Watch for fruiting bodies of the Sclerotinia or white mold fungus. Called apothecia, they are extremely small mushroom-like bodies that resemble tiny golf tees about 1/8 inch in diameter. Apothecia liberate millions of spores that are blown about by the wind. These spores initiate infections on the dead flower parts of dry beans, canola and other susceptible broad leaved crops if the canopy stays wet for most of a 40-48 hour period.

Apothecia begin to form after 10 days of saturated soil. Apothecia may begin to form in portions of north central and northeastern North Dakota and northwestern Minnesota by the middle of next week. Based on the Sclerotinia Risk Map for Canola, apothecia might begin to form by the end of this week in portions of northwestern North Dakota.

Apothecia develop from sclerotia, the hard black bodies of Sclerotinia that resemble rat droppings. The photos in this article illustrate apothecia attached to sclerotia that have been dug out of the soil (courtesy of Ieuan Evans, Alberta Agriculture Food and Rural Development), apothecia as they appear on the soil surface (courtesy of the Canola Council of Canada) and apothecia that have formed in the laboratory (courtesy of the NDSU Department of Plant Pathology).

The Sclerotinia Risk Map for Canola: Need for Reports of Apothecia. We need reports of sightings of apothecia for the Risk Map. They provide ground truth for the model. County and area extension personnel, crop consultants and others working on canola are encouraged to report this information to me at the email address shown below. These reports are essential to what is called ground truth for the Risk Map model.