Agronomy Update - East, Craig Green

Article taken from Farmers Guide, October 2017.


Variable oilseed rape emergence is evident in my area of Norfolk, directly related to seedbed moisture and subsequent rainfall.

Less pre-emergence spraying has been carried out as a result, either due to the weather or because growers have waited to see how crops establish.

Although metazachlor is an option, and propyzamide is an obvious choice later in the autumn, both are relatively expensive for growers that are not troubled by black-grass, which remains the case for most of my clients.

This season I'll be using Parish, which contains 320g/litre of phenmedipham, to control a similar range of broad-leaved weeds to metazachlor, as well as cranesbill.

At under £20/ha it's good value for money and brings more flexibility. Applied between cotyledon and two true leaves of the weed and before nine leaves of the crop, it will be a very useful addition to this season's armoury.

Although black-grass remains a relatively minor problem in my area, it and ryegrass are increasing, especially on the heavier land along the A47 corridor. This is the first year I have seen poor levels of control from a decent residual stack based on flufenacet, and a follow-up Atlantis.

Where that's the case, I'm advising growers not to rely on chemical control alone, but to delay drilling wherever possible to allow more time for weed seeds to germinate and to maximise pre-drilling control with glyphosate.

Anything we can do to reduce early pressure is vital. Sowing a wheat variety with a ground-hugging, spreading growth habit will help it out­compete black-grass plants which are trying to establish at the same time.

Prolific tillering

Belepi is prolific at tillering - so much so that we need to reduce seed rates even when it is sown towards the end of the year. It might be slightly off the yield pace being set by Recommended List heavyweights, but it is known to be highly competitive, which helps offset that yield gap where grass weed pressure is building.

A lot of customers are giving the new liquid Avadex (tri-allate) formulation a go this season. Although it only delivers 75 per cent of a granular application, people have until now not used the chemical at all, as the solid form required a specialist applicator.

Applied as soon as possible after drilling, Avadex should really give black-grass a headache, and it will be a valuable addition, especially where weed numbers are relatively low. At under £40/ha it should be cost­effective, and will take the pressure off other chemistry in the stack.

To help tackle the growing black­grass pressure in the county, I'm setting up four large-scale trials on four fields on four different farms, all within a three-mile radius. The idea is to look at what difference different drilling techniques, cover crops and chemistry can make.

Each farmer will be trialling their. own methods against ours. We hope to run these over several seasons and open up the trials to local growers so they can see the results for themselves.

Maize harvest has just started. Although about two weeks early, indications are that yields will be good, despite the dry, cold start. The benefits of good weed control are clear to see - delays or bad scorching early on have reduced yield by several percentage points.

I've recently discovered that flying a drone across maize fields is picking up eyespot before we can see it. This will help growers prioritise these areas for harvest, helping to minimise leaf loss and maintain yield and quality.

Craig Green is an agronomist with Agrovista, based at Great Ellingham, Norfolk (


04 October 2017

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