By Chuan Hong, Hampton Roads AREC Recent detection of sudden oak death pathogen (Phytophthora ramorum) in nurseries of Oregon and in British Columbia suggests that the risk of spreading this quarantine pathogen through shipments of ornamental plant materials from West Coast to East Coast is real. This risk is further compounded by a continuously growing list of host plant species. In order to safeguard the nursery and forestry industries in Virginia, we conducted Phytophthora ramorum surveys in selected nurseries and surrounding forestry areas from September 11, 2002 to September 10, 2003.
The nursery survey focused on high-risk host plants, including Rhododendron, Azalea, Pieris, Kalmia, and Viburnum. Host plant materials imported from the West Coast were surveyed most intensively. Survey sites included twelve nurseries located throughout the state. These nurseries were selected based upon extent of inventory of target plant species and location. In total, over 132,000 Rhododendron, 61,000 Azaleas, 16,000 Pieris, 42,500 Viburnum, and 22,600 Kalmia were surveyed. From these plants, 232 samples were collected and processed. Sample processing methods included plating plant tissue on selective media and a DNA fingerprinting technique developed in my lab, in addition to the detection protocols designated by USDA/APHIS. All samples were found to be negative for P. ramorum.
We also processed over 80 plant samples collected by the Virginia Department of Forestry personnel from surrounding forestry areas of the nurseries we surveyed. None of these samples was positive for P. ramorum. These surveys certified that Virginia is currently free of this quarantine pathogen. We will continue the survey in 2004 to safeguard the nursery and forestry industries in the state.
Growers are strongly advised to follow the guidelines described in previous articles (VNLA Newsletter (2002) 72(6):75-76, and (2003 73(3):26) to minimize the risk of pathogen importation and potential impact on business in the event that this pathogen is found in imported plant materials.
