Monitoring pest activity and forecasting a potential outbreak is vital to pesticide management, according to cesar research scientist James Maino.
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Speaking at the 2018 Crop Protection Forum held in Glenelg on Thursday last week, Dr Maino said because new pest management chemistry took an extended time to arrive on the market, growers were left vulnerable to pest damage if resistance emerged.
He said graingrowers therefore needed to reduce chemical usage and incorporate a targeted spraying approach.
“It is not to just reduce management costs but also to maintain control options,” he said.
“Understanding how to assess pest impacts on your crop allows you to make a decision on whether or not intervention is economically viable or cost-effective.
“A non-targeted pesticide application means that just because you are not targeting that pest does not mean it will not get hit with chemical.”
According to CropLife Australia, without crop protection products, Australian crops are worth about $6.9 billion a year but with them, it increases to about $9.6b.
“That is a 58 per cent value attributive to crop protection products,” Dr Maino said.
“Insecticides are attributed to about $1.9b.”
Recent research conducted on the resistance and evolution of the red-legged earth mite showed monitoring the pest within a crop was just as important as using forecasting tools to determine if an outbreak was likely.
“Monitoring informs good forecasting and good forecasting forms targeted monitoring – they need to work together,” Dr Maino said.
“When looking at RLEM evolutionary potential, basically the more plant families that an insect feeds on the more plant chemicals it is ultimately exposed to.”
And, emerging research showed that helped to pre-adapt the pest to resistance evolution.
If graingrowers have high pesticide use outside of summer combined with wet winters, low temperature seasonality and/or crops close to the coast, they should be monitoring RLEM activity.
Dr Maino said longer growing seasons also meant multiple RLEM generations would be produced within one cropping season, therefore increasing the capacity for evolution.
“If growers are ticking these boxes then they need to be paying close attention to how RLEM populations are responding to chemical applications but also whether or the not chemical applications are truly needed in all situations,” he said.
As pesticide resistance increased, so did the cost of chemicals, Dr Maino said.
“The main driver for the high price of chemicals is because the cost of discovery has skyrocketed – chemicals are costing hundreds of millions of dollars to come onto the market,” he said.
“The main reason for that is the success rate has plummeted. In the past, one in 1000 chemicals were screened for a mode of action but it has increased to about one in 160,000 – so that is a big difference that is costing a lot of money.”
Dr Maino said most available chemicals used the same active ingredients and have remained unchanged since 2000.
“We have had no new RLEM chemistry in terms of the mode of action since 2000, so despite increased resistance we are using repetitive chemicals and that is quite a concern,” he said.
“We are also seeing a similar trend with other resistant grain pests.”
