Phytophthora ramorum, the causal agent of sudden oak death, poses a threat to woody plants in the rest of the United States. Several plant species native to Gulf Coast and southeastern US forests were tested for reaction to P. ramorum, including eastern baccharis (Baccharis halmifolia), spicebush (Lindera benzoin), yaupon (Ilex vomitoria), southern magnolia (Magnolia grandiflora), sweetbay magnolia (M. virginiana), Virginia creeper (Parthenocissus quinquefolia), black willow (Salix nigra), and baldcypress (Taxodium distichum). The foliage of each species was inoculated with a zoospore suspension and placed in a dew chamber for 5 days. The average percentage of leaf area necrosis was 0.2, 4.9, 27.9, 32.1, 8.6, 1.5, 1.1, 0.2, and 5.0% for inoculated eastern baccharis, spicebush, yaupon, southern magnolia, sweetbay magnolia, Virginia creeper (Louisiana), Virginia creeper (Maryland), black willow, and baldcypress, respectively. Comparison of the percent necrotic leaf area between inoculated and non-inoculated plants showed significant differences (P ≤ 0.05) for yaupon (P = 0.0008), southern magnolia (P = 0.001), and sweetbay magnolia (P = 0.0009). The other species did not show significant differences although infection was confirmed on spicebush, Virginia creeper, and baldcypress. This is a first report of yaupon, sweetbay magnolia, and baldcypress being hosts of P. ramorum. Accepted for publication 2 April 2013. Published 30 July 2013.
Germination biology of Parthenocissus quinquefolia (L.) Planch. (Vitaceae)
