Inactivation of Phytophthora and bacterial species in water by a potential energy-saving heat treatment

• Published in: European journal of plant pathology 2012-10, Vol.134 (2), p.357-365
• Main Authors: Hao, W., Ahonsi, M. O., Vinatzer, B. A., Hong, C.
• Format: Article
• Language: English
• Subjects: Agriculture; Bacteria; Biological and medical sciences; Biomedical and Life Sciences; Chlamydospores; Crop diseases; Crops; Decontamination; E coli; Ecological footprint; Ecology; Economics; Energy; Energy conservation; Escherichia coli; Fundamental and applied biological sciences. Psychology; Greenhouses; Health risks; Heat treatment; Heat treatments; Inactivation; Irrigation; Irrigation water; Life Sciences; Oospores; Pathogens; Phytopathology. Animal pests. Plant and forest protection; Phytophthora; Phytophthora nicotianae; Plant Pathology; Plant Sciences; Survival; Vinca; Water temperature; Zoospores
• ISSN: 0929-1873; 1573-8469
• DOI: 10.1007/s10658-012-9994-4

Plant pathogens, especially Phytophthora and bacterial species, in re-circulated irrigation water present a significant health risk to nursery and greenhouse crops. Heat treatment at 95°C for 30 s is one of the most reliable technologies for irrigation water decontamination. The primary objective here was to examine whether the water temperature required to inactivate major pathogens in re-circulated irrigation water can be lowered from 95°C to conserve energy and improve horticultural profitability while reducing environmental footprint. Specifically, we investigated the effect of water temperature on Phytophthora nicotianae zoospore survival in the laboratory and on annual vinca under greenhouse conditions. We also assessed the effect of water temperature on survival of chlamydospores of P. nicotianae , oospores of P. pini , six plant pathogenic bacterial species and Escherichia coli . The zoospores of P. nicotianae did not survive and cause any disease on annual vinca when exposed to 42°C for 12 h or 48°C for 6 h. No chlamydospores of P. nicotianae survived 42°C for 24 h or 48°C for 6 h, nor did the oospores of P. pini at 42°C for 12 h or 48°C for 6 h. In addition, none of the seven bacterial species survived 48°C for 24 h. These results indicate that the required water temperature to eliminate Phytophthora and bacterial species may be lowered substantially from 95°C by longer exposure time, improving the economics and environmental footprint, without sacrificing efficacy of heat treatment.