Targeting wild radish as early as the label will allow and mixing herbicide modes of action (MOA) are keys to effective weed control and optimising grain yields.
This has been backed-up by findings from two separate GRDC-funded projects conducted in the central and northern Wheatbelt regions last year.
Trials in Bolgart and Tammin investigated wild radish control and cereal crop safety using an early application of Jaguar (Group C and F) and a range of MOA options for use with common phenoxy applications 2,4-D amine and LV Ester 680 for late control (prior to flag leaf).
Synergy Consulting conducted this research and found the use of multiple MOA increased the robustness of weed control.
An early spray of Jaguar at the full label rate of 1 litre/hectare achieved 100% control at both trial sites when used on small wild radish plants (two to six leaf stage). Control slipped to 39% at Bolgart using Jaguar on bigger weeds.
This highlights the importance of removing early weed competition and spraying when weeds are most susceptible, even when conditions are a little dry. If the soil is moist, there is useful ‘residual’ activity as a bonus.
When radish reaches the six leaf stage, herbicide dosage for control increases exponentially.
Although it is difficult to get back over crop at this stage it can be worth it to reduce the number of ‘carry-through’ radish which a second ‘late’ spray will have great difficulty handling.
The Synergy Consulting trials showed the new group H chemistry was the standout performer in plots that were not sprayed early.
MOA that performed well in these trials included:
|Velocity® - single spray
|Jaguar® - single spray
|| C & F
|Velocity® + LV Ester
|| H &C & I
|Precept® + Bromoxynil
|| H & I & C
|Jaguar® + LV Ester
|| C & F & I
|Tigrex® + Bromoxynil
|| F & I & C
|Velocity® + Tigrex®
|| H & F & I
There was a 1.1 t/ha advantage in spraying versus not spraying in the Bolgart and Tammin trials and, on average, early sprayed plots yielded 0.3 t/ha higher than late sprayed plots.
Trials in the northern Wheatbelt in 2012 found timing and application – rather than product choice – were the best ways to deal with wild radish.
Former Geraldton-based Department of Agriculture and Food WA weeds research officer Peter Newman and Planfarm consultant Andrew Sandison coordinated these trials, investigating more than 20 herbicide mixes and sequencing to find the most effective post emergent combinations.
Funded by the GRDC, as part of its Regional Cropping Solutions Network (RCSN) initiative, the aim was to find options that would help protect valuable new actives such as Velocity®, Precept® and Ecopar® from over-reliance by farmers and the development of resistance.
The trials found two spray strategies were the most effective for radish control, giving 60% to100% control over all herbicide treatments.
A one spray strategy, whether applied early or later, was far less effective in controlling radish - resulting in between 45% and 85% successful control.
Two spray strategies that used Velocity® as the first spray were generally more robust, with control ranging from 90% to 100%.
There were many effective combinations tested in the trials that used older actives as part of the spray strategy. Using some of the older actives could reduce reliance on the newer chemistries.
Recommendations stemming from the trial results include spraying early post-emergent when weeds are small (cotyledon to three leaf) – with good coverage – and then following-up with another application 3-4 weeks later to control subsequent germinations and mop up any survivors from the first spray.
This double-knock tactic proved to be highly effective in controlling very herbicide resistant wild radish in the northern Wheatbelt trials last year.
Using full label water rates and boosting spray capacity, where possible, with existing or new machinery will also increase weed control effectiveness.
To increase the efficiency of existing machinery, the key is to have chemical on-hand early, potentially employ extra staff and use nurse tanks to speed the application process.
Or, where possible, investing in new machinery to cover more ground faster may pay off in the longer term.
Andrew Sandison, Planfarm consultant,
08 9964 1170,
Peter Newman, Planfarm consultant,
0427 984 010,
Cameron Weeks, Geraldton Port Zone RCSN facilitator,
0427 006 944,
More details about the RCSN wild radish research trial results are contained in the May/June edition of the GRDC Magazine Ground Cover: www.grdc.com.au/RV/GC104W
See also GRDC’s Ground Cover May/June supplement Making Herbicides Last: www.grdc.com.au/GC104
To find out more about Australian research programs targeting herbicide resistance and resistance management, visit the AHRI website at www.ahri.uwa.edu.au
For comprehensive weed management information visit the WeedSmart website and information hub at: www.weedsmart.org.au
More information about the GRDC’s RCSNs is available at www.grdc.com.au/rcsn
Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of the Grains Research and Development Corporation.
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We do not endorse or recommend the products of any manufacturer referred to. Other products may perform as well as or better than those specifically referred to.
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CAUTION: RESEARCH ON UNREGISTERED PESTICIDE USE
Any research with unregistered pesticides or of unregistered products reported in this document does not constitute a recommendation for that particular use by the authors or the authors’ organisations.
All pesticide applications must accord with the currently registered label for that particular pesticide, crop, pest and region.
GRDC Project Code
West, North, South