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.
Phytophthora kernoviae
"Phytophthora kernoviae" spreads most quickly and detrimentally in moist conditions such as direct rainfall and also those of heavy humidity. Rain and heavy winds help in the dispersal of spores for further infection. This disease has an optimal growing range of . This range suggests that it may have originated in a temperate climate, possibly China, before being introduce to the UK. In some genus of the disease such as "P. ramorum" water transportation through the use of streams and rivers is seen from outbreak sites. This is a unique characteristic of the "P. ramorum" and has not been seen in the "kernoviae" species While there are no known insect vectors for the disease humans can transport spores via agricultural equipment, on shoe bottoms and direct plant movement. These are the most significant vectors for the disease.