Griesbach et al (2012) provides a good discussion of using a systems approach. However, this manual is generally directed toward larger commercial nurseries and includes standards that will minimize but not eliminate Phytophthora in the nursery. Kenneth Baker’s classic publication “The U.C. System for Producing Healthy Container-Grown Plants” (https://archive.org/details/ucsystemforprodu23bake) is still an excellent reference for a wide variety of clean propagation practices. The discussions about the use of chemicals are out of date, but the discussion of cultural practices and sanitation are timeless.
Baker, K.F. Editor. 1957. The U.C. System for Producing Healthy Container Grown Plants, Manual 23. University of California, Division of Agricultural Sciences, Agricultural Experiment Station Extension Service.
Griesbach, J.A.; Parke, J.L.; Chastagner, G.A.; Grünwald, N.J.; Aguirre, J. 2012. Safe procurement and production manual: a systems approach for the production of healthy nursery stock. Wilsonville, OR: Oregon Association of Nurseries. 98 p.
Parke, J.L.; Grünwald, N.J. 2012. A systems approach for management of pests and pathogens of nursery crops. Plant Disease 96:1236-1244.