01965nas a2200217 4500008004100000022001400041245014500055210006900200260001200269300001200281490000800293520124400301653003601545653001301581653002201594100001501616700002101631700002101652700001901673856005501692 2012 eng d a1574-696800aSurvival of Phytophthora alni, Phytophthora kernoviae, and Phytophthora ramorum in a simulated aquatic environment at different levels of pH0 aSurvival of Phytophthora alni Phytophthora kernoviae and Phytoph c07/2012 a54–600 v3323 a

Phytophthora ramorum, Phytophthora alni, and Phytophthora kernoviae present significant threats to biosecurity. As zoosporic oomycetes, these plant pathogens may spread through natural waterways and irrigation systems. However, survival of these pathogens in aquatic systems in response to water quality is not well understood. In this study, we investigated their zoospore survival at pH 3–11 in a 10% Hoagland’s solution over a 14-day period. The results showed that all three pathogens were most stable at pH 7, although the populations declined overnight irrespective of pH. Extended survival of these species depended on the tolerance of pH of their germinants. Germinants of P. alni ssp. alni and P. ramorum were more basic tolerant (pH 5–11), while those of P. kernoviae were more acidic tolerant (pH 3–9). These tolerant germinants formed compact hyphae or secondary sporangia to allow longer survival of these pathogens. Long-term survival at a broad pH range suggests that these pathogens, especially P. ramorum, are adapted to an aquatic environment and pose a threat to new production areas through water dispersal.

10aquarantine Phytophthora species10awater pH10azoospore survival1 aKong, Ping1 aLea-Cox, John, D1 aMoorman, Gary, W1 aHong, Chuanxue uhttp://dx.doi.org/10.1111/j.1574-6968.2012.02574.x