The unit hits target weeds in fallow paddocks – instead of relying on a blanket spray across both weeds and bare soil – offering chemical savings of up to 80 per cent.

With Roundup herbicide prices at $11 a litre and rising, grower interest in the WeedSeeker technology – which at $105,000 to outfit a 24-metre boom used to seem too expensive – is rising rapidly.

In fact, the unprecedented demand has caused a backlog of orders and a two-month wait for the technology out of the United States.

Crop Optics sales manager, Scott Jameson, Tamworth, said the company had sold 16 broadacre units in the year to last September, and had orders for 19 units since.

The technology, used in the US for the past 12 years, was first used in Australia in 2002 by Liverpool Plains farmers, Gordon and David Brownhill, Merrilong Pastoral Company, Spring Ridge.

Mr Jameson said skyrocketing glyphosate prices was the main reason for the sales hike.

“We’ve had a bit of rain and grain prices are high so some people got some crop off and have got a bit more money,” he said.

“There are still times when growers have to do an overall spray such as in-crop, but when they’re using the WeedSeeker they’re saving 80pc on chemical.”

He said although the US manufacturer had been warned of a likely boom in local sales, there had been an initial backlog in orders “but they’re getting on top of it”.