Species: Phytophthora lacustris
Phytophthora lacustris Brasier, Cacciola, Nechwatal, T. Jung & Bakonyi, 2012
- Nechwatal, J. et al. 2012 (Online) 2013 (Print): The morphology, behaviour and molecular phylogeny of Phytophthora taxon Salixsoil and its redesignation as Phytophthora lacustris sp. nov.. Plant pathology 62(2): 355–369. DOI: 10.1111/j.1365-3059.2012.02638.x Reference page.
Hosts and Symptoms: P. lacustris has a wide host range as well as a very wide geographical range, being found worldwide (Nechwatal et al., 2012). Known hosts for P. lacustris include members of the Salix and Prunus genera. The Salix genus includes willow and poplar trees and the Prunus genus includes many economically important shrubs and trees such as peache, nectarine, cherry, almond, plum, and apricot (Phytophthora Database). P. lacustris causes dieback in ash and alder trees (Akilli et al.). Other symptoms that are caused by P. lacustris include fine root damage as well as bark lesions (Kanoun-Boulé et al., 2016).
Disease Cycle: P. lacustris is an oomycete that does not have a sexual life cycle, meaning the formation of oospores has not been observed (Phytophthora Database). It also lacks chlamydospores. This means the only spores produced by P. lacustris are the asexual zoospores which are formed in the sporangia. 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 (Nowak K.J. et al., 2015). Flooding or other forms of running water, such as irrigation 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 characteristics (Nechwatal et al., 2012).
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 (Nechwatal et al., 2012). This is significantly wider range than other taxonomically similar Phytophthora species. The wide tolerable temperature range that allows growth to occur allows P. lacustris to be present at a wide range of latitudes 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 (Milenkovic et al., 2018). 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 habitats, or the area of land near a river or stream, which are susceptible to flooding.
References: Kang, Seogchan. “Species Browser.” Phytophthora Database, www.phytophthoradb.org/species.php?a=dv&id=394589.
Nowak, Katarzyna, et al. “Characterization of Polish Phytophthora Lacustris Isolates Obtained from Water Environments.” Polish Journal of Environmental Studies, vol. 24, 2015, doi:10.15244/pjoes/29195.
Milenković, Ivan, et al. “Isolation and Pathogenicity of Phytophthora Species from Poplar Plantations in Serbia.” Forests, vol. 9, no. 6, June 2018, p. 330., doi:10.3390/f9060330.
Nechwatal, J., et al. “The Morphology, Behaviour and Molecular Phylogeny of Phytophthora Taxon Salixsoil and Its Redesignation as Phytophthora Lacustris Sp. Nov.” Plant Pathology, vol. 62, no. 2, 2012, pp. 355–369., doi:10.1111/j.1365-3059.2012.02638.x.
Kanoun-Boulé, M., et al. “Phytophthora ×Alni and Phytophthora Lacustris Associated with Common Alder Decline in Central Portugal.” Forest Pathology, vol. 46, no. 2, Sept. 2016, pp. 174–176., doi:10.1111/efp.12273.
Akilli, S., et al. “Phytophthora Dieback on Narrow Leaved Ash in the Black Sea Region of Turkey.” Forest Pathology, vol. 43, no. 3, May 2013, pp. 252–256., doi:10.1111/efp.12024.