Jaesoon Hwang

TL;DR: Phytophthora spp.

Abstract: To evaluate the number of stream sample sites needed to effectively survey a given stream network for species of Phytophthora, two stream networks, Davidson River and Cathey’s Creek, in western North Carolina (USA) were studied. One-litre water samples were collected from the terminal drainage points and most of the tributaries in each stream network and filtered through polycarbonate membrane filters with 3-μm pores. Ten taxa of Phytophthora were detected in the two stream networks: six species—P. cinnamomi, P. citricola, P. citrophthora, P. gonapodyides, P. heveae, and P. pseudosyringae—and four distinct groups of isolates based on morphological and molecular characters. A total of nine taxa were detected in the Davidson River network on two sample dates in 2007, and five of these taxa eventually were found downstream at the drainage point. In the Cathey’s Creek network, a total of seven taxa were found on two sample dates in 2008, and five of these taxa eventually were found at the drainage point. Even though all the taxa found within a stream network were not detected at the terminal drainage point, all of the taxa in the network that represented at least 10% of the total population were detected at the drainage point. More intensive sampling throughout a stream network may be necessary to detect a species with a low population density.

TL;DR: In this paper, a 1 liter water sample was collected from each stream and vacuum-filtered with Nuclepore and Durapore membrane filters, and wound or non-wounded leaves of Rhododendron maximum were used as baits.