Herbicide efficacy in retained stubble systems

2015
CC BY 4.0

Research organisatons
Funding source

Trial details

Researcher(s) Amanda Cook (SARDI), Andy Bates (Bates Agricultural Consulting), Wade Shepperd and Ian Richter (SARDI)
Year(s) 2015
Contributor Eyre Peninsula Agricultural Research Foundation
Trial location(s) Site 23, Minnipa Agricultural Centre, SA
Related trials
Herbicide efficacy in retained stubble systems locations
Aims

The GRDC project ‘Maintaining profitable farming systems with retained stubble - upper Eyre Peninsula’ aims to improve farm profitability while retaining stubble in farming systems on upper Eyre Peninsula (EP). Weed control in stubble retained systems can be compromised when stubbles and organic residues intercept the herbicide and prevent it from reaching the desired target, or the herbicide is tightly bound to organic matter. Reduced herbicide efficacy in the presence of higher stubble loads is a particular issue for pre-emergence herbicides. Current farming practices have also changed weed behavior with a shift in dormancy in barley grass genotypes now confirmed in many paddocks on Minnipa Agricultural Centre (MAC) (B Fleet, EPFS Summary 2011, p 177). As a part of the stubble project this trial was undertaken to assess herbicide efficacy in different stubble management systems.

Key messages
  • In 2015 the drier start to the season and low soil moisture resulted in lower herbicide efficacy and less chemical damage than expected.
  • In different stubble management systems the activity and resulting weed control of specific herbicides will be influenced by the solubility index (movement through the soil profile with rainfall events) of that herbicide. Soil texture and soil chemical properties can affect chemical movement and availability in the soil profile.
  • Herbicide performance will vary seasonally due to soil moisture levels, rainfall pattern post application, timing of weed germination, position and number of weed seeds in the profile, etc. Understanding how the various herbicides work can reduce the likelihood of failures.
  • Herbicides are only one tool for weed control – always adopt an integrated weed control package that includes non-chemical control, and where possible, consecutive seasons of total weed control.
  • Consider the whole farming system when making chemical decisions as the impact may last for several seasons (eg. effects on medic germination and medic seed bank).
Lead research organisation Eyre Peninsula Agricultural Research Foundation
Host research organisation SARDI Minnipa Agricultural Centre
Trial funding source GRDC EPF00001
Related program Maintaining profitable farming systems with retained stubble
Acknowledgments

Thanks to Sue Budarick for her help and processing samples from this trial. Trial funded by GRDC Maintaining profitable farming systems with retained stubble - upper Eyre Peninsula (EPF00001).


Other trial partners Not specified
Download the trial report to view additional trial information

Method

Crop type Wheat
Treatment type(s)
  • Herbicide: Type
  • Herbicide: Rate
  • Stubble: Management
Trial type Experimental
Trial design Replicated

Minnipa Agricultural Centre 2015

Sow rate or Target density 60kg/ha
Sowing machinery

The trial was sown at 3-4 cm depth with an Atom-Jet spread row seeding system with press wheels (plot seeder)

Sow date 10 May 2015
Harvest date Not specified
Plot size 20m x 2m
Plot replication 3
Fertiliser

DAP @ 60 kg/ha

Herbicide

knockdown of 1.2 L/ha of Roundup Attack on 11 May

Chemical treatments listed below were individually mixed in small pressure containers and applied on the 11 and 12 May using a shrouded boomspray at 100 L/ha of water.

Control Untreated

Trifluralin (1.5 L/ha)

Trifluralin (2 L/ha)

Trifluralin (1.5 L/ha) + Lexone (Metribuzin) 180 g (post)

Trifluralin (1.5 L/ha) + Diuron 900 (400 g/ha) (pre-emergent)

Trifluralin (1.5 L/ha) + Diuron 900 (high rate) (pre-emergent)

Trifluralin (1.5 L/ha) + Avadex (Tri-allate) (1.6 L/ha) (pre-emergent)

Trifluralin (1.5 L/ha) (pre) + Monza (sulfosulfuron) (25 g/ha) (post)

Monza (sulfosulfuron) 25 g (pre-emergent)

Sakura (118 g) (pre-emergent)

Monza (sulfosulfuron) (25 g) + Sakura (118 g) (pre-emergent)

Sakura (118 g)+ Avadex (Tri-allate) 3 L (pre-emergent)

Boxer Gold (2.5 L/ha) (pre-emergent)

Boxer Gold (2.5 L/ha) (post)

Sakura (118g)+ Avadex (Tri-allate) 3 L (pre-emergent) + Boxer Gold 2.5 L (post)

Download the trial report to view additional method/treatment information

Download results

Trial results Table 1

# Treatment 1
Crop Establishment (plants/m2) Average medic growth ((0-3) rating) Chemical cost ($/ha) Dry matter (t/ha) Yield (t/ha) Early in-crop barley grass 24 July (plants/m2) Late barley grass 26 Oct (plants/m2) Income less chemical cost ($/ha)
1 Control Untreated 102 1.5 0 0.23 1.55 7.3 11.1 391
2 Trifluralin (1.5 L/ha) 98 1.4 9 0.2 1.63 4.6 8.8 402
3 Trifluralin (2 L/ha) 99 1.1 12 0.21 1.58 2 8 386
4 Trifluralin (1.5 L/ha) + Lexone (Metribuzin) 180 g (post) 98 0.3 15 0.2 1.64 5.3 11.7 399
5 Trifluralin (1.5 L/ha) + Diuron 900 (400 g/ha) (pre-emergent) 98 1 14 0.21 1.64 3.4 7.8 399
6 Trifluralin (1.5 L/ha) + Diuron 900 (high rate) (pre-emergent 102 1 19 0.24 1.67 3.5 5.7 402
7 Trifluralin (1.5 L/ha) + Avadex (Tri-allate) (1.6 L/ha) (pre-emergent) 95 1.2 25 0.23 1.64 2 8.3 388
8 Trifluralin (1.5 L/ha) (pre) + Monza (sulfoslfuron) (25 g/ha) (post) 101 0.2 35 0.21 1.66 3.3 7.1 384
9 Monza (sulfosulfuron) 25 g (pre-emergent) 98 0 26 0.2 1.65 5.3 2.8 390
10 Sakura (118 g) (pre-emergent) 96 0.8 40 0.17 1.64 2.5 1.8 373
11 Monza (sulfosulfuron) (25 g) + Sakura (118 g) (pre-emergent) 101 0 66 0.19 1.61 2.6 1 340
12 Sakura (118 g) + Avadex (Tri-allate) 3 L (pre-emergent) 96 0.8 70 0.22 1.64 1 0.5 343
13 Boxer Gold (2.5 L/ha) (pre-emergent) 97 0.9 37 0.21 1.59 4.1 9.7 364
14 Boxer Gold (2.5 L/ha) (post) 103 1.3 37 0.26 1.6 5.6 11.6 366
15 Sakura (118 g) + Avadex (Tri-allate) 3 L (pre-emergent) + Boxer Gold 2.5 L (post) 97 0.6 107 0.18 1.63 1.5 1 304

Average medic growth (0-3) rating


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Chemical cost $/ha


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Crop Establishment plants/m2


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Dry matter t/ha


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Early in-crop barley grass 24 July plants/m2


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Income less chemical cost $/ha


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Late barley grass 26 Oct plants/m2


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Yield t/ha


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Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Site 23, Minnipa Agricultural Centre, SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Site 23, Minnipa Agricultural Centre, SA Calcarosol
Soil Moisture Source: BOM/ANU
Average amount of water stored in the soil profile during the year, estimated by the OzWALD model-data fusion system.
Year Site 23, Minnipa Agricultural Centre SA
2015 362.5mm
2014 418.7mm
2013 359.7mm
2012 398.5mm
2011 425.7mm
2010 407.2mm
2009 421.5mm
2008 355.4mm
2007 357.4mm
2006 394.7mm
2005 368.2mm
2004 367.4mm
2003 380.2mm
2002 375.4mm
2001 420.1mm
2000 422.7mm
National soil grid Source: CSIRO/TERN
NOTE: National Soil Grid data is aggregated information for background information on the wider area
Actual soil values can vary significantly in a small area and the trial soil tests are the most relevant data where available

Soil properties

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Climate

Site 23, Minnipa Agricultural Centre SA 2015


Observed climate information

Rainfall avg ann (mm) 325mm
Rainfall avg gsr (mm) 241mm
Rainfall trial total (mm) 333mm
Rainfall trial gsr (mm) 258mm

Derived climate information

Site 23, Minnipa Agricultural Centre SA

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Some data on this site is sourced from the Bureau of Meteorology

SILO weather estimates sourced from https://www.longpaddock.qld.gov.au/silo/
Jeffrey, S.J., Carter, J.O., Moodie, K.B. and Beswick, A.R. (2001). Using spatial interpolation to construct a comprehensive archive of Australian climate data , Environmental Modelling and Software, Vol 16/4, pp 309-330. DOI: 10.1016/S1364-8152(01)00008-1.



Trial last modified: 04-06-2019 13:29pm AEST