A WA grower's need to cut the numbers of weed seeds has led to the commercialisation of a new mechanical product the Grains Research and Development Corporation (GRDC) hopes will give growers another weed management option.
The Harrington Seed Destructor (HSD) will have evaluation in South Australia, Victoria and NSW next year.
The HSD has been developed by Western Australian grower and inventor Ray Harrington. Towed behind a harvester like a chaff cart, the HSD has been developed around a cage mill crushing unit originally developed for use in the mining industry.
The unit, complete with its own power supply, incorporates chaff and straw delivery systems. During harvest, chaff collected from the top sieves of the harvester is delivered into the cage mill where it is processed sufficiently to destroy any weed seeds present.
Mr Harrington said a third prototype of the HSD has now been designed by the Agricultural Machinery Research and Design team at the University of South Australia, further progressing commercialisation of the machine.
He said four new units were expected to be built within the next year and evaluation would continue to measure the machine’s short-term impact on weed seed removal as well as its longer-term effects on weed populations and crop production.
The results are certainly promising thus far. Field testing so far has determined that the HSD potentially has a ryegrass seed destruction capacity of up to 95 per cent.
There have been similar results for other major problem weeds, such as wild radish, wild oats and brome grass seed present in the chaff fraction during harvest.
Although Mr Harrington stressed that the HSD was not a “silver bullet in weed management”, growers reliant on herbicides will pleased to have another string in their bow in terms of overall integrated weed management.
The HSD was developed after Mr Harrington saw the massive potential impact ryegrass resistance could have in crop yields.
“I decided that if I could manage weed seed set at harvest I would have a chance to combat the weed problem and after looking at all the options and logistics, crushing the seed seemed to be the answer,” Mr Harrington said.
Adapting the cage mill technology used in the mining industry for initial experiments, the first seed destructor prototype was developed and tested on Mr Harrington’s farm in 2007.
Since then, the unit has been progressively modified and a more extensive field testing program has been undertaken by the Australian Herbicide Resistance Initiative (AHRI) and Mr Harrington with GRDC support.
Based at the University of WA, AHRI researcher Michael Walsh said the HSD would be important in allowing growers to manage herbicide resistance.
Dr Walsh said the frequency and distribution of herbicide resistant weed populations continued to escalate across all Australian dryland grain production regions, coinciding with the adoption of conservation cropping systems heavily reliant on selective herbicidal weed control.
“The negative consequence of herbicide resistance is that highly effective herbicides can no longer be used for the control of a problematic weed population,” Dr Walsh said.
“Therefore the avoidance of herbicide resistance is imperative in the continuation of intensive conservation cropping systems. But the management of herbicide resistant populations in these systems is essential.
“Targeting the seed production of annual ryegrass populations facilitates continuous cropping regardless of the resistance status.”
Dr Walsh said several effective options including chaff carts, windrow burning and baling were now available to growers to target the seed-bearing chaff fraction of harvest residues.
“And the positive results from the HSD testing to date are very encouraging. With the continuing focus on the research and development of this system it is likely that a chaff grinding system will be available in the near future.”
