When Fall armyworm (FAW) first appeared in Nat McGhee’s maize crop in 2021, he wasn’t quite sure what to expect. Like many growers, the highly destructive pest was “a bit of an unknown” for Mr McGhee, who manages Nindooinbah Pastoral at Beaudesert in Queensland’s Scenic Rim.
It didn’t take long, however, for the FAW to show their full capabilities.
“Prior to FAW’s arrival at Nindooinbah, we didn’t understand just how big of an impact the pest could have,” Mr McGhee said.
“Within 2 to 3 weeks, the windowing and shattering of the leaves in the mature crop looked like a hailstorm had gone through.
“The damage to our crop resulted in a 30 to 40 per cent production loss, and some other growers in the region recorded 100 per cent losses, particularly in young maize crops.”
The loss was a “bitter pill to swallow” on top of what was already an expensive crop to produce, and had a significant impact on their feed resources for the year ahead.
“Nindooinbah Pastoral is a large-scale artificial breeding company that focuses on stud Ultrablack cattle, as well as contract breeding for a large northern pastoral operator,” Mr McGhee said.
“Due to the intensity of our program, we rely heavily on maize silage to top up the paddock feed and fill any feed gaps we may experience with our pastures.
“On average, we feed between 15 and 25 tonnes of silage per day, and our aim is to generate about 6000 tonnes per year.”
Key to stopping the FAW in their tracks and limiting further damage was an application of Corteva’s Intrepid Edge® Jemvelva® active.
“We didn’t know how to control it to start with,” Mr McGhee said.
“We tried several products, but by far the best result we had was with Intrepid Edge.”
Two modes of action a game changer
Elders Beaudesert Senior Agronomist, Brendan Magee, puts the success of Intrepid Edge down to its combination of two modes of action from Group 5 and 18 insecticides, with active ingredients Jemvelva and methoxyfenozide delivering both a fast-acting knockdown of pests and a residual activity that protects the crop between applications.
“It was really exciting when Intrepid Edge came to market to have two active ingredients in one solution, and it has been a big game changer, particularly for our Integrated Pest Management (IPM) plans,” Mr Magee said.
“When you start leaning on a single chemistry group too hard, it really backs you into a corner, so to have a combination that’s not a Group 28 insecticide was also a huge bonus.
“Add to that the fact Intrepid Edge has prolonged activity but has no effect on our beneficial insects and it’s a plus for me.
“We haven’t found too many products that work as good as Intrepid Edge and fit into our IPM strategies so well.”
FAW pressure prompts changed planting windows
In addition to finding success with Intrepid Edge, the learnings from two successive summers of FAW destruction have prompted maize growers in the Scenic Rim region to change their planting practices.
“Due to FAW, the pressure it puts on us and the relentlessness of the pest in the hotter months, we’ve forced our maize planting window back into the late parts of August and have given up on December plantings,” Mr Magee said.
“The most surprising thing about FAW is its aggressiveness in taking over, and it's quite mind-blowing how quick it can spread across a paddock.
“When it first arrived, you'd see spots on a couple of leaves and a bit of windowing. Then, very quickly, you'd see an area the size of a car park would be completely eaten to the ground.
“Within a week, the scale of damage in a paddock would be 10 times that.”
It’s this behaviour, characteristic of the pest, that makes a successful control solution so vital, Mr Magee said.
“FAW is a problem that's going to be around for a while, and we need solutions that will both fix the problem and fit our systems – something Intrepid Edge does very well.
This article was written by Corteva Agriscience for Seasons magazine.
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