@article {JPH:JPH1895, title = {Defining plant resistance to Phytophthora cinnamomi: a standardized approach to assessment}, journal = {Journal of Phytopathology}, volume = {160}, year = {2012}, pages = {269{\textendash}276}, publisher = {Blackwell Publishing Ltd}, abstract = {

Phytophthora cinnamomi is a soil-borne plant pathogen that causes devastating disease in agricultural and natural systems worldwide. While a small number of species survive infection by the pathogen without producing disease symptoms, the nature of resistance, especially under controlled conditions, remains poorly understood. At present, there are no standardized criteria by which resistance or susceptibility to P.\ cinnamomi can be assessed, and we have used five parameters consisting of plant fresh weight, root growth, lesion length, relative chlorophyll content of leaves and pathogen colonization of roots to analyse responses to the pathogen. The parameters were tested using two plant species, Zea mays and Lupinus angustifolius, through a time course study of the interactions and resistance and susceptibility defined 7\ days after inoculation. A scoring system was devised to enable differentiation of these responses. In the resistant interaction with Z.\ mays, there was no significant difference in fresh weight, root length and relative chlorophyll content in inoculated compared with control plants. Both lesion size and pathogen colonization of root tissues were limited to the site of inoculation. Following inoculation L.\ angustifolius showed a significant reduction in plant fresh weight and relative leaf chlorophyll content, cessation of root growth and increased lesion lengths and pathogen colonization. We propose that this technique provides a standardized method for plant{\textendash}P.\ cinnamomi interactions that could be widely used to differentiate resistant from susceptible species.

}, keywords = {Phytophthora cinnamomi, resistance, root pathogen, Zea mays, zoospores}, issn = {1439-0434}, doi = {10.1111/j.1439-0434.2012.01895.x}, url = {http://dx.doi.org/10.1111/j.1439-0434.2012.01895.x}, author = {Allardyce, Jane A. and Rookes, James E. and Cahill, David M.} } @article {PPA:PPA2614, title = {Effect of electrical conductivity on survival of Phytophthora alni, P.~kernoviae and P.~ramorum in a simulated aquatic environment}, journal = {Plant Pathology}, volume = {61}, year = {2012}, pages = {1179{\textendash}1186}, publisher = {Blackwell Publishing Ltd}, abstract = {

This study investigated survival of the pathogens Phytophthora ramorum, P.\ alni and P.\ kernoviae as zoospores or sporangia in response to an important water quality parameter, electrical conductivity (EC), at its range in irrigation water reservoirs and irrigated cropping systems. Experiments with different strengths of Hoagland{\textquoteright}s solution showed that all three pathogens survived at a broad range of EC levels for at least 3\ days and were stimulated to grow and sporulate at ECs\ \>\ 1{\textperiodcentered}89\ dS\ m-1. Recovery of initial populations after a 14-day exposure was over 20\% for P.\ alni subsp. alni and P.\ kernoviae, and 61{\textperiodcentered}3\% and 130\% for zoospores and sporangia of P.\ ramorum, respectively. Zoospore survival of these pathogens at ECs\ \<\ 0{\textperiodcentered}41\ dS\ m-1 was poor, barely beyond 3\ days in pure water; only 0{\textperiodcentered}3\% (P.\ alni), 2{\textperiodcentered}9\% (P.\ kernoviae) and 15{\textperiodcentered}1\% (P.\ ramorum) of the initial population survived after 14\ days at EC\ =\ 0{\textperiodcentered}21\ dS\ m-1. The variation in rates of survival at different EC levels suggests that these pathogens survive better in cropping systems than in irrigation water. Containment of run-off and reduction in EC levels may therefore be non-chemical control options to reduce the risk of pathogen spread through natural waterways and irrigation systems.

}, keywords = {aquatic biology, electrical conductivity, quarantine pathogen, zoospores}, issn = {1365-3059}, doi = {10.1111/j.1365-3059.2012.02614.x}, url = {http://dx.doi.org/10.1111/j.1365-3059.2012.02614.x}, author = {Kong, P. and Lea-Cox, J. D. and Hong, C. X.} }