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 nicotianae
Chemical control is most successful if used with resistant varieties. Metalaxyl or mefenoxam are chemistries used to control "Phytophthora nicotianae". Ridomil Gold is an example a systemic pesticide with a Metalaxyl chemistry. Mefenoxam is twice as active as metalaxyl, but they both have the same mode of action. Successful chemical control is difficult because we are limited to these two chemistries that are basically identical. A study by A. S. Csinos and P. F. Bertrand found out at a rate of 3.36 kg/ha would not inhibit many of the common races used in their study. Overall, from their study they observed that Black Shank severity was increasing in Georgia due to Metalaxyl sensitivity and resistant races of Black Shank.