Expert shares three tips for farmers considering early OSR drilling

By the end of July, Agrii had seen a 50% uplift in OSR seed sales compared with the same period last year. 

Reports also indicate a likely upturn in the overall national crop area following a 40-year low for the crop just harvested. Decent farm yields have been recorded and backed up by the AHDB, which reports that yields so far are 21% above the five-year average. Add to that a price above £400/t and it is easy to see why farmers may see it as worth sowing this season, Mr Leaper said. 

He continued: “Most breeders also provide risk-share schemes. For example, with a variety like RAGT’s Kanzzas, if the crop fails, a proportion of the seed cost is paid back to the growers.” 

Although early drilling allows the crop to become established before the main adult CSFB migration in mid-to-late August, the expert said it comes with agronomic challenges that farmers should be aware of before sowing the crop. 

“The risk of cabbage root fly increases, as does clubroot, verticillium, light leaf spot, and grass weed pressure. It also exposes the crop to more risk from CSFB larval damage. My concern is that by focusing on adult CSFB, we may exacerbate problems with other pests,” he added. 

But with land cleared and ready to go, what can OSR growers do to set next year’s crop up for the best start? The Agrii expert highlights three areas to focus on. 

Consider sowing a companion crop now and the OSR later 

Companion crops help hide small OSR plants from adult CSFB, both visually and by masking the volatile compounds emitted by oilseed rape, which attracts CSFB, Mr Leaper explained.  

They also improve soil structure and increase nutrient availability for the crop. Although popular, most companion crops are sown at the same time as the OSR because of time pressures, but an early season allows the sowing to be split.  

“The advantage of splitting the drilling is that in a month’s time, there will be a good green cover to sow the OSR into, protecting the OSR and negating any of the difficulties that come with an early sowing,” he said. 

Adjust seed rates

“Historically, we have always advocated sowing hybrid varieties at 50 seeds/m2, but with CSFB, this has crept up to around 60 seeds/m2.  

“Sowing early allows the opportunity to go back down to 50, you could even go lower to 40 seeds/m2, but as you still need to account for potential losses, I’d recommend no lower than 40,” Mr Leaper added. 

Reducing the sowing density will account for an extra month’s growth, and it has benefits further on in the year by providing more room for additional branching in the spring, he explained.  

This can help mitigate the effects of CSFB larvae by keeping them out of the main stem and in the lower side branches, where their yield impact is minimal.    

Select the right variety

With early drilling, farmers are tackling one issue, the adult CSFB, while opening the door to another, the CSFB larvae. However, David says that the right variety can help alleviate some of the additional pressures an early-drilled crop is subjected to. 

“You need a variety with good light leaf spot and Verticillium resistance, as well as an adaptable growth habit that can compensate for any damage once it gets going again in the spring. 

“Agrii trials over several years show a strong relationship between larval damage and early spring biomass, which then corresponds to yield. One variety that has stood out with its early spring biomass is RGT Kanzzas. It also has the best light leaf spot score of any variety we have ever tested. 

“RGT Kanzzas is very adaptable to the situation, with its growth habit also suiting a later planting if there’s a change of plan,” Mr Leaper concluded. 

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