Firebreaks and fencelines will require weed control in the coming months. It is vital to get this right, as uncontrolled weeds contribute significantly to weed populations within paddocks. Weeds on firebreaks often have higher levels of herbicide resistance from repeated exposure to herbicides.

It is important to use different chemistry when spraying firebreaks to those regularly used in-crop. The most common firebreak chemical control strategy is to apply a broad-spectrum knockdown herbicide such as Glyphosate, followed by a double-knock containing Paraquat plus a residual herbicide.

Applying a residual herbicide significantly reduces the number of weeds that germinate post-application, reducing the need for additional passes. All residual herbicides should be applied to bare ground, as plant material will significantly inhibit the ability of the chemical to reach the soil surface. This means that spraying firebreaks should be done as soon after sowing as possible.

Diuron was used very successfully in the past as a residual firebreak herbicide as it is cheap and very effective, however it is no longer registered on firebreaks. Group B herbicides have also been widely used to improve control of weeds, however most of these are not registered for use along firebreaks. The addition of other modes of action such as a group G spike may be necessary when hard to kill weeds are present, such as Mashmallow or Stinging Nettles.

The following table outlines some common chemical mixes that can be used. All chemicals mixed per 100L water.

Clients who have been using only Glyphosate, either alone or with a double-knock of Paraquat should consider swapping to an application of Alliance or Basta to control weeds that are resistant to Glyphosate. his may require an additional pass on any areas where weeds germinate post application. Trial applications of Terrain or Uragan should be considered, to determine if the long residual justifies the extra cost, as soil type can influence the length of control. If these products are applied to bare ground, they will not require a knockdown pass.

Firebreak Spraying