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.
Garden roses
Fungal leaf diseases affect some cultivars and species more than others. On susceptible plants fungicidal sprays may be necessary to prevent infection or reduce severity of attacks. Cultivation techniques may also be used, such as ensuring good air circulation around a plant. Stem cankers are best treated by pruning out infection as soon as it is noticed. Root diseases are not usually possible to treat once infection has occurred; the most practical line of defence is to ensure that growing conditions maximise plant health and thereby prevent infection. "Phytophthora" species are waterborne and therefore improving drainage and reducing waterlogging can help reduce infection.