New Phytophthora species
Within the genus Phytophthora, many new species have recently been described (see also EPPO RS 2009/159). Outbreaks of invasive species such as P. alni, P. ramorum and P. kernoviae in forests and woodlands of Europe and North America have triggered surveys in different types of environments. In addition, the development of new molecular tools together with the use of adequate isolation techniques and observation of morphological characteristics has facilitated the identification of new Phytophthora species. The list below has been compiled by the EPPO Secretariat from recent publications but is not an exhaustive list.
P. acerina is a new species causing bleeding cankers and dieback of Acer pseudoplatanus trees. It was isolated from bark and rhizosphere soil of A. pseudoplatanus trees planted in the Boscoincittá Park in Milano, Northern Italy (Ginetti et al., 2014).
This new species was found to be associated with kauri dieback in New Zealand, a disease which has been observed since the 1970s. Kauri (Agathis australis - Araucariaceae) is a large conifer tree (trunks can measure more than 4.5 m in diameter), considered to be one of the most ancient tree species still existing, and is therefore of high patrimonial value (Weir et al., 2015).
P. aquimorbida is a new species which has been recovered from agricultural irrigation reservoirs in Virginia (US). During experiments, P. aquimorbida has shown some pathogenicity to rhododendrons but its host range and pathogenicity under field conditions need to be further investigated (Hong et al., 2012).
Phytophthora arenaria and P. constricta
These two new species have been found in sclerophyllous shrubland (locally called Kwongan) in Western Australia (AU). P. arenaria and P. constricta were mainly associated with dead and dying Banksia species (Proteaceae), and studies have confirmed their pathogenicity to Banksia attenuata (Rea et al., 2011).
This new species was isolated from kudzu plants (Pueraria montana var. lobata – EPPO A2 List) showing leaf and stem blight in the Toyama and Ishikawa prefectures (Honshu) in Japan (Rahman et al., 2014).
This new species was isolated from the rhizosphere soil and roots of declining or dead Rubus anglocandicans in the southwest of Western Australia (AU). There are indications that P. bilorbang could be responsible for the decline syndrome of blackberry which is observed in the Warren and Donelly river catchments in the southwest of Western Australia (Aghighi et al., 2012).
Phytophthora borealis, P. riparia and P. pluvialis
P. borealis and P. riparia were found during surveys carried out in forest waterways and adjacent riparian vegetation in Oregon (US). However, their pathogenicity and ecology remains to be elucidated (Hansen et al., 2012). During another survey, P. pluvialis was found in streams, soil and canopy drip in the mixed tanoak-Douglas fir forest (Notholithocarpus densiflorus - Pseudotsuga menziesii) in Curry county, Oregon, and in two additional streams in other areas of Western Oregon (Reeser et al., 2013).
This new species, formerly known as Phytophthora taxon Pgchlamydo, has now been described and called Phytophthora chlamydospora. It has been found in streams, rivers, adjacent riparian soils in temperate forests in the western parts of North and South America, Europe, Asia, Africa and Australia. It has also occasionally been recovered from bark cankers, roots, and foliage of nursery plants (Hansen et al., 2015).
P. chrysanthemi was isolated from chrysanthemums showing stem and root rot in the Gifu and Toyama prefectures (Honshu) in Japan (Naher et al., 2011).
Phytophthora cichorii, P. dauci, and P. lactucae
These three new species were described during studies on Phytophthora isolates collected from different vegetable crops. P. cichorii was found in roots of chicory plants (Cichorium intybus). P. dauci was isolated from carrot (Daucus carota) roots. P. lactucae was found in lettuce (Lactuca sativa) (Bertier et al., 2013).
This new species was isolated from husks of diseased fruit of Cocos nucifera (coconut) collected in Hawaii (US) and Côte d’Ivoire. P. cocois causes a severe disease (plant wilting and premature fruit drop) which has killed hundreds of coconut trees in Hawaii (Weir et al., 2015).
Phytophthora gibbosa, P. gregata, P. litoralis, P. thermophila
These four new taxa have been identified during surveys of dying vegetation in natural ecosystems and associated waterways in Australia. Their pathogenicity remains to be studied (Jung et al., 2011).
This new species was found in roots of tobacco (Nicotiana tabacum) plants affected by a yellow stunt disease known as Amarelão in Brazil. Pathogenicity tests showed that P. glovera causes root rot and yellowing on tobacco under greenhouse conditions (Abad et al., 2011).
P. himalsilva was found in the rhizosphere of Quercus, Castanopsis, Carpinus and Cupressus species in a remote forest in Western Nepal. No disease symptoms were observed on the trees associated with the soil samples. In the laboratory, P. himalsilva was able to cause lesions on Juglans regia (Vettraino et al., 2011).
This newly described species has frequently been isolated from irrigation water in ornamental nurseries in Virginia, Maryland and North Carolina (US). In two nurseries in Virginia, it has also been found that P. hydropathica could cause leaf necrosis and shoot blight on Rhododendron catawbiense, as well as collar rot on Kalmia latifolia. However, during surveys conducted on irrigation waters in other ornamental nurseries, no severe disease outbreaks caused by this pathogen were observed (Hong et al., 2010). The occurrence of P. hydropathica has recently been reported from Italy in association with wilting and shoot dieback of Viburnum tinus (Vitale et al., 2014).
This species was first isolated from Salix matsudana roots in 1972 in Southern England (as Phytophthora taxon Salixsoil). It was then frequently obtained from wet or riparian habitats in different parts of the world, and from roots of Alnus and Prunus species. It has recently been described and called P. lacustris. This species appears to be widespread in Europe and has also been detected in Australia, New Zealand and the USA. During inoculation studies, it was shown to be weakly or moderately aggressive to Alnus, Prunus and Salix. Evidence suggests that P. lacustris has entered the nursery trade in Europe and is causing root rots in commercial Prunus and other fruit tree plantations in Italy and Central Europe (Nechwatal et al., 2013).
Phytophthora macilentosa and Phytophthora stricta
These two new species were recovered from an irrigation reservoir of an ornamental nursery in Mississippi (US). P. stricta has also been found in two water streams in Virginia during a survey. Their host range and pathogenicity need to be further investigated (Yang et al., 2014).
This species was first found in Oregon (US), infecting foliage of Kalmia latifolia showing leaf blight, and in soil substrate underneath a diseased Pieris japonica. P. obscura has also been found in Germany, in soil samples collected underneath an Aesculus hippocastanum tree showing a bleeding canker. Its morphological and ecological characteristics are very similar to those of P. syringae (Grünwald et al., 2012).
This new species has been found associated with mortality of Aucuba japonica (Garryaceae) in the United Kingdom. Preliminary studies have shown that this pathogen has the potential to affect other ornamental species (Henricot et al., 2014).
P. pisi is a newly described species which has been isolated from Pisum sativum (pea) and Vicia faba (faba bean) plants in Sweden exhibiting root rot. P. pisi can also infect Lens culinaris (lentil), Cicer arietinum (chickpea), Lathyrus spp. (pea), Vicia sativa (garden vetch), and V. benghalensis (purple vetch) (Hayman et al., 2013).
This new species has been found during large-scale surveys for soilborne Phytophthora species in forests, semi-natural stands and nurseries in Europe. P. plurivora was previously identified as P. citricola or less frequently as P. inflata in Europe and North America based solely on morphological and physiological characters. P. plurivora has a wide host range including Acer platanoides, Aesculus hippocastanum, Alnus glutinosa, Fagus sylvatica, Quercus robur, Tilia spp., and conifer species (Jung and Burgess, 2009).
Abad ZG, Ivors KL, Gallup CA, Abad JA, Shew HD (2011) Morphological and molecular characterization of Phytophthora glovera sp. nov. from tobacco in Brazil. Mycologia 103(2), 341-350.
Aghighi S, Hardy GESJ, Scott JK, Burgess TI (2012) Phytophthora bilorbang sp. nov., a new species associated with the decline of Rubus anglocandicans (European blackberry) in Western Australia. European Journal of Plant Pathology 133(4), 841-855.
Bertier L, Brouwer H, de Cock AWAM, Cooke DEL, Olsson CHB, Höfte M (2013) The expansion of Phytophthora clade 8b: three new species associated with winter grown vegetable crops. Persoonia 31, 63-76.
Ginetti B, Moricca S, Squires J, Cooke D, Ragazzi A, Jung T (2014) Phytophthora acerina sp. nov., a new species causing bleeding cankers and dieback of Acer pseudoplatanus trees in planted forests in Northern Italy. Plant Pathology 63(4), 858-876.
Grünwald NJ, Werres S, Goss EM, Taylor CR, Fieland VJ (2012) Phytophthora obscura sp. nov., a new species of the novel Phytophthora subclade 8d. Plant Pathology 61(3), 610-622.
Hansen EM, Reeser P, Sutton W, Brasier CM (2015) Redesignation of Phytophthora taxon Pgchlamydo as Phytophthora chlamydospora sp. nov. North American Fungi 10(2), 1-14.
Hansen EM, Reeser PW, Sutton W (2012) Phytophthora borealis and Phytophthora riparia, new species in Phytophthora ITS Clade 6. Mycologia 104(5), 1133–1142.
Henricot B, Pérez Sierra A, Jung T (2014) Phytophthora pachypleura sp. nov., a new species causing root rot of Aucuba japonica and other ornamentals in the United Kingdom. Plant Pathology 63(5), 1095-1109.
Heyman F, Blair JE, Persson L, Wikström M (2013) Root rot of pea and faba bean in southern Sweden caused by Phytophthora pisi sp. nov. Plant Disease 97(4), 461-471.
Hong C, Gallegly M, Richardson PA, Kong P, Moorman GW, Lea-Cox JD, Ross D (2010). Phytophthora hydropathica, a new pathogen identified from irrigation water, Rhododendron catawbiense and Kalmia latifolia. Plant Pathology 59(5), 913-921.
Hong CX, Gallegly ME, Richardson PA, Kong P, Moorman GW, Lea-Cox JD, Ross DS (2010) Phytophthora hydropathica, a new pathogen identified from irrigation water, Rhododendron catawbiense and Kalmia latifolia. Plant Pathology 59(5), 913-921.
Hong CX, Richardson PA, Hao W, Shimire SR, Kong P, Moorman GW, Lea-Cox JD, Ross DS (2012) Phytophthora aquimorbida sp. nov. and Phytophthora taxon ‘aquatilis’ recovered from irrigation reservoirs and a stream in Virginia, USA. Mycologia 104(5), 1097-1108.
Jung T, Burgess TI (2009) Re-evaluation of Phytophthora citricola isolates from multiple woody hosts in Europe and North America reveals a new species, Phytophthora plurivora. Persoonia 22, 95-110.
Jung T, Stukely MJC, Hardy GEStJ, White D, Paap T, Dunstan WA, Burgess TI (2011) Multiple new Phytophthora species from ITS Clade 6 associated with natural ecosystems in Australia: evolutionary and ecological implications. Persoonia 26, 13-39.
Naher M, Motohash K, Watanabe H, Chikuo Y, Senda M, Suga H, Brasier C, Kageyama K (2011) Phytophthora chrysanthemi sp. nov., a new species causing root rot of chrysanthemum in Japan. Mycological Progress 10(1), 21-31.
Nechwatal J, Bakonyi J, Cacciola SO, Cooke DEL, Jung T, Nagy ZA, Vannini A, Vettraino AM, Brasier CM (2013) The morphology, behaviour and molecular phylogeny of Phytophthora taxon Salixsoil and its redesignation as Phytophthora lacustris sp. nov. Plant Pathology 62(2), 355-369.
Rahman MZ, Mukobata H, Suga H, Kageyama K (2014) Phytophthora asiatica sp. nov., a new species causing leaf and stem blight of kudzu in Japan. Mycological Progress 13, 759-769.
Rea AJ, Burgess TI, Hardy GEStJ, Stukely MJC, Jung T (2011) Two novel and potentially endemic species of Phytophthora associated with episodic dieback of Kwongan vegetation in the south-west of Western Australia. Plant Pathology 60, 1055-1068.
Reeser P, Sutton W, Hansen E (2013) Phytophthora pluvialis, a new species from mixed tanoak-Douglas-fir forests of western Oregon, U.S.A. North American Fungi 8(7), 1-8.
Vettraino AM, Brasier CM, Brown AV, Vannini A (2011) Phytophthora himalsilva sp. nov. an unusually phenotypically variable species from a remote forest in Nepal. Fungal Biology 115(3), 275-287.
Vitale S, Luongo L, Galli M, Belisario A (2014) First report of Phytophthora hydropathica causing wilting and shoot dieback on Viburnum in Italy. Plant Disease 98(11), p 582.
Weir BS, Paderes EP, Anand N, Uchida JY, Pennycook SR, Bellgard SE, Beever RE (2015) A taxonomic revision of Phytophthora Clade 5 including two new species, Phytophthora agathidicida and P. cocois. Phytotaxa 205(1), 21-38.
Yang X, Copes WE, Hong C (2014) Two novel species representing a new clade and cluster of Phytophthora. Fungal Biology 118(1), 72-82.