resistance testing
Introduction
Annual ryegrass and wild oat resistance has been detected on properties scattered widely over most areas of Australia where these grasses are important weeds. There is little doubt that this problem is now a matter of great concern to all farmers involved in cropping.
There have been many cases of annual ryegrass and wild oat resistance documented worldwide. Resistance has also been detected in wild radish to herbicides popularly used for it's control. In extreme cases of resistance, farmers may lose the ability to employ a specific herbicide for weed control, which was previously considered essential.
Resistance is not a problem that will suddenly overwhelm a particular property. It may first occur in one paddock or even in small areas within a paddock, particularly where herbicides with the same mode of action have been utilised for several consecutive years. Detection of these areas will allow farmers to take action to prevent or delay the spread of resistance throughout their property.
Early detection of the resistance status of weeds is clearly desirable to enable appropriate cropping and rotational decisions to be made.
Need for a Test
Testing and knowledge of the resistance status of weeds on your property will put you in command of what is happening and allow you to manage the problem. The Agrisearch Resistance Test is the most economical way of acquiring this knowledge.
In comparison, herbicide failure as a result of resistance can be expensive and result in an increase in the development of resistant plants. The test will tell you whether resistant plants are present and the degree of resistance in the population.
The Agrisearch Services tests generally include the following herbicides, however, any single herbicide can be nominated by the client.
| Herbicides Tested Against | Herbicide Group |
|---|---|
| HOEGRASS (diclofop-methyl) | A: Aryloxyphenoxypropionate |
| SELECT (clethodim) | A: Cyclohexanedione |
| SERTIN PLUS (sethoxydim) | A: Cyclohexanedione |
| GLEAN (chlorsulfuron) | B: Sulfonylurea |
| GESATOP (simazine) | C: Triazine |
| TREFLAN (trifluralin) | D: Dinitroanaline |
| ROUNDUP MAX (glyphsate) | M: Phosphorous compound |
| AVADEX XTRA (tri-allate) | E: Thiocarbamate |
| MATAVEN-L (flamprop-methyl) | K: Amino propionate |
| BRODAL (diflufenican) | F: Phenoxynicotinalinide |
Type of Test
Five types of tests are performed at our laboratory. These tests have been continually fine-tuned over the past 11 years and are constantly validated through the use of known susceptible samples. They are:
- Multiple-Resistance Ryegrass Test
This test will indicate the level of resistance to four herbicide groups. Herbicides tested include HOEGRASS, SELECT, SERTIN PLUS, GLEAN, GESATOP and TREFLAN. If you have resistance on your farm this test may be necessary to plan control strategies. ROUNDUP MAX can also be tested if required.
Retail Price $253 (Inc. ROUNDUP $319) - Modified Multiple-Resistance Ryegrass Test
This test will indicate the level of resistance to members of two herbicide groups. Herbicides tested include HOEGRASS, SERTIN PLUS and GLEAN.
Retail Price $165 - Multiple-Resistance Wild Oats Test
This test will indicate the level of resistance to three herbicide groups. Herbicides tested include HOEGRASS, SELECT, SERTIN PLUS, AVADEX XTRA and MATAVEN-L. If you have resistance on your farm this test may be necessary to plan control strategies.
Retail Price $253 - Multiple-Resistance Wild Radish Test
This test will indicate the level of resistance to four herbicide groups. Herbicides tested include GLEAN, GESATOP, BRODAL and ROUNDUP MAX.
Retail Price $253 - Single Herbicide Resistance Test for Annual Ryegrass, Wild Oat, or Wild Radish
This tests whether or not the samples are resistant to any nominated herbicide and gives an indication of the degree of resistance in the population. Tests can be done with any currently registered herbicide to which resistance is suspected.
Retail Price $116 per Herbicide
Test kits are available from Agrisearch Services. If the customer is going through a dealer, they should make payment for the test when purchasing the test kit from the dealer. Agrisearch Services will then charge the dealer a wholesale price for test kits received, in one easy end of season transaction. Dealers should ensure that their name and address is stamped on the test kit in the appropriate place.
Further information may be obtained from Kathryn Adams - NSW/VIC (Ph: 02 6362 4539) Bill Frost - SA (08 8365 7266) or Michael Lamond - WA (Ph: 08 9641 2059).
Timing
Seed sampling is best done in the late spring and early summer period before grazing and/or weather removes the source.
Sampling
A sample of mature weed seed should be collected from within each area suspected of containing resistance. For the single herbicide tests, collect about 1 large handful. For multiple-resistance tests at least 2 large handfuls are required. A suspected area may be a complete paddock or as little as a few square metres.
Collect seeds from plants taken from all parts of the suspected area. For larger areas it is recommended that at least one sample should be taken from within an area no greater than 50 hectares. Keep detailed records of the sampling process including a small map indicating from where the seeds were collected.
Sampling should be done before stock are put into the area to be sampled or at least before they have eaten the seed heads of the surviving weeds.
Availability of Results
Seed collected in spring and early summer will generally not germinate for several months due to natural seed dormancy. Thus results from samples sent during that period will take about 3-4 months.
Samples collected later will have experienced some weathering and conditioning and should germinate earlier and therefore results will be available within a shorter period. All samples received by the end of January should have results by late April.
Obtaining Kits
Further information and kits may be obtained from:
Kathryn Adams (New South Wales/Victoria)
Agrisearch Services
50 Leewood Drive
Orange NSW 2800
Phone: 02 6362 4539
Email: agrisearch@agrisearch.com.au
Bill Frost (South Australia)
Agrisearch Services
16 Sunbeam Road
Glynde SA 5070
Phone: 08 8365 7266
Email: adelaide@agrisearch.com.au
Michael Lamond (Western Australia)
Agrisearch Services
Suite 1/134 Avon Terrace
York WA 6302
Phone: 08 9641 2059
Email: york@agrisearch.com.au