Arable News

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No single answer to the black-grass problem

Machinery supplier Opico staged a ‘Beating Black-grass’ seminar last month

Machinery supplier Opico staged a ‘Beating Black-grass’ seminar last month where cultivation options as well as the application of key grass weed herbicide Avadex were the focus. Dominic Kilburn writes.
Opico managing director James Woolway and the Micro-Pro 16.
All farming cultivation systems have problems with black-grass, pointed out Opico managing director James Woolway at his company’s recent seminar entitled ‘Beating Black-grass’. However he said that a combination of different cultivation techniques and the ability to be able to vary the approach to cultivation when required is what is needed. “Our climate in the UK is very variable and so we have to vary our systems accordingly,” he stressed.
Mr Woolway suggested that ploughing was a short-term fix when it came to controlling black-grass and that other systems must be employed during the years in-between.
Min-till, he said, could provide control of black-grass but it can result in deeper cultivations which are too deep for effective black-grass control, while direct drill and strip-till systems often need the plough, or shallow cultivation systems to help control the black-grass.
He questioned whether drainage maintenance was a priority on farms currently, given the relentless spread of black-grass, and if moleing and subsoiling was carried out “every few years” to alleviate soil pans.
“Subsoiling improves drainage and rooting but it mustn’t be done too fast as it will mix the black-grass seed throughout the soil profile,” he commented. “It’s key not to mix the soil profile and, if anything, it’s better to go wider, rather than faster,” he advised.
“Set the subsoiler wings by changing the angle to lift less, with minimum ‘soil boil’, so you can go a little faster if needed but leave the soil down there,” he added.

Creating the right mix
According to Mr Woolway, the fact that the popularity of time and cost saving combination cultivators – featuring subsoiler tines and discs – coincided with the increase in black-grass populations over the past decade, was probably not a coincidence. “With these implements we are turning the soil upside down through the whole soil profile and, in a bad black-grass situation, it can proliferate the problem.
Opico says that it is the only company that does a patternation spread test of its Avadex applicators prior to them being purchased by growers. Corrugated sheets are laid on the floor across the full 12m working width and the application spread is measured every 7.5cm.
“It’s much better to subsoil slowly and then chop and mix the surface afterwards with a set of discs, rather than tines, moving the soil shallow and to a similar depth, and leaving the black-grass seeds deeper than 6cm,” Mr Woolway said.
“Discs move the soil to the same depth and the flatter the discs the better, rather than the traditional concave type which, with their weight, can smear the soil as they turn.”
He suggested that in preparing stale seedbeds, growers needed to think about how they would prepare a normal seedbed and focus on creating seed-to-soil contact. “Consolidation is often under utilised and so the more discs per metre the better, to increase the amount of consolidated soil across the full width.
“Finally, it’s better to roll, rather than press, to make the black-grass seed germinate,” he added.

Chemical options
With the renewed interest and use of grass weed herbicide Avadex (tri-allate) in growers’ autumn weed control strategies over the past few seasons, Mr Woolway highlighted that care was needed in its application for the product to be a success.
“Avadex is difficult to apply, particularly as granules vary in size making it impossible to ‘throw’ them,” he suggested, adding that the product is also very light and easily affected by wind.
“With Avadex we are trying to create an even and accurate layer of chemical across the soil otherwise there simply won’t be the black-grass control, and therefore a specific applicator is required rather than using a Variocast, or similar machine, if we want Avadex to work properly,” he emphasised.
Opico’s Micro-Pro 16 is the company’s latest kit specifically developed to apply Avadex. A 12m machine featuring 16 metering rollers for 16 outlets, it has additional applications including slug pellets, grass seed, clover, stubble turnips and fodder rape (more details on the Micro-Pro 16 can be found on page 43 of this magazine).
Mr Woolway pointed out that it’s not possible to apply Avadex accurately using a mushroom-type distribution head as the product is too light at low rates and, especially so, if the ‘seed’ pipes are all of different lengths.
The fundamental starting point of any machine designed to apply Avadex, he said, was the number of outlets – and the more the better. The less distance between outlets (maximum 0.75cm) means a more reliable and robust pattern, with less effect from the wind, he suggested.
“We set out to produce the most accurate micro-granular applicator on the market,” continued Mr Woolway, who said that SCS Spreader & Sprayer Testing has been involved with its development from the start. “Using NSTS micro-granular applicator protocols the Micro-Pro achieved +/- 3% in outlet tests while the NSTS acceptable pass rate is as much as +/- 10%. If you work to +/- 10% then an intended application rate of 13.5kg/ha could be as much as 16.6kg/ha applied, resulting in poor or variable control of black-grass and an illegal over application,” he warned.
Likewise, in metering tests across the full width of the machine, the Micro-Pro measured +/- 1%, well within the NSTS’ +/- 5% target rate at 15kg/ha.
“We don’t think that the NSTS protocols demand enough accuracy and they don’t look at, or check, spread patterns.
“SCS helped us to develop our own spread pattern test and analysis shows that the Micro-Pro 12m has a coefficient of variation of 5.36%. We feel that it’s very important to have this kind of accuracy when you are dealing with expensive chemical and we are the only people to do this to a machine before it goes out of the door,” said Mr Woolway.

Farm development
Rob Golland, farm manager at the 1,000ha (2,470-acre) Vine House Farm, Deeping St Nicholas, near Spalding applies Avadex to wheat in the autumn with an applicator kit off the back of his 12m He-Va King Rollers.
Working with Opico, he converted the farm’s Variocast Air 16 (seeder) using a hopper, metering unit and outlet system which was further developed and became the basis of Opico’s Micro-Pro applicator.
“We started using Avadex again two years ago as black-grass was an increasing problem on the farm and this system, off the back of the rolls straight after drilling, has worked well,” he reported.
Mr Golland said that speed of application is typically 10kph, governed by the speed rolls are operated at, as is the number of outlets (16 at 0.75m spacing) across the rolls’ 12m width.
“It’s a very light product to apply and so the more outlets the better in terms of maintaining the accuracy of application,” he commented.
As well as proving to be a success in applying Avadex, the same kit is also commandeered for slug pellet applications during the autumn. “The problems that are occurring with pellet active metaldehyde and water courses is a big concern, but this system offers us far more accuracy and reassurance than a spinning disc applicator,” concluded Mr Golland.

Herts contractor
Attending the Opico event was Hertfordshire-based contractor and County Council tenant farmer Diccon Burman (right) who built his own 24m Avadex applicator and, last season, applied product to over 2,700ha (6,660 acres).
He said that accuracy of operation is key and, with 0.5m spaced outlets along the 24m booms on his machine, and enough airflow to deliver sufficient pressure to each of the seed pipes, he is getting the required spreading coefficient from his machine when operating at 12kph.
“Having seen Opico’s new machine, it’s clear that it is delivering the required accuracy and they’ve taken the time to develop it properly, however too many growers are applying Avadex with machines that are too old. They are OK if they are set up properly and conditions are ideal, but on the one hand they are using the latest GPS-controlled sprayers to apply other chemicals on the farm, and then on the other they resort to a 30-year old machine for Avadex.”
Mr Burman, whose business is based near Hitchin and operates across north Hertfordshire, Bedfordshire and Cambridgeshire, said that the majority of his Avadex application work is on autumn wheat although he is seeing an increase in use in spring barley where there are fewer options to control black-grass.
“More growers are using Avadex now because they have found themselves with a bad black-grass problem, but why not use it to stop the problem before it happens?
“Avadex also has an affect on some broad-leaved weeds, which is an additional bonus,” he added.

Black-grass cultivation success at a glance
– Subsoil with low disturbance tines- Create shallow stale seedbeds with discs- Roll after

Micro-Pro options
Mounted boomed Micro-Pro
– 12m boomed applicator with 400-litre hopper, radar, electronic metering and a manual folding suspended boom with 16 outlets
– Optional – Trailed chariot chassis with single or tandem axle to be towed behind UTV or a large ATV
Micro-Pro with fitting kit for 12.3m He-Va King Roller
– Loading platform with steps and applicator with 400-litre hopper, radar, electronic metering and 16 outlets
Micro-Pro for fitting to customers own machine

Black-grass battle
Just to stand still and keep black-grass populations at the current level requires as much as 97 per cent control each season. That is the harsh reality facing farmers in the UK in their battle against black-grass, stated ProCam’s head of crop production Nick Myers (left), speaking at the event.
He highlighted several challenges: legislation continuing to restrict available products; no new major black-grass herbicides coming through; reduced efficacy and variable performance of residual herbicides (mainly influenced by differences in seasonal weather); ever-more stacks of herbicides required for control and involving complicated mixes and sequences; a general decline in performance of post-emergence contact material; and the increasing spread of resistance across the country.
“Growers have all this to contend with never mind trying to run down black-grass populations still further,” he pointed out.
Mr Myers referred to the company’s ‘4Cast’ survey data (2000-2014) which confirmed that average herbicide spend had risen on wheat farms in line with the increased use of non-inversion cultivation techniques. “The average spend on herbicides in 2014 was #110/ha which is unsustainable at current wheat prices. Non-inversion techniques do mean a greater spend on herbicides, but it’s understandable in terms of trying to reduce establishment costs,” he explained.
He encouraged growers to fully embrace cultivation control and herbicide use.
“Most black-grass won’t germinate below 6cm and, once ploughed down, seed does degrade quickly – usually within three years – so having ploughed, and it must be good inversion, just work the surface for the next three years.
“False or stale seedbeds are not the total answer, particularly if they are not left long enough for the black-grass to germinate properly. However they must be consolidated, like a seedbed, if good germination is to be achieved,” he commented.
Mr Myers emphasised the point that delayed drilling in the autumn is a tool that can be used to improve black-grass control and reduce herbicide costs, but yield tends to drop. “Residual chemistry goes on better in cool and moist conditions when drilling is delayed although we know that later sowing can be unreliable.
“That said, there is relatively little difference in yield when drilling between mid-September and mid-October,” he added.
“Spring cropping is a major benefit to black-grass control and our 4Cast for average crop gross margins in 2014 shows very little difference between winter and spring wheat, with input spend on the latter being much less,” he highlighted, pointing out that the gross margin for spring barley was not too far behind.


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