| Researcher(s) |
Linda Bailey |
|---|---|
| Year(s) | 2021 |
| Contributor | Northern Grower Alliance |
| Trial location(s) |
Edgeroi, NSW
|
To evaluate herbicide options for residual control of Phalaris paradoxa in cereals
The trial was conducted in a paddock near Bellata in Northern NSW that was fallowed from faba beans in 2020. Stubble levels were low and the paddock was sown to LRPB Lancer wheat in early May.
The majority of herbicide treatments were applied in late April and incorporated by sowing (IBS) 5 days later using a John Deere single disc planter on 38 cm row spacings. Rainfall totaling 11 mm was recorded 3-4 days after planting (3-4 DAP) with an additional 7 mm within the first fortnight. One herbicide was applied as a post sowing pre-emergent (PSPE) split application, 5 days after sowing and the remaining 3 treatments applied at an early post-emergent timing in wheat, at ~4 leaf crop stage.
Wheat establishment was assessed at 12 DAP when a majority of plants were already at ~1-2 leaf stage. The untreated population was ~96 plants/m2. Severe damage to crop emergence was apparent from a number of herbicides.
Treatments containing trifluralin (TriflurX or Bolta Duo) caused the greatest damage and reduced crop emergence by >90% (0-8 plants/m2). Rifle 440 (pendimethalin) and Luximax (cinmethylin) had less impact but still reduced emergence by ~50-60% (50 and 37 plants/m2). Diablo Duo (triallate and prosulfocarb) reduced emergence by ~15% (82 plants/m2). No other treatment had a significant impact on crop emergence although there was a non-significant trend to a ~10% reduction in emergence from both Boxer Gold (s-metolachlor plus prosulfocarb) treatments and Overwatch (bixlozone). There was no effect on crop emergence from Sakura or Dual Gold. A second assessment of emergence was not conducted, as there was no apparent change in crop emergence at later inspections.
Trace levels of paradoxa grass were apparent at 23 DAP when the in-crop treatments were applied but with no detection in the untreated. Paradoxa grass control was assessed in late June at 59 DAP with a density of ~0.7 plants/m2 in the untreated. All herbicides significantly reduced the weed counts under a low paradoxa grass density. Sakura, the split application of Boxer Gold, Luximax and all treatments containing trifluralin reduced paradoxa grass counts by >90%. Arcade 3 L/ha and Mateno Complete applied at 23 DAP also reduced paradoxa counts by >90%.
All treatments provided useful levels of suppression or control of paradoxa grass for ~3-7 weeks after application. All herbicides with paradoxa grass control claims provided >90% reduction in counts with encouraging activity from the split application of Boxer Gold, Luximax and Arcade 3 L/ha applied 23 DAP.
An effective commercial knockdown spray was applied shortly after the 59 DAP assessment. The site was inspected in August and October with no new paradoxa grass emergence in the untreated but trace levels where severe crop damage had occurred.
This trial however was an example where residual herbicide crop safety was very poor. The actual cause is unclear but may be due to a combination of early planting with very rapid seedling development (wheat to 2 leaf by 12 DAP) and the use of a single disc planter which failed to remove adequate soil from the planting furrow. Depth of planting was unfortunately not assessed but the rapid crop emergence would suggest planting seed was relatively shallow. Rainfall after planting was obviously a factor but the amounts were relatively low with ~8 mm at 3 DAP and ~3 mm at 4 DAP.
In this situation, with low paradoxa grass density, the treatments with the best combination of crop safety and paradoxa grass efficacy were Sakura, Mateno Complete and Arcade 3 L/ha.
| Lead research organisation |
Northern Grower Alliance |
|---|---|
| Host research organisation | N/A |
| Trial funding source | GRDC NGA2009-002RTX |
| Related program | N/A |
| Acknowledgments | N/A |
| Other trial partners | Not specified |
| Crop type | Cereal (Grain): Durum |
|---|---|
| Treatment type(s) |
|
| Trial type | Experimental |
| Trial design | Randomised,Replicated,Blocked |
| Sow date | Not specified |
|---|---|
| Harvest date | Not specified |
| Plot size | Not specified |
| Plot replication | Not specified |
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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