|Miles, Carol - Washington State University|
Submitted to: Extension Fact Sheets
Publication Type: Experiment Station
Publication Acceptance Date: 1/11/2016
Publication Date: 3/25/2016
Citation: Dugan, F.M., Miles, C.A. 2016. White mold of Jerusalem artichoke. Extension Fact Sheets. Publication number FS208E, pages 1-5.
Interpretive Summary: Jerusalem artichoke (sunchoke) is a Native American food plant closely related to the common sunflower. The edible tubers contain inulin, which converts with cooking to fructose, a sweetener preferable to sucrose for diabetics. The tubers of Jerusalem artichoke are gaining popularity as an alternative to other carbohydrate foods, and so are increasing in availability in retail grocery outlets. White mold (caused by the fungus Sclerotinia sclerotiorum) is a major, destructive disease of sunchoke. Diagnosis is made by symptoms (wilting of the sunchokes) and signs (white cottony masses at the base of plants and on roots, black bb-sized sclerotia on plants and in soil). Rotation for a minimum of three years into a grass family crop (such as maize) is recommended. Some commercial formulations for control of white rot contain a biological control agent, but weeding, removal of "volunteer" sunchokes and canopy reduction are helpful.
Technical Abstract: Jerusalem artichoke (Helianthus tuberosus) is a Native American food plant closely related to the common sunflower (Helianthus annuus). Tubers of Jerusalem artichoke are increasingly available in retail grocery outlets. White mold (Sclerotinia stem rot), caused by the fungus, Sclerotinia sclerotiorum, is a major disease of Jerusalem artichoke. Initial symptoms consist of wilting of tops with eventual formation of a "shepherd's crook" at the top as leaves darken and become desiccated. Signs of Sclerotinia sclerotiorum consist of dense white mycelium at the base of plants and on roots, often accompanied by formation of sclerotia. Sclerotia are dark brown to black with a white interior, and along with mycelium may occur on tubers in the soil or in storage. Wilting of tops, plus white, dense mycelium and sclerotia that have a dark rind with a pale, whitish medulla are, in combination, diagnostic for white mold. Once established, it is very hard to manage white mold because of the extensive host range and because sclerotia can survive for years in the soil. Jerusalem artichoke has limited varietal resistance. Crop rotation is essential. Rotate fields for a minimum of three years into a resistant crop, primarily maize or other plants in the grass family. The fungal biological control agent Coniothyrium minitans has been shown to provide control against white rot on Jerusalem artichoke. Biological control tends to work best in conjunction with other strategies, such as canopy reduction, weed control and removal of 'volunteer' Jerusalem artichokes.