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Keep stacking residuals, in spite of the dry autumn
Date added: 05/10/09 |
In spite of the dry conditions, growers must keep faith in robust pre/peri-emergence residual-acting herbicide treatments, whilst continuing to use as many different actives as possible in winter cereals, says ProCam Group Technical Director, Dr. David Ellerton.
“The debate on dry conditions has now overtaken the debate on grass-weed dormancy, but the fundamental principles of weed control remain,” he says.
“Growers must remove weed competition as early as possible, without putting undue pressure on any one herbicide group when it comes to resistance. My advice is to start your programme in both winter wheat and winter barley by stacking as many residuals as possible as early as you can.”
In winter barley, a crop which Dr. Ellerton thinks has been overlooked by some herbicide manufacturers, many growers have been using IPU as their standard post-em treatment.
“With IPU and trifluralin gone, we have a few pre-em options, including Crystal, Liberator and Defy but very few post-emergence options, with the exception of chlortoluron (such as Dicurane or Lentipur). If you had difficulties applying a pre-em and you are growing a chlortoluron-susceptible winter barley variety, you’re snookered!
“In winter wheat, you always have Atlantis, Horus or Othello, but with the number of black-grass resistance cases doubling since last year, it is vital that these herbicides are protected and used only when other options have been exhausted.”
The 250 plus confirmed cases of black-grass resistance are probably a vast under estimate, Dr. Ellerton believes and Atlantis should only be used where absolutely necessary and always following a robust pre or peri-emergence treatment.
He points out that Guillotine (flumioxazin) offers an alternative post-em option for situations with Annual Meadow-grass and broad-leaved weeds or in low black-grass populations and its new lower price makes it more of a viable option to integrate into a weed control programme in wheat.
“New for this autumn, Broadway Star (pyroxulam + florasulam) is also useful for non-black-grass situations and has given better than claimed control of wild-oats, rye-grass and brome. However, it too needs to be used as part of a programme.”
In ProCam trials and manufacturers trials, using a range of residuals in mix or in sequence has produced the best start to the weed control programme, Dr. Ellerton says.
“In wheat a treatment of Defy applied pre-em followed by Crystal and chlorotoluron post-em gave black-grass control close to 100%. Such a programme applies four different actives – prosulfocarb, flufenacet, pendimethalin and chlortoluron - and that can only be positive when it comes to reducing resistance risk.
“It appears that the more residual applied, the better the control particularly in serious grass-weed situations. Certainly the strategy of stacking residuals appears to be a sound approach.
“Although we haven’t had to contend with dry soils for the past few years, growers should try to create as best a seedbed as they can, drill and then apply a good early herbicide treatment. Manufacturers are saying that pre-em herbicides won’t break down in the dry and growers should wait until moisture arrives for activity to kick in,” he adds.
Ends
PRM220
5th October 2009
For further information please contact Dr. David Ellerton, ProCam Ltd., Royston, Herts. Telephone: 01763 261592
Issued by Philip Hainey, Proterra Ltd., Stamford, Lincs. Telephone: 01780 756299 |
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