The top zone soil moisture map indicates that the top 4 inches of soil over much of the western part of North Dakota is in the 100-200% capacity range.

The germination of Sclerotinia sclerotia requires about 10 days of moist soil to germinate. When they germinate, sclerotia produce the spore bearing structures called apothecia that release spores, which attack canola and cause stem rot. Spores are released by the apothecia at about the same time as canola comes into flower. It is unlikely that any Sclerotinia sclerotia have germinated yet in the forecast area. Based on previous years observations apothecia usually start to appear in the last week of June. Local weather, soil and crop conditions may result in a slightly more favorable condition for germination of the Sclerotinia sclerotia than is indicated in this report. The most likely areas to find apothecia are in fields that were planted to canola, sunflowers or dry beans in 2005 and are under a heavy cereal crop canopy in 2006.

In assessing the risk for individual fields in addition to the weather conditions the following points should be considered:

• Crop rotation. Other crops susceptible to Sclerotinia include sunflower, and pulse crops such as field bean, field pea, and lentil. Although crop rotation is important, environmental conditions are the main determining factor in the development of Sclerotinia in canola.
• Has Sclerotinia been a problem in the immediate area on canola or other crops in recent years? Sclerotinia sclerotia can remain viable in the soil for up to four years.
• Is there a high yield outlook for the field based on fertilizer application and heavy crop stand? The higher the target yield, the greater the chance of Sclerotinia occurrence.

The next Sclerotinia risk forecast, is scheduled for release Thursday, June 15th 2006. The Sclerotinia forecast maps and interpretations can be accessed at:

http://www.northerncanola.com/maps/index.asp