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
July 8 2012
Sclerotinia stem rot
The risk of infection by Sclerotinia is increasing in the region in response to more favorable weather conditions. Growers are encouraged to look for apothecia in their fields. Fungicide applications are suggested when the risk of infection is high in a field where apothecia are present and the plants have not passed the 50% flowering stage. Illustrations of flowering stages can be found in NDSU extension publication PP-1410.
In general, plants are at 20% bloom when they have approximately 15 open flowers on main stem. This stage is reached usually within six days from the time the first flower opens and is heavily influenced by temperature. Warmer temperatures usually speed up the flowering process. Plants at 30% bloom have 20 or more open flowers on the main stem, have little to no petals dropped, and do not have pods forming. This stage could be reached two or three days after reaching the 20% bloom stage. Plants that have reached the 50% bloom stage usually have at least 20 flowers open on the main stem and their lateral branches have started to flower too. At this stage the fields reached their maximum color intensity. At 50% bloom pods are evident. Fungicide applications after plants have reached the 50% bloom stage usually do not provide an economic return.
Fungicides registered for control of Sclerotinia stem rot in North Dakota are: azoxystrobin (Quadris), boscalid (Endura), metconazole (Quash), prothioconazole (Proline), pyraclostrobin (Headline), and thiophanate methyl (Topsin). Also, the biological control compounds Serenade, and Polyversum are registered for use against Sclerotinia in foliar applications. For application rates consult your extension agent.
May 17, 2012
Flea beetles could enhance damage by blackleg
According to NDSU Crop and Pest Report of May 17, 2012 flea beetle populations are increasing in canola fields near Langdon. The wounds created by these insects on canola seedlings could increase the probability of infection by blackleg. The action threshold for control of flea beetles is 25% defoliation. Information on insecticides registered in North Dakota for control of flea beetles in canola can be found in the ND Field Crop Insect Management Guide 2012.
May 15 2012
Blackleg is making a comeback
Blackleg is becoming more prevalent in canola fields throughout North Dakota. The reason for this is that new strains capable of infecting commercial cultivars previously considered to be resistant are developing.
Blackleg spores spread from canola residues by air currents, thus this year growers should avoid planting canola next to fields that had severe blackleg in the 2011 growing season.If that is not possible, then fungicide use should be considered. Fungicides azoxystrobin (Quadris), prothioconazole (Proline), and pyraclostrobin (Headline), are registered in North Dakota for control of blackleg in canola. These products should be applied when canola plants have no more than four leaves. Older plants are in general less prone to develop the stem cankers that are responsible for yield loss, and thus the economic return of a fungicide application may be reduced.