Effect of sowing time x seed rate x herbicides on ryegrass management in wheat (Lake Bolac, VIC)

CC BY 4.0

Research organisatons
Funding source

Trial details

Researcher(s) Ben Fleet
Gurjeet Gill
James Manson
Year(s) 2018
Contributor School of Agriculture, Food and Wine - The University of Adelaide
Trial location(s) Lake Bolac, VIC
Effect of sowing time x seed rate x herbicides on ryegrass management in wheat (Lake Bolac, VIC) locations

To investigate factorial combinations of sowing time, seed rate and herbicides on the management of annual ryegrass in wheat.

Key messages

General application of Sakura + Avadex over the whole trial site provided good control of ARG. As a result, follow-up application of Boxer Gold @ 1.5 L/ha or 2 L/ha at GS 11 (1-leaf stage) did not significantly reduce ARG plant density.  Post-emergence application of Boxer Gold at 1.5 or 2 L/ha after pre-emergence Sakura + Avadex extended the period of weed control, which reduced spike density of ARG (P=0.02). At both sowing times, increase in wheat plant density from 100 to 200 plants/m2 reduced ARG spike density by 44%. Delayed sowing at this site reduced the competitive ability of wheat against ARG. Averaged across the seed rates and herbicide treatments, ARG produced 234 spikes/m2 in TOS 2 as compared to 75 spikes/m2 in TOS 1 (68% reduction in TOS 1). Additional post-emergence application of Boxer Gold significantly increased wheat grain yield (P=0.008) compared to the baseline treatment of Sakura + Avadex. Wheat yield increased by 9% or 0.4 t/ha with the additional post-emergence treatment of Boxer Gold as compared to Sakura + Avadex treatment alone. Wheat grain yield was also significantly affected by wheat seed rate (P<0.001). Wheat grain yield increased from 4.6 t/ha at the density of 100 plants/m2 to the maximum of 5.48 t/ha at the seed rate of 200 plants/m2. This yield gain of 0.9 t/ha clearly indicates that early sowing, wheat density of 200 plants/m2 and effective use of herbicides can have a large influence on the profitability of wheat in the HRZ.

Lead research organisation School of Agriculture, Food and Wine - The University of Adelaide
Host research organisation Southern Farming Systems
Trial funding source GRDC 9175134
Related program GRDC - Weeds

GRDC for providing funds for this project and SFS for hosting this trial. We also thank local growers for their interest in this research.

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


Crop types Weed: Ryegrass Cereal (Grain): Wheat
Treatment type(s)
  • Herbicide: Type
  • Sowing: Rate
  • Sowing: Timing
Trial type
Trial design

Lake Bolac 2018 Ryegrass

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

Lake Bolac 2018 Wheat

Sow date TOS 1: 21 May, 2018 TOS 2: 6 June, 2018
Harvest date Unknown
Plot size Not specified
Plot replication Not specified
Download the trial report to view additional method/treatment information
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
Lake Bolac, VIC Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Lake Bolac, VIC Sodosol
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 Lake Bolac VIC
2018 664.6mm
2017 709.0mm
2016 714.6mm
2015 669.1mm
2014 680.6mm
2013 667.3mm
2012 660.1mm
2011 725.2mm
2010 749.4mm
2009 715.6mm
2008 707.8mm
2007 689.8mm
2006 650.2mm
2005 709.9mm
2004 714.8mm
2003 707.2mm
2002 712.8mm
2001 687.0mm
2000 607.7mm
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



Derived climate information

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

Lake Bolac VIC

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

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

2018 trial report

Trial last modified: 03-01-2023 15:13pm AEST