Oregon and Indiana have quarantined plants grown in California that could be carrying sudden oak death fungus (Phytophthora ramorum). This brings the total number of states restricting imports to at least
12 13 since the disease was discovered in two California nurseries one month ago (Delaware, Kentucky, Louisiana, Mississippi, South Carolina, Tennessee, Utah, West Virginia, plus the 4 listed here).
Update to the Update: Seems California is not happy about all those states quarantining California nursery stock, especially with the spring planting season about to burst into full bloom. I have been waiting for this to break in the general media, but for some reason only the L.A. Times is reporting on it (sorry, free registration required). One story from March 31st describes the negotiations between the USDA and Florida regarding that state's strict quarantine of potentially-infected plants. Now this story from April 10th describes an impending ruling by the USDA that will supersede all state rulings regarding the transport of plant species susceptible to sudden oak death. I will post a link to the new USDA regulations, which are expected to be less strict than those imposed by several states, as soon as I can find them online.