Oilseed Rape Choices Autumn 2012
It has been a long winter –
or so it seems, but today at last, the first days of Spring have arrived! Woopee!
That said we need to start
planning for the 2012 / 2013 campaign if only in getting together first ideas
on varieties. I had the opportunity of attending one of the HGCA Oilseed
Agronomy Workshops back in January and also had a long conversation with the
soil-borne disease guru of oilseed rape – ADAS Peter Gladders yesterday
specifically about verticilium wilt and thought I would share some real
‘nuggets’ of information with you.
Club Root
I’m sure you are all aware
that once you have clubroot then your days growing oilseed rape have pretty
much ended unless you grow resistant varieties.
Historically clubroot has
been pretty much a Scottish issue, but more recently as a steady increase in
the implementation of short rape rotations and the commodity value meaning more
rape is being grown on poorer quality land (light and marginal land) then the
disease has increasingly appeared in England too. Most recently clubroot has
been found in the Midlands and now in North Norfolk. Equally the intense
pressure we are now seeing as a result of close rotational cropping (rape one
year in two or three relative to soil type and minimal tillage) has meant that
resistant varieties are being exposed to a rapidly evolving disease pathogen
which through mutation will ultimately overcome the ‘single-gene resistance’ of even the
most recently introduced variety Cracker.
That said in the presence of
clubroot and the wish to grow oilseed rape, Cracker remains your best
option until its ‘multi-gene resistant relative reaches the market – and it’s
not far away!. Perhaps more importantly in the interim other breeders will be
highlighting the introduction of their latest ‘break-through’ in clubroot
resistance, proclaiming – no doubt that they are superior to anything else on
the market (I can be as cynical as the next man!). The likelihood however, will be
that they carry exactly the same resistance gene as Cracker and so will
be equally susceptible to any mutation of the current clubroot pathogen.
It remains critical to the
longevity of Cracker within the market (and indeed any other variety carrying a single-gene resistance to any disease) that this variety is ONLY grown
where the disease (in this instance clubroot) is already in existence. In Scotland 2011, Cracker
out-yielded even conventional varieties and as such many farmers may have
bought it and drilled it without clubroot being present (that is only conjecture on
my part, but seems likely to me). They won’t be doing Cracker's resistance to clubroot any
favours.
Anyone who has identified
clubroot on their farm and has not as yet tried Cracker, please do ring
me as I have stocks available for this autumn. With a light leaf spot score of
‘9’ It sits fully recommended on the HGCA RL for 2012/13 and is unsurpassed in
its field.
Verticilium Wilt
As part of a continued
assessment of Verticilium wilt (VW) in the UK and its current impact on oilseed
rape yields, Peter Gladders ADAS has a trial site containing 34 varieties
(relative to which breeders are funding the trial) at Hacconby in the
Lincolnshire fen - a site that is heavily infected and was the first indication
in the UK three years ago that VW could be devastating in oilseed rape. It is
Hutchinson managed and purely funded by breeders. Peter’s ‘ brief’ is to bring
awareness to the farming community to the potential severity of VW and to give
impartial judgement on the disease etc. If you get an opportunity to visit the
site I would recommend that you take it as unless you are on a 1 in 5 rape
rotation, are on good deep-rooting land such as fen soils, with yield potential
hitting 7 or 8 tonnes per hectare, there is the likelihood that VW will have an
impact in some way on your land.
Note despite the potential
damage VW could do to the national rape crop, funding is very poor and Peter
can only afford one trial site per year. He told me yesterday of the
reservations he has on the 2012 site -
1. Lincolnshire fen as a location is not going to stress the crop too much, the roots will be sitting in moisture and fields have the ability to yield up to 8t/ha so verticilium wilt is unlikely to cause any serious measurable degree of yield loss even if present.
2. The plots are under an intensive management regime by Hutchinsons so again, stressed plants are unlikely.
Peter Gladders is the first to admit that one trial a year is not enough to thoroughly monitor or research this disease as there are many unanswered questions and its possible that the Germans or French are further ahead in their research than we are – I hope to visit the German breeder responsible for Cracker, Thorin and the new-comer Avatar later this month so will ask the question.
1. Lincolnshire fen as a location is not going to stress the crop too much, the roots will be sitting in moisture and fields have the ability to yield up to 8t/ha so verticilium wilt is unlikely to cause any serious measurable degree of yield loss even if present.
2. The plots are under an intensive management regime by Hutchinsons so again, stressed plants are unlikely.
Peter Gladders is the first to admit that one trial a year is not enough to thoroughly monitor or research this disease as there are many unanswered questions and its possible that the Germans or French are further ahead in their research than we are – I hope to visit the German breeder responsible for Cracker, Thorin and the new-comer Avatar later this month so will ask the question.
Points mentioned in our conversation:
1. Excalibur is a major problem. It 'bulks up' the disease quicker than any other variety. As the most widely grown variety nationally, the likelihood that it is harbouring the pathogen to further infect neighbouring crops seems most likely, Castille isn’t much better, but is less grown these days.
2. The strain of verticilium wilt appears to be a hybrid, originating from a broad spectrum form to one specific to crucifers. That said while it is hosted predominantly by brassicas there is evidence to suggest that it may be harboured by mayweed and even possibly wheat!
3. Verticilium presence tends to be an expression of plant stress so where no stress exists the pathogen is unlikely to do much harm - hence the issues Peter has with the Hacconby site this year.
4. There is often other problems before VW finishes off the plant. Castille for example was severely affected by it last year, but on further examination the variety had been suffering with a major stem canker infection initially.
5. It's easy to find extremes of the disease in a stressful year, but many of the big hybrid and big canopy varieties can withstand its presence – PR46W21 in particular, DK Cabernet and Sesame.
Considering the above there is clearly a question mark over point 1. How come if Excalibur is a major carrier did it clearly perform so well on grower’s farms last year? I guess it’s a warning note that we would be foolish not to register. If you are on a short rotation, minimal cultivate or marginal rape-growing land, don’t over-do the Excalibur area, or place your Excalibur crop well away from your other rape. The other thought may be that Excalibur’s earliness to harvest means that it has produced its seed and oils before the WV can cause major damage. If the latter is the case then this is excellent news for AVATAR which is an ‘early to harvest’ variety too. But if that were the only varietal issue, then Cabernet and Sesame should be far worse than Excalibur for reduced yield effect in the presence of VW and this is not the case!
The other ‘nugget’ of
information to me is that there is some negative correlation to wheat.
In the short term the warning
is clear – avoid any highly
susceptible variety (Excalibur principally) in a short rotation situation in the presence of wheat
(wheat/rape/wheat or wheat, wheat, rape, wheat). If on a min-till situation
review your pre-cultivation techniques for more marginal soils, perhaps
reintroducing ploughing. View Peter Gladder's HGCA presentation
It would appear as with many
soil-borne diseases there are many factors that interact to impact on yield
loss and the mere presence of one or two of those factors does not necessarily
mean that even in the presence of the disease yield will be affected. That said
if by variety selection and careful field matching incidence of the disease can
be reduced without impacting on potential yield then that has to be the way
forward.
I have access to most rape varieties for sale this autumn and as with Thorin semi dwarf last year I have personal responsibility for a number of AVATAR trial crops situated around the UK. You can watch AVATAR develop yourself at www.watchitgrow.co.uk The breeder is having a few teething troubles up-loading the latest pictures but it will be sorted soon. Please feel free to contact me for a chat at your convenience. I hope to meet many current and new members in the course of the spring summer when we can review your particular situation. Any feedback you can offer from your own experiences or observations I would be delighted to receive.
I have access to most rape varieties for sale this autumn and as with Thorin semi dwarf last year I have personal responsibility for a number of AVATAR trial crops situated around the UK. You can watch AVATAR develop yourself at www.watchitgrow.co.uk The breeder is having a few teething troubles up-loading the latest pictures but it will be sorted soon. Please feel free to contact me for a chat at your convenience. I hope to meet many current and new members in the course of the spring summer when we can review your particular situation. Any feedback you can offer from your own experiences or observations I would be delighted to receive.
Contact me by email at info@farming4profit.co.uk
Stuart
Cree
