The mycelia should be grown in a liquid medium e.g clarified 10% V8 Campbell's V-8 juice and incubated at 25 C for most Phytophthora species. After a week, the mycelia can be harvested either by filtration or centrifugation.
use vacuum filtration as you see at: https://chem.libretexts.org/Ancillary_Materials/Demos%2C_Techniques%2C_and_Experiments/General_Lab_Techniques/Vacuum_Filtration
The mycelia should be grown in a liquid medium e.g clarified 10% V8 Campbell's V-8 juice and incubated at 25 C for most Phytophthora species. After a week, the mycelia can be harvested either by filtration or centrifugation.