New weed management tool in the nick of time at Inverleigh

Stewart Hamilton and his wife, Pip, together with his parents, John and Hillary, crop about 2800 hectares, including leased land, to mainly wheat, barley, canola and oaten hay, while they also run about 750 Merino wethers.

The recently acquired Wycheproof property has added vital risk management to the high rainfall and difficult to manage soils at Inverleigh and Wingeel.

The Wycheproof property receives about 400 millimetres of rainfall annually and comprises from black, self-mulching soils through to red rises. The Inverleigh farm, ‘Leighview’, is in a 500 mm rainfall zone and features sandy loams, while the Wingeel land, which is farmed in conjunction with a grazing company, comprises tough clay soils.

The cropping programs follow a canola-wheat-barley rotation at Inverleigh; long-term pasture followed by summer crop then wheat at Wingeel, where canola has also been grown this year before wheat next season; and while the program at Wycheproof is more mixed, they aim to follow a break crop-wheat-barley-barley-break crop rotation.

Some of the land at Inverleigh has been under crop production for 34 years and has increasing weed control issues, particularly resistance to Group A and B herbicides.

With the aim of 5 t/ha yields, the resultant high stubble loads have also reduced the effectiveness of trifluralin herbicide.

“It’s a numbers game and so you do whatever you can to reduce it (resistant weed populations),’’ Stewart said.

For the Hamiltons, this has included double knockdown sprays, rotating chemicals, growing herbicide tolerant canola, windrow burning following canola, stubble baling and stubble mulching, including the use of speed discs.

“Using speed discs to incorporate the stubble provides a nice, clean platform instead of burying it and results in a nice, even germination to kill,’’ Said Stewart.

Weed seed management options at harvest are also being considered.

Stewart said following two consecutive years of large annual ryegrass populations at Inverleigh, the family started to “run out of ideas’’ and so decided to trial the new Group K pre-emergent herbicide, Sakura® 850 WG.

“It did a great job on the ryegrass,’’ he said.

The Hamiltons are now using the herbicide on all properties, with brome grass the more primary target at Wycheproof.

Sakura, from Bayer, contains the active ingredient, pyroxasulfone, and, as a highly concentrated granule, it has a low use rate of 118 g/ha. It controls annual ryegrass, barley grass, silver grass, annual phalaris, toad rush and also offers wild oat and great brome suppression in wheat (not durum wheat) and triticale crops.

The herbicide was incorporated via the family’s custom-designed seeder featuring knife points and following press wheels.

Leading into seeding at Inverleigh this year, it was dry for six months before the annual rainfall was received all within about three months.

Sakura was applied in a mix with Spray.Seed® (or paraquat and diquat mixture), and triasulfuron following an earlier knockdown and there was no rain until five weeks after the sowing application.

It was a similar story at Wingeel, although no knockdown was applied, while rainfall occurred three weeks after sowing at Wycheproof.

“The length of control on the grasses is great. We didn’t have to go back (over the crop with another spray) and there is nothing poking up through the canopy,’’ Stewart said.

“It is also good for the annual phalaris and wild oats.

“If it (Sakura) was going to do any crop damage it would have this year (with the conditions at Inverleigh), but the wheat is trying to fill five wide.

“It also did an unbelievable job at Wingeel. The rain kept coming and activating the chemical.’’

He said at Inverleigh, they would probably follow a strategy of windrow burning after canola, applying Sakura with the wheat and then rotating to tri-allate and trifluralin with the barley.

“We will throw it (Sakura) in the toolbox. It is not a silver bullet, but it is another tool for management.’’