Update on Newly Identified Strain of Blackleg (PG3)

In areas where PG3 was identified, it is usually present at low frequency relative to the old strains. In 2003, Pioneer researchers did extensive testing of Pioneer canola products and experimental materials for reaction to PG3. Unfortunately we were unable to obtain enough data to assign quantitative ratings or to clearly categorize our products at this time.

However, based on the limited information that we have available, the following products appear to have a good level of resistance to both the “old” and “new” strains of blackleg—45H21, 46H23 and 46H02. The following products appear to have a slightly lower level of resistance to the “new” strain of blackleg—46A76 and 43A56.

The old strains of blackleg are still by far the most widespread and predominant ones in all areas of Western Canada. These strains are most likely to cause economic loss to growers and should be the first consideration in selecting canola varieties based on resistance to blackleg.

Based on WCC/RRC registration data, the chart below shows the blackleg ratings for all Pioneer® brand canola products offered for sale in 2004.

In 2003, there were over 850,000 acres of 45H21 seeded across Western Canada. These acres covered a myriad of different geographies, soil types and cropping conditions. It is very plausible that some of these acres would have been on fields that carried the new strain of blackleg. However, in 2003 Pioneer did not receive any reports indicating a lack of blackleg resistance with 45H21. This supports our preliminary research observations that 45H21 exhibits a high level of resistance to PG3.

In 2004, there will be industry-wide efforts aimed at defining a new system for classifying the resistance of canola products to all strains blackleg (old and new). All commercial varieties will also be classified under this new system. Pioneer Hi-Bred will work closely with industry organizations and public sector pathologists to ensure our products are accurately characterized for resistance to all strains of blackleg.

1. Choose a canola variety based upon what “complete package” is best for your operation. Consider all agronomic factors including yield potential, standability and disease resistance package.
2. The old strain of blackleg is still the most predominant one in Western Canada. It should be the first consideration when selecting a variety based on resistance to blackleg.
3. Crop rotation is a key component of keeping blackleg under control. Tightening up your rotation does not allow enough time for the disease to break down in the soil. A 4-year rotation is recommended between canola crops on the same acres.

For more information contact your local supplier of Pioneer canola seed or email Wilt Billing, Pioneer field sales agronomist, (204) 822-1291.