Pythium is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of parasitic oomycete. Most species are plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 parasites, but Pythium insidiosum

Pythium insidiosum

Pythium insidiosum is a species of Pythium.It can cause pythiosis....

is an important pathogen

Pathogen

A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...

 of animal

Animal

Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...

s. Because this group of organisms were once classified as fungi, they are sometimes still treated as such.

Morphology

Hyphae: Pythium, like others in the family Pythiaceae

Pythiaceae

Pythiaceae is family of water moulds. The family includes plant pathogenic fungus-like organisms in the genus Phytophthora; as well as serious plant and animal pathogens in the genus Pythium.-Lifecycle:...

, are usually characterized by their production of coenocytic hyphae, hyphae without septations

Septum

In anatomy, a septum is a wall, dividing a cavity or structure into smaller ones.-In human anatomy:...

.
Oogonia: Generally contain a single oospore

Oospore

An oospore is a thick-walled sexual spore that develops from a fertilized oosphere in some algae and fungi. Also the result of plasmogamy/karyogamy in oomycetes, which in turn leads to the development of hyphae, then mycelium....

Antheridia: Contain an elongated and club-shaped antheridium

Antheridium

An antheridium or antherida is a haploid structure or organ producing and containing male gametes . It is present in the gametophyte phase of lower plants like mosses and ferns, and also in the primitive vascular psilotophytes...

Ecological importance

Pythium root

Root

In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...

 rot is a common crop disease caused by a genus of organisms called Pythium. These are commonly called water moulds. Pythium damping off

Damping off

Damping off is the term used for a number of different fungus-caused ailments that can kill seeds or seedlings before or after they germinate....

 is a very common problem in fields and greenhouses, where the organism kills newly emerged seedlings. This disease complex usually involves other pathogens such as Phytophthora

Phytophthora

Phytophthora is a genus of plant-damaging Oomycetes , whose member species are capable of causing enormous economic losses on crops worldwide, as well as environmental damage in natural ecosystems. The genus was first described by Heinrich Anton de Bary in 1875...

and Rhizoctonia

Rhizoctonia solani

Rhizoctonia solani is a plant pathogenic fungus with a wide host range and worldwide distribution. This plant pathogen was discovered more than 100 years ago. Rhizoctonia solani frequently exists as thread-like growth on plants or in culture. Asexual spores are not produced, only the sexual stage...

. Pythium wilt is caused by zoospore 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.

Pythium in turfgrass

Pythium in turfgrass

Pythium disease, also known as "Pythium blight," "cottony blight," or "grease spot," is a highly destructive turfgrass disease caused by several different Pythium species. All naturally cultivated cool-season turfgrasses are susceptible to Pythium and if conditions are favorable to Pythium it can...

Many Pythium species, along with their close relatives, Phytophthora

Phytophthora

Phytophthora is a genus of plant-damaging Oomycetes , whose member species are capable of causing enormous economic losses on crops worldwide, as well as environmental damage in natural ecosystems. The genus was first described by Heinrich Anton de Bary in 1875...

species are plant pathogens of economic importance in agriculture. Pythium spp. tend to be very generalistic and unspecific in their host range. They infect a large range of hosts, while Phytophthora spp. are generally more host-specific.

For this reason, Pythium spp. are more devastating in the root rot

Root rot

Root rot is a condition found in both indoor and outdoor plants, although more common in indoor plants with poor drainage. As the name states, the roots of the plant rot. Usually, this is a result of overwatering. In houseplants, it is a very common problem, and is slightly less common in outdoor...

 they cause in crops, because crop rotation

Crop rotation

Crop rotation is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons.Crop rotation confers various benefits to the soil. A traditional element of crop rotation is the replenishment of nitrogen through the use of green manure in sequence with cereals...

 alone will often not eradicate the pathogen (nor will fallowing the field, as Pythium spp. are also good saprotrophs, and will survive for a long time on decaying plant matter).

It has been noted that 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 greenhouses, where extensive monocultures of plants are maintained in plant nutrient solution (containing nitrogen, potassium, phosphate, and micronutrients) 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.

Several Pythium species, including P. oligandrum

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 reduces pathogen load and concomitant plant disease.P. oligandrum can grow...

, P. nunn, P. periplocum, and P. acanthicum

Pythium acanthicum

Pythium acanthicum is a plant pathogen.- External links :* *...

are mycoparasites of plant pathogenic fungi and oomycetes, and have received interest as potential biocontrol agents

BioControl

BioControl is a peer-reviewed scientific journal published by Springer Science+Business Media covering all aspects of basic and applied research in biological control of invertebrate, vertebrate, and weed pests, and plant diseases. The journal was established in 1956 as Entomophaga and published by...

.

Species

• Pythium acanthicum
  Pythium acanthicum
  Pythium acanthicum is a plant pathogen.- External links :* *...
  
  
• Pythium acanthophoron
• Pythium acrogynum
• Pythium adhaerens
• Pythium amasculinum
• Pythium anandrum
• Pythium angustatum
• Pythium aphanidermatum
  Pythium aphanidermatum
  Pythium aphanidermatum is a plant pathogen.- External links :**...
  
  
• Pythium apleroticum
• Pythium aquatile
• Pythium aristosporum
  Pythium aristosporum
  Pythium aristosporum is a plant pathogen.- External links :**...
  
  
• Pythium arrhenomanes
  Pythium arrhenomanes
  Pythium arrhenomanes is a plant pathogen.- External links :* *...
  
  
• Pythium attrantheridium
• Pythium bifurcatum
• Pythium boreale
• Pythium buismaniae
  Pythium buismaniae
  Pythium buismaniae is a plant pathogen.- External links :* *...
  
  
• Pythium butleri
• Pythium campanulatum
• Pythium canariense
• Pythium capillosum
• Pythium carbonicum
• Pythium carolinianum
• Pythium catenulatum
• Pythium chamaehyphon
• Pythium chondricola
• Pythium citrinum
• Pythium coloratum
• Pythium conidiophorum
• Pythium contiguanum
• Pythium cryptoirregulare
• Pythium cucurbitacearum
• Pythium cylindrosporum
• Pythium cystogenes
• Pythium debaryanum
  Pythium debaryanum
  Pythium debaryanum is a plant pathogen.- External links :**...
  
  
• Pythium deliense
  Pythium deliense
  Pythium deliense is a plant pathogen.- External links :* *...
  
  
• Pythium destruens
• Pythium diclinum
• Pythium dimorphum
• Pythium dissimile
• Pythium dissotocum
  Pythium dissotocum
  Pythium dissotocum is a plant pathogen.- External links :* *...
  
  
• Pythium echinulatum
• Pythium erinaceum
• Pythium flevoense
• Pythium folliculosum
• Pythium glomeratum
• Pythium graminicola
  Pythium graminicola
  Pythium graminicola is a plant pathogen.- External links :**...
  
  
• Pythium grandisporangium
• Pythium guiyangense
• Pythium helicandrum
• Pythium helicoides
• Pythium heterothallicum
  Pythium heterothallicum
  Pythium heterothallicum is a plant pathogen.- External links :* *...
  
  
• Pythium hydnosporum
• Pythium hypogynum
  Pythium hypogynum
  Pythium hypogynum is a plant pathogen.- External links :* *...
  
  
• Pythium indigoferae
• Pythium inflatum
• Pythium insidiosum
  Pythium insidiosum
  Pythium insidiosum is a species of Pythium.It can cause pythiosis....
  
  
• Pythium intermedium
• Pythium irregulare
  Pythium irregulare
  Pythium irregulare is a plant pathogen.- External links :**...
  
  
• Pythium iwayamae
  Pythium iwayamae
  Pythium iwayamae is a plant pathogen.- External links :**...
  
  
• Pythium jasmonium
• Pythium kunmingense
• Pythium litorale
• Pythium longandrum
• Pythium longisporangium
• Pythium lutarium
• Pythium macrosporum
• Pythium mamillatum
• Pythium marinum
• Pythium marsipium
• Pythium mastophorum
  Pythium mastophorum
  Pythium mastophorum is a plant pathogen.- External links :* *...
  
  
• Pythium megacarpum
• Pythium megalacanthum
• Pythium middletonii
  Pythium middletonii
  Pythium middletonii is a plant pathogen.- External links :* *...
  
  
• Pythium minus
• Pythium monospermum
• Pythium montanum
• Pythium multisporum
• Pythium myriotylum
  Pythium myriotylum
  Pythium myriotylum is a plant pathogen.- External links :**...
  
  
• Pythium nagaii
• Pythium nodosum
• Pythium nunn
• Pythium oedochilum
• Pythium okanoganense
  Pythium okanoganense
  Pythium okanoganense is a plant pathogen.- External links :**...
  
  
• Pythium oligandrum
  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 reduces pathogen load and concomitant plant disease.P. oligandrum can grow...
  
  
• Pythium ornacarpum
• Pythium orthogonon
• Pythium ostracodes
• Pythium pachycaule
• Pythium pachycaule
• Pythium paddicum
  Pythium paddicum
  Pythium paddicum is a plant pathogen.- External links :* *...
  
  
• Pythium paroecandrum
  Pythium paroecandrum
  Pythium paroecandrum is a plant pathogen.- External links :* *...
  
  
• Pythium parvum
• Pythium pectinolyticum
• Pythium periilum
• Pythium periplocum
• Pythium perniciosum
  Pythium perniciosum
  Pythium perniciosum is a plant pathogen.- External links :* *...
  
  
• Pythium perplexum
• Pythium phragmitis
• Pythium pleroticum
• Pythium plurisporium
• Pythium polymastum
• Pythium porphyrae
• Pythium prolatum
• Pythium proliferatum
• Pythium pulchrum
• Pythium pyrilobum
• Pythium quercum
• Pythium radiosum
• Pythium ramificatum
• Pythium regulare
• Pythium rhizo-oryzae
• Pythium rhizosaccharum
• Pythium rostratifingens
• Pythium rostratum
  Pythium rostratum
  Pythium rostratum is a plant pathogen.- External links :* *...
  
  
• Pythium salpingophorum
• Pythium scleroteichum
  Pythium scleroteichum
  Pythium scleroteichum is a plant pathogen.- External links :* *...
  
  
• Pythium segnitium
• Pythium spiculum
• Pythium spinosum
  Pythium spinosum
  Pythium spinosum is a plant pathogen.- External links :* *...
  
  
• Pythium splendens
  Pythium splendens
  Pythium splendens is a plant pathogen.- External links :**...
  
  
• Pythium sterilum
• Pythium stipitatum
• Pythium sulcatum
  Pythium sulcatum
  Pythium sulcatum is a chromalveolate plant pathogen. Because this organism was once thought to be a type of fungus, it is still often treated as such.- External links :* *...
  
  
• Pythium sylvaticum
  Pythium sylvaticum
  Pythium sylvaticum is a plant pathogen.- External links :* *...
  
  
• Pythium terrestris
• Pythium torulosum
• Pythium tracheiphilum
  Pythium tracheiphilum
  Pythium tracheiphilum is a plant pathogen.- External links :* *...
  
  
• Pythium ultimum
  Pythium ultimum
  Pythium ultimum is a plant pathogen.- External links :***...
  
  
  • Pythium ultimum var. ultimum
    Pythium ultimum var. ultimum
    Pythium ultimum var. ultimum is a plant pathogen.-External links:* * *...
    
    
• Pythium uncinulatum
• Pythium undulatum
• Pythium vanterpoolii
• Pythium vexans
  Pythium vexans
  Pythium vexans is a plant pathogen.- External links :* *...
  
  
• Pythium viniferum
• Pythium violae
  Pythium violae
  Pythium violae is a plant pathogen.- External links :* *...
  
  
• Pythium volutum
  Pythium volutum
  Pythium volutum is a plant pathogen.- External links :**...
  
  
• Pythium zingiberis
• Pythium zingiberum