Phytophthora ramorum
Trials of silvicultural methods for treating "P. ramorum" began in Humboldt County in northwest coastal California in 2006. The trials have taken place on a variety of infested properties both private and public and have generally focused on varying levels and kinds of host removal. The largest () and most replicated trials have involved removal of tanoak and bay laurel by chainsaw throughout the infested stand, both with and without subsequent underburning designed to eliminate small seedlings and infested leaf litter. Other treatments included host removal in a modified “shaded fuelbreak” design in which all bay laurel is removed, but not all tanoaks; bay and tanoak removal using herbicides; and removal of bay laurel alone. The results of these treatments are still being monitored, but repeated sampling has so far detected only very small amounts of "P. ramorum" in the soil or on vegetation in the treated sites.
Phytophthora tentaculata
Phytophthora tentaculata is a plant pathogen that causes root and stalk rot. It was first isolated in 1993 in a nursery in Germany infecting "Chrysanthemum", "Verbena", and "Delphinium ajacis". It has since been found infecting a "Verbena" in Majorca, Spain in June 2001 but was thought to be restricted to nurseries in Germany and the Netherlands. Other species have since been found to be infected, "Santolina chamaecyparissus" (Lavender cotton) in Spain in 2004, "Gerbera jamesonii" in Italy 2006, and "Aucklandia lappa" in China in 2008.