BATTLING annual ryegrass is an ever-evolving process for Marchagee farmer Mick Callaghan.
Herbicides that were once effective in controlling weeds on the family farm for Mick’s parents, Molly and Bevan, have become futile over time due to resistance.
It has meant Mr Callaghan has had to become more vigilant when it comes to rotating chemicals and fighting resistance, as effective weed control is essential to maximising profit.
The property is farmed by Mr Callaghan and his wife Julia as a total cropping enterprise using a minimum tillage system on predominately sandy soils.
The farm is near Coorow and receives an annual average rainfall of 350 millimetres, including 250-280mm during the growing season.
Last year they cropped 7300 hectares and the program typically comprises 40 per cent wheat, 20pc canola, 20pc barley and 20pc lupins.
Mr Callaghan has been farming full-time since 1992 after a near 10-year stint working fly-in, fly-out at Argyle Diamond Mine and working on the farm during his rostered weeks off.
He said wild radish and annual ryegrass were the biggest weed burdens, followed by brome grass, and over the years resistance to traditionally effective chemicals had become extremley obvious.
“As little as 10 years ago, we were using clethodim at what was considered a high rate of 200 millimetres per hectare and now, 1L/ha of the same product has no effect,” Mr Callaghan said.
“We’ve got to do anything we can to protect new chemicals that effectively control weeds like ryegrass and radish.”
Mr Callaghan takes a keen interest in any trial work on resistance and new herbicides, particularly those done by independent farm groups such as the Liebe Group and West Midlands Group.
It was a trial that first introduced him to the pre-emergent herbicide, Sakura 850 WG from Bayer, when he visited a small trial on a privately-owned farm north of Coorow facilitated by the company’s customer advisory representative, Rick Horbury.
The same herbicide was also recommended by Mr Callaghan’s agronomist, Craig Topham from Agrarian Management, Geraldton.
“I went and had a look and spoke to the farmer who ran the trial,” Mr Callaghan said.
“It was good to hear his feedback and he swore by it and that it effectively controlled annual ryegrass.
“I’m someone that has to see a product in action before I believe it works, rather than just reading literature, which is why I like to look at independent trials.
“The main thing that stood out with Sakura was its flexibility.
“Alternative herbicides are applied pre-seeding and then they become active and attack germinating ryegrass, but they would stick to stubble and really need that soil contact.
“Sakura can wash off the straw and into the soil, which is a big advantage.”
Containing the active ingredient, pyroxasulfone, Sakura controls annual ryegrass, barley grass, silver grass, annual phalaris and toad rush, and also suppresses wild oats (black oats) and brome grass in wheat (not durum wheat), triticale, chickpeas, field peas, lentils and lupins.
Mr Callaghan said they never waited for rain to start seeding, although last year was their earliest start on record, kicking off on March 28 with plenty of soil moisture.
He said generally they would start around April 10, season dependent.
They began using Sakura when it became commercially available in 2012 and have been achieving a control rate of about 80pc of annual ryegrass and brome grass in wheat crops.
“Sakura has its place here and seems to be working,” he said.
“We use it to cover 1000ha each year, which is one third of our wheat program and that is generally due to the cost – we would use more if we could.
“But it allows us flexibility during seeding and what value do you put on that?
“We’ll ideally incorporate Sakura within two days of seeding, but we have the ability to spray it out and seed within three days, rather than four to six hours with trifluralin.
Mr Callaghan said even though it was a high-priced product it delivered good weed control.
“If I used trifluralin in a similar area, I may lose up to 50pc if it stuck to the straw, and then a further 20-30pc through volatilisation,” he said.
This year, in conjunction with his agronomist, Mr Callaghan said they would start to do some mixes with other chemicals such as trifluralin to avoid total reliance on Sakura.
He said they used other Integrated Weed Management (IWM) practices such as windrow burning to help control weed seed numbers, as outlined in the Diversity Can’t Wait website.
“Weed control is our main priority,” Mr Callaghan said.
“If you can control weeds eight years out of 10, you can make money farming in this area.
“I just appreciate that companies are out there trying to work on the resistance issue and we need more chemicals like Sakura, so I can maintain minimum tillage practices.”
Landmark Coorow agronomist Andy Regan said Mr Callaghan’s story was not an isolated one, with Sakura being one of the most popular pre-emergent herbicides in the region.
Mr Regan said he generally recommended to clients to use Sakura in a rotation with canola.
“I recommend using Sakura following a canola rotation, so you get a really clean crop during the canola phase and then go in with Sakura to get a really clean wheat crop,” Mr Regan said.
“It’s such an effective product, but also growers don’t have that pressure of a small window of incorporation.”
Andy said a grass control trial last year at four sites across WA, including Coorow, highlighted just how valuable Sakura could be, citing its impact on crop yield and the extended weed control achieved.
The trial, run by Bayer’s Rick Horbury, compared the performance of a range of different pre-emergent grass control options, including prosulfocarb, trifluralin, Boxer Gold, Sakura and Avadex Xtra.
Different tank mixes of some of the products were used and applications were performed at the lowest and highest label rates.
“Sakura achieved 90pc control and yielded an average 2.14 t/ha, achieving an average $73.48/ha return on investment,” Mr Regan said.
“The return on investment is huge by using a premium product like Sakura, so while it can seem expensive upfront, it’s well worth the cost when it’s making such a big difference to the bottom line.”
