

'' *''

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 ...

'' *''

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'' 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 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 ...

'' *'' Pythium okanoganense'' *''

Pythium oligandrum ''Pythium oligandrum'' is an oomycete. It is a parasite of many fungi and other oomycetes including '' Botrytis'', ''Fusarium'' and ''Phytophthora''. It has been licensed as a biocontrol agent in the form of an oospore soil treatment, which redu ...

'' *''

Pythium oopapillum ''Pythium oopapillum'' is a plant pathogen, first isolated in Canada. References Further reading *Weiland, Jerry E., Bryan R. Beck, and Anne Davis. "Pathogenicity and virulence of Pythium species obtained from forest nursery soils on Douglas-f ...

'' *''

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 ...

'' *''

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'' 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 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 ...

'' *''

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 paroecandrum'' is a plant pathogen infecting carrots and impatiens. References External links Index FungorumUSDA ARS Fungal Database Water mould plant pathogens and diseases Carrot diseases Ornamental plant pathogens and dise ...

'' *''

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 ...

'' *''

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 ...

'' *''

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 ...

'' *'' Pythium periplocum'' *''

Pythium perniciosum ''Pythium perniciosum'' is a plant pathogen infecting strawberries and poinsettias. References External links Index FungorumUSDA ARS Fungal Database Water mould plant pathogens and diseases Water mould strawberry diseases Ornamental pl ...

'' *'' Pythium perplexum'' *''

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 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 ...

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Pythium polare ''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 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 ...

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Pythium porphyrae ''Pythium porphyrae'', is a parasitism, parasitic species of oomycete in the family Pythiaceae. It is the cause of red rot disease or red wasting disease, also called ' () in Japanese language, Japanese. The Botanical name, specific epithet '' ...

'' *'' Pythium prolatum'' *''

Pythium proliferatum ''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 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 ...

'' *'' Pythium radiosum'' *'' Pythium ramificatum'' *''

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 ...

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Pythium rhizosaccharum ''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 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 ...

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Pythium salpingophorum ''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 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 ...

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Pythium splendens ''Pythium splendens'' is a plant pathogen. It is a potentially useful organism for the synthesis of large amounts of eicosapentaenoic acid, which is a polyunsaturated fatty acid Polyunsaturated fatty acids (PUFAs) are fatty acids that contain ...

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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 ...

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Pythium sulcatum ''Pythium sulcatum'' is a chromalveolate plant pathogen infecting carrots. Because this organism was once thought to be a type of fungus, it is still often treated as such. Host and symptoms ''Pythium sulcatum'' causes diseases predominately o ...

'' *'' Pythium tardicrescens'' *''

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 ...

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Pythium tracheiphilum ''Pythium tracheiphilum'' is a plant pathogen infecting lettuce Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae. It is most often grown as a leaf vegetable, but sometimes for its stem and seeds. Lettuce is most ofte ...

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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 peronosporal ...

'' ** ''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 ...

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Pythium violae ''Pythium violae'' is a plant pathogen infecting carrots. It is a soil-borne oomycete that causes the cavity spot disease of carrots. '' Pythium sulcatum'' also causes a less serious form of this disease. ''Pythium violae'' causes elliptical sh ...

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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 ...

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Pythium zingiberis ''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 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 ...

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

Morphology

Ecological importance

Species

See also

References

Further reading