| Researcher(s) |
Linda Bailey |
|---|---|
| Year(s) | 2022 |
| Contributor | Northern Grower Alliance |
| Trial location(s) |
Macalister, QLD
|
To evaluate residual control of tall fleabane in fallow
This trial was established to screen potential options for the residual control of tall fleabane in fallow. Stubble levels were very high (~95%) following harvest of the 2021 wheat crop. The trial was established in the second week of February 2022, ~ 1 week after the site recorded ~57 mm of rain. Total rainfall of ~530 mm was received during the 6 months that the trial was conducted with ~14 mm of rain received ~9 days after residual herbicide application.
An initial assessment was conducted 31 days after application (31 DAA) with very low weed numbers present despite ~170 mm of rainfall being received. Seedling common sowthistle (~1-3 leaf) were present at ~0.2/m2. Although there were no common sowthistle present in treatments that included Valor, Voraxor, Terbyne Xtreme, the experimental Group 14 herbicide or Tordon 75-D, the untreated weed density was too variable and low to show significant differences.
During the following 7 weeks, an additional ~107 mm of rainfall was recorded with a second weed assessment made at 80 DAA. Common sowthistle densities had increased in the untreated to ~0.6/m2. The majority of sowthistle were at the 4-7 leaf stage but advanced plants weeds were at early flowering. No treatment provided complete control of common sowthistle but with >80% reduction in numbers where Valor was used alone or in mixture with Impose. Only Valor 280 g/ha provided a significant reduction in common sowthistle counts compared to the untreated. Neither Dual Gold alone or the experimental Group 27 herbicide showed any suppression of common sowthistle numbers, at either assessment.
Low fleabane numbers were present at 80 DAA with untreated populations of tall fleabane at 0.2/m2 and flaxleaf fleabane at 1.7/m2. There were no significant differences for either species.
A new cohort of tall fleabane was present 3 months later when a final count of weeds was made at 172 DAA. An additional 254 mm of rain had been recorded between assessments 2 and 3. Although tall fleabane counts were still low, there was no apparent effect from any herbicide.
At this site, with very high levels of groundcover from the 2021 wheat harvest and ~170 mm of rainfall in the first month after application, no herbicide showed useful residual activity against either tall or flaxleaf fleabane. Valor 280 g/ha was the only treatment to provide significant control of a trace population of common sowthistle at 80 DAA.
| 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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