New Phytophthora species
Within the genus Phytophthora, new species have recently been described (see also EPPO RS 2009/007, 2009/159, 2009/197, 2015/169). 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.
In Brazil, Phytophthora acacia sp. nov. was found to be associated with gummosis in plantations of Acacia mearnsii. The disease has been observed in the subtropical humid areas of Southern Brazil (Rio Grande do Sul). A pathogenicity trial confirmed that this new Phytophthora species causes necrotic lesions on the plant stem, with either the presence or absence of gum. It is noted that other Phytophthora species (P. boehmeriae, P. frigida, P. nicotianae) have also been associated with gummosis of A. mearnsii in Brazil (Alves et al., 2019).
In Colombia, Phytophthora betacei sp. nov. was found to be associated with Solanum betaceum (tree tomato) crops showing leaf symptoms resembling those of potato late blight. No symptoms were observed on fruit, and rarely on stems. In inoculation experiments, the host range of P. betacei appeared to be restricted to S. betaceum. In the field, affected plants can be completely defoliated within one week, and the disease can lead to total loss of S. betacerum crops (Mideroset al., 2018).
Phytophthora cacuminis and Phytophthora oreophila
During studies conducted in alpine and sub-alpine regions of Tasmania (Australia) to elucidate the cause of dying vegetation and progressive thinning of the plant canopy, several Phytophthora species were isolated including two new species. Phytophthora cacuminis sp. nov. was recovered from asymptomatic vegetation (Eucalyptus coccifera and Proteaceae species) and Phytophthora oreophila sp. nov. was isolated by baiting rhizosphere soil and associated roots collected from a disturbed alpine herbfield (Khaliq et al., 2019).
In Italy, Phytophthora oleae sp. nov. was found to be consistently associated with a rot of mature fruit of two local cultivars of olive (Olea europaea cvs. Carolea and Ottobratica) in Calabria. Affected olives showed symptoms of soft rot with a faint white mycelial efflorescence, mainly in the lower part of the tree canopy. Inoculation trials on fruits of three olive cultivars (cvs. Carolea, Ottobratica and Leccino) confirmed the pathogenicity of P. oleae (Ruano-Rosa et al., 2018).
In the central Peruvian Andes, Phytophthora urerae sp. nov. was isolated from symptomatic foliage of Urera laciniata (Urticaceae), a wild plant growing in hedgerows along roadsides or riverbanks (Grünwald et al., 2019).
Alves TCA, Tessmann DJ, Ivors KL, Ristaino JB, Santos AF (2019) Phytophthora acaciae sp. nov., a new species causing gummosis of black wattle in Brazil. Mycologia 111(3), 445-455. DOI: 10.1080/00275514.2019.1575685 (via PestLens).
Grünwald NJ, Forbes GA, Perez‐Barrera W, Stewart JE, Fieland VJ, Larsen MM (2019) Phytophthora urerae sp. nov., a new clade 1c relative of the Irish famine pathogen Phytophthora infestans from South America. Plant Pathology 68(3), 557-565. DOI: https://doi.org/10.1111/ppa.12968
Khaliq I, St. J. Hardy GE, McDougall KL, Burgess TI (2019) Phytophthora species isolated from alpine and sub-alpine regions of Australia, including the description of two new species; Phytophthora cacuminis sp. nov and Phytophthora oreophila sp. nov.Fungal Biology123(1), 29-41.
Mideros MF, Turissini DA, Guayazán N, Ibarra-Avila H, Danies G, Cárdenas M, Myers K, Tabima J, Goss EM, Bernal A, Lagos LE, Grajales A, Gonzalez LN, Cooke DEL, Fry WE, Grünwald N, Matute DR, Restrepo S (2018) Phytophthora betacei, a new species within Phytophthora clade 1c causing late blight on Solanum betaceum in Colombia. Persoonia41, 39-55.
Ruano‐Rosa D, Schena L, Agosteo GE, Magnano di San Lio G, Cacciola SO (2018) Phytophthora oleae sp. nov. causing fruit rot of olive in southern Italy. Plant Pathology67(6), 1362-1373.