CCC Blackleg and canola rotation

[wd9]

Seems the canola council agronomists are recommending rotating from liberty to roundup or vice versa in order to reduce blackleg issues.

Problem is, they don't know which geno type is in the field, they don't know which type of resistance is in which variety, that resistance is not based on herbicide tolerance, and that rotating varieties within the same company may even be better than guessing who has what resistance.

Why would the council be stating this since it sure is not science based in any way?

[ado089]

The different herbicide systems come from very different germ plasm, therefore have different inherent characteristics. The trouble with switching withing RR varrieties is the fact that several different companies may source seed from the same breeder. i.e. Canterra, Brett Young and FP all source alot of varrieties from DL seeds. Though I agree that this is a over simplified recomendation from the CCC. It would be far more helpful if the seed industry would adopt the practice of publishing their resitance. TKW and nutrient response curves would for everything would be nice to see as well.

[wd9]

It is not that simple Ado, for blackleg there is an interaction between the pathotypes in the field and the genes in the variety of interest. So just knowing the source of resistance doesn't mean a lot. Biology isn't always usually simple.

Maintaining at minimum a 3 year rotation is the only guard against this. People grow back to back canola then try to push even harder and justifying in their heads that if i rotate liberty then roundup, i'll be ok. Not good agronomic info.

DL breeds seeds for other companies yes, but do not use those varieties for their own use. They may have their own varieties which may have different resistance then Brett's or Canterra etc or liberty for that matter.

It just is not known which varieties have which resistances, sources in individual fields and how they react, it is a crapshoot. That should be the message on short rotation canola.

[wd9]

Recommendations should be based on scientific data. Not just give an answer that seems or sounds plausible and easy for farmers to understand.

[ward.toma]

wd9

Did you hear the CCC agronomists make that recommendation or did you hear it second hand? You are right that rotating herbicide systems won't do anything for disease. However, CCC agronomists and others have discussed rotating herbicide systems as a method of controlling volunteers because volunteers can act as a disease bridge. Perhaps this was the context in which this point was raised?

Ward Toma
General Manager ACPC

[JurkeCCC]

I am an agronomist with the Canola
Council.

I am fairly certain that we emphasize
very strongly to canola growers to use
long rotations along with resistant
varieties to control blackleg. That is
our first message, always.

But we do know that growers are using
shorter rotations, and that puts them at
risk. Also, we do know that using the
same variety in a tight rotation is a
high risk for selecting races of L.
maculans (the blackleg fungus) which
will overcome the resistance in that
variety. So our message for growers in
this situation is to:
1. DO NOT use the same variety in a
tight rotation
2. increase blackleg scouting regime to
determine risk
3. use a fungicide if high levels of
blackleg are observed in the early
season

wd9, you are correct in that we do not
know what varieties have which
resistance genes and what races are
present in which fields. What we do know
is that using the same variety is a high
risk (and there is a lot of scientific
data that shows this), so using any
other variety is a better choice. The
good news is that most breeding
organisations claim to be using multiple
sources of resistance; so there is
diversity in germplasm within the
market, within herbicide systems, and
within breeding companies. So we are not
in the position to recommend which
varieties to switch to - yet. The
industry has agreed that one of our top
priorities is to get to work on
identifying resistance genes and to
develop methods to test for L. maculans
races. We are a few years away from
getting to this point, but the work has
begun.

But again, the best choice is to avoid
this high risk situation by employing a
longer rotation - and this is our key
message. But if growers do make the
choice to take on this higher risk, then
they need the right information as to
how to do it so they do not endanger
their farm or their neighbours (by
selecting for more virulent races). And
that message is simply to not use the
same variety in a tight rotation - we do
not make recommendations as to what to
varieties to rotate.

Hope this is clear. Thanks for getting a
good discussion rolling.

Clint Jurke

[wd9]

Ado's post demonstrated the usual answer and message. I understood the recommendation was to rotate between companies and not varieties.

[JurkeCCC]

wd9,
The CCC is quite clear about rotating
varieties in tight rotations. I am quite
certain we have not advocated rotating
between companies - there is no certain
benefit to doing this since seed co's
can use the same source of resistance in
their germplasm. Perhaps there is a
misunderstanding.

For more background on the subject, go
to:
http://www.canolawatch.org/2011/04/26/bl
ackleg-risk-rises-with-tight-rotations/

Clint

[wd9]

While i appreciate your clarity, i am not the one with the clarity issue.

This spring i spoke to a fellow farmer who was quite convinced that after a presentation he was to switch companies as a blackleg management strategy rather than varieties. It is also coming from consultants who received the same information. Bad info needs to be cut off.

I posted this message not to be told repeatedly on blackleg strategy (I totally get this) but rather to make an awareness that there is confusion in the market regarding strategies such as HT system or company or variety.

You have been quite clear in your posts about the strategy here in the anonymous agriville world, the perception and messages however in the real world seem inconsistent.

If information is put into the marketplace it should be clear as you have posted above from all members. While i usually am one, I'm not that much of a sh*t disturber without doing my homework first.

I am however a strong advocate of this industry, always have been, always will be and i will challenge any statements to ensure what is being said is true if i hear the contrary as in this post. In the process, usually piss off a bunch of people, but generally we end up with a better industry.

Is this clear?

[ward.toma]

Thanks for clearing that up wd9. So, just to
make sure I understand, you asked in your
first post why council would make an
recommendation that wasn't right. Ado's
response confirmed that the recommendation
you had heard was out there. CCC agronomist
Clint confirmed that council has not been
making that recommendation. However, the
incorrect information is still out there.

So, the CCC agronomists will have to be
clearer when talking to farmers and other
extension people about this in the upcoming
winter extension season.

Wd9, I hope you will be attending one of the
meetings the CCC agronomists will be at this
winter to ensure this happens.

Ward Toma
General Manager
ACPC

[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