IWM 101

As more weeds become herbicide resistant to one or more MOA’s, and with new MOA’s not on the horizon, it is imperative to integrate non-herbicide tactics into weed management. 

What is IWM?

IWM is the combination of a range of weed control tactics, both herbicide and non-herbicide, to reduce weed pressure and to keep weeds at low levels.
IWM involves a diverse range of weed control methods.

As WeedSmart promotes, IWM is about controlling every weed, every seed, every farm, every year, so that farmers call the shots rather than the weeds.

The goals of an IWM plan are;

  1. Suppress weed growth and development to limit their ability to decrease yield
  2. Minimise weed seed production to reduce weeds returning to the seed bank
  3. Deplete the seed bank to minimise subsequent germinations
  4. Prevent or reduce the spread of weeds


What can I do about it?

Globally, Bayer is focused on the challenge of managing herbicide resistance because the challenge of feeding a global population – estimated to be over 9 billion by 2050 - is being made more difficult with resistant weeds. Every year weeds steal yield from food crops sufficient to feed an estimated 1 billion people.

Bayer has developed IWM Core Guidelines to help growers and advisors.


1.    Know your weed – consider

  • Different weeds respond to management differently
  • Some weeds are more competitive than others
  • Seed production and shattering characteristics
  • Weed emergence characteristics
  • Annual vs perennial weeds
2.    Develop a plan
  • Diversify weed management measures to keep weeds off balance
  • Enhance crop competiveness - competitive varieties, row spacing, high seeding rates, early sowing, optimised fertiliser rates and placement
  • Start clean - allows good establishment
  • Aggressively manage weeds - keep numbers low
  • Maximise herbicide activity – recommended rates on small weeds in optimum application conditions
3.    Do it!
  • The best time to start is now

Nationally, Bayer CropScience is a strong supporter of WeedSmart’s Big 6 weed management measures
  1. Rotate Crops and Pastures
  2. Double Knock to Preserve Glyphosate
  3. Mix and Rotate Herbicides
  4. Stop Weed Seed Set
  5. Crop Competition
  6. Harvest Weed Seed Management
Contact your local Bayer Representative for more information on Integrated Weed Management
Benefits of integrating several non-chemical methods with herbicide use.

Use the free Resistance Tracker to learn more about weed resistance in your area. Enter your postcode and pin point exactly which weeds you should be on the lookout for. 
Understand herbicide modes of action and find out which weeds have developed resistance to specific MOAs. 
Searching Bayer herbicides that may help
Remembering to ‘Mix It Up’
Find out why ‘mixing it up’ matters locally and around the world