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A new 20-page guide aims to help rape growers make the most of early August drilling. The booklet provides a wealth of practical advice for... Make the most of early drilling

A new 20-page guide aims to help rape growers make the most of early August drilling.

The booklet provides a wealth of practical advice for early drillers alongside the most important establishment essentials. Produced by Bayer and Opico, it includes advice from ADAS, NIAB and Wright Solutions.

Sowing in the first two weeks of August has been invaluable in allowing many crops to survive cabbage stem flea beetle. But it brings with it a number of challenges that must be addressed to make the most of this opportunity.

Chief among these is the danger of increased flea beetle larvae in spring. While reducing the pressure from phoma, earlier drilling is also recognised as adding to risks from light leaf spot, clubroot – and possibly also verticillium and turnip yellows virus.

Agronomic pressure

At the same time, the guide points to the increased agronomic pressure presented by overly-large canopies susceptible to pre-mature stem extension in mild winters and serious damage from frost and snow if it turn colds.

Higher lodging risk is highlighted as a particular consideration too; especially where a combination of higher seed rates and better establishment results in dense stands of thinner-stemmed plants. 

In addition, of course, sowing in early August means very little time from harvesting the previous crop. This has implications for previous cropping, straw management, grass weed control and correcting any soil structural problems.

Machinery and workload issues at the peak of cereal harvest for most growers cannot been ignored either – especially at a time when good farm labour is hard to come by in many areas.

To make the most of the valuable opportunities earlier drilling brings while avoiding its main pitfalls, the Guide to Early OSR Drilling identifies a number of important rotational, varietal, machinery and management priorities in easy-to-read section.

Rotational priorities

Oilseed rape should never be sown if there is insufficient moisture in the seeding zone or soil structure is compromised, says the guide.

Soil structural issues need to be corrected ahead of the crop in the rotation wherever possible, and ground with a history of clubroot problems should be avoided.

Winter barley offers the best entry, with winter oats, winter wheat and spring barley also suitable providing their maturity is not delayed by genetics or management.

Leaving long cereal stubbles will ensure the most rapid combining and effective straw chopping and spreading while providing OSR with a good micro-climate for establishment.

Sowing with companion crops can improve establishment, and brassica-containing cover crops sown later in nearby fields may be useful in ‘trapping’ migrating CSFB.

Varieties

As well as establishing vigorously, varieties should be rapid in their development to get crops away but not so fast that they produce excessively-forward pre-winter canopies.

Varieties that are earlier or faster in their spring regrowth can provide valuable extra tolerance to higher levels of flea beetle larvae.

First-class standing power based on the best combination of stem stiffness and lodging resistance is more essential than ever.

Strong light leaf spot resistance is also crucial, combined with good resistance to verticillium where possible.

Turnip yellows virus resistance can be a useful extra safeguard, although only in addition to the more important priorities.

Management

Seed rates leading to higher-than-ideal plant populations should be avoided to ensure the most productive canopies and stems with the least susceptibility to CSFB larval damage.

The reduced threat from phoma should give more flexibility to delay autumn fungicide treatment, targeting it more effectively against the higher light leaf spot risk.

An early autumn application of metconazole may be needed to regulate the growth of crops that are particularly forward – especially if they are also very thick.

Relatively large canopies coming out of the winter put the onus on careful spring N management to Green Area Index (GAI) and effective plant growth regulation.

Flea beetle larvae can be reduced by sheep grazing or mechanical defoliation but this must be neither too intense nor too close to stem extension to avoid compromising yields.

Tim Scrivener 07850 303986

Machinery

Single pass establishment is essential, with speed balanced by sufficient care and precision in seed placement in particular.

Where the soil is in good enough condition with an unrestricted structure for root penetration and drainage, no-till drilling should be preferred.

Alternatively, structural concerns and any harvest trafficking damage can be tackled with some low disturbance metal at depth as part of a tailored seeding regime.

Seed should always be sown through coulters into soil re-consolidated after any disturbance to provide good depth control and seed-to-soil contact.

Machines should be able to cope with long stubbles and trash; apply fertiliser with the seed; and, ideally, also be able to sow companion crops and apply slug pellets.