first_img“Despite this quarantine, there have been several outbreaks inOregon, Washington and British Columbia,” she said. “Theseoutbreaks are believed to have originated from ornamental plantsbrought into the U.S. from Europe.”In an effort to keep the disease from entering the Southeasternstates, Williams-Woodward and her counterparts in Tennessee,Virginia, North Carolina and South Carolina are surveyingnurseries in their states. The survey is being conducted incooperation with the USDA and the U.S. Forest Service.”We are sampling high risk plants in high risk areas of eachstate,” she said. “In Georgia, that’s the northern part of thestate above the fall line. This is the area that has the mostoak and rhododendron forests.”The researchers are collecting samples of leaf spot and die backand checking the samples for the disease. “So far, we have collected 500 samples from six nurseries inGeorgia and we haven’t detected the pathogen,” she said. “Overall, across the five states, we have collected about 2,000samples and haven’t found the disease.” By Sharon OmahenUniversity of Georgia Research on chemical control is being conducted by researchers inCalifornia. However, Williams-Woodward says fungicides areunlikely to truly control Sudden Oak Death. “Limiting the spread of infected plants and soil from areas knownto have the disease is still the best approach to controlling thedisease,” she said. “Quarantining infected nurseries is anothercontrol method.”For now, Williams-Woodward sees some potentially positiveoutcomes for Georgia growers.”The California quarantine has opened up a market that could befilled by Georgia growers,” she said. “Korea is refusing toaccept ornamentals from California. Other countries may impose asimilar quarantine. Georgia growers could be filling this need.” Tanoaks and other true oak species first began showing signs ofthe disease in 1995 in Marin County, California. Quarantine in California Can it survive in southern climates?Williams-Woodward believes it’s just a matter of time untilsudden oak death arrives in the South. How it will fare isunknown.”We don’t know if it would even survive in Georgia,” she said. “It prefers cooler, wetter climates so it may not be able tosurvive the hot, humid weather here.” To help control the spread of the disease, 12 counties inCalifornia and one county in Oregon have been quarantined.Growers there cannot ship plants out unless they are declareddisease-free. Concern grew when the disease began to affect live oaks. Thedisease actually affects diverse plant species other than oaksincluding, but not limited to, Douglas fir, California bay laureland camellia. The disease causes dark, rust-colored cankers that seep at thetree’s base. Sudden oak death has also been seen on understoryplants such as rhododendron, causing leaf spots or scorch-likesymptoms.”It spreads to other plants when the spores are splashed by waterfrom rain,” said Williams-Woodward. “It appeared as if one year the trees were green and the nextthey were brown,” said Williams-Woodward. “It first strucktanoaks, which many people consider to be a weedy tree, so notmany people were concerned.” Oak trees in California appear to be suddenly dying, but thedisease that’s striking them down isn’t actually fast acting. University of Georgia researchers are working with otherscientists in the Southeast to track the disease and make sure itdoesn’t head this way. “Sudden oak death is actually a misnomer,” said JeanWilliams-Woodward, an extension plant pathologist with the UGACollege ofAgricultural and Environmental Sciences. “It isn’t sudden and itdoesn’t just affect oak trees.”Actually takes three or more yearsSudden oak death was coined because a number of oak treesappeared to be suddenly dying in California, she said. Thedisease, caused by the fungus Phytophthora ramorum, actuallytakes three or more years to cause the death of a tree.last_img read more