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 inflata
Phytophthora inflata is an oomycete plant pathogen. It was first identified in 1949 in Michigan, USA causing a pit canker on elm trees. It was found in the United Kingdom in 1992 in the roots of "Sambucus tenuifolium" and Lilac ("Syringa vulgaris"), in 2003 it was found in a UK nursery infecting "Rhododendron ponticum". In the same year it was found in a nursery in Ohio also infecting "Rhododendron".