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 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.