CCC Blackleg and canola rotation

[wd9]

Clint, I've been growing canola from the same company for 15 years on a 4 year rotation and never had a blackleg issue. I've recently gone to a two year rotation. Should I consider going to a different company?

[wd9]

Article in Alberta express last week suggesting rotating varieties and herb tolerant system. But not that it matters, i'm sure you've stopped reading this post.

[JurkeCCC]

Sorry about the late response. For some
reason I was not receiving notification
that this thread was still going.

But thank you wd9 for your comments. You
have made some good points that there is
confusion in the industry on this
subject. Ward is right, we will have our
work cut out for us this winter in
correcting the perceptions out there.

So your question about switching
companies is a common one. But before I
answer it directly, I want to make sure
that you are aware that this is a high
risk decision by going to a tight
rotation. If not done right, you will at
least put that field at risk, but at
worst put the neighbouring fields and
industry at risk if this activity ends
up selecting a new more virulent race of
blackleg. Scouting become extremely
important with this decision. And you
should be prepared to use a fungicide if
disease is evident in early season. And
controlling canola volunteers is
critical too as they will have the same
resistance gene as the previous canola
crop and will harbour the disease.

So to answer your question, if I were
you I would ask your seed co as to which
variety they would recommend - which
variety has a different source of
resistance from the one you had grown
last. That is, if you want to stay with
that company. I do not think there is
any need to switch companies if they can
provide genetics with different sources
of resistance. Again, the most important
thing is not to use the same variety.

Hope this answers your questions
adequately. I will watch this thread a
little more closely.

Clint

[wd9]

Would love to ask, but nobody knows the answer to which variety carries which resistance.

[JurkeCCC]

Well, it's true that it is not public
information as to which varieties have
which resistance gene. And it would be
good to get that information - and work
is being done on it now. But in absence
of that information you can ask if a
variety has a different source of
resistance - which they might know. But
odds are still better that you will get
a different resistance gene by using a
seed co's variety recommendation than it
will be by using the same variety you
had on your field last. Doesn't hurt to
start the conversation.

Clint

[wd9]

It may not be an issue as our almost continuous use of canola will quickly swallow up these limited resistances available for blackleg.

Should the CCC be more vocal or more steadfast, not sure the wording, in the minimum 3 year or more rotation rather than provide guidelines or almost quietly agree with a short rotation?

[JurkeCCC]

Good points.

The first one about resistance failing.
There is always a risk that a super race
of L. maculans may be selected that none
of our resistance genes work against.
But in reality, judging from the
experience in Australia (where blackleg
is much more severe), there are huge
swings in the L. maculans populations
from one race to another in a field
simply depending on which variety is
grown. There is data now showing that
resistance that did not work in one year
suddenly works great again five or six
years later. So the solution of rotating
resistance genes seems to give very good
control. The theory and the practice
seem to match up well under the very
harsh blackleg conditions of Australia.
There is no reason to think that it
would be any different in Canada.

Your second point about whether the CCC
should be providing tools for tight
rotations is kinda of a philosphical
point. But I think the CCC is taking the
right approach - our first
recommendation for blackleg control is
still to use a long rotation. The
message about rotating varieties is a
new one, so it likely is getting a lot
more air-play right now than the long
rotation messaging, I guess. But the
rotating varieties message is not our
first recommendation. Economics arguably
has the strongest influence on grower
planting decisions, (which the CCC has
no control over), so growers need to
have the information available if they
find themselves faced with dealing with
tightened rotations. But your point
about us being more vocal on the long
rotation piece is a fair one to make.

Thanks for the discussion, wd9.

Clint

[wd9]

Thank you Clint for taking the time to post this stuff. I appreciate it.