The most common soil-borne pathogens that infect bedding plants are Fusarium, Phytophthora, Pythium, and Thielaviopsis. When it comes to scouting for them, greenhouse growers often desire an instant answer and would like to distinguish between root rot diseases immediately.
Growers scouting their crops may come upon damping off symptoms in a plug tray or finished plant material that is wilted despite being watered. This would indicate the possible presence of a pathogen, although Michigan State University (MSU) Extension experts suggest growers first remove the plant from its container and inspect the roots. Are they white and healthy?
One article on the MSU Extension website provides a listing of disease and disease type, characteristics of that disease, and photos of disease symptoms on a host and of reproductive structures. These root rot diseases have many very similar symptoms such as chlorosis, stunting, and wilting. Because of these similarities, it is recommended that growers send a sample of a plant with a suspected root rot pathogen to a diagnostics lab such as MSU Diagnostic Services for accurate identification. Plant diagnosticians will observe the sample under the microscope and often culture it on media to isolate and identify the pathogen. Growers will benefit from knowing which root rot they have in order to develop an effective disease management plan.