Hüberli, D., Paap, T., Gower, K., Long, N., Dell, B. and Hardy, G.E.St.J. (2008) Does waterlogging influence phosphite protection of Banksia species against Phytophthora cinnamomi? In: ICPP 2008 9th International Congress of Plant Pathology, 24 - 29 August, Torino, Italy,.
Parts of the southwest of Western Australia are subject to periodic flooding in areas that are also devastated by Phytophthora dieback disease caused by P. cinnamomi. Phosphite has been shown to be effective in controlling this pathogen. Waterlogging induces multiple physiological dysfunctions in plants, but it is unknown whether waterlogging alters the uptake, distribution and efficacy of phosphite in controlling P. cinnamomi. Waterlogging trials were conducted in the greenhouse using Banksia attenuata and B. baxteri. The response of these plants and subsequent recovery from waterlogging was examined. A phosphite spray treatment was applied pre- and post-waterlogging of either 3 or 14 days duration. Leaf gas exchange, leaf water potentials, lesion development and phosphite concentrations in leaf, stem and root tissue were monitored 1 week, 1 month and 4 months after the phosphite treatment. For the 1 week harvest when phosphite was applied pre-waterlogging, phosphite in plant tissue was at similar levels for each species and was not affected by waterlogging. But lesions on B. baxteri stems were not reduced in treated plants as they were for B. attenuata. Photosynthesis and water potentials were reduced for waterlogged B. attenuata, but had no impact on waterlogged B. baxteri. Leaf water potentials, leaf gas exchange, lesion lengths on inoculated stems, and phosphite concentration in leaves, stems, and roots measured at different time periods after waterlogging will be presented.