Cotton chemical use cut to lowest level in 29 years at Brookstead farm

Hiring a crop duster to spray insecticides on yield-destroying pests, mainly Helicoverpa (often called heliothis or bollworm), was not only costing money, it was potentially affecting beneficial insects like spiders and wasps.

"It was one of the things that made cotton farming pretty much unsustainable at that point," Johannes Roellgen said.

However, with the help of plant technology and their agronomist, their insecticide use has dropped to its lowest levels since starting at Tyunga near Brookstead in 1994.

Plenty of their progress was down to Monsanto (now Bayer) continually improving its Ingard and then Bollgard cotton program.

"The first Ingard variety wasn't quite the silver bullet, but we reduced the spraying quite dramatically," Mr Roellgen said.

But another major part has been insect pest management (IPM), which agronomist Matthew Holding has helped Johannes and his wife Scarlett implement.

"It's not necessarily the cost of that spray that's holding us back, but often enough, we see that once you put that one spray on - and if you put a fairly disruptive spray on - you actually then knock a lot of beneficials out of the system as well and then all of a sudden you've got other pest species coming up in numbers and then you have to spray a second and third and fourth and fifth time," Mr Roellgen said.

"If you plotted on a graph over the years, we've been spraying less and less to the point where this year, we [barely sprayed], so that really gives us a lot of confidence.

"It hasn't been uncommon this year that [some farmers'] crops have been sprayed four or five or six times."

This season, they planted 1100ha of Sicot 606, 746, and 714 cotton, 400ha of Jade mungbeans and 400ha of P1837 and P1756 gritting corn.

At flowering, mirids were their biggest concern and numbers were high enough to warrant a spray.

"We thought we might have to control them and then we put this quite soft chemistry on (dinotefuran) with the plane," Mr Roellgen said.

"It becomes more and more of a balancing act, because sometimes, with the softer chemistry, you might not have the same knockdown effects on your pest species."

For the remaining 80pc of the crop, they just held off for a bit longer and ultimately saw that their numbers never increased.

Mr Roellgen said while insect counts were important, focusing on the damage could save applications.

"Sometimes, just by more intensive scouting and looking at damage rather than just sticking to theoretical technical thresholds, you can prevent a spray from going on."

He also said a lot of trial and error, along with experience went into it.

"Then you have to be prepared to hold your breath a bit as well and accept that there are a few insects around, but we seem to be getting this positive feedback with what we're doing; in that beneficial numbers keep on building up during the season," he said.

"It's very much credit to Matthew that we can grow a cotton crop that's in the paddock for six months and don't have to spray it a single time for insects.

"You're never sure that this is the end before something else comes in to knock the system over, but that's where we are at the moment."

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