Disease: White MoldPathogen: Sclerotinia sclerotiorumHost: Many crop and ornamental species
Tomato stem rot caused by Sclerotinia sclerotiorum. Note large black sclerotia (survival structures) inside infected stem. White mold is an important disease of many plants caused by the fungus, Sclerotinia sclerotiorum. In 1999, this disease alone caused more than $100 million in losses on sunflower in Nebraska, North Dakota and Minnesota. It is easily diagnosed by the abundant white mycelium and large black sclerotia (survival structures). The disease can be minimized by spacing plants for good air movement and rapid leaf drying after rain or irrigation. If white mold occurs, remove infected plant material to reduce spread and infections in the next season.