Harrington destructor keeps weeds at bay

Grower Graham Kotzur sourced a Case IH Axial-Flow 9120 header retrofitted with a prototype weed seed destructor produced by the University of South Australia, and has used it across the recent harvest on his Culcairn farm.

Regional growers were given the opportunity to see the destructor in action in a 5.5 tonne/ha crop of Beckom wheat, during a field day organised by Riverine Plains, GRDC and FarmLink.

Riverine Plains project officer Kate Coffey outlined the GRDC-funded research project, 'Harvest Weed Seed Control for the Southern High Rainfall Zone'.

According to Coffey, harvest weed seed capture was a new concept for the eastern states.

“It is the non-chemical control, removal or destruction of weed seeds at or after harvest, such as the weed seed destructor, narrow windrow burning and chaff carts,’’ she said.

Riverine Plains committee member, Eric Nankivell, said WA growers are rapidly adopting the Integrated Harrington Seed Destructor and the Seed Terminator or chaff lining as an alternative to narrow windrow burning.

“Chaff lining is the practice of collecting small seeds and a minor chaff fraction in one row directly behind the header with the intention to naturally mulch,” Nankivell said.

“Chaff decking is the practice of collecting small seeds and a minor chaff fraction and diverting on to the wheel tracks.”

A great alternative

Kotzur had been disappointed with narrow windrow burning and was looking for an alternative method when he came across the Integrated Harrington Seed Destructor at a field day in Western Australia 18 months ago.

Ryegrass, wild radish and wild oats are the key weeds dictating herbicide use and integrated weed management program on his farm.

“I wasn’t happy with putting the harvest residue in a narrow windrow as wet summers are a problem here,” he said.

Kotzur recommended the weed seed destructor as a valuable tool in wheat crops and desiccated, direct-headed canola. However, he did find the greener stalks of Roundup Ready canola resulting in blockages in the destructor.

“In wheat, the machine just powders up (the residue) and shoots it out,” he said.

“In barley, it was pretty dusty and the air cleaner had to be blown out twice a day.

“I see more of a place for it in wheat – feed barley can be sprayed out while canola can be desiccated and ryegrass removed early,” he said.

When it comes to fuel usage, the header used an additional 27 to 30 litres an hour with the mills operating in a 3t/ha canola crop.

“The mills are running at 2700rpm – you need to keep the motor at 2600rpm for it to be effective,” he said.

Kotzur said a long-term approach is needed to evaluate the destructor as a weed seed control option.

“It needs to be used for a few years to get weed seed numbers down,” he said.

Kotzur said the weed seed destructor had aroused plenty of interest among local growers. He rated it among one of the most significant breakthroughs in decades in grain growing.

“If you can rely on mechanical means, apart from chemicals, to destroy seeds, it has to be good.

“It is another tool in the toolbox – if seeds are developing resistance to the chemical spray, this will destroy them from reseeding next year.”

Harrington Weed Destructor

The Harrington Weed Destructor (HSD) was conceived by WA grower Ray Harrington, more than 20 years ago, with commercial units launched as a tow-behind vehicle in 2012.

Input from the University of South Australia enabled the HSD to evolve into a retrofit kit for modern headers, becoming the Integrated Harrington Seed Destructor (iHSD).

The iHSD was launched in WA in 2016, with 10 units fitted to Case and New Holland headers, and a dealer network supporting the technology.

Harrington has completed 15 years of trials with the HSD and five years of trials with the iHSD fitted to his own 9120 and 8230 headers, controlling brome grass, wild radish and ryegrass on his property.

In headers set up for normal harvesting, up to 85 per cent of weed seeds exit in the straw while the iHSD pulverizes up to 99 per cent of weed seeds to the point of being no longer viable.

The integrated system consists of two hydraulically driven cage mills mounted to the rear of the header just below the sieves, a dedicated hydraulic drive system, reservoir and oil cooler.

Steel vanes operate at 3000rpm to pulverise the weed seeds, often into a fine powder, resulting in a single-pass harvest.

The iHSD operates at 3000rpm to reduce blocking and increase throughput.

The units weigh 450kg and measure 1500mm by 800mm, and have a normal running load of about 100hp.

The iHSD control system logs integrated information on the header’s CAN bus system, including mill speeds, temperature, chaff, weed seed kill and hydraulic pressures.

HSD and iHSD efficacy has been evaluated in long-term studies with all weed seed control taking three to four years to affect seed numbers in the soil seed bank.

De Bruin Engineering, SA, has the exclusive licence to manufacture the iHSD and has developed units to fit Case IH models (8230, 8240, 9120, 9230 and 9240), New Holland models (CR9090, CR8.90, CR9.90 and CR 10.9), CLAAS models (770TT) and John Deere models (S680 and S690), with new ones being added this year.

The iHSD is distributed on the east coast by McIntosh & Sons, O’Connors and Sunrise Ag.

Testing continues…

Kondinin Group research general manager, Ben White, said growers can expect to see increased competition in the market as the technology is refined.

“We need to get more information around mill life in different crop types and yields,” White said.

“Crops like beans harvested close to the ground can see a lot of soil put through the mills which can reduce operating life considerably.

“There is a lot more chaff and other material going through the mill in a wheat crop than say, barley or canola.

“The biggest cost of running the machines is not fuel but potentially the reduced capacity (rotor hours) of the header at an estimated 25 to 30 per cent.”

White and the Kondinin Group research team have collected data from over 20 machines fitted with iHSD and Seed Terminators this year, and expect to publish the results in February 2018.

Kate Coffey said harvest weed seed techniques need to be used in conjunction with other control methods where ryegrass weed populations are high.

She said ryegrass weekly seed shedding measurements in the month before the 2016 harvest revealed shedding rose from 500 to 1300 seeds per square metre.

“The data collected indicates that when there are high populations of ryegrass, the large amounts of ryegrass seed shed prior to harvest limits the amount that can be collected during the harvesting process,” Coffey said.

“We are finding farmers are continually modifying their techniques to suit their situation – harvest weed seed techniques usually involves extra time due to the lower harvest height.”

The GRDC project has sites at Riverine Plains, Southern Farming Systems, the Mackillop Group and FarmLink, investigating the impact on weed seed banks of narrow windrow burning, using a weed seed mill, and baling the chaff and straw compared to a traditional blanket burn.