Some Comments on the Relationship of Climate to Phytophthora Infection of Pinus radiata

Authors: R. J. Newhook
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1959, Issue N.Z.J.For. 8(2) 1960, pp 261-268, Aug 1960
Publisher: New Zealand Institute of Forestry

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Abstract: A disease of Pinus radiata in New Zealand in which trees die or become severely defoliated following infection with Phytophthora spp. in wet seasons is compared with similar diseases of other hosts overseas. As is the case with these other diseases, it is concluded that the role of soil saturation is to provide conditions necessary for production and spread of free-swimming spores of the pathogen.
It has been stated recently that climatic conditions are the "major cause" of this disease, the fungi being "secondary". Present findings, however, emphasise that host, pathogen, and environment are mutually interdependent; no one factor can rightly be singled out as "more important" than another.
Phytophthora spp. appear to be indigenous in New Zealand soils and it is not surprising therefore to find them present in many forest areas, where they must be regarded as one of the factors limiting production.

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