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Barley grass control in a pasture-wheat-pasture rotation

2019 - 2021

Research organisatons
Funding sources
Department of Primary Industries and Regional Development WA Kellerberrin Demonstration Group Department of Agriculture and Food WA
<abbr title='Grains Research and Development Corporation'>GRDC</abbr> <abbr title='Department of Primary Industries and Regional Development (Western Australia)'>DPIRD WA</abbr>

Trial details

Researcher(s) Catherine Borger
Brad Joyce
Contact email catherine.borger@dpird.wa.gov.au
Contact phone 0467816082
Year(s) 2019 - 2021
Contributor Department of Primary Industries and Regional Development WA
Trial location(s) North Kellerberrin, WA
Related trials
Barley grass control in a pasture-wheat-pasture rotation locations
Aims

Barley grass is becoming an increasingly problematic weed in Western Australia. A GRDC funded project sought to increase the adoption of integrated weed management tactics for barley grass, by working with grower groups to develop regionally appropriate rotations for optimal control.

A survey indicated that in the central-eastern wheatbelt, barley grass is mainly an issue in pasture. While barley grass also grows in crops, it is rarely the most prominent cropping weed. The KDG group aimed to investigate grass selective herbicides and late-season control in pasture, and pre-emergent herbicides in-crop, to find the best combination of practices that would control barley grass while also removing other grass weed species in a three-year rotation.

The trial aimed to investigate Group 1 herbicides and spray topping in 2019, pre-emergent herbicides and knockdowns in 2020 and Group 2 herbicides and spray topping in 2021.

Key messages
  • Group 1 (A) selective herbicide in 2019 gave good barley grass control, with an early application (2-4 leaf) better than a late application (Z31). Group 2 (B) herbicide in 2021 pasture gave similar results but control was not as effective.
  • Paraquat spray topping in 2019 did not reduce seed set.
  • Slashing in 2021 gave excellent seed set control.
  • Effective Group A weed control in 2019 combined with Sakura® + Treflan® in 2020 successfully reduced this very dense barley grass population by 98% compared to a rotation of grazing (no herbicide) in 2019 and Treflan® alone in 2020, but barley grass was still dense in 2021.
  • The seedbank lasts 3-4 years, particularly in dry years where not all seed has the opportunity to emerge.
North Kellerberrin WA 2019 Mixed species

The trial was a volunteer pasture, which was not sown or harvested. Seeding date entered here is when the pasture species emerged. Harvest date is when the pasture senesced.

North Kellerberrin WA 2020 Wheat

Effective Group 1 (A) weed control in 2019 combined with Sakura® + Treflan® in 2020 successfully reduced this very dense barley grass population by 98% compared to a rotation of grazing (no herbicide) in 2019 and Treflan® alone in 2020.

North Kellerberrin WA 2021 Mixed species

Group 2 (B) herbicide in 2021 pasture controlled barley grass at the 2-4 leaf stage but was not as effective as Group 1 (A) herbicide in the 2019 pasture.

Slashing in 2021 removed all panicles and prevented seed set.

Lead research organisation Kellerberrin Demonstration Group
Host research organisation Department of Agriculture and Food WA
Trial funding source GRDC UOA1903-004SAX
Trial funding source DPIRD WA UOA1903-004SAX
Related program Demonstrating and validating the implementation of integrated weed management strategies to control barley grass in the low rainfall zone farming system
Acknowledgments

We would like to thank Gavin Morgan for providing the trial site, staff at ConsultAg, Nerys Wilkins and Pete Gray (DPIRD) for their assistance with the trial management and measurements.
Other trial partners University of Adelaide, ConsultAg
Download the trial report to view additional trial information

Method

Crop types Pasture: Mixed species Cereal (Grain): Wheat
Treatment type(s)
  • Herbicide
  • Herbicide: Timing
  • Herbicide: Type
Trial type
Trial design

North Kellerberrin 2019 Mixed species

Sow rate or Target density Not specified
Sowing machinery Not specified
Sow date 21 May 2019
Harvest date 17 November 2019
Plot size 12m x 20m
Plot replication 3
Psuedoreplication Not specified
Plot blocking Yes
Fertiliser Not specified
Herbicide

Treatments

1. Untreated

2. Targa® 100 at 250ml/ha applied at 2-4 leaf stage

3. Targa® 100 at 250ml/ha applied at 2-4 leaf stage + paraquat at 400ml/ha spray topped

4. Targa® 100 at 250ml/ha applied at Z31

5. Targa® 100 at 250ml/ha applied at Z31 + paraquat at 400ml/ha spray topped

6. Paraquat at 400ml/ha spray topped

Herbicide 5 July 2019. Targa® at 2-4 leaf stage 19 August 2019. Targa® at Z31 24 September 2019. Paraquat spray topped

 
Other trial notes

In 2019, selective weed control was highly effective and early weed control led to higher pasture biomass production than late weed control. However, weed emergence was still high in 2020 in the plots with Treflan® alone. Since there was zero seed set in the Targa® treatments in 2019, these plants have emerged from the dormant seed bank. Prior research (GRDC project UA00156) highlighted that even in irrigated/ideal conditions it takes 3-4 years to eradicate a barley grass seed bank. In the field, with dry seasons and potentially non-wetting soil, it may take longer than 3-4 years to remove the seed bank. The low rainfall in 2019 would have reduced the potential emergence of barley grass, allowing a larger proportion of the seed bank to remain dormant until 2020.

Since the paraquat spray topping treatments in 2019 both had similar barley grass density to the control plots in 2020, it is clear that spray topping did not reduce seed production. It is difficult to get the timing of a spray top right, particularly in a dry season like 2019 when barley grass plants can mature rapidly.

Sakura® with Treflan® in 2020 gave better control than Treflan® alone, and the difference was still evident in 2021. While early, effective Group A weed control in 2019 combined with Sakura® + Treflan® in 2020 successfully reduced this very dense barley grass population by 98%, weed density was still high in 2021.

Selective herbicide was not as effective in the 2021 pasture but still reduced barley grass seed production. Slashing was highly effective in preventing seed set.

North Kellerberrin 2020 Wheat

Sow rate or Target density 50 kg/ha
Sowing machinery

Seeding rig 30 ft John Deere bar 550 lbs breakout, knife points and press wheels, 10 inch spacing. JD bin with 2 compartments. No Flexi N, all urea playing the season. SOA spread up front where required.
Sow date 27 May 2020
Harvest date 6 November 2020
Plot size 20m x 12m
Plot replication 6
Psuedoreplication Not specified
Plot blocking Yes
Fertiliser

27 May 2020. Agstar 60kg/ha
Herbicide

27 May 2020. Pre-emergent herbicide treatments.

  • Treflan® at 2L/ha or Sakura® 118g/ha + Treflan® 2L/ha.

8 July 2020. Jaguar® 1L/ha, MCPA LVE 570 400mL/ha
Other trial notes

In 2019, selective weed control was highly effective and early weed control led to higher pasture biomass production than late weed control. However, weed emergence was still high in 2020 in the plots with Treflan® alone. Since there was zero seed set in the Targa® treatments in 2019, these plants have emerged from the dormant seed bank. Prior research (GRDC project UA00156) highlighted that even in irrigated/ideal conditions it takes 3-4 years to eradicate a barley grass seed bank. In the field, with dry seasons and potentially non-wetting soil, it may take longer than 3-4 years to remove the seed bank. The low rainfall in 2019 would have reduced the potential emergence of barley grass, allowing a larger proportion of the seed bank to remain dormant until 2020.

Since the paraquat spray topping treatments in 2019 both had similar barley grass density to the control plots in 2020, it is clear that spray topping did not reduce seed production. It is difficult to get the timing of a spray top right, particularly in a dry season like 2019 when barley grass plants can mature rapidly.

Sakura® with Treflan® in 2020 gave better control than Treflan® alone, and the difference was still evident in 2021. While early, effective Group A weed control in 2019 combined with Sakura® + Treflan® in 2020 successfully reduced this very dense barley grass population by 98%, weed density was still high in 2021.

Selective herbicide was not as effective in the 2021 pasture but still reduced barley grass seed production. Slashing was highly effective in preventing seed set.

North Kellerberrin 2021 Mixed species

Sow rate or Target density Not specified
Sowing machinery

Not applicable.
Sow date 1 April 2021 The site was not sown. Volunteer pasture.
Harvest date 1 December 2021 The site was grazed, not harvested.
Plot size 12m x 20m
Plot replication 3
Psuedoreplication Not specified
Plot blocking Yes
Fertiliser Not specified
Herbicide

11 June 2021. Raptor® at 2-4 leaf stage

2 July 2021. Raptor® at Z31

  1. Raptor® (imazamox 700 g/kg) at 45g/ha applied at 2-4 leaf stage
  2. Raptor® (imazamox 700 g/kg) at 45g/ha applied at 2-4 leaf stage + slashing
  3. Raptor® (imazamox 700 g/kg) at 45g/ha applied at Z31
  4. Raptor® (imazamox 700 g/kg) at 45g/ha applied at Z31 + slashing
Other trial notes

In 2019, selective weed control was highly effective and early weed control led to higher pasture biomass production than late weed control. However, weed emergence was still high in 2020 in the plots with Treflan® alone. Since there was zero seed set in the Targa® treatments in 2019, these plants have emerged from the dormant seed bank. Prior research (GRDC project UA00156) highlighted that even in irrigated/ideal conditions it takes 3-4 years to eradicate a barley grass seed bank. In the field, with dry seasons and potentially non-wetting soil, it may take longer than 3-4 years to remove the seed bank. The low rainfall in 2019 would have reduced the potential emergence of barley grass, allowing a larger proportion of the seed bank to remain dormant until 2020.

Since the paraquat spray topping treatments in 2019 both had similar barley grass density to the control plots in 2020, it is clear that spray topping did not reduce seed production. It is difficult to get the timing of a spray top right, particularly in a dry season like 2019 when barley grass plants can mature rapidly.

Sakura® with Treflan® in 2020 gave better control than Treflan® alone, and the difference was still evident in 2021. While early, effective Group A weed control in 2019 combined with Sakura® + Treflan® in 2020 successfully reduced this very dense barley grass population by 98%, weed density was still high in 2021.

Selective herbicide was not as effective in the 2021 pasture but still reduced barley grass seed production. Slashing was highly effective in preventing seed set.
Download the trial report to view additional method/treatment information

Download results

Trial results Table 1. Final barley grass density, barley grass seed head production and dry pasture biomass for each treatment (p<0.001). Note that barley grass density and seed head production means are back-transformed from a square root transformation.

# Treatment 1
Barley grass density (plants/m2) Pasture biomass (g/m2) Barley grass (heads/m2)
1 █ Untreated 32 145 65
2 █ Targa® at 2-4 leaf stage 0 145 0
3 █ Targa® at 2-4 leaf stage + paraquat spray topped 0 154 0
4 █ Targa® at Z31 0 126 0
5 █ Targa® at Z31 + paraquat spray topped 0 138 0
6 █ Paraquat spray topped 30 134 54

Barley grass heads/m2

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Barley grass density plants/m2

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Pasture biomass g/m2

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Trial results Table 2. Barley grass density, panicles, seeds and wheat yield in 2020, following pasture control options in 2019 (Treatment 1) and varying pre-seeding herbicides in 2020 (Treatment 2). LSD values are included for separation of means. Note that barley gra

# Treatment 1
Treatment 2
Grain yield (t/ha) Barley grass panicles (heads/m2) Barley grass density (plants/m2) Barley grass seeds (seeds/m2)
1 █ Untreated █ Treflan® 0.71 311 162 5754
2 █ Targa® at 2-4 leaf stage █ Treflan® 1.26 37 24 646
3 █ Targa® at 2-4 leaf stage + spray topped █ Treflan® 1.31 68 36 1318
4 █ Targa® at Z31 █ Treflan® 0.97 148 38 3020
5 █ Targa® at Z31 + spray topped █ Treflan® 0.97 270 20 5888
6 █ Spray topped █ Treflan® 1.03 205 186 3890
7 █ Untreated █ Sakura® + Treflan® 1.44 35 21 589
8 █ Targa® at 2-4 leaf stage █ Sakura® + Treflan® 1.55 11 3 9
9 █ Targa® at 2-4 leaf stage + paraquat spray topped █ Sakura® + Treflan® 1.54 8 8 52
10 █ Targa® at Z31 █ Sakura® + Treflan® 1.24 55 72 977
11 █ Targa® at Z31 + paraquat spray topped █ Sakura® + Treflan® 1.43 28 6 437
12 █ Spray topped █ Sakura® + Treflan® 1.2 80 22 1349

Grain yield t/ha

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Barley grass density plants/m2

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Barley grass panicles heads/m2

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Barley grass seeds seeds/m2

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Trial results Table 3. Barley grass density, panicles, seeds and pasture biomass for each treatment. P and LSD values are included for separation of means. Note that barley grass density, panicle and seed production means are back-transformed from a log10+1 transformat

# Treatment 1
Barley grass density (plants/m2) Barley grass seeds (seeds/m2) Barley grass panicles (heads/m2) Pasture biomass (t/ha)
1 █ Untreated 102 2343 597 3.2
2 █ Raptor ® at 2-4 leaf stage 32 691 486 2.8
3 █ Raptor ® at 2-4 leaf stage + slashed 45 0 1 2.6
4 █ Raptor ® at Z31 109 218 357 1.6
5 █ Raptor ® at Z31 + slashed 58 0 0 2.5
6 █ Slashed 101 0 0 2.3

Barley grass density plants/m2

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Barley grass panicles heads/m2

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Barley grass seeds seeds/m2

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Pasture biomass t/ha

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Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
North Kellerberrin, WA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
North Kellerberrin, WA Sodosol
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

North Kellerberrin WA 2019

Observed climate information

Rainfall avg ann (mm) 330mm
Rainfall avg gsr (mm) 253mm
Rainfall trial total (mm) 192mm
Rainfall trial gsr (mm) 183mm

North Kellerberrin WA 2020

Observed climate information

Rainfall trial total (mm) 225mm
Rainfall trial gsr (mm) 125mm

North Kellerberrin WA 2021

Observed climate information

Rainfall trial total (mm) 326mm
Rainfall trial gsr (mm) 223mm

Derived climate information

North Kellerberrin WA

NOTE: Exact trial site locality unknown - Climate data may not be accurate
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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 report and links

2019 trial report



Trial last modified: 26-11-2024 13:23pm AEST