HSD step closer to acceptance

Just released trial results have confirmed the efficacy of the Harrington Seed Destructor (HSD) in reducing annual ryegrass emergence, paving the way for its introduction into Australian farming systems.

The HSD has been developed by farmer and inventor Ray Harrington with support from the Australian Herbicide Resistance Initiative (AHRI), based at the University of WA, and the Grains Research and Development Corporation (GRDC).

Results from 2010 AHRI harvest trials across 12 locations in the WA grainbelt have shown that the HSD is equally as effective as two other harvest weed seed management systems — chaff carts and windrow burning — in reducing ryegrass emergence.

But unlike chaff carts and windrow burning systems, the HSD has the advantage of conserving all crop residues and does not require any post-harvest management activities.

AHRI researcher Michael Walsh said significant reductions in ryegrass emergence of between 40 and 60 per cent occurred at each site for the three different systems.

“This equated to reductions in autumn plant counts from about 150 to 70 plants per square metre, ” he said.

Dr Walsh said factors including the very dry finish to the 2010 cropping season and pre-harvest seed shed reduced the overall impact of all harvest weed seed management systems.

“This result clearly demonstrated to us that a long-term view must be taken in assessing the impact of harvest weed seed management systems on weed populations, ” he said.

“But with most ryegrass seed remaining upright on intact seed heads, there was still the opportunity to compare the systems and the critical result is that at all 12 sites they were equally effective in reducing ryegrass emergence.”

Dr Walsh said the trials were the most extensive and rigorous testing so far for the harvest weed seed management systems under commercial harvest conditions.

The 12 trial sites chosen were wheat crops with typical ryegrass infestations of between 15 and 26 plants per square metre.

He said that while the trials focused on ryegrass because it was the most problematic weed in Australian cropping, the HSD was equally effective in controlling other weed seeds including wild radish, wild oat and brome grass.

The action of the HSD results in the destruction of at least 95 per cent of weed seeds that exit the header in the chaff fraction during harvest.

“These very high levels of weed seed destruction have repeatedly been achieved under commercial harvest conditions in wheat, barley and lupin crops, ” Dr Walsh said.

He said an indication of the importance of targeting annual ryegrass seed at crop maturity was that although the ryegrass plant densities were not excessive at the 12 trial sites, the seed production was.

“On the upright tillers there were, on average, 3100 ryegrass seeds per square metre, ranging between 1200 and 5300 seeds per square metre across the 12 sites.”

Dr Walsh said the WA trials of the HSD attracted a lot of interest from growers, with more than 200 farmers observing the HSD in action and learning more about this new weed control tool.

Similar trials will be conducted in Australia’s south-eastern grain growing areas over the 2011 harvest period.

These trials will be conducted as part of a new Rural Industries Research and Development Corporation (RIRDC) funded project focusing on harvest weed seed management systems.

Again, the aim of these trials will be to give producers across this region the opportunity to observe and learn more about the use of the new weed control tool in Australian cropping systems.

The GRDC is managing the commercial development of the HSD.