Phytophthora pinifolia is a new pathogen of Pinus radiata in Chile: addition to the EPPO Alert List
Pinus radiata (Monterey pine) originates from the Californian coastal region (US) and grows well in areas which have a Mediterranean type of climate (e.g. Australia, Chile, New Zealand, South Africa, Spain). In Chile, it was first introduced for ornamental purposes in 1885 and it is now widely planted for forestry purposes over approximately 1.5 million ha (representing more than a third of the total area planted with P. radiata in the world). In February 2004, unusual tree mortality was observed in a 6-year old P. radiata stand (of 70 ha) located on the Arauco coast of Chile. In October 2004, a serious needle blight disease was observed in the same area, and was also associated with tree mortality. In the following years, damage increased dramatically and reached 60 000 ha by the end of 2006. The disease was called ‘daño foliar del pino’ and its overall pattern of development suggested that it was caused by a pathogen. In July 2007, isolations made from diseased needles and stems consistently yielded a Phytophthora species. Investigations (morphology, DNA sequence comparison, pathogenicity tests) concluded that the disease was caused by a new Phytophthora species. The latter was described and called Phytophthora pinifolia sp. nov. Considering the rapid spread of P. pinifolia in Chile and the significant mortality it can cause to P. radiata plantations, the EPPO Secretariat decided to add P. pinifolia to the EPPO Alert List.
Phytophthora pinifolia (a new pathogen of Pinus radiata)
Why: Dr Webber (Forest Research, GB) attracted the attention of the EPPO Secretariat to a newly described species of Phytophthora which is severely damaging plantations of Pinus radiata in Chile.
Where:
EPPO region: Absent.
South America: Chile (Arauco province, Región del Biobío (VIII)).
On which plants: So far, the disease has only been observed on Pinus radiata. In Chile, other coniferous trees (P. pinaster and Pseudotsuga menziesii) growing in the vicinity of affected P. radiata did not show any symptoms. However, further studies are needed to determine the host range of P. pinifolia.
Damage: The disease is characterized by needle infection, defoliation and tree mortality. Initially, small dark resinous bands appear on green needles. A reddish discoloration of the needles is subsequently observed, appearing first on the lower side of the branches. Dead and dying needles remaining on the trees give them a scorched appearance. Needles then fall from the trees which can be almost totally defoliated. Exudation of resin at the basis of the needles and necrotic lesions under the bark are also observed. The disease causes the rapid death of young seedlings, and mature trees can be killed after 2 or 3 years of repeated infections. In Chile, it is considered that P. pinifolia is the most important problem affecting P. radiata plantations, and that it is a serious threat to the local forestry industry.
Dissemination: The life cycle of P. pinifolia remains to be studied, and for the moment data is lacking on its means of dissemination. However, as for other Phytophthora, it is likely that the disease can be transmitted by infected plants, water, and soil.
Pathway: Plants for planting of Pinus radiata from Chile, cut branches? wood? cones? soil?
Possible risks: In Europe, the main forest plantations of Pinus radiata are located in Spain (Northwest), but the tree is also grown at a smaller scale in France (south of the Atlantic coast) and the United Kingdom (West Wales, Southwest England, Channel Islands). P. radiata is also planted in parks and gardens for ornamental purposes. So far, P. pinifolia has only been reported from Chile, but it is suspected that it is an introduced species (severity of damage, rapidity of spread). Although much data is still missing on the biology, host range, control methods, potential of establishment, it is quite clear that P. pinifolia can cause extensive tree mortality and hence economic damage. It seems desirable to avoid the introduction of P. pinifolia into the EPPO region, where it could be a threat to P. radiata trees growing in forest plantations, nurseries, and amenity areas.
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EPPO RS 2009/006
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Panel review date: -
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Entry date 2009-01
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Sources
Durán A, Gryzenshout M, Slippers B, Ahumada R, Rotella A, Flores F, Wingfield BD, Wingfield MJ (2008) Phytophthora pinifolia sp. nov. associated with a serious needle disease of Pinus radiata in Chile. Plant Pathology 57(4), 715-727.
Wingfield MJ (2007) A new species of Phytophthora associated with dying pine needles in Chile. http://src.fabinet.up.ac.za/tpcp/news/pinifolia.pdf