New approach to companion cropping underpins OSR agronomy

Publish on February 16, 2024
Reading time : < 1 min
A new and unique companion crop approach that helps protect oilseed rape crops from two significant insect pests whilst offering valuable SFI payments will be available for next season’s sowing campaign.

GreenPack Gold offers growers a mixture of suitable companion crop species together with a specially selected early flowering oilseed rape variety, offering a flexible tactic that suits a range of farm requirements.

Camille Florin, RAGT’s commercial development agronomist, says the companion crops have been chosen to protect small, vulnerable OSR plants from cabbage stem flea beetle attack in the autumn, while the early flowering OSR inclusion helps reduce pollen beetle damage to the main crop the following spring. 

Good companions

Camille says: “The companion crop mixtures include species such as fenugreek and buckwheat. Fenugreek emits a garlic-like odour that repels flea beetle, while buckwheat grows very quickly, rapidly camouflaging OSR seedlings. We also add quick-growing, frost-susceptible legumes to provide additional biomass.”

Companion crop with OSR
Companion crop with OSR

 

 

 

 

 

 

 

 

As well as offering protection against CSFB, particularly from emergence to the four-leaf stage when OSR crops are most vulnerable, companion crops provide additional benefits that help promote oilseed rape growth throughout the season, such as competing with weeds and conditioning soils. Legumes also take up nitrogen from the air, which then becomes available to the OSR crop as they decompose.

“RAGT has access to some very good companion crop varieties through our partner companies, so we can select ones that make the best matches for oilseed rape in terms of speed of establishment, growth habit and biomass,” says Camille.

“All are bred to be frost susceptible, so in most winters they will die naturally, reducing or eliminating spray costs.”

Beetle ‘trap’

The early flowering OSR inclusion, which is sown at around 10% of the main commercial variety seed rate, acts as a ‘trap crop’ for pollen beetles in the spring.

“It comes into bloom seven to 12 days earlier than the main commercial variety so attracts pollen beetle away from it, offering protection through the vulnerable green bud stage,” says Camille.

“If any of the sacrificial crop does survive, being a hybrid it won’t compromise yield.”

RAGT is also offering GreenPack Duo, which contains the same companion crops as GreenPack Gold but without the early-flowering oilseed rape. “Not all growers want the pollen beetle control element, so this will suit their needs perfectly,” says Camille.

The products are available in 2ha packs, with each element – companion crops and the early OSR variety in the gold option – bagged separately to maximise flexibility.

“Best results are obtained from sowing the companion crops ahead of the OSR so they offer protection from the start,” says Camille. “Both Greenpack products enable growers to do this, or they can be sown at the same time.”

SFI payment

It is well worth noting that growers who adopt the companion crop approach can apply for an SFI payment, says Camille. “The companion crop option is worth £55/ha, which will provide a useful contribution to seed and establishment costs.”

Years of experience in France also show growers can make significant reductions on insecticides and herbicides when using companion crops, and can expect to save 25-35kg/ha of nitrogen across the season. “More than 15% of the French OSR crop is now established using companion crops,” says Camille.

Companion cropping – an exciting development

Rob Adamson, technical development manager at ProCam, says using seed as an agronomic tool is “a really exciting development” as the chemical armoury continues to decline.

“We no longer have flea beetle solutions so we need to think of seeds as part of the toolbox. Using companion crops can be very useful in this regard, and can have clear additional agronomic benefits when establishing OSR, including soil conditioning and weed suppression.”

It is important to choose high quality varieties that are suited for planting alongside oilseed rape. “RAGT selects for the key traits so growers know exactly what they are buying, which is not always the case with off-the-shelf generic seed.”

Early vigour of the companion crop is critical, says Rob. “We want plants to emerge quickly to provide a shielding effect, but without smothering the OSR.”

Buckwheat is a key constituent, he adds. “It grows quickly, with a big leaf that sits within the rape, and it is good at phosphorus mobilisation. It is also very frost sensitive so dies quickly. From agronomy point of view that’s good – it’s around long enough to do its job disguising the crop from flea beetle and supplying nutrition, but not too long to become competitive.”

Striking a similar balance with legumes like clover and vetch is also important, says Rob. Rapid root growth will help increase nitrogen fixing capability, improve soil conditioning and, particularly with vetch, boost biomass to aid weed suppression, before the companions are killed naturally by frosts.

“Often seedbeds are less than ideal for OSR as it is sown at busy time of year, and the crop is a lazy rooter,” says Rob. “Any extra below-ground biomass will help soil conditioning and make it easier for the crop to put down roots.

“Weed suppression is important; you can’t use pre-emergence herbicides as they might kill the companion crop. A wider range of post-emergence products can be used, but you’ll need to go later. The best advice is, where possible, to wait until the first frosts, or at least until the companion crops have done the bulk of their work.”

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