Effects of hydrostatic pressure, agitation and CO₂ stress on Phytophthora nicotianae zoospore survival

• Published in: Pest management science 2010-07, Vol.66 (7), p.696-704
• Main Authors: Ahonsi, Monday O, Banko, Thomas J, Doane, Stargel R, Demuren, Ayodeji O, Copes, Warren E, Hong, Chuanxue
• Format: Article
• Language: English
• Subjects: aeration; agitation; Air; Biological and medical sciences; carbon dioxide; Carbon Dioxide - pharmacology; Catharanthus roseus; cysts (developmental stages); disease severity; disinfestation; encysted zoospore; Fundamental and applied biological sciences. Psychology; fungal diseases of plants; Fungal plant pathogens; Hydrostatic Pressure; inactivation; irrigation systems; irrigation water; Lupinus; Lupinus polyphyllus; mortality; motile zoospore; Motion; ornamental plants; Phytopathology. Animal pests. Plant and forest protection; Phytophthora - drug effects; Phytophthora - pathogenicity; Phytophthora - physiology; Phytophthora nicotianae; plant pathogenic fungi; pressure; spore germination; Spores - drug effects; Spores - pathogenicity; Spores - physiology; Stress, Physiological - drug effects; Survival Analysis; viability; Vinca; virulence; water decontamination; water reuse; water treatment; zoospores
• ISSN: 1526-498X; 1526-4998; 1526-4998
• DOI: 10.1002/ps.1926

BACKGROUND: Phytophthora nicotianae Breda de Haan is a common pathogen of ornamental plants in recycled irrigation systems. In a previous study, annual vinca (Catharanthus roseus Don) inoculated with zoospore suspensions using a CO₂-pressurized sprayer had less foliage blight than plants inoculated using a hand sprayer. Here, the impact of hydrostatic pressure, agitation and aeration with CO₂ on the survival of P. nicotianae zoospores was examined.RESULTS: Exposure of zoospores to 840 kPa hydrostatic pressure for 8 min or agitation at a mixing intensity (G) of 6483 s⁻¹ for 4 min at 22-23 °C did not kill zoospores, but resulted in viable cysts. Motile and forcefully encysted zoospores of P. nicotianae were equally infectious on vinca or lupine (Lupinus polyphylus Lindl.). Bubbling CO₂ into zoospore-infested water at 110.4 mL (0.2 g) min⁻¹ for 5 min caused 81% reduction in the number of germinated zoospores. Pressure at 630 kPa (16.3 g CO₂) or 70 kPa (3.85 g CO₂) facilitated CO₂ injection and shortened the zoospore inactivation time to 30 s. When air was bubbled through the suspension, germination was similar to the control.CONCLUSIONS: Exposure to CO₂ killed P. nicotianae zoospores in water. Neither pressure nor agitation had an effect on zoospore viability or infectivity. Based on results of this study, the authors designed a recycling CO₂ water treatment system that is currently under evaluation. Copyright