Wimmera growers and advisers are invited to learn the ‘ABC’ of herbicide resistance during a series of pre-sowing workshops being coordinated by Agriculture Victoria this month.
Director of Plant Science Consulting, Dr Peter Boutsalis, who also works as a research officer with the University of Adelaide’s herbicide resistance team, will present an update on ‘alphabet’ herbicide resistance in the Wimmera and tactics for growers to address the issue.
Alphabet resistance refers to weed populations that are resistant to multiple herbicide types (e.g. Groups A, B and D).
How ‘alphabet resistance’ has occurred will be explained, as well as ways of avoiding and addressing it.
According to Dr Boutsalis, paddock surveys of southern Australia show that ‘alphabet resistant’ ryegrass is becoming more prevalent in intensively cropped areas, where herbicide selection pressure is high.
He said the last survey in the Wimmera-Mallee was held in 2015, with the next one planned for 2020.
“The 2015 survey showed widespread resistance to a range of post-emergent herbicides in the Wimmera-Mallee,” Dr Boutsalis said.
“In the Wimmera, only five per cent of sampled paddocks contained annual ryegrass susceptible to all tested herbicides.
“However, 30 per cent of the Wimmera paddocks surveyed contained ryegrass with resistance to one mode of action and a further 50 per cent contained ryegrass resistant to two modes of action.”
Dr Boutsalis said that a range of new mode of action herbicides would soon be available, but they need to be carefully managed to ensure their longevity.
The event’s coordinator, Heather Drendel, from Agriculture Victoria, said that growers should use a range of tools to minimise the risk of ‘alphabet resistance’ developing in weeds on their farm.
“Testing weed seeds for herbicide resistance is the first step for growers in understanding the extent of resistance on their farm,” she said.
The workshops are being supported by the Wimmera Farming Network,Wimmera Regional Agriculture Landcare Facilitator and the Wimmera Catchment Management Authority through funding from the Australian Government’s National Landcare Program.
The aim of the workshops, and the partner-based approach, is to increase awareness and adoption of land management practices that improve and protect the condition of the soil, biodiversity and vegetation in the Wimmera.
Workshops: ABCs of herbicide resistance in the Wimmera