TACKLING Australia’s number one weed was not specifically on Ray Harrington’s mind when he decided something had to be done at harvest to stop his property being swamped by herbicide resistance.
However, the Western Australian grain grower and inventor has come up with a new tool in the fight against ryegrass and other weeds which will help maintain the sustainability of Australia’s grain industry.
Now known as the Harrington Seed Destructor, the machine’s been more than a decade in the making and there will be several out in paddocks this year for extensive testing.
At harvest, chaff – and weed seeds – are delivered to the device, which sits on a trailer towed by the harvester. It pulverises the weed seeds, turning them to dust or rendering them unable to germinate.
Since the first prototype was built for Mr Harrington by locals Mike and Geoff Glenn and Ron Knapp, there has been support and funding from the WA Herbicide Resistance Initiative (WAHRI), the Grains Research and Development Corporation (GRDC) and the CBH Group, among others.
Despite his property at Darkan being in great sheep country, Mr Harrington decided in 1997 to switch to a total cropping program.
“I knew it would be only a matter of time before weeds were a problem if I didn’t tackle them from the start, especially herbicide resistant ryegrass,” Mr Harrington said.
“I’d seen chaff carts in action and knew they were effective – but they were difficult to clean up after, and I thought I could improve on the system.
“I went through all the possibilities for the chaff – catching, carting, cooking, cremating, crushing.
“Microwaving wouldn’t work because the moisture content is too low; towing a furnace behind the harvester might – but can you imagine anyone wanting to do that in 40 degree heat?
“Eventually I settled on an impact machine which collects the material that would go into a chaff cart and pounds it with iron bars,” Mr Harrington said.
The first machine Mr Harrington built himself with the help of some mates with a local engineering works. It was static, driven by a tractor, and ended up sitting in the paddock for a couple of years.
Then Mr Harrington met Professor Steve Powles, the head of WAHRI, and after a discussion about herbicide resistance and the destructor some testing was organised through WAHRI.
The results were convincing and a long collaboration began.
“Australian grain growers spend around $1 billion every year on herbicide. Ryegrass is often the target, can rapidly evolve herbicide resistance,” Professor Powles said.
“Ryegrass is the world’s most spectacular example of resistance, and a very competitive plant in grain crops.
“However, ryegrass does have some weaknesses and the seed destructor exploits two of them – its seed does not have a long life in the soil, and doesn’t shatter before harvest.
“Every year, about 80 per cent of any ryegrass seed will germinate. If you can stop plants getting seed back to the ground, you can very quickly drive down the seed bank.
“The destructor is killing more than 80 per cent of seeds such as ryegrass and wild radish so, like the chaff cart and windrow burning, it is a very effective non-chemical control method. It will not suit every farmer or every farming system, but I still believe it has great promise,” Professor Powles said.
With the help of WAHRI, the destructor attracted GRDC funding which has seen its design refined over recent years.
Three machines will be tested in Western Australia during the 2010 harvest, and in other states in 2011. Further research is being conducted to develop machines suitable for Class 8 harvesters and for crops with larger residue volumes such as lupins and canola.
Most of the testing to date has been on Mr Harrington’s 1400 hectare property, and last season he used the machine for large areas of barley, wheat and lupins.
“Without the assistance of WAHRI over the years and funding from the GRDC, this would never have gone further than me building a few for my own headers,” Mr Harrington said.
“I often say to growers that if they’ve delivered a tonne of grain into the system, they’re part owners of the development through their GRDC levies.”
Mr Harrington says the machine has very little impact on the header despite weighing about 1.5 tonnes, and the mill’s motor only uses three litres of fuel per hectare.
“When we still had sheep, we ran about 30 per cent wheat with a pasture and barley rotation. We also use canola and lupins as a break crop to control the grass weeds.
“I really do think we will be able to grow wheat on wheat with very little danger of resistance by using the destructor every year and swathing every two to three years.
“We’ll never totally eliminate weeds, but we must do something at harvest to keep numbers low. That will make a huge difference in the long term,” Mr Harrington said.
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