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


Research organisatons
Funding source

Trial details

Researcher(s) Gurjeet Gill and Ben Fleet
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) Site 3, Minnipa, SA
Effect of sowing time x seed rate x herbicides on ryegrass management in barley locations

Investigate the impact of sowing time, seed rate and herbicide treatments on the management of annual ryegrass in barley in a low rainfall environment.

Key messages

A field trial was undertaken at Minnipa in 2019 to investigate combinations of barley sowing time, seed rate and herbicide treatments to control annual ryegrass. The average seedbank of annual ryegrass (ARG) at the site was 4168 ± 411 seeds/m2. ARG plant density was significantly influenced by the time of sowing (P<0.001), herbicide treatment (P<0.001) and the interaction between the time of sowing and herbicide (P<0.001). There was a large impact of the 3 week delay in seeding barley on ARG plant density. This was particularly evident in the untreated control in which ARG density decreased from 676 plants/m2 in TOS 1 to 379 plants/m2 in TOS 2. This large reduction in ARG density due to delayed sowing is most likely related to rainfall events in early May, which would have caused weed emergence. Pre-emergence herbicides had higher efficacy in TOS 2 where the density of ARG plants had been reduced by the delay in seeding. This trend held through the season in the untreated control in which ARG spike density decreased from 306 spikes/m2 in TOS 1 to 199 spikes/m2 in TOS 2. In the trifluralin treatment, ARG produced 5078 seeds/m2 in TOS 2 as compared to 9192 seeds/m2 in TOS 1, a 45% reduction in ARG seed production. Unlike wheat in 2018, barley grain yield at Minnipa was not significantly influenced by the time of sowing (P=0.644). However, seed rate (P<0.001), herbicide treatment (P<0.001) and had a significant effect on barley grain yield. As stated earlier, there were large benefits of delayed sowing on weed control. In barley a three week delay did not significantly reduce grain yield as it had in the previous year in wheat. Lower yield penalty in barley from delayed sowing may be related to its earlier maturity than wheat.

Lead research organisation School of Agriculture, Food and Wine - The University of Adelaide
Host research organisation South Australian Research and Development Institute
Trial funding source GRDC 9175134
Related program GRDC - Weeds

Thanks to GRDC for funding the project and Bruce Heddle for hosting the trial.

Other trial partners Not specified


Crop type Barley
Treatment type(s)
  • Herbicide: Type
  • Sowing: Rate
  • Sowing: Timing
Trial type Experimental
Trial design Randomised

Minnipa 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
Site 3, Minnipa, SA Not specified
Derived trial site soil information
Australian Soil Classification Source
Trial site Soil order
Site 3, Minnipa, SA Anthroposol
National soil grid Source
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.

Site 3, 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.

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Trial last modified: 13-05-2020 10:06am AEST