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 cinnamomi
"Phytophthora cinnamomi" is a diploid and heterothallic species with two mating types, A1 and A2. Sexual reproduction in heterothallic "Phytophthora" species ordinarily occurs when gametangia of opposite mating type interact in host tissue. This interaction leads to the formation of oospores that can survive for long periods in or outside the host. "Phytophthora cinnamomi" is also capable of self-fertilization (i.e. it can be homothallic). "Phytophthora cinnamomi" mating type A2 cultures can be induced to undergo sexual reproduction by exposure to damaging conditions, that is by exposure to hydrogen peroxide or mechanical damage.