The 2025 Australian turf herbicide resistance groups chart shows herbicide groups and their mode of action (MOA). This turf grass herbicide groups chart includes:
- The sulfonylureas.The Monument herbicide alternative, Recondo herbicide is a sulfonylurea and a Class 2 herbicide. Duke herbicide is also in this group.
- Group 27; the Pyrazoles (Pylex).
- Group 30; Benzyl ethers (Poacure).
- Pre emergent herbicides.
The herbicide resistance chart also has a pre-emergent and post emergent weed management strategy. For example, granular pre emergents are under Groups 3, 14 and 15.
Why use a Herbicide Resistance Chart?
Stop The Development of Resistance.
If you understand the herbicide Mode of Action (MOA), you can avoid the repeat use of chemicals with the same MOA. This is the main driver for the development of resistance in weeds.
Manage Any Existing Resistance.
The chart helps you develop an integrated weed management (IWM) strategy.
You can use this resistance chart with our other free tools for turf managers.
- Turf fungicide resistance.
- Turf insecticide resistance.
- Weed ID.
- The free 2024 turf chemical Guide. This is to help turf managers get the best results from their weed, disease and insect programs.
Herbicide Mode of Action Groups.
A herbicide’s mode of action is how it interferes with processes in plants. Different turf herbicides may have the same mode of action, and those that have the same mode of action are categorised into groups that range from 1 to 30 (see below).
Herbicide Groups.
Some Groups have a higher risk of developing herbicide resistance. For example, Groups 1 and 2 are much more likely to develop resistance than Groups 4, 22 and 9.
- Group 1. You only use Group 1 herbicides to control grass weeds. They have no effect on broadleaf weeds. A good example of a Group 1 herbicide is Destro which contains Diclofop-methyl. This group is the second most likely to develop resistance.
- Group 2. Herbicide resistance is common with Group 2. This group contains Recondo/Monument, Destiny/Duke, Coliseum and Sempra/Prosedge. These are the most likely of all the groups to develop resistance.
- Group 3. These are root growth inhibitors. These are easy to identify because of their yellow colour. They control grass weeds, and small broad leaf seedlings.
- Group 4. These are mainly selective for broad leaf weeds in turf.
- Group 5. Group 5 includes Metribuzin. They control grass and dicot weeds.
- Group 6. These control grass weeds and dicot weed seedlings.
As we discuss in our blog “factors that affect herbicide performance”, resistance is a weed’s genetic ability to survive a chemical dose that normally kills a weed. When this happens It means that you get poor results, because resistant weeds are able to survive doses way above the label rate.
In Australia, there are now over 25 weeds that are resistant to at least one herbicide group. In turf grass, this has become an increasing global issue. For example in 2019 there were over 40 reports of resistance.
This means this herbicide resistance chart is a great tool to continue to get long-term results from your weed control programs into the future.
This link goes to a herbicide classification tool.
Download 2025 Herbicide Resistance Chart
How to reduce herbicide resistance?
How to reduce the herbicide resistance chart.
- Always Rotate Modes of Action (MOA) groups. If you always use herbicides with the same MOA you tend to select for resistant plants within a population.
- If you use tank mixes of different herbicide groups it helps delay herbicide resistance.
- Try and use mixes of Pre- and Post-Emergents in the same tank. This is a key strategy to help prevent resistance.
- When you spray treat the entire area. This minimises any “escapes”.
- A cultural program that favours turf grass at the expense of weeds is an excellent non chemical approach to manage resistance.
- There are 12 MOA groups that manage Winter grass. Four of these are pre-emergents and eight are post emergents. Winter grass has confirmed resistance to eight of these MOA groups.
- If you intend to seed, use cultivars that outcompete weeds.
Why isn’t my herbicide working on weeds?
What is “Mode of Action (MOA)?”
How a herbicide controls susceptible plants is the MOA. It can be:
- The biological process or enzyme in the plant that the herbicide interrupts.
- The injury symptoms seen on susceptible plants.
The best way to manage resistance is to adopt an integrated weed management (IWM) strategy and:
- Make sure that resitant weeds do not seed.
- Regularly check for resistant plants.
- Do not rely on the same chemical group for weed control (rotate herbicides from different Groups).
Jerry Spencer
Jerry has an Hons Degree in Soil Science (1988) from Newcastle Upon Tyne University. He then worked as a turf agronomist for the Sports Turf Research Institute (STRI) until 1993.
He gained a Grad Dip in Business Management from UTS in 1999. He has held a number of technical roles for companies such as Arthur Yates (Commercial Technical Manager) and Paton Fertilizers (Organic, turf specialty and controlled release fertiliser) portfolios.
In 2013 he established Gilba Solutions as independent sports turf consultants and turf agronomists. Jerry has written over 100 articles and two books on a wide range of topics such as Turf Pesticides and turfgrass Nutrition which have been published in Australia and overseas.