The 2012 Sclerotinia Risk Map for canola will be available this week, says Sam Markell, North Dakota State University extension planth pathologist.
The risk map for Sclerotinia, or white mold, is generated by analyzing humidity, air temperature and soil moisture. One to two weeks before canola and other susceptible crops bloom there must be enough soil moisture for apothecia (the little mushrooms that release ascospores to form. Usually, 1-2 inches of rain is enough. During bloom, humid conditions in the canopy must exist and temperatures must be cool or moderate. Temperatures exceeding 85 degrees in the day suppresses the pathogen.
In moderate and high risk areas you should be ready to apply fungicide to prevent the blossoms from getting infected.
"The risk map is one of the best decision making tools we have to manage white mold," Markell says.
You will also need to take the field's history of white mold problems, length of the crop rotation and other factors into account. Also, rainfall can be pretty sporadic in the region. Your fields may be wetter or drier than the nearest North Dakota ag weather station where the data is gathered.
"Your risk may be higher/lower than the model may indicate.," Markell says.
Luis del Rio, NDSU plant pathologist, maintains the risk map with funding from the Northern Canola Growers Association, Minnesota Canola Council and the National Sclerotinia Initiative.
See the map at http://www.ag.ndsu.edu/sclerotinia/ or http://www.northerncanola.com/maps/index.asp