Effect of sowing time x seed rate x herbicides on ryegrass management in barley

CC BY 4.0

Research organisatons
Funding source

Trial details

Researcher(s) N/A
Contact email gurjeet.gill@adelaide.edu.au
Contact phone +61428592825
Year(s) 2021
Contributor School of Agriculture, Food and Wine - The University of Adelaide
Trial location(s) Minnipa, SA
Effect of sowing time x seed rate x herbicides on ryegrass management in barley locations

This field trial at Minnipa aims to investigate factorial combinations of sowing time, seed rate and herbicides on the management of annual ryegrass in barley.

Key messages
  • Three week delay in seeding barley reduced annual ryegrass (ARG) plant density by 45% in the control (knockdown only) and by 28% for the weaker Trifluralin treatment. However in the most effective herbicide treatments (Boxer Gold and Overwatch), high levels of ARG control was achieved in both TOS 1 and TOS 2.
  • The interaction between sowing time and herbicide (P<0.001) was reflected in 45-50% lower ARG spike density in TOS 2 than in TOS 1 for the control and Trifluralin treatments. However, no such effect of delayed sowing was observed for the more effective treatments of Boxer Gold and Overwatch that reduced ARG spike production by 81% and 78%, irrespective of sowing time.
  • Barley seed rate did have a significant effect on ARG seed production (P=0.022) with crop sown at 150 and 200 seeds/m2 having 29% and 21% lower ARG seed set than seed rate of 100 seeds/m2. It is a serious cause for concern that ARG was able to set 7705 and 8700 seeds/m2 in the most effective herbicide treatments Boxer Gold and Overwatch. These results highlight the need for growers to integrate tactics such as improved crop competitiveness and harvest weed seed control along with herbicides to achieve a decline in the seedbank of this difficult to manage weed.
  • Herbicide treatment had a significant effect on barley grain yield with Trifluralin (1.99 t/ha) increasing grain yield by 16%, Overwatch (2.30 t/ha) 34% and Boxer Gold (2.33 t/ha) by 36% compared to the control (1.72 t/ha). These yield gains approximately equate to a 5:1 return on the cost of Trifluralin, a 4.5:1 return on Overwatch and a 5.8:1 return on Boxer Gold.  
Lead research organisation School of Agriculture, Food and Wine - The University of Adelaide
Host research organisation SARDI Minnipa Agricultural Centre
Trial funding source GRDC 9175134
Related program GRDC - Weeds

We thanks GRDC for funding this research and the local grower for hosting this trial.

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


Crop types Cereal (Grain): Barley Weed: Ryegrass
Treatment type(s)
  • Herbicide: Type
  • Sowing: Rate
  • Sowing: Timing
Trial type Experimental
Trial design Randomised,Replicated

Minnipa 2021 Barley

Sow date 20 May and 9 June
Harvest date Not applicable
Plot size Not specified
Plot replication Not specified

Minnipa 2021 Ryegrass

Sow date Not specified
Harvest date Not specified
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
Minnipa, SA Not specified
Derived trial site soil information
Australian Soil Classification Source: ASRIS
Trial site Soil order
Minnipa, SA Calcarosol
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.

Minnipa SA

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

2021 trial report

Trial last modified: 20-03-2023 16:22pm AEST