Sclerotinia Risk in Canola
This forecasting program has been developed by the North Dakota State University Canola Pathology program with support from the
Sclerotinia Initiative, the Northern Canola Growers Association, and the Minnesota Canola Council. While the information presented
by this program is based on data generated through extensive research, it is only intended to serve as a guide for growers.
This forecasting program has two components, a general risk map and a risk calculator. The general risk map uses weather information
to estimate risk of disease development throughout the canola growing areas of the state. This map is updated twice every week
starting in mid June and continuing during the canola flowering period. The risk calculator combines information on cultural
practices and the field past history of Sclerotinia with weather information retrieved from the nearest NDAWN weather station to
estimate the risk of disease development for a specific field. To access the risk calculator visitors are asked to set an account
and to provide information pertinent to the field of their interest.
News and Tips for You
June 10, 2016
Blackleg present in Cavalier County fields
Weather conditions in the previous three weeks were favorable for blackleg infection and now symptoms are visible on cotyledon leaves as well as on the first true
leaves of canola seedlings (Figure 1).
For additional pictures of blackleg check our gallery. Lesions that develop before the plants reach the 4th leaf stage usually cause significant yield reductions.
Thus growers are encouraged to scout their fields for blackleg symptoms. Incidences greater than 20% may warrant a fungicide application.
For a list of fungicides registered in North Dakota for use in canola against blackleg please see NDSU extension publication
2016 Fungicide Guide (Canola-Rapeseed).
June 1, 2016
Early detection is critical to avoid losses due to blackleg
Blackleg infections that take place when canola plants have less than four leaves are more likely to result in yield losses than those happening when plants are older.
Growers should scout their fields for symptoms of early infection on cotyledon leaves starting two weeks after planting.
These lesions may be irregular in shape and have a light brown color. Numerous pycnidia which look like tiny grain of black pepper may be produced in the dead tissues
especially if humid conditions prevail for several days. The fungus will move from the cotyledon leaves into the stem but will do so without showing further symptoms of infection.
In this way, infected plants that have already dropped their cotyledon leaves may look healthy.
As the plants continues developing, symptoms on true leaves may also appear. Usually these lesions are not produced by the same
fungus that caused the cotyledon lesions but by spores that arrived at later time. Nevertheless, their presence in plants with less than four true leaves is an indication
that blackleg may be a problem that requires fungicide applications. A list of fungicides registered for use in canola against blackleg can be found in NDSU extension
publication 2016 Fungicide Guide (Canola-Rapeseed).