| Researcher(s) |
Amanda Cook (SARDI) Ian Richter (SARDI) |
|---|---|
| Year(s) | 2017 |
| Contributor | Eyre Peninsula Agricultural Research Foundation |
| Trial location(s) |
Minnipa Agricultural Centre, SA
|
| Related trials |
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.
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 |
| Crop type | Cereal (Grain): Wheat |
|---|---|
| Treatment type(s) |
|
| Trial type | Experimental |
| Trial design | Replicated |
| 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) |
| # |
Treatment 1
|
Establishment plants (plants/m2) | Cost ($/ha) | Grain yield (t/ha) | Barley grass density (plants/m2) |
|---|---|---|---|---|---|
| 1 | █ Control Untreated | 116.9 | 0 | 0.47 | 24.6 |
| 2 | █ Trifluralin (1.5 L/ha) | 114.6 | 9 | 0.47 | 22.9 |
| 3 | █ Trifluralin (2 L/ha) | 109.6 | 12 | 0.48 | 23.8 |
| 4 | █ Trifluralin (1.5 L/ha) + Lexone (metribuzin) 180 g (post)* | 104.2 | 15 | 0.47 | 5.6 |
| 5 | █ Trifluralin (1.5 L/ha) + Diuron 900 (400 g/ha = 360 ga/ha)*(pre-emergent) | 105.2 | 14 | 0.49 | 13.8 |
| 6 | █ Trifluralin (1.5 L/ha) + Diuron 900 (high rate)* (pre-emergent) | 121.5 | 19 | 0.5 | 14 |
| 7 | █ Trifluralin (1.5 L/ha) + Avadex (Tri-allate) (1.6 L/ha) (pre-emergent) | 113.1 | 25 | 0.52 | 11.1 |
| 8 | █ Trifluralin (2 L/ha) + Avadex (1.6 L/ha) + 900diuron (500 g/ha)* (pre-emergent) | 115.8 | 28 | 0.47 | 12.9 |
| 9 | █ Trifluralin (1.5 L/ha) (pre) + Monza (sulfosulfuron) (25 g/ha) (post) | 108.4 | 35 | 0.5 | 18.2 |
| 10 | █ Monza (sulfosulfuron) 25 g (pre-emergent) | 117.3 | 26 | 0.5 | 4.2 |
| 11 | █ Sakura (118 g) (pre-emergent) | 112.6 | 40 | 0.51 | 7.6 |
| 12 | █ Monza (sulfosulfuron) (25 g) + Sakura (118 g) (pre-emergent) | 113.3 | 66 | 0.49 | 4.7 |
| 13 | █ Sakura (118 g)+ Avadex (Tri-allate) 3 L (pre-emergent) | 111.9 | 70 | 0.49 | 5.6 |
| 14 | █ Boxer Gold (2.5 L/ha) (pre-emergent) | 105.7 | 37 | 0.49 | 10.4 |
| 15 | █ Boxer Gold (2.5 L/ha) (post) | 117 | 37 | 0.44 | 24 |
| 16 | █ Sakura (118g)+ Avadex (Tri-allate) 3L (pre-emergent) + Boxer Gold 2.5 L (post) | 109.1 | 107 | 0.52 | 5.1 |
| Rainfall avg ann (mm) | 325mm |
|---|---|
| Rainfall avg gsr (mm) | 242mm |
| Rainfall trial total (mm) | 281mm |
| Rainfall trial gsr (mm) | 155mm |
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.
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