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 kernoviae
"Phytophthora kernoviae" spreads most quickly and detrimentally in moist conditions such as direct rainfall and also those of heavy humidity. Rain and heavy winds help in the dispersal of spores for further infection. This disease has an optimal growing range of . This range suggests that it may have originated in a temperate climate, possibly China, before being introduce to the UK. In some genus of the disease such as "P. ramorum" water transportation through the use of streams and rivers is seen from outbreak sites. This is a unique characteristic of the "P. ramorum" and has not been seen in the "kernoviae" species While there are no known insect vectors for the disease humans can transport spores via agricultural equipment, on shoe bottoms and direct plant movement. These are the most significant vectors for the disease.