Christopher Preston1, Samuel G L Kleemann1, Sarah Noack2, Peter Hooper3, Gurjeet S Gill1
1 University of Adelaide, PMB 1, Glen Osmond, SA, 5064, firstname.lastname@example.org
2 Hart Field Site Group, PO Box 939, Clare, SA, 5453
3 Hooper Consulting, Clare, SA, 5453
Trials were conducted to investigate the interaction between time of sowing in wheat and pre-emergent herbicide over 3 years at Hart, SA. The delay in sowing time was between 27 days in 2015 and 43 days in 2016. In two of the three years, grain yield was significantly higher in the earlier time of sowing. In 2016 a higher wheat yield was obtained with the later time of sowing. In 2014 and 2015 there was no significant difference in annual ryegrass numbers in crop between the two times of sowing; however, there were significant effects of the pre-emergent herbicides. In 2016, there was a significant herbicide x time of sowing interaction. There was a significant herbicide treatment by time of sowing interaction in all years for annual ryegrass spike production. In the nil herbicide treatment there were significantly more annual ryegrass spikes in the first time of sowing in one of the three years, but no difference between times of sowing where pre-emergent herbicides were used. Early sowing with effective pre-emergent herbicides provided effective control of annual ryegrass and limited seed production to no more than observed with later sowing and may be a more profitable option due to increased grain yield.