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.
Aphanomyces euteiches
In alfalfa, "A. eutiches" is especially damaging in conjunction with "Phytophthora medicaginis", which causes Phytophthora root rot (PRR) in alfalfa. After initial studies in Wisconsin, "A. euteiches" was identified as an economically significant alfalfa pathogen in other states as well. In Wisconsin, Iowa and Kentucky it often exceeds "P. medicaginis" in prevalence in fields where alfalfa is grown. Due to these diseases, conventional advice was to avoid growing alfalfa in any wet soils. However, with the development of ARR- and PRR-resistant varieties, wet soil conditions have become less of a concern for alfalfa production, at least as far as disease pressure is concerned. Today, modern alfalfa varieties are required to have both PRR and ARR resistance.