Phytophthora pinifolia

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: Phytophthora pinifolia was first observed on a large Pinus radiata plantation in Raqui, on the Arauco coast in 2004. It rapidly spread from the initial foci (70 ha) to 60 000 ha in 2006. Between 2007 and 2008, the affected area reduced to less than 500 ha. Genetic studies on the population structure of P. pinifolia supported the hypothesis that P. pinifolia is an alien species of recent introduction into Chile (but its area of origin remains unknown).
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. Studies have showed that green sawn timber was not a likely pathway for introducing P. pinifolia to new areas.

Pathway: Plants for planting of Pinus radiata from Chile, cut branches? 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.

Source(s)                     
Ahumada R, Díaz C, Peredo M, Barría C, González P, Cuevas G (200?) Detection of possible Phytophthora pinifolia infection in Pinus radiata green sawn timber produced in Chile. Abstracts from the 4th Sudden Oak Death Science Symposium, 2009-06-15/18, Santa Cruz, California, USA, p 18. http://nature.berkeley.edu/comtf/sodsymposium4/pdf/book_of_abstracts.pdf
Durán A, Gryzenhout M, Drenth A, Slippers B, Ahumada R, Wingfield BD, Wingfield MJ (2010) AFLP analysis reveals a clonal population of Phytophthora pinifolia in Chile. Fungal Biology 114(9), 746-752.
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

EPPO RS 2009/006, 2009/164, 2011/177

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