Controlling Fleabane in Stubbles and Fallows

Flaxleaf Fleabane (Conyza spp.) was a problem weed last summer and given the large amount of seed that was produced, it is likely that Fleabane will be a major factor in fallow weed management decisions again. Following are some considerations when controlling Fleabane:

• The aim should be to treat weeds that are small and fresh. Very few chemical treatments give satisfactory results on large, old Fleabane plants.

• Fleabane is very sensitive to stress and becomes much harder to control once exposed to stress from heat, moisture, physical damage or previous herbicides.

• Glyphosate alone will not control Fleabane.

• Robust mixtures of Group I herbicides such as 2,4-D, or Group B herbicides such as Ally with Glyphosate, will give satisfactory control of young Fleabane.

• Once Fleabane plants exceed 70mm in diameter, or start to elongate, a double-knock strategy may be required.

• A “Double Knock” consists of Glyphosate and 2,4-D followed 7 to 10 days later by Gramoxone or Spray.Seed.

• It is important to allow ample time for the 2,4-D to be translocated around the plant prior to Gramoxone or Spray.Seed application.

• The second pass must be applied with water volumes of at least 80L/ha to obtain adequate coverage. Twin jet nozzles or application in the opposite direction to the first application will also assist with coverage.

• While the “Double Knock” strategy is one of the only reliable treatments for large, old Fleabane, it is both costly (approximately $20/ha) and time consuming. For these reasons, it is better to treat young, fresh plants before they require such action.

• Where infestations are severe, cultivation may be a more effective control measure, as old plants can be cut out and seeds will not germinate if buried greater than 1cm.

See more Fleabane control information by clicking here