Drawing on generations of accumulated knowledge and every one of the WeedSmart Big 6 strategies, continuous cropper Jordan Wilksch has a handle on weeds – for now

Jordan Wilksch’s family has been cropping at Yeelanna on the Lower Eyre Peninsula for more than six decades. In fact, one paddock at the original property has been under continuous crop for 64 years.

This long history means he is in a fortunate position to take important lessons from his forebears as they strived for continual improvement as land stewards and profitable grain growers, particularly in the face of challenges such as weeds.

Over the years, continuous cropping has put the Wilksches on the frontline of evolving weeds issues and, as a consequence, they have also been early adopters of problem-solving or weeds control technologies.

When it comes to the “curse” of weeds, ryegrass is their biggest problem, with evidence of herbicide resistance dating back to the 1980s, says Jordan, who hosted a machinery expo at his property as part of WeedSmart Week. Brome grass and wild oats are also common grass weeds, while, typical of the region, broadleaves such as marshmallow, sow thistle, vetch and wild radish cause the biggest headaches.

With a reluctance to use fire in their system, no livestock and the nearest hay market a cost-prohibitive 600 kilometres  away, the Wilksches do not have the option of these mitigating practices: “When you discount those really useful weed management tools, you’ve got to implement every other tool that you can, and implement them correctly,” Jordan says.

Therefore, their operation draws on  every one of the WeedSmart integrated weed management program’s ‘Big 6’ to control weeds and slow resistance.

These strategies, combined with “decades of attention to detail” on-farm and the accelerated development over the past five years of more genetic, engineering and chemical tools has meant that, for now, the Wilksches have a handle on weeds.

Jordan says no one factor has stood  out as being more critical than another in their approach.

“It is years of good work, building on all the science, all the best technology and implementing as many tools as we can all  at once,” he says.

On rotation

Jordan says the Big 6 strategies work to maintain the efficacy of herbicides.

“Thankfully, we do have a suite of them available and it’s up to my generation of managers to try and prolong them as best  we can,” he says.

“And the way you prolong them is to keep your weed numbers low, use weed seed control, use competitive crops and just try  and stay on the front foot.”

Crop rotations, for example, have been critical in fighting resistance by providing opportunities to use different herbicides and modes of action.

After implementing deliberate strategies to aid weed control in the past, such as double breaks and introducing pulses to diversify herbicide options, the Wilksches are now  at a point where decisions on rotations  are based firstly on economics and then  weed control.

Today, for example, their favoured double break of a pulse followed by canola is designed primarily to maximise the profit of canola. A bonus is that the herbicide-tolerant canola also helps to control ryegrass and broadleaves, boosting subsequent cereal crops.

A double break is not only critical in ryegrass control but also provides added benefits of aiding moisture retention and increasing available soil nitrogen, which leads to healthier crops to compete with weeds.

Stacking the competition

The Wilksches have long used crop competition in their weed control strategy, choosing competitive varieties that are “fed well and given every opportunity to smother weeds”.

Vigorous barley varieties, for example, help to fight weeds through competition while also providing the opportunity to crop-top and windrow, and use a weed seed impact mill  to prevent seed-set.

High seeding rates (a standard of 100 kilograms per hectare) and narrower row spacings (250 millimetres) have also aided competition and weed suppression while also bringing the bonus of higher yields, Jordan says.

Soil health is also being boosted by an amelioration program to correct acidity  levels, serviced by handy lime and gypsum resources nearby.

Jordan has also changed paddock orientation where possible, based on research that shows that shadows cast in low latitudes can halve ryegrass seed-set if crop rows run east-west rather than north-south.

“So, with orientation, narrow row spacing, high seeding rates and competitive cultivars, we’re stacking competition traits on top of each other,” he says.

Herbicide equation

When it comes to chemical controls, the Wilksches draw on all available tools, rotating between modes of action and using full label recommendations for maximum impact.

They often employ a double knock of glyphosate with paraquat to target stubborn weeds. They are taking a keen interest in the Australian Pesticides and Veterinary Medicines Authority review of paraquat in cropping systems, concerned they might lose one of the key ingredients in their strategy.

If this happens, Jordan says the Big 6 tactic to ‘Optimise spray efficacy’ becomes even more important.

Using optimal rates is part of their efficacy program, which includes rotating chemicals, using premium products and aligning application with appropriate weather conditions to reduce spray drift. This is guided by a number of weather stations on the property.

Treating the ‘hard’ Eyre Peninsula water with ammonium sulfate to increase acidity and prevent it from binding to and inhibiting the function of chemicals also contributes to spray efficacy.

Stopping the source

Ultimately, Jordan says the most effective approach to weed control is to stop weed set and, to this end, he crop-tops where possible and windrows to collect any early shedding weed seed.

Weed seed survivors are destroyed at harvest with impact mills.

This will be our sixth harvest using Seed Terminators and, as a non-chemical control, they have been marvellous in reducing our weed seedbank,” he says. “Plus, it means we are no longer burning windrows and dealing with the stress (of fire) associated with that.

Overall, Jordan says that over the years, weed control has become both harder and easier.

On one hand, “super-tough” herbicide-resistant weeds continue to evolve and remain a growing challenge, he says. However, on the other, the variety of tools and strategies to counter weeds as articulated by the Big 6 has led to a level of weed suppression in his system that has given him the freedom to choose rotations for maximum economic and agronomic impact beyond just weed control.

“Historically, weeds drove our decisions and limited our options, but at the moment our system is manageable and sustainable, and we have a reasonable handle on the challenges,” he says.

“But I won’t say it’s completely under control, because it never is, and that’s just the nature of it. If you take your eye off the ball, weeds will always come back.”

Read GroundCover story: Precision seeding lays the foundation for weed control