Flaxleaf fleabane continues to frustrate northern region grain growers in their attempts to manage the problematic weed but early control is key to success.
Tony Cook, NSW Department of Primary Industries (NSW DPI) weeds technical specialist based at Tamworth says prevention is better than cure when it comes to controlling fleabane and he recommends pre-emergent or seedling management.
Mr Cook says fleabane has spread largely because it thrives in the no-till farming system due to its surface-germinating seed which, under this system, lies undisturbed by tillage or soil coverage.
“We’ve found populations evenly distributed over the northern grain belt and some in South Australia that are resistant to glyphosate,” he said.
“If they are surviving glyphosate they have the opportunity to grow into large plants in the fallow and can be very difficult to control.”
Mr Cook says good results have been achieved using the double knock technique researched by the Grains Research and Development Corporation (GRDC)-funded NSW DPI and Northern Grower Alliance (NGA) but it can prove expensive.
He says winter fallow control of seedlings or pre-emergent management prior to winter sowing are also key management strategies for fleabane leading into winter cereal or pulse crops.
“There are a range of practices that can be effective including crop competition, herbicides and strategic tillage prior to winter crops.”
Mr Cook said fleabane typically germinates in autumn, although can germinate in summer fallows if the conditions are right.
“Fleabane loves wet, cool to mild autumns and it’s a surface-germinating, small seed which requires a few days when the soil surface is wet and under these conditions growers will see emergence.”
“In this case growers should target their control strategies there and then because weeds are much easier to control at seedling stage.”
He says once the plants grow bigger herbicide options and crop competition become less effective.
“It’s important to monitor spray events to see what level of control has been achieved as a second knock could be needed to achieve one hundred per cent control.”
Mr Cook says every grower has the responsibility to keep an eye out for survivors or patches of resistant weeds, including on roadsides, fencelines and around buildings.
“These could be the source of seedbanks for fleabane as each plant produces around 100,000 seeds so a patch of fleabane is just a nursery for in-crop infestations,” he said.
Knowing all parts of the weed lifecycle and what management tool to use when is vital to good control, Mr Cook says.
“Most often growers look at fleabane as a survivor after a crop has been harvested but we strongly advocate crop inspections throughout the growing season, particularly after the tillering stage under the canopy of the crop to see if there are any weeds hiding there that may need treatment.”
For more information, visit www.grdc.com.au/weedlinks.
CAPTION: Early control is the key to successful management of fleabane
For interviews contact:
Tony Cook, NSW DPI
Technical specialist – weeds
Rachel Bowman, Cox Inall Communications
07 3846 4380 / 0412 290 673
GRDC Project Code