''Phytophthora lacustris'' is an

oomycete Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...

plant pathogen.

Hosts and symptoms

''P. lacustris'' has a wide host range as well as a very wide geographical range, being found worldwide.Nechwatal, J., et al. "The Morphology, Behaviour and Molecular Phylogeny of ''Phytophthora'' Taxon ''Salix'' soil and Its Redesignation as ''Phytophthora lacustris'' Sp. Nov." Plant Pathology, vol. 62, no. 2, 2012, pp. 355–369., Known hosts for ''P. lacustris'' include members of the genera ''

Salix Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

'' and ''

Prunus ''Prunus'' is a genus of trees and shrubs, which includes (among many others) the fruits plums, Cherry, cherries, peaches, Peach#Nectarine, nectarines, apricots, and almonds. Native to the North American temperate regions, the neotropics of Sou ...

''. The genus ''Salix'' includes

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist so ...

and poplar trees and the genus ''Prunus'' includes many economically important shrubs and trees such as

peach The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, non-f ...

nectarine The peach (''Prunus persica'') is a deciduous tree first domesticated and cultivated in Zhejiang province of Eastern China. It bears edible juicy fruits with various characteristics, most called peaches and others (the glossy-skinned, non-f ...

, cherry, almond, plum, and apricot.Kang, Seogchan. "Species Browser." ''Phytophthora'' Database, http://www.phytophthoradb.org/species.php?a=dv&id=394589 ''P. lacustris'' causes dieback in

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

and

alder Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...

trees. Other symptoms that are caused by ''P. lacustris'' include fine root damage as well as bark lesions.

Disease cycle

''P. lacustris'' is an

that does not have a sexual life cycle, meaning the formation of

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 fusion of two species or the chemically-induced stimulation of mycelia ...

s has not been observed. It also lacks

chlamydospore A chlamydospore is the thick-walled large resting spore of several kinds of fungi, including Ascomycota such as '' Candida'', Basidiomycota such as '' Panus'', and various Mortierellales species. It is the life-stage which survives in unfavourable ...

s. This means the only spores produced by ''P. lacustris'' are the asexual

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 ...

s which are formed in the

sporangia A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cyc ...

. It is an opportunistic pathogen with a wide range of allowable temperatures. This allows it to lay dormant in soil or water as well as cause latent infections in hosts for years, waiting for unfavorable host conditions to become symptomatic. Flooding or other forms of running water, such as

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...

canals, is favorable for the discharge and dispersal of zoospores from the sporangia which inoculate the host via the root system. ''P. lacustris'' has also been found to be a colonizer of dead plant material, showing

saprotrophic 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 ( ...

characteristics.

Environment

The optimal temperature for growth of ''P. lacustris'' on artificial media ranged from 28–33 °C, while the minimum and maximum temperatures for growth to occur were 2–4 °C and 36–37 °C respectively. This is significantly wider range than other

taxonomically In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given ...

similar ''

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 ...

'' species. The wide tolerable temperature range that allows growth to occur allows ''P. lacustris'' to be present at a wide range of

latitude In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...

s in nature. ''P. lacustris'' is an aquatic pathogen that disperses via natural and irrigation waterways. During inoculation method trials, ''P. lacustris'' was discovered to be more pathogenic when the host was inoculated through contaminated water in the root system than through an underbark inoculation.Milenković, Ivan, et al. "Isolation and Pathogenicity of ''Phytophthora'' Species from Poplar Plantations in Serbia." Forests, vol. 9, no. 6, June 2018, p. 330., These results suggest that the presence of flooding is important for ''P. lacustris'' to be pathogenic. More evidence for this is that ''P. lacustris'' is often found in

riparian A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks a ...

habitats, or the area of land near a river or stream, which are susceptible to flooding.

References

{{Taxonbar, from=Q21307023 lacustris Water mould plant pathogens and diseases