Granular applicator options for tackling grassweeds

Horstine Cascade 6786

© Horstine

Loss of herbicide actives and increasing resistance to post-emergence products in grassweed populations have all conspired to make several species much tougher to control.

Just shy of 10 years ago, this meant a reinvigorated interest in the herbicide active tri-allate, better known as Avadex Excel 15G, which hit its 60th birthday this year.

Application of the granular product requires specialist kit, and some of the companies making it reported a major sales spike in 2013, as contractors, in particular, purchased machines to add another offering to their repertoires.

However, demand has remained steady since, and growers with grassweed problems are increasingly looking to invest in applicators themselves, allowing them the flexibility to apply when and where they want.

Here, we round up the options for growers and contractors alike, which include basic implements for mounting on Cambridge rolls or drills, and standalone tractor-mounted units with booms.

See also: Farmers rate their Horstine and Opico Avadex applicators


Sold in the UK by Chafer Machinery, Horstine has a long history in the precision application of granular products and offers three specialist Avadex applicator options.

Horstine’s sales and marketing manager, Joe Allen, says the initial flurry of sales in 2013 predominantly involved smaller 12m TMA4 units – either mounted on a tractor’s three-point linkage or towed behind an ATV or UTV. Demand for its Twin Air applicator, which is often attached to on Cambridge rolls, was also pretty strong.

Horstine TMA4-1188_ in field

© Horstine

However, with the 12m version resulting in additional traffic away from tramlines and mounting on rolls relying on good conditions to travel and apply the product, both have their limitations.

This is leading to more customers opting for the Cascade 24m mounted applicators, which offer Isobus-compatible four-section control and the ability to apply other products such as fertiliser, slug pellets and small-seeded cover crops.

For those who want to go wider, there is also the option of fitting two Twin Air units on a self-propelled sprayer, piping out product across boom widths up to 36m.

All Horstine Avadex applicators have individual metering, so each outlet across the boom has its own rotor to ensure accurate and even spreading across the width of the machine.

This is key to good tri-allate efficacy and reduces the risk of overapplication, which can compromise crop safety.

The TMA4 is available as a 12m mounted or trailed version with a 380-litre hopper and manually folding boom – a hydraulic folding option is available for those mounted on a tractor. Its fan is hydraulically driven (a small Honda petrol engine delivers hydraulic drive on the trailed version) and electronic rate control is provided via a simple on/off RDS Wizard control unit.

Horstine Twin Air on a Bateman sprayer

Horstine Twin Air on a Bateman sprayer © Horstine

On-farm prices for a mounted TMA4 start at £12,650, with a trailed version from £17,280.

The Casade has a 1,500-litre hopper with low-level sensors as standard, and buyers can go up to a 2,000-litre tank if additional capacity is needed.

The vertically folding, four-section steel booms allow it to operate on half widths of 12m, 15m, 18m, as well as its full 24m, depending on the tramline system.

A 70-litre/min hydraulic supply is required to drive the fan and four motors on the metering unit, which is controlled by an RDS Isocan box as standard. A Topcon X25 option adds auto section control for improved accuracy. Isobus compatibility allows operators to run the Cascade machine through the tractor’s own terminal. Prices for a 24m Cascade start at £41,525.

Meanwhile, each Twin Air unit has a 450-litre hopper and, like other Horstine Avadex machines, has an individual rotor for each distribution outlet, with a maximum of 16 an applicator.

It is available with a single hydraulic metering system, or a twin version that allows application across two sections to improve accuracy. Doubling up gives four sections across 36m.

The Twin Air is available with the same auto control system options as the Cascade, so it varies rate based on forward speed and can be set up for section control to reduce overlap on headlands or apply product based on application maps.

Cost for a single Twin Air starts at £10,750 on-farm.

Stocks Ag

The company’s Turbo Jet pneumatic seeder unit has been helping establish oilseed rape for a long time, but five years ago Stocks Ag began offering a specially adapted feed block and purpose-built roller kit that coverts it into an Avadex applicator.

Two models – the Turbo Jet 8 and Turbo Jet 10 – were predominantly fitted to Cambridge rolls but, increasingly, growers are mounting the units on drills to apply Avadex immediately after sowing.

Stocks FanJet

Stocks FanJet © Stocks Ag

Maximum application width is 10m when set up with 20 outlets on 500mm centres, with any attempt to go wider potentially compromising coverage.

The company’s Andrew Wright says fitting a Turbo Jet on multi-section rolls at greater widths can also cause problems with pipework when folding and unfolding, so is not recommended.

For Avadex and other products, units are ideally fitted to end-tow or three-section Cambridge rolls or drills and at the front of its host machine up high to keep granules flowing smoothly through the pipework.

The Turbo Jet runs off a 12V supply and is controlled by Stocks Ag’s i-Con GPS touchscreen terminal, which requires the product rate, machine width and a simple catch-and-weigh calibration for accuracy.

Hopper level sensors are an option, along with Isobus compatibility that allows for easier swapping between tractors.

The firm doesn’t carry out installations or offer fitting kits. Some implement manufacturers will provide ready-to-go units on new machines – otherwise the dealer or farmer will have to fit it themselves.

Each unit comes with the applicator, rollers, hoses, spreaders, clamps and a C-rail to support the outlets. A new Turbo Jet 8 has a base list price of £6,875.

For existing Turbo Jet owners, a block assembly to allow application of Avadex can be bought separately for £600.


Lincs-based importer Opico has worked with Avadex manufacturer Gowan to develop its purpose-built applicator and now offers two iterations – the Micro-Pro 8 and Micro-Pro 16.

As with any residual herbicide application, uniform and precise coverage is needed to maximise efficacy and Opico’s Glenn Bootman says metering accuracy is the easy part.

The tricker element is delivering it to the outlets evenly so, like Horstine applicators, the Micro-Pro uses individual metering for each outlet, rather than splitting pipes or using distribution heads. This guarantees a consistent flow of product across the width of each pass.

The principles of the Micro-Pro 8 and Micro-Pro 16 are the same – the only difference is in the number of outlets (eight versus 16). These are on a 75cm spacing to give a double overlapping spread pattern across a maximum working width of 6m for the 8 and 12m for the 16.

The 8 has a 180-litre hopper, with the option of increasing to 400 litres, while the 16 comes with a 400-litre hopper as standard. Both have a hydraulically driven fan and a metering system based on the seeding unit from Austrian maker Hatzenbichler, which is upgraded for accurate application of microgranules.

A push-button in-cab box is supplied, which offers electronic calibration and radar rate control. Isobus compatibility and mapping are not currently an option.

Micro-Pro units can be mounted on implements such as drills or rolls, run as a standalone machine on a three-point linkage or, in its most popular guise, as a trailed skid unit behind small tractors or UTVs (with a small engine to drive the hydraulics).

Opico has run independent tests to measure complete spread pattern and boasts a coefficient of variation of less than 5% for its Micro-Pro 16 at 12m. Roller kits are available for spreading slug pellets or establishing cover crops.

To buy a basic unit and mount it to a drill or set of rolls, the Micro-Pro 8 starts from £8,715 and the 16 is £9,309.


Littleport-based Techneat offers its Avacast GR200 with a 200-litre hopper, which is typically mounted on drills, rolls or UTVs and can apply the product to widths up to 12m.

The GR400 has a 400-litre capacity, boom widths of 12-15m and can be mounted on implements, a tractor’s three-point linkage, or towed behind a quad or UTV.

The Avacast Twin Air is an option for those looking to apply Avadex from sprayers out to a maximum of 36m. It has a 400-litre hopper, high-output fan and two metering units feeding distribution heads fixed to each boom side. This allows for half-width shut-off on headlands.

Finally, there is the tractor-mounted Avacast GR1200, which has a 1,200-litre hopper and hydraulic lifting, folding and levelling of the fully suspended 24m steel boom.

Techneat applicator in field

© Techneat

Like its smaller Avacast models, Techneat’s James English says the GR1200 can be used for slug pellet application and broadcasting small-seeded cover crops by a simple change of metering rollers.

All machines essentially work the same, with an electronic metering unit feeding distribution heads before the product is piped to the outlets on 50cm spacings.

The firm is looking at introducing the option of Isobus compatibility, but for now its standard setup is a Garmin GPS system, which holds the 15kg/ha rate steady according to forward speed.

All units have a hydraulically driven fan, apart from the ATV or UTV towed version, which draws power from a belt drive and 5.5hp Honda petrol engine instead.

Trailed and tractor-mounted GR models are all tested before leaving the factory yard, so come with an NSTS certificate. Any units mounted on drills, rolls or sprayers need to be tested after fitting on farm.

Rigging up mounted versions is relatively straightforward and most are installed by the customer, with kits including a T-frame, hoses, outlets, switches, cables/loom and control unit.

Prices start at £7,200 for a drill-mounted GR, or £12,000-£13,000 for mounted and trailed versions with booms. A Twin Air is about £18,000 and the GR1200 comes in at £30,000.

Horsch with Techneat ˙

Horsch with Techneat ˙ Horsch


Avadex applicators from Austrian manufacturer APV are available through Yorkshire-based dealer ST Gowan, with three options offered.

The models are essentially a modified air seeder, with Avadex application accuracy verified by trials in Austria and here in the UK by spreading and sprayer testing experts SCS.

They can be mounted on drills and Cambridge rolls to achieve working widths of up to 18m from 16 individually metered outlets. The metering unit is powered by a 12V supply, while a remote hydraulic supply is required to drive the fan.

The PS200 M1D Avadex and PS300 M1D Avadex comprise the same basic unit, but have 200-litre and 300-litre hoppers, respectively.

The firm also offers a 500-litre PS500 M1D Avadex which sits on a slightly larger A-frame, but there are few situations where the additional hopper capacity is necessary, according to ST Gowan director Steve Gowan.

All machines come as a complete unit with distribution hose and spreader plates.
ST Gowan offers a fitting service, but as a mounting plate is supplied, most buyers will be capable of installation themselves.

A standard APV 5.2 control box allows the operator to calibrate and control rates, with an APV 6.2 touchscreen and Isobus capability available as upgrades.

A range of options are available for matching rate to forward speed, including a simple wheel sensor, radar or GPS. However, Mr Gowan says most farmers simply opt for a seven-pin plug to take forward speed from the tractor’s system directly.

Other extras include an on/off top link sensor for mounted machines or a pull switch for units fitted to trailed implements.

Prices start at £7,200 for the PS200 M1D Avadex with mounting plate, hose and spreader plates.

Contractor’s Agribuggy offers light-touch Avadex application

Despite an increasing number of farms opting to run their own kit, many contractors remain flat out with Avadex application, including Bedfordshire-based spraying contractor SL Gurrey and Son.

The business currently operates two 24m/30m/32m Sands Vision 4000 self-propelleds covering some 16,000-18,000ha of ground each year, and has been running an Avadex application service alongside for decades.

Simon Gurrey's Agribuggy in field

An Agribuggy and TMA4 weighs about 2,000kg unladen © Adam Clarke

Simon Gurrey, whose father founded the business in the late 1970s, says they were running two machines – including an applicator mounted on a Toyota Hilux – until the introduction of highly effective post-emergence herbicides such as Atlantis (iodosulfuron + mesosulfuron).

Demand then cooled and meant just one 12m Horstine TMA4 applicator was retained, initially towed behind an ATV, then mounted on a 1985 C-reg Frazier Agribuggy.

Following some key grassweed herbicide losses and Atlantis becoming less effective due to resistance, Avadex came back in vogue and the machine has been worked hard since.

Simon Gurrey with the Agribuggy

Simon Gurrey © Adam Clarke

While there is a temptation to change to something like a 24m tractor-mounted version, an unladen weight of just 2t means it comes into its own in the autumn when ground conditions are less favourable. In comparison, a 150hp tractor would weigh about 6t plus the applicator, so has the potential to make a mess in a wet year.

Mr Gurrey says going back to a quad or UTV is one option to maintain low ground pressure, but the experience with that setup before purchasing the Agribuggy in 2000 wasn’t great for operators covering large areas.

“Particularly on long, cold days, it wasn’t a pleasant experience and after a shift you’d be very tired from the rough ride and using bout markers.”

The Agribuggy had a 12m sprayer attached when purchased but, with his sheet welding experience, it was a simple job to remove it, build a chequer-plate flatbed for the applicator to sit on and fabricate three mounting points to hold it in place. A 5.5hp Honda engine sits in front of the machine to drive the hydraulic fan.

Back of the Agribuggy

Extra engine cooling was added to solve overheating issues © Adam Clarke

Maintenance costs are very low thanks to the Agribuggy’s simple 1.6-litre Ford Escort engine and Land Rover running gear, and with the ability to cover 100ha a day, it has paid for itself many times over.

Additions include extra cooling capability at the front of the cab, as the engine had been prone to overheating.

About five years ago, Mr Gurrey also invested in a Trimble 250 Ez-Steer auto-steer system for just shy of £2,000, which has improved ease of operation for the machine’s dedicated driver throughout the application period.

Agribuggy cab

Operator comfort is better than a quad or UTV, especially in cold weather © Adam Clarke

The TMA4 is NSTS-tested each year, and he has never encountered any metering accuracy issues, despite the age of the machine and the fact that it is land-wheel-driven.

“It is always correct, whether working in one 100-acre field or six fields in 100 acres,” he adds.

A quick search online will find a similar Agribuggy and TMA4 setup on a K-plate (1992) for about £7,500, so it could be an option for those looking to pick up a bargain.

Agribuggy wheel

The land-wheel-driven metering system is always accurate in NSTS testing © Adam Clarke