- A successful fire will leave feathertop plants burnt to the ground
When should I consider burning?
Burning to control feathertop is a viable strategy provided:
- more than 25% of the plants in a paddock are feathertop (see Feathertop wire grass: rating infestation for more detailed information)
- conditions allow for a successful burn (see Mitchell grass: safe burning for more detailed information)
- you are able to spell the burnt pasture over the following summer.
Conditions for burning
A successful burn for feathertop control is moderately hot, clean and conducted when the soil is dry followed by two to three months of further dry conditions. If there is moisture in the top 30 cm of the soil profile, or rain within six weeks, it is likely that feathertop will re-shoot and that kill rates will be as low as 10 to 30%. A moderately hot fire can be safely achieved with:
- a well-cured pasture to carry the fire
- a pasture yield of 1600 kg/ha or more to carry the fire
- air temperatures between 20 and 27ºC to promote the fire
- low to moderate humidity to promote the fire
- wind speeds of 10 to 15 km/hr (on average) to promote a fire front
- consistent wind direction to maintain a well-defined fire front.
- An unsuccessful fire will leave feathertop plants with stems left standing
Burning for feathertop control is recommended during the day in July or early August. This maximises the probability of dry conditions following the burn whilst providing conditions that suit a moderately hot fire.
The use of improved long-range weather forecasting may provide the key to strategic burning. Controlled burning in late July or early August when the Southern Oscillation Index (SOI) is in a rising phase would enhance the probability of receiving sufficient summer rains for pasture production, but provide the additional post-burn moisture stress to enhance feathertop control.
Pre- and post-burning management
De-stocking, or lightening off, may be required to build up sufficient fuel before burning. However, feathertop will generally be worst during a run of above average rainfall years. This may mean that the worst affected areas can be burnt without the need to spell. It may also mean that there is sufficient feed to spread stock over the rest of the property, and that burning an area of feathertop will not reduce your short-term carrying capacity.
The burnt area will need to be spelled or stocked lightly over the following one to two summers to avoid stock over-utilising Mitchell grass as it regrows and to allow pasture recovery. You will therefore need sufficient pasture on the rest of your property to carry the stock normally run in the area, or the ability to de-stock through selling or agistment.
If at least average rainfall is received over the following summer, the burnt area should be spelled until the majority of Mitchell grass plants have started to produce seed heads. This allows the plants to build up reserves of energy and to put additional seed into the soil.
If the summer immediately following the fire receives well below average rainfall, then a second summer may be required to promote effective pasture recovery. It is recommended that the burning activity be incorporated into usual property planning and management procedures. Generally the opportunity will only exist to burn approximately 10% of a property within any year.
If 50 mm or more rain falls within six weeks of burning, there is little that can be done. The feathertop kill rate will be reduced to 10 to 30%, but the current crop of seed will have been destroyed and the pasture quality improved over the following few months. In this instance the pasture can be lightly stocked when the green pick starts growing, but should not be grazed any heavier over the coming summer.
Remember that a permit to light fire from your local warden is required for any area over two metres.
Related feathertop wire grass management information:
Related Mitchell grass management information: