Effect of combinations of sowing time, seed rate and herbicides on ryegrass management in wheat

2019
CC BY 4.0

Research organisatons
Funding source

Trial details

Researcher(s) Ben Fleet
Gurjeet Gill
Sarah Noack
Contact email gurjeet.gill@adelaide.edu.au
Contact phone 08 83137744
Year(s) 2019
Contributor School of Agriculture, Food and Wine - The University of Adelaide
Trial location(s) Washpool, SA
Washpool, SA, SA
Effect of combinations of sowing time, seed rate and herbicides on ryegrass management in wheat locations
Aims

This field trial at Washpool was undertaken to investigate factorial combinations of sowing time, seed rate and herbicides on the management of annual ryegrass in wheat.

Key messages

A field trial was undertaken at Washpool in 2019 to investigate combinations of wheat sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was 2249 ± 284 seeds/m2. There was no evidence at this site of any reduction in ryegrass infestation in wheat by delaying sowing by three weeks between TOS 1 (77plants/m2) and TOS (74plants/m2). This result suggests the Washpool ARG population likely has a high level of seed dormancy, reducing the rate of ryegrass germination after the opening rainfall events. Herbicide treatment had a significant influence on ARG plant density (P<0.001). Boxer gold and Sakura + Avadex reduced ARG plant density by 45% and 73% from the untreated control (125 ARG plants/m2). Wheat was much more competitive against ARG when it was sown early. This was made evident by the large increase in ARG seed production when seeding was delayed. When averaged across all other treatments TOS 1 produced 1634 ARG seeds/m2, which was 73% lower than 5974 ARG seeds/m2 produced in TOS 2 (P=0.013). Wheat seed rate had a significant influence on ARG seed production (P=0.005), with the high wheat seed rate supressing ARG seed production by 37% when compared to the lowest wheat seed rate (100 seeds/m2). Wheat grain yield at this site was significantly influenced by the time of sowing (P=0.001), seed rate (P=0.001), herbicide treatments (P=0.001), and the interaction between the time of sowing and herbicides (P=0.011). Wheat was much more tolerant to ryegrass competition when sown early (TOS 1) as shown by the small increase in grain yield in herbicide treated plots. In contrast, there was a significant increase in wheat grain yield in herbicide treatments in TOS 2. The results of this study clearly show that delayed sowing of wheat allows for greater seed set by ryegrass and is also associated with a large yield penalty.

Lead research organisation The University of Adelaide
Host research organisation Hart Field Site Group
Trial funding source GRDC 9175134
Related program N/A
Acknowledgments

We thank GRDC for funding this research project.


Other trial partners Not specified

Method

Crop type Wheat
Treatment type(s)
  • Herbicide: Type
  • Sowing: Rate
  • Sowing: Timing
Trial type Experimental
Trial design Randomised,Replicated,Blocked

Washpool 2019

Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified

Washpool, SA 2019

Sow date Not specified
Harvest date Not specified
Plot size Not specified
Plot replication Not specified
Trial source data and summary not available
Check the trial report PDF for trial results.
Observed trial site soil information
Trial site soil testing
Not specified
Soil conditions
Trial site Soil texture
Washpool, SA Not specified
Washpool, SA, SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Washpool, SA Chromosol
Washpool, SA, SA Chromosol
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 Washpool SA Washpool, SA SA
2019 355.2mm238.1mm
2018 399.3mm282.1mm
2017 464.3mm373.3mm
2016 428.4mm347.8mm
2015 386.2mm296.5mm
2014 441.1mm356.3mm
2013 450.2mm367.7mm
2012 513.8mm427.5mm
2011 504.3mm446.8mm
2010 473.2mm405.3mm
2009 402.9mm318.8mm
2008 395.2mm281.7mm
2007 427.1mm319.8mm
2006 412.5mm311.0mm
2005 428.3mm342.8mm
2004 377.3mm290.7mm
2003 400.7mm312.5mm
2002 392.1mm311.1mm
2001 439.5mm386.2mm
2000 425.4mm369.4mm
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

Derived climate information

No observed climate data available for this trial.
Derived climate data is determined from trial site location and national weather sources.

Washpool SA

Washpool, SA SA

Washpool SA

NOTE: Exact trial site locality unknown - Climate data may not be accurate
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Washpool, SA SA

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 last modified: 18-05-2020 17:01pm AEST