Australasian Plant Pathology (2021) 50, 747-759

Rebecca L. McDougal and Rebecca J. Ganley (2021)
Foliar Phytophthora in New Zealand plantation forests: historical presence of Phytophthora kernoviae and association with a previously undiagnosed disorder of Pinus radiata
Australasian Plant Pathology 50 (6), 747-759
Abstract: Two foliar Phytophthora species are impacting New Zealand's pine forests. Both Phytophthora pluvialis and Phytophthora kernoviae cause similar symptoms on pine needles, however P. pluvialis is a recent arrival to New Zealand and is the primary cause of red needle cast disease in Pinus radiata. The objective of this study was to determine if Phytophthora species could be detected in archived foliage collections from plantation forests in New Zealand, to ascertain how long they have been associated with foliar disorders. Foliage samples were selected from dried collections of P. radiata and Pseudotsuga menziesii made between 1963 and 2004. From these, DNA extractions and polymerase chain reactions (PCR) were performed for both host and pathogen detection. Phytophthora species were detected in eight (of 44) pine mycological herbarium samples; of these, three contained P. kernoviae. The positive P. kernoviae samples were collected in 1999 from Northland, and in 2000 and 2002 from Gisborne. Phytophthora species were detected in an additional six archived foliage samples, collected for nutrient analysis: P. kernoviae in a 1986 sample from Riverhead, Auckland, a putative Phytophthora cactorum in a 1972 sample from Glenbervie, Northland, and other Phytophthora spp. in samples collected in 1972, 1986, 1994 and 1996. Phytophthora pluvialis was not detected in any of the samples tested. The results of this study indicate that some Phytophthora species have been present in pine foliage since at least the 1970s. The presence of P. kernoviae in pine foliage since 1986 suggests that P. kernoviae may be associated with physiological needle blight, a disorder of P. radiata with a previously unknown cause.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Rebecca J. (Beccy) Ganley

Research topic(s) for pests/diseases/weeds:
general biology - morphology - evolution

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora kernoviae	Pine (Pinus)	New Zealand