Herbicide resistance testing
Herbicides have become the most efficient and cost-effective methods of weed control in farming.
With repeated use of the same herbicide or herbicides with similar modes of action however, resistance can develop.
What is herbicide resistance?
Herbicide resistance is the ability of an individual plant to survive the application of a herbicide that would kill a normal population of the same species. This means that a herbicide you used to spray, no longer works and the weeds continue to grow.
Herbicide resistance testing is an important tool in a farmers toolbox. Testing enables us to confirm suspected cases of weed resistance to available chemicals. This is becoming more important in our ever-changing environment as it allows us to make the best decisions both economically and agronomically.
Doing a herbicide resistance test will help to:
- understand what herbicides your weeds are susceptible to
- avoid spending money on a chemical strategy that may not work
- assist in making a crop and herbicide rotation plan.
Types of tests
There are two types of resistance tests available. Each have their own advantages and disadvantages as explained below.
The quick test
|Can test any time throughout the year||Cannot test pre-emergent chemistry|
|Takes a couple of weeks to get results||Tests can be influenced by a bias sample|
|Provides information for current season decisions||Results heavily reliant on quality sample|
The seed test
The Seed Test takes ripe weed seeds which are collected around harvest time. Weed seeds are planted out and once dormancy is broken the weeds are sprayed and tested with the required herbicides. This process normally takes a few months. Charles Sturt University’s John Broster or Plant Science Consulting are both able the complete this form of testing.
|Provides information for future seasons||Samples need to be collected within a limited window|
|Can test pre-emergent chemistry||Takes a couple of months to get results|
|Easy collection process to obtain quality sample||Seed dormancies need to be broken|
The cost of doing herbicide resistance testing is small by comparison to the damage that can be done to a crop. Pricing does depend on the number of chemicals being tested for resistance. Investment typically starts at $150.
Other weed and crop tests are also available from Plant Science Consulting.
Article written by Lisa Gillogly, agronomist at Elders West Wyalong.
Elders offers a range of crop protection products.
For expert advice specific to your crop consult your local Elders agronomist.