Herbicide efficacy in retained stubble systems

2017
CC BY 4.0

Research organisatons
Funding source

Trial details

Researcher(s) Amanda Cook (SARDI)
Ian Richter (SARDI)
Year(s) 2017
Contributor Eyre Peninsula Agricultural Research Foundation
Trial location(s) Site 9, 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). One of the barriers to retaining stubble is the perceived reduction in pre-emergent herbicide effectiveness (efficacy) in stubbles. This component of the project is testing whether various stubble management activities impact on herbicide efficacy.

 

Weed control in stubble retained systems can be compromised when stubbles and other plant 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; eg prolonged dormancy in barley grass has been confirmed in many paddocks on Minnipa Agricultural Centre (MAC). As a part of the stubble project this trial was undertaken to assess herbicide efficacy in different stubble management systems.

 

This article reports on the results of the third and final year of the trial. See EPFS Summaries 2015 and 2016 for previous trial reports.

Key messages

Dry seeding conditions and lack of rainfall at the start of the 2017 season resulted in challenging conditions for both establishing crops and weed control.

Stubble residues reduced plant establishment and weed numbers; standing stubble in dry conditions had higher wheat germination than chained stubble.

April dry sowing had lower wheat numbers than later sowings, which reduced grass weed competition during the season. Grass weed numbers were also higher and set more seed in the April sowing.

No pre-emergent herbicide provided total barley grass weed control and keeping the weed seed bank low through other methods is important.

Under the production regimes of upper EP, stubble management is unlikely to impact negatively on performance of pre-emergence herbicides targeting grass weed control, providing adequate water rates and best practice application techniques are used.

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

Thank you to Ian Richter, Brett Hay, Katrina Brands and Rochelle Wheaton for collecting grass weeds data. Trial funded by GRDC Maintaining profitable farming systems with retained stubble - upper Eyre Peninsula (EPF00001). Registered products: see chemical trademark list.


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

Method

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

Minnipa Agricultural Centre 2017

Sow rate or Target density 60kg/ha sowing rate
Sowing machinery

Plot seeder and header

Sow date 26 April 2017
Harvest date 17 November 2017
Plot size 12m x 2m
Plot replication 3
Fertiliser

DAP @ 60 kg/ha at sowing

Herbicide

All spray treatments were applied at 8 km/h using a shrouded boom with a 100 L/ha water rate, pressurised canisters at 2 bar and medium size spray nozzles.

 

Weed germination early in the season at the site was nil, due to low rainfall with no knockdown being required before any of the sowing times. The plants in TOS 1 and TOS 2 had poor emergence and did not fully emerge until late June/early July when significant rainfall events occurred. Due to the very late start to the season another small replicated trial was sown into a moist seedbed with selected treatments.

TOS1

Control

Trifluralin (2 L/ha)

Sakura (pre-emergent)

Boxer Gold (pre-emergent)

Trifluralin (2 L/ha) + Avadex (1.6 L/ha) + 900diuron (500 g/ha)

TOS2

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 = 360 ga/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 (2 L/ha) + Avadex (1.6 L/ha) + 900diuron (500 g/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) 3L (pre-emergent) + Boxer Gold 2.5 L (post)

TOS3

Control

Trifluralin 2 L/ha (pre-emergent)

Sakura (pre-emergent)

Boxer Gold (pre-emergent)

Download the trial report to view additional method/treatment information

Download results

Trial results Table 1

# Treatment 1
Grain yield (t/ha) Barley grass density (plants/m2) Establishment plants (plants/m2) Cost ($/ha)
1 Control Untreated 0.47 24.6 116.9 0
2 Trifluralin (1.5 L/ha) 0.47 22.9 114.6 9
3 Trifluralin (2 L/ha) 0.48 23.8 109.6 12
4 Trifluralin (1.5 L/ha) + Lexone (metribuzin) 180 g (post)* 0.47 5.6 104.2 15
5 Trifluralin (1.5 L/ha) + Diuron 900 (400 g/ha = 360 ga/ha)*(pre-emergent) 0.49 13.8 105.2 14
6 Trifluralin (1.5 L/ha) + Diuron 900 (high rate)* (pre-emergent) 0.5 14 121.5 19
7 Trifluralin (1.5 L/ha) + Avadex (Tri-allate) (1.6 L/ha) (pre-emergent) 0.52 11.1 113.1 25
8 Trifluralin (2 L/ha) + Avadex (1.6 L/ha) + 900diuron (500 g/ha)* (pre-emergent) 0.47 12.9 115.8 28
9 Trifluralin (1.5 L/ha) (pre) + Monza (sulfosulfuron) (25 g/ha) (post) 0.5 18.2 108.4 35
10 Monza (sulfosulfuron) 25 g (pre-emergent) 0.5 4.2 117.3 26
11 Sakura (118 g) (pre-emergent) 0.51 7.6 112.6 40
12 Monza (sulfosulfuron) (25 g) + Sakura (118 g) (pre-emergent) 0.49 4.7 113.3 66
13 Sakura (118 g)+ Avadex (Tri-allate) 3 L (pre-emergent) 0.49 5.6 111.9 70
14 Boxer Gold (2.5 L/ha) (pre-emergent) 0.49 10.4 105.7 37
15 Boxer Gold (2.5 L/ha) (post) 0.44 24 117 37
16 Sakura (118g)+ Avadex (Tri-allate) 3L (pre-emergent) + Boxer Gold 2.5 L (post) 0.52 5.1 109.1 107

Grain yield t/ha


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Barley grass density plants/m2


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Cost $/ha


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Establishment plants plants/m2


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Observed trial site soil information
Trial site soil testing
Site Depth Type pH EC P K N A OC CAT
Site 9, Minnipa Agricultural Centre, SA 0 - 10cm 7.70 36.00
Site 9, Minnipa Agricultural Centre, SA 0 - 100cm 67.00
Soil conditions
Trial site Soil texture
Site 9, Minnipa Agricultural Centre, SA Red loam
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Site 9, 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 9, Minnipa Agricultural Centre SA
2017 437.2mm
2016 409.0mm
2015 381.0mm
2014 439.7mm
2013 385.5mm
2012 407.7mm
2011 453.8mm
2010 454.3mm
2009 466.5mm
2008 380.6mm
2007 367.6mm
2006 384.7mm
2005 350.4mm
2004 343.8mm
2003 348.6mm
2002 343.5mm
2001 396.8mm
2000 422.6mm
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 9, Minnipa Agricultural Centre SA 2017


Observed climate information

Rainfall avg ann (mm) 325mm
Rainfall avg gsr (mm) 242mm
Rainfall trial total (mm) 281mm
Rainfall trial gsr (mm) 155mm

Derived climate information

Site 9, 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 13:31pm AEST