Farmers have dug up the 1980s Agriculture Department research data on ryegrass control with isoproturon (IPU).
The results are spectacular.
This data shows that we have compromised ryegrass control for a few decades by not having IPU.
IPU gave an extra 200 kilograms per hectare more grain yield than traditional ryegrass herbicides, of the time, being Glean, Treflan or Hoegrass.
And for about the same cost as the other herbicides of $20/ha.
Farmers estimate about $47 billion in profit was lost to Australian agriculture since 1980 from not having IPU.
While this sounds perhaps far-fetched, I have done some of my own calculations.
With a 10,000ha wheat crop at a 200kg/ha loss per year, over 40 years the loss would be 10,000ha x 0.2t x 40 years, equalling 80,000t.
At $300/t this is $24m to a business, which is a staggering statistic.
So, why did this molecule never get registered in Australia?
Further, what can be done to get the molecule registered?
Especially since many other countries had access to IPU.
Isoproturon was first registered by Hoechst in the late 1970s, and it was the herbicide of choice in much of Europe until 10-15 years ago.
It is similar to diuron and linuron but it works much better on ryegrass.
IPU was sold to Bayer in about 1986.
Crop safety, resistance and soil residues
IPU shows good crop safety with 4 litres/ha on loamy soils being very safe.
Sometimes on sandier soils an application of 6L/ha gave brief crop yellowing, however it was less damaging than 20g/ha of chlorsulfuron, the benchmark at the time.
Further, the adoption of no-tillage made all pre-emergent chemicals safer.
In Australia no ryegrass resistance has been recorded to this sub-group of IPU, according to Dr Peter Boutsalis.
The residual activity is low, particularly in acidic soil, while it takes longer to degrade in alkaline soils.
Very cold conditions can also extend the plant back period.
But Australian researchers have consistently shown that there was no evidence of adverse negative residual effects, and typically four to six weeks after the application, there was another flush of susceptible weeds germinating.
The rest of the world
In the 1970s, IPU became the herbicide of choice for weed control over much of Europe and the USA.
Sadly, it was over-used on urban footpaths and road verges, ending up in the waterways of Europe and America.
Now, farmers in these countries no longer have access to this wonderful chemical.
IPU is still registered for use in Ireland, India and New Zealand, where its responsible use allows for cheap and effective control of ryegrass on farms.
4Farmers even has a registration in New Zealand that only cost $4500.
Meetings with the Australian Pesticides and Veterinary Medicines Authority (APVMA) about IPU
4Farmers has been trying to get IPU registered in Australia for about 10 years and has interacted with the APVMA many times, however the cost of registering an old molecule with a long and safe track record is just as complicated as registering a novel molecule.
APVMA has asked for $105,000 up front to start the application process.
After that, it requires full testing, or data, to be done on crop and environmental safety.
This could tally $5 million which is a lot of money for a small Australian company.
Yet, most of this work has already been done elsewhere around the world.
Hoechst did the work in the 1970s and Bayer is the current holder of the registration data.
How helpful would it be if we could control mature ryegrass in a paddock that would otherwise need to be cut for hay.
A trial at Trevor Whittington's property in Corrigin (see photo of 5L IPU applied to a crop, right) showed high rates controlled large ryegrass plants extremely well.
Bayer and the Grains Research and Development Corporation (GRDC)
As we know, GRDC uses farmers money for research into ways to manage resistant ryegrass.
GRDC gave Bayer $45m to look for new modes of action to kill ryegrass.
The visual result was perhaps only Mateno Complete.
Bayer charges for Australian farmers to use it, yet I think it would have been more helpful to the dryland Wheatbelt farmer if Bayer could have registered IPU in Australia, instead.
4Farmers has a track record of registering and releasing off patent molecules.
These are the chemicals that have lowered the cost of farming, and 4Farmers is the company that drove it.
I encourage GRDC, Bayer and the APVMA to smooth the path for the commercialisation of IPU, which has a 45-year history of use globally.
I appeal on behalf of 4Farmers, and on behalf of dryland farmers, for the release of locked data that can move the regulatory process along, rather than leave IPU, this extremely useful molecule, on the shelf.
