Navigating precision agriculture for weed control

Precision agriculture is undoubtedly the new frontier of weed control. Although the capabilities of new technologies are astonishing, there are many challenges to navigate.

Chris Davey, WeedSmart’s extension agronomist in South Australia, says that the rapid changes and complexity of many new technologies can make it difficult to know when to commit to substantial changes or investments.

“Sometimes it is ‘hard to see the wood for the trees’,” he says. “Emerging technologies are being developed at such a rapid pace that it is difficult to know when to adopt and how best to integrate new tools into your farming system. These days, autonomy, weed detection and drones are commonly mentioned in discussions about weed management strategies.”

Since the emergence of herbicide resistance in broadacre cropping systems in the 1980s and 1990s, the loss of various effective chemistries has always been associated with a tendency to rely too heavily on a single solution. The advent of new herbicides or application techniques will never provide the panacea of complete weed control.

“Weeds are incredibly adaptive, and the only way to keep herbicides and other technologies working effectively is to focus on weed seed bank management,” says Chris. “Objectively asking, ‘how would this technology help me reduce weed seed set’ can cut through the complexity of choosing what technology to adopt.”

The spring planning season is an excellent time for growers and their advisors to look at the overall weed management program and identify areas where new technology might have a good fit.

“The WeedSmart Big 6 framework is a straightforward way to look at your weed control plan,” says Chris. “There are technologies and systems that have the potential to achieve gains in each of the six pillars of the WeedSmart Big 6.”

What crop rotation and crop competition technologies are there?

Plant breeding technologies continue to provide more options in herbicide tolerance and competitive advantage. Keep weeds guessing with crops and varieties that offer different planting timing, rapid canopy closure, vigorous early growth, and enable the use of diverse herbicide modes of action and or application timing.

A robust crop rotation will underpin a successful weed management program and provide multiple benefits to the farming system, including stubble biomass, nitrogen fixation and friable soil structure.

Crop competition technology is wrapped up in precision planting and variable rate applications of seed, fertiliser and ameliorants. Variable rate capability is now almost standard in new planting equipment. Many growers have realised benefits from mapping their soils and addressing soil constraints that allow weeds to outcompete crops.

Row spacing, stubble management, crop safety and depth control all play a part in planter decisions.

What should I consider for a diverse herbicide program and effective spray application?

Diversity is also paramount within the herbicide program. The increasing availability of proprietary mixes is making it easier to incorporate more modes of action against a single cohort of weeds. Testing for herbicide resistance and susceptibility in weeds is going to save money and keep you one step ahead of evolving resistance in weed populations.

Advances within the spray application realm are rapid – particularly in weed detection technologies. Investing in technologies that ensure accurate delivery of herbicides to the target under optimal plant and environmental conditions will make every drop count.

What are the best technologies to stop seed set and destroy weed seeds?

Once efficient spray capacity and logistics are in place, the next layer is knowing where weeds are and having a rapid response in place for managing patches. Low-tech scouting for weeds can be as simple as dropping a pin, and sometimes sacrificing a patch of crop using chemical fallow or cutting for hay or silage is the most economical and effective way to stop herbicide resistant weeds setting seed.

Weed detection in fallow and in the crop opens the door for targeted management that can also reduce the impact and cost of herbicides. New technologies in automated weed detection and spot-spraying are bringing many benefits for weed control, herbicide stewardship and maintaining a willing workforce within reach for more cropping enterprises.

Then finish the season with technologies that collect and destroy weed seeds that have evaded control. Harvest weed seed control decisions need to dovetail with your seeding system, header front, controlled traffic farming and stubble management.

Weed control will always be a numbers game. When considering any new technology, the big question is whether it will help you achieve 96 per cent weed control or better.

More resources

Testing optical spot sprayers in a low weed environment

Robotic weed control at Breeza, NSW – Pursehouse family

Soil mapping and variable rate technology – I’Anson family

Can increasing wheat sowing rate maintain yield and suppress weeds?