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Spraying Backward Rape Crops with Kerb Flo 500
Some judgement on risk may be
necessary for crops which have yet
to reach the three leaf stage.
Many crops are yet to grow much beyond the two to four leaf stage.
Crop selectivity for propyzamide is by depth protection of the roots. Applications to very small oilseed rape plants can cause problems such as stunted growth with leaves fused to the axil, or stem/yield depression. Once a crop has reached the three true leaf stage the roots are at sufficient depth to not take up a dose of propyzamide that could cause problems.
The “best” blackgrass approach, proven by extensive trials, is to apply Kerb* Flo 500 at the correct timing - usually November/December This means there is still time to spray providing it doesn’t get any wetter, preventing travel completely.
Kerb Flo 500 applications may be made to 31st January.
For additional control, Kerb Flo 500 can be tank mixed with a ‘fop/dim’. In high populations of “difficult” blackgrass, superior control can be achieved by adding a ‘fop/dim’ to Kerb Flo 500 (even when ‘fop/dim’ resistance is present) over a carbetamide/propyzamide treatment.
Thinking ahead to later this year, Kerb Flo 500 may be applied in frosty conditions but do avoid application onto frozen ground where subsequent rainfall could result in run-off into water–courses.
Due to slugs, pigeons and slow growth so far, some are thinking ahead as to spring cropping options just in case the rape does not pull through. Options after a November application of Kerb Flo 500 include March drilled beans and peas, and April drilled spring oilseed rape at farmers’ own risk.
‘Rake ‘n’ Roll’ – An integrated approach to blackgrass management
The benefits of achieving a stale seed bed prior to the establishment of cereals and oilseed rape are well-known, but not always easy to achieve when a fast turnaround between harvest and drilling, as with oilseed rape establishment, is required.
To highlight the importance of an integrated approach to grassweed management, Dow AgroSciences are supporting the trial of a new cultural technique, the ‘Rake ‘n’ Roll’ cultivator. The trailed implement manufactured by Tillso consists of spring tines which scratch the stubble surface, distributing straw trash and allowing any shed grassweed seed to some into contact with the soil. Tines go no deeper than 5mm so soil to seed contact is achieved without burying the seed. This is crucial as blackgrass seed needs UV light to germinate, and if seed is buried it is more likely to lie dormant. A studded rubber roller follows the tines, pushing the seed into the soil and promoting conditions favourable for germination. The emerged flush of weeds can then be sprayed off prior to drilling with a non-selective herbicide. This approach is ideal in situations where resistance is known or suspected and will optimise the performance of post-emergence herbicides.
Ian Corr, Dow AgroSciences’ Regional Business Manager based in Yorkshire visited the ‘Rake ‘n’ Roll’ site last week.

Ian said “What we have now is a flush of blackgrass uniformly germinating from the same depth, ideal to control with Kerb Flo 500, which will be sprayed when soil temperatures are less than 10oC and conditions allow travel. We hope to see the positive impact of this blackgrass control in the next crop and in the rotation.
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