AUSTRALIAN farmers will have to adapt to utilising more than just herbicide in terms of weed management if they are to avoid dangerous weed resistance.
A researcher with the Australian Herbicide Resistance Initiative (AHRI), Michael Walsh, has thrown up the example of harvest weed seed control systems (HWSCSs) as a method of driving down weed populations without relying on herbicides.
Dr Walsh said the problem of herbicide resistant weed populations globally was particularly severe in production systems where herbicide dependence resulted in a lack of weed control diversity.
“The dramatic consequences of this can be extreme levels of herbicide resistance in weed populations,” he said.
Dr Walsh said a glaring example of this was in the Western Australian grainbelt where annual ryegrass and wild radish populations were now very difficult to control with herbicides alone.
“Here, as in other regions of the world, herbicide resistance has resulted in a loss of valuable herbicide resources and driven the search for alternate weed control strategies,” he said.
Dr Walsh said it was well known that a key to managing dominant annual weed species was to prevent the input of fresh seed into their short-lived seed banks.
“We are lucky in Australia that our most problematic weeds hold onto their seed at harvest so we have the opportunity to remove or destroy some of these seeds,” he said.
Dr Walsh said a number of HWSC systems, such as the Harrington Seed Destructor, were now being used effectively to target weed seed production in the Australian grain belt.
“Although herbicides remain the number one weed control tool in Australian cropping systems, it is now clear that the inclusion of HWSC systems in weed management programs is enabling weed populations to be driven to very low levels, providing some insurance for the sustainability of remaining herbicide resources,” he said.
“What is absolutely evident is that herbicide sustainability in global cereal production areas will only be achieved if there is diversity in both the agro-ecosystem and in the herbicide and non-herbicide tools employed for weed control.”