Clearfield®: an opportunity to surpass risks in OSR?
16 Aug 2019
Clare Tucker, BASF Business Development Manager, acknowledges that winter oilseed rape agronomy has certainly got its challenges. The Clearfield® system can’t promise to be a cure-all but it can help with some of the key things which make life easier to manage the crop and improve the chances of a successful harvest. It’s still a good crop to include in the rotation both for agronomic reasons and financially, as prices are currently buoyant. Clare outlines the benefits of the system in this blog.
Getting the crop off to a good start
Everyone agrees that the most important factor is to drill when seedbed conditions are right, for fast and even emergence of the crop, followed by strong early leaf development to help combat csfb adults. Unlike the desert conditions of last autumn there will be much more moisture available this year for good conditions for quick germination which is key for the battle against csfb. Clearfield® hybrids are known to grow away quickly, unaffected by SU soil residues, and some varieties have strong autumn vigour.
Keeping Erucic Acid in check
The legal limit for erucic acid in vegetable oil will be reduced to 2% for harvest 2020, making it more difficult to ‘blend’ the problem away. A routine NIAB-TAG test of 900 farm samples in 2018 found 13% had levels of >2% and 9% of 1-2% so the risk of rejection or penalties is not insignificant. The main source is volunteer OSR which can only be removed by a Clearfield® herbicide. High risk fields for erucic acid are those with historic tight WOSR rotations or where farm saved seed or HEAR OSR has been grown in the past. Fields with high brassica weed populations also pose a risk.
Straightforward weed control
A wish list might be a wide weed spectrum, flexible post-emergence timing, convenient to fit around the clethodim spray, and help with black-grass control.
How does the Clearfield system deliver?
- Wide weed spectrum? Yes, it controls the common broad-leaved weeds + brassica weeds + volunteer cereals + volunteer rape. There is also observed field activity against ryegrass, bromes, wild oats.
- Flexible post-em timing? Safe, flexible crop timing (cotyledon to 8 true leaves) and flexible weed timing of 1-4 leaves on broad-leaved weeds and 2-3 leaves of grasses.
- Convenient to fit around the clethodim spray? Fitting in 2 post-em sprays can be tricky but flexible crop timing helps.
- Help with blackgrass control? Clearfield® herbicides will not give adequate control of blackgrass; use your standard programme against this.
Clearfield® herbicide recommendation
Good foliar uptake is important. Always include Dash® HC which aids spread and uptake. Achieve adequate cover with 100 litres water/ha and a medium spray. Allow a minimum of 2 hours to become rain-fast.
The following weeds can grow away quickly, so we recommend a maximum weed size for application:
- Crane’s-bill spp: 2 leaves
- Runch: 3 leaves
- Mayweed spp: 4 leaves
- Poppy 4 leaves
It’s not always easy to get all the weeds at the right growth stage, so where there are high populations of mayweed, poppy and cranesbill expected, then you could use metazachlor pre-emergence followed Cleravo®. Alternatively, you could follow either Cleranda® or Cleravo® with the Astrokerb black-grass treatment.
For more detailed information on the Clearfield® system, click here.
Cleranda® contains imazamox and metazachlor; Cleravo® contains imazamox and quinmerac. Cleranda® and Cleravo® are registered trademarks of BASF. All other products are those of other manufacturers where proprietary rights may exist.