| Researcher(s) |
Linda Bailey |
|---|---|
| Year(s) | 2022 |
| Contributor | Northern Grower Alliance |
| Trial location(s) |
Tummaville, Qld
|
To evaluate residual control of common sowthistle in fallow
This trial was established to evaluate residual control of common sowthistle in fallow. Treatments were applied in late December 2021 to a paddock cropped to cotton in 2020/21 and then conventionally farmed. No stubble cover was present and dead or dying weeds provided ~20-40% ground cover. The trial received ~23 mm of rainfall during the first 4 days after application.
The site was inspected at 40, 58, 75 and 126 days after application (40, 58, 75 and 126 DAA) with no seedling weeds present at the initial or final inspection. Seedling weed counts were conducted at 58 and 75 DAA with glufosinate at 5 L/ha applied at 62 DAA to control weeds present at the 58 DAA count. In the fortnight following the clean-up spray, ~180 mm of rainfall was received. A new seedling weed flush was counted at 75 DAA. Seedling common sowthistle and caustic weed (caustic creeper) were present at each assessment.
Despite ~120 mm of rainfall since residual application, common sowthistle was only at trace levels at the 58 DAA assessment with no significant treatment differences. Untreated common sowthistle populations of ~4 /m2 were present at the 75 DAA assessment. Both rates of Valor alone and the experimental Group 14 R provided complete control with mixtures of Valor with Dual Gold or Impose, Voraxor at both rates and Tordon 75-D reducing common sowthistle counts by >90%. Dual Gold, Balance and Terbyne Xtreme did not provide acceptable levels of common sowthistle control under these conditions.
At the 58 DAA assessment, caustic weed was present in the untreated at ~0.6/m2. All treatments other than Balance and Gp 27 C reduced caustic weed numbers by >90%. By the assessment at 75 DAA, caustic weed density was ~2/m2 with complete control from both rates of Valor alone, Valor + Dual Gold, Group 14 R and both rates of Voraxor. The mixture of Valor with Impose also provided >90% control.
In this situation with ~300 mm of rainfall, all treatments containing Valor (alone or in mixture), Voraxor, Tordon 75-D and an experimental Group 14 herbicide provided excellent levels of residual common sowthistle control (95-100%), up to ~70 days after application. Valor, Voraxor and the experimental Group 14 herbicide also provided excellent levels of residual control of caustic weed. Balance, Dual Gold and Terbyne Xtreme only provided moderate levels of weed suppression under the high rainfall conditions.
| 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 | None: No crop specified |
|---|---|
| Treatment type(s) |
|
| Trial type | Experimental |
| Trial design | Replicated |
| 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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