Discovery Seed Labs offers growers the ability to purchase a test kit for testing the infestation of canola petals with Sclerotinia.  Sclerotinia stem rot is a disease familiar to many canola growers. Sclerotinia spores produced in a flowering canola crop, or blown in from nearby fields, land on petals of open flowers. When the petals fall off and lodge on leaves and in leaf axis and branched, the fungus grows from them into the leaf bases and stems. The amount of disease that develops in a field is determined by both the number of spore-carrying petals and by weather conditions. Rainfall, humidity, and temperature all affect how many plants actually become diseased. Disease risk prediction, however, can be based on the numbers of pores present during flowering.

The percentage of petals infested indicates the risk of disease development later in the season. The risk factor can be used to decide whether or not a fungicide should be applied. However, changes in weather conditions during the rest of the growing season will affect the final amount of disease.

Check your canola fields periodically in order to anticipate when to sample. The petals should be sampled from the canola plants at early bloom. There are three different ways to decide when the crop is at early bloom and ready to be sampled. The crop is 4 – 6 days after first flowering, the crop is at 20% bloom stage, there are about 15 flowers open on the main stem.

The ideal time to collect is between noon and 5 pm. When possible do not collect before 8 am, or while it is raining, or at least 2 hours after a light rain and 4 hours after a heavy rain. Collect samples at 8 sites per field. These sites should be at least 50 paces apart. Collect 16 petals per site placing two petals in each of the eight tubes.

With the forceps gently pull off the petals, use the disinfectant wipes to clean the forceps in between petals. Try not to tear the petals or take other flower parts along with them.  As you pick them off place two petals in each tube. Continue in this manner until all eight tubes in one strip are filled with two petals each. Continue onto your second site in the field and repeat the petal collecting process. Continue to do this throughout your field until all eight sites have been completed.