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 medicaginis
"P. medicaginis" is an water mould pathogen that causes root rot and damping off of seedlings. "P. medicaginis" is specific to alfalfa and chickpea and can reside in soil or water, but since it is a water mold, it requires free water to infect another plant. This disease is most prevalent in newly seeded fields that experience flooding but can also be found in mature plants. "P. medicaginis" commonly causes seedling death but if this pathogen is present in mature crops, "P. medicaginis" causes root rot which limits the plant’s ability to acquire nutrients and water. This leads to secondary symptoms such as chlorosis, wilting, stunting, root decay, lesions and death. This disease is difficult to identify but reddish-brown or black root lesions will exist and oospores, sporangia, zoospores, antheridia, and oogonia are spore types that will be visible under a microscope. An ELISA test can confirm the presence of "Phytophthora", but to confirm the species, a PCR test is effective. Several host factors will affect disease development including damage/stress to the plant and also the degree of resistance of host cultivar.