There may be blackish or purple lesions at the base of the plant. Although not extremely common, the use of PCR to detect this disease is also another diagnostic tool. Specifically, PCR was studied for the detection of "Phytophthora fragariae" var. "rubi". It was found the use of PCR with conventional "Phytophthora" primers yields more favorable results, is less time consuming, and is more convenient than PCR using specific var. "rubi" primers. Also, using PCR with primers DC1 and DC5 in the second round was also found to yield favorable results to detect "Phytophthora fragariae" var. "rubi". "P. fragariae" survives in the soil in the form of oospores. These oospores can survive for up to 4 years; there are some reports of spores remaining viable 13 – 15 years. The oospores germinate to form usually one sporangia. Sporangia germinate in the presence of water to release motile zoospores. The presence of water is important because the zoospores have no way to reach a host without swimming. The zoospores swim through the water in the soil to find roots where they encyst and form germination tubes to infect the plant. This usually occurs in the late autumn or early spring. Growth of the disease occurs mostly in the stem and root. Hyphae protrude out of the root and produce new, secondary sporangia. The secondary sporangia are usually produced in winter months and the process takes a few days. The sporangia are produced more quickly in cold temperatures. The new sporangia move through water in the soil to infect new plants. The infection can be spread from field to field by unsanitized tools or equipment, floodwater, or any other activity that will move infected soil. Also, the replanting of infected nursery stock will spread the infection of "P. fragariae." There are three main components of the environment that affect the effectiveness, speed, and ability of "P. fragariae" to infect: soil moisture, temperature, and pH. "P. fragariae" occurs frequently in wet, cool soils. Soil moisture has been proven to carry the greatest importance. Soils that receive lots of steady water from rain or melting snow, as well as soils with poor water drainage that become waterlogged, produce the ideal conditions. In fact, there is a direct correlation between the soil moisture and the percentage of roots that were infected with "P. fragariae".