01968nas a2200181 4500008004100000022001400041245011600055210006900171260001600240300001600256490000800272520136300280100001801643700001701661700002201678700002101700856006501721 2016 eng d a0191-291700aComparison of Five Detection and Quantification Methods for Phytophthora ramorum in Stream and Irrigation Water0 aComparison of Five Detection and Quantification Methods for Phyt cJan-06-2016 a1202 - 12110 v1003 a

Propagules of Phytophthora ramorum, the causal agent of sudden oak death (SOD) and ramorum blight, can be recovered from infested stream and nursery irrigation runoff using baiting and filtration methods. Five detection methods, including pear and rhododendron leaf baits, Bottle O’ Bait, filtration, and quantitative polymerase chain reaction (qPCR) performed on zoospores trapped on a filter were compared simultaneously in laboratory assays using lab or creek water spiked with known quantities of P. ramorum zoospores. The detection threshold for each method was determined and methods that could be used to quantify zoospore inoculum were identified. Filtration and qPCR were the most sensitive at detecting low levels of zoospores, followed by wounded rhododendron leaves, rhododendron leaf disks, and pear baits. Filtration, qPCR, and leaf disks were able to quantify P. ramorum zoospores ranging from 2 to 451 direct-plate CFU/liter while wounded leaves and pear baits appeared to be better at detection rather than quantification. The ability to detect and quantify P. ramorum inoculum in water will assist scientists, regulatory agencies, and nursery personnel in assessing the risk of spreading P. ramorum in nurseries and landscape sites where untreated infested water is used for irrigation.

1 aRollins, Lucy1 aCoats, Katie1 aElliott, Marianne1 aChastagner, Gary uhttp://apsjournals.apsnet.org/doi/10.1094/PDIS-11-15-1380-RE