Australasian Plant Pathology (2022) 51, 273-279

Shannon Hunter, Rebecca McDougal, Nari Williams and Peter Scott (2022)
Variability in phosphite sensitivity observed within and between seven Phytophthora species
Australasian Plant Pathology 51 (3), 273-279
Abstract: Phosphite is used to control and manage many phytophthora diseases in horticultural systems worldwide and natural ecosystems in Australia, Africa, New Zealand and parts of Northern America and Europe. Phosphite does not kill Phytophthora species, but inhibits growth while also stimulating host defence responses. Phytophthora species differ in their underlying tolerance to phosphite and isolates have been shown to acquire tolerance after prolonged exposure. Intra- and inter-specific variability in phosphite sensitivity is of interest to determine the efficacy and sustainability of phosphite for the treatment of phytophthora diseases, which continue to spread globally. Seven Phytophthora species were tested for their sensitivity to phosphite in vitro in a mycelial growth experiment. Phytophthora agathidicida was the species most sensitive to phosphite, being inhibited by 98.7% on average at the lowest phosphite treatment (15 µg/mL phosphite), followed by P. aleatoria, P. cinnamomi, P. pluvialis, P. multivora, P. kernoviae and P. citricola. Huge intraspecific variability was observed with P. kernoviae, which raises the question of whether diseases caused by P. kernoviae such as phytophthora needle blight of Pinus radiata could be managed effectively with phosphite. Further work is required to determine the phosphite sensitivity of different introduced and native Phytophthora species growing in key hosts and whether tolerance observed in vitro is also expressed in vivo.
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Link to article at publishers website

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora cinnamomi	Pine (Pinus)	New Zealand
	Phytophthora citricola	Avocado (Persea americana)	New Zealand
	Phytophthora kernoviae	Pine (Pinus)	New Zealand
	Phytophthora multivora	Agathis (genus)	New Zealand
	Phytophthora pluvialis	Pine (Pinus)	New Zealand
	Phytophthora agathidicida	Agathis (genus)	New Zealand