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 ramorum
In 2009, the pathogen was found to be infecting and killing large numbers of Japanese larch trees ("Larix kaempferi") in the United Kingdom at sites in the English counties of Somerset, Devon, and Cornwall. It was the first time in the world that "Phytophthora ramorum" had been found infecting this species. Since then, it has also been found extensively in larch plantations in Wales and in southwest Scotland, leading to the deliberate felling of large areas. The UK Forestry Commission noted that eradication of the disease would not be possible, and instead adopted a strategy of containing the disease to reduce its spread. Symptoms of the disease on larch trees include dieback of the tree's crown and branches, and a distinctive yellowing or ginger colour beneath the bark. In August 2010, the disease was found in Japanese larch trees in Counties Waterford and Tipperary in Ireland. It had spread to Japanese larch plantations across the south of the country by February 2014. Coillte, who owned twenty forests where the disease was present, felled 16,000 trees in one of its forests, having already felled 150 hectares to contain the disease.