Tactics for integrated weed management
| Management tactic | Most likely % control (range) | Comments on use |
|---|---|---|
| Improving crop competition | 50 (30-70) | Avoid wide row cropping in weedy paddocks. |
| Pre-emergent herbicides | 90 (85-99) | Long-term control applied pre-, at or post-planting. Use high recommended rates for better control. |
| Selective post-emergent herbicides | 90 (85-99) | Target young weeds; timing is critical. Rely on mixtures at sufficiently high rates, especially in fallow. |
| Spot spraying, chipping, hand roguing, wiper technologies | 90 (80-99) | Very effective to reduce potential populations where there are small numbers of survivors. |
Control
Fleabane can most effectively be controlled when they are emerging, mainly in early spring while they are still small. Small fleabane plants are relatively easy to kill and a late post-emergent application of some Group I (phenoxy) herbicides during spring can control them in cereals.
- The new Health (Pesticides) Regulations 2011 now allows for ‘The Use of a Pesticide for an Unspecified Pest on a Registered Crop’. This is important where the herbicide is registered for the crop but the weed in question is not on the label. A range of Group I herbicides are registered in WA for a range of weeds (for example, wild radish) for use in cereals.
- Flaxleaf fleabane is not on the Group I herbicide label but work done by Andrew Storrie and Tony Cook in NSW suggest that phenoxy herbicides are very effective on small fleabane.
- Post-emergent application of Group B herbicides (chlorsulfuron) could also be effective on the new emergence of flaxleaf fleabane.
- Fleabane germinates in late winter/early spring in WA around the time that a late application of these Group I herbicides is registered and can be applied in cereals.
- Monitoring winter crops following spring rain will enable effective control of small fleabane before harvest.
Mature fleabane can be difficult and expensive to kill, especially in mid to late summer.
- Trials conducted by Department of Primary Industries and Regional Development (DPIRD) researcher Sally Peltzer in 2009 and by Mohammad Amjad in the summer of 2014/2015 indicated that the best control of large fleabane in stubble used a ‘double-knock’ approach with a range of primary herbicides followed by paraquat 7-10 days later.
- The most effective treatment was an application of glyphosate (540 grams per litre (g/L)) at 2 litres per hectare (L/ha) or glyphosate (540g/L) at 2L/ha + 2,4-D amine (625g/L) at 2L/ ha with a follow up spray of paraquat at 2L/ha seven days after the initial treatment
- Glyphosate (540g/L) at 2L/ha or glyphosate (540g/L) at 2L/ha plus 2,4-D amine (625g/L) at 2L/ha applied as a single dose and without the follow spray of paraquat provided good but incomplete control.
Fleabane is also difficult to control in late spring but can be achieved if the plants are less than 5cm.
- Trials conducted in 2009 indicated that diquat (200g/L) at 3L/ha can be used as a salvage spray in-crop in late spring provided the fleabane is small (less than 5cm) The larger plants tended to grow out of it.
- A mixture of 2,4-D (625g/L) at 1.7L/ha plus metsulfuron (600 grams per kilogram (g/Kg)) 5g/ha provided adequate control of fleabane in the late vegetative stage. This treatment was used after the crop was harvested for hay.