AUSTRALIAN farmers will be forced to come up with holistic strategies and not just rely on pesticides to deal with the increasing problem of insect, weed and disease resistance to crop protection products according to the extension lead at pest control organisation Cesar.
Speaking in the lead up to the Crop Protection Forum to be held at Moama, NSW on December 3, Jess Lye said there was a worrying trend of increased resistance in insect populations right across the nation's cropping belt.
"In recent years we have seen an escalation in the number of green peach aphid and red legged earth mite populations with confirmed resistances across more than one mode of action (MoA) group," Dr Lye said.
And she warned farmers more insect pest species, along with fungal diseases and weeds could join the resistant ranks.
"Recent predictive work carried out at Cesar has identified several additional insect pests with a high risk of developing insecticide resistance in the future.
This trend is also being observed when it comes to herbicide and fungicide resistance.
Dr Lye said there was no one size fits all solution.
"Not every case of resistance can be managed in the same way - knowing how the resistance works at the molecular level is quite important for developing good management tactics."
She said recent cases of selection and evolution of resistance, such as the evolution of multiple resistance to pre-emergent herbicides in annual ryegrass and reduced fungicide sensitivities being identified, demonstrate the fast-paced nature of this issue.
In terms of lowering the pest burden with non-chemical means Dr Lye said an important component in reducing resistance risks was to reduce the selection pressure for resistance evolution and persistence in local pest populations through non-chemical management tactics, such as cutting hay to reduce seed set in problem weeds or encouraging beneficial insect species that are predators of pests.
"When it comes to insect pests, practices such as the removal of alternate plant hosts, strategic grazing and the creation of refuges to support beneficial species can help to keep pests under an economic threshold and reduce that selection pressure."
Dr Lye said these non-chemical controls, along with targeted, rather than prophylactic applications of effective chemicals were even more important given the paucity of new chemical modes of action on the horizon.
"In recent years we have seen very few new MoAs enter the market and while no one can predict the future, there is little reason to believe that this trend is likely to drastically change soon.
"Resistance to pesticides is already reducing the number of actives we have available for controlling some key pests such as redlegged earth mite.
"As a result, it is really important that we protect the MoAs that we have already on the market by taking an integrated management approach and applying chemicals according to risk rather than prophylactically.
Farmers do not just need to plan to manage pests in the paddock.
Dr Lye said an integrated pest control strategy was critical for grain storage.
"It all comes back to reducing that selection pressure and looking at non-chemical methods of reducing pest infestation and feeding damage.
"In the case of grain storage good hygiene measures, strong monitoring systems, reducing moisture and pest entry points will all contribute to reducing that selection pressure."