With weather conditions presenting challenges for oilseed rape, experts are providing advice for growers on bestpractice methods and tips to ensure effective establishment this autumn.
Achieving the ideal conditions for efficient establishment and minimising the adverse effects of cabbage stem flea beetle (CSFB) must be based on several key factors, said Philip Wright of Wright Resolutions.
“The process starts with the combine at harvest; growers must manage residues present so they are evenly spread across the field, as opposed to being concentrated in heaps or trails.
“Chaff spread, and straw spread if relevant, should be even,” Mr Wright said.
And with many residues likely to have been removed due to the current commercial value of straw, Mr Wright highlighted minimising soil damage by harvest traffic including harvesting and bale handling kit would be vital.
Growers should prioritise keeping to known traffic lanes and reducing ground pressures to safe minimum limits, he added.
Research has indicated there is an increased damage to the crop if the CSFB migration was at or before emergence.
Mr Wright said: “Stubbles should be kept long and retain a light soil surface colour as this will help deter CSFB from laying their eggs.” Cultivations to establish the crop should be ‘minimised’ and for precise seed placement leading to efficient germination, seed is best drilled, rather than broadcast.
“Soil moisture loss can be critical, so minimising soil disturbance is vital.
“Uninhibited root growth and efficient water passage means any compaction layers must be removed.” The key to managing this compaction demands a ‘low disturbance loosening’ action to help minimise creation of a loose structure, but Mr Wright warned extreme weather over the past two seasons had compromised this.
“A low surface disturbance sward lifting effect will break any compaction present and can also allow for good root growth.
"Soil moisture loss can be critical, so minimising soil disturbance is vital."
“But the weather patterns we have seen have led to a denser soil structure below weathered surface crumb in many cases, which can present a barrier to roots and germination if the levels of soil disturbance are high,” he said.
The sward lifting effect is therefore ‘ideal’ for growers when establishing OSR.
“It retains surface soil crumb, minimises excessive disruption and reduces moisture loss,” Mr Wright said.
Mr Wright added post drilling consolidation (which could include pressing and surface rolling) is often necessary to allow for ‘good seed-to-soil contact’ and it helps to retain soil moisture which, in turn, would also be beneficial for priming the field for effective pre-em herbicide applications.
Speaking to the importance of pre-em applications in the establishment process, BASF business development manager Clare Tucker explained the advent of CSFB had ‘understandably’ led to questioning the risk of front-loading costs by using a pre-emergence herbicide.
But she said where establishment conditions looked promising, there were still reasons to consider a pre-em in the programme.
“Pre-ems are vital for preventing broad-leaved weeds growing quick, especially in the early drilled crops.
Belkar, for example, cannot be used before September 1; weeds need to be small and it is contact-acting only.
“The pre-em provides valuable residual activity of a wide spectrum of weeds and gets the weed control out of the way early before the workload demands of cereal drilling,” she said.
Pre-ems also have a valuable role to play in grass-weed control, Ms Tucker added.
“Applications are able to remove 60-70% of black-grass and provides a different low risk mode of action to clethodim for resistance management.” Despite worries over pre-ems slowing the crop down, Ms Tucker highlighted this only happens if seedbeds and seed cover are poor, or if there is heavy rainfall within 48 hours of the herbicide application, both of which can be guarded against.
For growers to get ahead with their cultivations, Mr Wright said the following components would be key to achieving an effective sward lifting process:
And with the bonus of Clearfield OSR technology accessible to growers, Ms Tucker said Clearfield varieties could be used where a range of weeds are expected, including problematic weeds, such as charlock and hedge mustard, which have been difficult to control with conventional chemistry.
“BASF has two herbicide options available for growers this autumn, including Clevaro (imazamox + quinmerac) and Cleranda (imazamox + metazachlor),” she said.
“Both control the widest range of broad-leaved weeds compared to any other herbicide and also remove volunteer oilseed rape to achieve the desired target population.
The trend for earlier sowing means there is a risk of over thick canopies, resulting in thin-stemmed plants which are less resilient to CSFB larvae.
Mr Wright added: “The upshot of achieving the techniques discussed will provide the ideal conditions for efficient OSR establishment and fast early growth.”
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