Sclerotinia virus

Sclerotinia virus (Deltaflexivirus sclerotiniae) is a type of mycovirus that specifically infects the fungus Sclerotinia sclerotiorum. As a viral agent, it serves as an intracellular parasite that compromises the physiological health of the fungus, which is well-known globally as the primary cause of white mold disease in various crops.

The host range of the virus includes different isolates of Sclerotinia sclerotiorum, a fungus that attacks a wide variety of economically significant crops such as sunflowers, canola, soybeans, and numerous vegetables. By infecting this fungus, the virus can modulate its development and overall disease severity.

The main symptom observed in infected fungal colonies is hypovirulence. This manifests as a significant reduction in mycelial growth rate, limited colonization of plant tissues, and a disrupted life cycle, specifically in the formation of sclerotia—the hard, black resting structures that allow the fungus to survive in the soil for years.

The spread of the virus occurs primarily through hyphal anastomosis, where the virus is transmitted between fungal hyphae that come into contact with one another. This natural mechanism facilitates the movement of the virus through the fungal population within the soil or contaminated plant debris, potentially mitigating the impact of the disease on neighboring plants.

While the virus possesses biological control potential, current agronomic practices focus on standard management strategies. These include crop rotation, the use of certified, clean seeds, tillage practices that bury sclerotia at depths where they cannot produce fruiting bodies, and the application of chemical fungicides to prevent initial infection by the fungus.