Phytophthora ramorum
Detection of "P. ramorum" in watercourses has emerged as the earliest of early detection methods. This technique employs pear or rhododendron baits suspended in the watercourse using ropes, buckets, mesh bags, or other similar devices. If plants in the watershed are infected with "P. ramorum", zoospores of the pathogen (as well as other "Phytophthora" spp.) are likely present in adjacent waterways. Under conducive weather conditions, the zoospores are attracted to the baits and infect them, causing lesions that can be isolated to culture the pathogen or analyzed via PCR assay. This method has detected "P. ramorum" at scales ranging from small, intermittent seasonal drainages to the Garcia, Chetco, and South Fork Eel Rivers in California and Oregon (144, 352, and 689 mi2 drainage areas, respectively). It can detect the existence of infected plants in watersheds before any mortality from the infections becomes evident. Of course, it cannot detect the exact locations of those infected plants: at the first sign of "P. ramorum" propagules in the stream, crews must scour the watershed using all available means to find symptomatic vegetation.
Rosellinia bunodes
Despite best management practices, black root rot can still occur necessitating human intervention.  Root pruning and digging various styles of trenches to eliminate root contacts is one way of preventing disease spread. This approach is labor-intensive and may only be feasible for small-scale growers or for very localized outbreaks. Fungicide treatments usually include broad-spectrum approaches such as metam sodium, benzimidazoles, chlorophenyls, imidazole, morpholine, oxathiin, triazoles, and some inorganic compounds. Some research has shown biocontrols using mycorrhizal or mycoparasitic fungi (i.e.: "Trichoderma" spp., "Clonostachys" spp., "Glomus manihotis", and "Entrophospora colombiana") to be effective in suppressing the disease, but it is not clear if these interventions are successful only in certain environments or in specific host-pathogen combinations. Biocontrol interventions, however, are most effective when used in conjunction with cultural practices like canopy pruning and liming soil to raise pH. Crop rotation or including non-host species as part of planting schemes can also restrict the spread of the pathogen. Soil solarization has also shown to eliminate up to 75% of inoculum for closely related "Rosellinia" spp., but has not been evaluated with "R. bunodes".