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​Tips for Diversity and Integration in Weed Control

weed controlIf you look at the chemical control of weeds specifically, there have been no new herbicide mode of action groupings for around 20 years.

With the cost of bringing a new mode of action to market thought to be around 250 million AUD and taking 10 to 15 years, longevity of chemistry is paramount.
However, a look at the ever increasing list of herbicide resistant weeds identified around Australia paints a troublesome picture (see the Croplife Australia website for a current listing of herbicide resistant weeds by Mode of Action groupings, where 19 grass species and 24 broadleaf species are listed as resistant to one or more MOA at one or many sites around the country).

What does this all potentially mean for weed controllers?
  • A changing weed scape whereby herbicide resistant/tolerant weeds increase in prevalence, as we see with stinging nettle, wild radish, flaxleaf fleabane marshmallow, erodium etc.
  • Greater cost as new chemistries are developed and used, the higher cost reflecting the need to recover the 250 million in R&D plus some profit
  • Public funding for weed control covers a lesser area due to the increased costs (and diminished funding in some areas)
  • Yield and quality loss of produce
  • Lesser land value for arable land with weed resistance to multiple modes of action
  • Weed control becoming an ever-increasing biosecurity concern for all land managers
  • Higher risk of musculoskeletal injury from hand rogueing/chipping resistant weeds.

So what is the solution?

Is there a breakthrough or dynamic solution in the wings which will be as revolutionary as glyphosate was at first release?

The skeptics would say a broad spectrum non selective herbicide is both the solution and the problem, creating bare ground for opportunistic weeds to colonise. Who knows, but in the interim the best way forward is a systemic, diversified and integrated approach employing as many techniques as possible from the Integrated Weed Management (IWM) toolkit:

1. Start off by learning more about the enemy, its correct identification, its life cycles, growth and reproduction. Hand roguing may work well for an annual, but obviously more difficult for a perennial with a deep tap root. Check out the GRDC weed ID app for help with identification as well as the WeedSmart app to assess herbicide resistance and weed seed bank risk. 

2. Broaden your knowledge further with a free online course on herbicide resistance. Go to www.diversityera.com for both theory and some practical tips to help you manage herbicide resistance in the field.

3. Often overlooked are the spray application fundamentals including tank mixing surfactant choice and weather. There are various spray workshops around the country, Chemcert training courses and some exciting new drift retardants such as Caltex Dead Sure which has been shown to work well for glyphosate/2,4-D herbicide mixes. A herbicide resistance test may prove negative on your property and prompt you to improve your spray applications, their timing and surfactant choice. A “Quick Test” from Plant Consulting costs $150 for one MOA; $495 for 5 MOA’s and their website details the correct sampling process, note the test is for grasses and some broadleaf weeds.


Using physical controls such as mowing or slashing is another tool but without proper timing (vegetative not reproductive) and appropriate hygiene (cultural controls such as machinery washdown) weed seed can be spread over great distances as can be seen with roadside vegetation control.

Make weed control a key biosecurity focus both at your workplace and collectively with your neighbours and we are on our way to a more productive and aesthetically pleasing landscape.