01938nas a2200157 4500008004100000022001400041245010300055210006900158260001600227300001400243490000700257520141200264100002201676700001301698856006901711 2014 eng d a0191-291700aPhytophthora cinnamomi as a Contributor to White Oak Decline in Mid-Atlantic United States Forests0 aPhytophthora cinnamomi as a Contributor to White Oak Decline in  cJan-03-2014 a319 - 3270 v983 a

To evaluate Phytophthora cinnamomi as a cause of white oak (Quercus alba) decline in mid-Atlantic forests, sampling was conducted at 102 sites from 2011 to 2012. Soil and roots from healthy and declining white oak trees were collected. Phytophthora spp. were isolated using baiting and CFU of P. cinnamomi quantified using wet-sieving. Fine roots were scanned and measured. Phytophthora spp. were isolated from 43% of the sites. P. cinnamomi was common; six other species were isolated infrequently. Little difference in lesion size existed on white oak seedlings inoculated with 32 isolates of P. cinnamomi; only 13 isolates caused significant mortality. Soils from white oak versus nine other hosts did not have significantly different CFU. P. cinnamomi was restricted to United States Department of Agriculture hardiness zones six and seven and never found in zone five. The presence of Phytophthora spp. in soil can be associated with white oak fine root health. When Phytophthora spp. were present, white oak trees in zones five and six had less fine roots. In mid-Atlantic oak forests, however, environmental conditions appear to play a key role in determining the impact of P. cinnamomi on the root system. P. cinnamomi alone does not appear to be a causal factor of white oak decline.

1 aMcConnell, M., E.1 aBalci, Y uhttp://apsjournals.apsnet.org/doi/abs/10.1094/PDIS-06-13-0649-RE