Get crops working against weeds

28 Mar, 2016 01:00 AM
Chris Preston, of the University of Adelaide, says bulky crops can help weed management by out-competing problem weeds.
Chris Preston, of the University of Adelaide, says bulky crops can help weed management by out-competing problem weeds.

ONE OF Australia’s leading weed management specialists has said farmers should embrace heavier crops as a means to outcompete problem weed species such as rye and brome grass.

Chris Preston, of the University of Adelaide, said ryegrass resistance to post-emergent herbicides was now common in many high rainfall zones, such as southern Victoria and south-east South Australia, and he urged growers to implement an integrated strategy to minimise the risk of herbicide resistance.

As part of this, he said high biomass crops could play a role in outcompeting weeds.

“In trials, a high biomass canola species, Hyola 750TT, significantly reduced the number of ryegrass spikes at harvest compared to the two other cultivars in the trial at harvest,” Dr Preston told a meeting at last month’s Grains Research and Development Corporation (GRDC) update in Bendigo.

He said growers could halve the amount of ryegrass that sets seed simply by switching from an open pollinated to a hybrid canola.

“Crop competition against the weeds is important, especially as we look to retain the efficacy of herbicides.”

Dr Preston said trial results at Lake Bolac in Victoria showed that on a pure basis of lowering ryegrass numbers a high intensity herbicide strategy was the best method.

“It is more costly, you can find yourself spending $100 a hectare on ryegrass control along, but the effectiveness is there.”

He said for growers in areas where there was the potential for multiple ryegrass germinations during the season, this higher cost strategy was the safest.

“At trials at Frances, in SA, we saw a low intensity ryegrass control program lead to a high number of ryegrass plants setting seed.

“The message is clear, in high rainfall zones, low intensity management plans don’t work.”

Dr Preston also said growers needed to look long term with their rotations to lower the amount of seed.

“If there is a high burden of grass weeds, one year of a break crop is good, but two is better.”

“We have found that with two break crops you can virtually control any weed seed set.”

He said the innovation of glyphosate tolerant, triazine tolerant (RT) canola gave growers a stronger suite of management tools.

“Having RT canola in the system gives growers the chance to utilise different sets of chemistry and to use both post-emergent and residual herbicides.”

Gregor Heard

Gregor Heard

is the national grains writer for Fairfax Agricultural Media
Date: Newest first | Oldest first


30/03/2016 5:39:44 AM

Mr Preston have u any independent (not done by u or people in the GM industry) Aust'n field research studies into Horizontal gene transfer (HGT) of the added roundup tolerance gene? if this gene was transferred back into soil from GM plants, could it then be transferred to any weed that grows nearby via HGT? if so, aren't the risks too great that roundup ready crops will heighten the likelihood of widespread resistance to roundup, our most effective post patent herbicide? Proof already exists of cross pollination of this gene, has this research been done for HGT.
30/03/2016 8:33:46 PM

Herbicide tolerance genes are subject to breakdown and need to be managed as part of a whole farming systems strategy and in combination with other genetics (like biomass). GM, non GM, Crispa, mutant derived is irrelevant !
1/04/2016 4:28:15 AM

So how is releasing a gene resistant to Rup and not previously present in our paddocks good management? How many of these genes in a crop of canola/cotton?, only 1 needs to be transferred by HGT or cross pollination to any weed to make Rup useless. All this alarm over food security (not evidenced by real returns since 73 oil crisis) and yet the GM industry seek to destroy our use of Rup as a fallow method with no viable alternative at this point. That's as laughable as a profit driven company worried about food security in LDCs.
Mike Tancock
1/04/2016 10:40:15 AM

History repetition!!!!!! What makes Chris Preston think he has discovered weed control. In the mid nineties the WA ag-dept conducted trials of heavier sowing rates (100kg >150kg>200kg per ha) to assertain if thicker foliage would result in the smothering of emerging weed species In the med > high rainfall areas it was OK In the low > med areas, not so good The risk of a dry finish is too great resulting in pinched grain
1/04/2016 6:16:23 PM

Varied Genetic solutions used in conjunction with agronomy is and has proven to be sustainable.Farmers have a vested interest in adopting and deploying multiple technologies. Non GM and GM genes are subject to the same principles of genetics and gene flow ! This argument is irrelevant. Weed management needs a whole farming systems approach of which novel genetics is a part off.
5/04/2016 5:55:08 AM

No argument from me on IWM, however my question was and is where is the scientific evidence to prove the safety to our farming system of RR crops? u have failed to provide any. We have a long history of biological introduction which turned out to be poorly researched (eg cane toad), will this be another?. The govt expects due diligence from us, where is theirs on RR gene? I bet its in the same black hole as their due diligence on FTAs, privatisation of Commonwealth bank, floating of the dollar, etc.


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