Read time: 5 minutes

Will longer crop rotations really help manage weeds?

With Peter Newman, Australian Herbicide Resistance Initiative Communication Lead.

Peter Newman, Communication Leader with the Australian Herbicide Resistance Initiative says the real culprit is always a lack of diversity. He recalls a grain grower friend taking him to a paddock that had been in a lupin / wheat rotation for 30 years. “He said his wheat was always full of brome grass and his lupins were full of wild radish and blue lupins,” he says. “Then one year he decided to break the cycle and planted barley after wheat, instead of lupins, and the barley came up full of wild radish and blue lupins.”

This grower concluded that his weeds were responding to what had become a predictable farming system.

“Managing resistant weeds requires farming systems that are diverse—using different crops, different chemical modes of action and including non-herbicide control tactics,” Mr Newman says.

The days of simply changing from one chemical to another when the first one becomes ineffective are gone. All chemical options need the support of other tactics and this is where longer crop rotations can provide much more diversity to confuse the enemy than short rotations.”

“Diverse rotations can include longer rotations with different crop species, using varieties with different herbicide tolerance traits or sowing dates, and using an array of tactics to reduce weed numbers and prevent seed set.”

“We are seeing growers win in the battle against herbicide resistance and that is great news,” he says. “It’s time to get serious and to start looking for ways to make every farming operation as diverse as possible.”


Peter Newman, Communication Leader with the Australian Herbicide Resistance Initiative says the real culprit causing herbicide resistance is always a lack of diversity.

How does lengthening a crop rotation help manage herbicide resistance?

Short answer: By adding diversity.

Longer answer: A longer crop rotation means having more tools in the toolbox—better herbicide rotation, a range of seed set control options, varied planting times, competitive crop species or varieties and the ability to implement a variety of harvest weed seed control options.

What can I do if I need to keep a fairly tight rotation?

Short answer: Still look to add diversity.

Longer answer: If you can’t see your way clear to lengthen your crop rotation, look for ways to increase diversity within the crops you grow. Changing varieties may allow a different sowing time and in herbicide tolerant crops such as canola, you can rotate between the RR and TT hybrids. In a tight rotation harvest weed seed control and maximum crop competition are even more important.

Peter Newman, Tom Murphy and Rob Hughes discuss the benefits of narrow row spacing for yield and weed suppression.

What other benefits can I expect from longer crop rotations?

Short answer: A more sustainable farming system.

Longer answer: Increasing diversity in the crop rotation is good for pest and disease management as well as weed management. Adding a legume will also have a lasting impact on soil nutrition. In the longer term a diverse rotation reduces overall production risk.

Are there limiting factors?

Short answer: Yes.

Longer answer: Crop sequencing can have impacts beyond weed management. A rotation should be planned and the use of residual herbicides must take the following crop into account.

Related Articles

Related Articles

View all
Article
Ask an Expert

How does crop competition support other weed control tactics?

Crop competition is a quiet achiever in weed control that also has a synergistic effect when applied with other tactics. Read More...
Article
News

WeedSmart Big 6 for Mallee farms in NSW, Vic and SA

Get started with the WeedSmart Big 6 tailored for the Mallee region. Read More...
Article
Ask an Expert

Can faba bean crops outcompete sowthistle?

Faba bean crops have the potential to significantly curb common sowthistle, a problematic weed with widespread resistance to key herbicides. Read More...

Webinars

View all
Video
Webinar

How faba beans pack a punch against sowthistle

Research shows there are opportunities to alter the agronomy of faba beans to suppress sowthistle growth and seed production in crop. Read More...
Video
Webinar

Combat Velocity® resistant wild radish with the WeedSmart Big 6

AHRI researcher Dr Roberto Busi explains in this webinar how he discovered Velocity® resistant wild radish populations in two paddocks in the northern Wheatbelt of Western Australia. Read More...
Video
Webinar

No survivors – weed control in cotton, what does it look like in 2022?

Research Agronomist Eric Koetz and WeedSmart Northern Extension Agronomist Paul McIntosh discuss key weed control challenges cotton growers are facing. Read More...

Videos

View all
Video
Webinar

How faba beans pack a punch against sowthistle

Research shows there are opportunities to alter the agronomy of faba beans to suppress sowthistle growth and seed production in crop. Read More...
Video
Webinar

Combat Velocity® resistant wild radish with the WeedSmart Big 6

AHRI researcher Dr Roberto Busi explains in this webinar how he discovered Velocity® resistant wild radish populations in two paddocks in the northern Wheatbelt of Western Australia. Read More...
Video
Webinar

No survivors – weed control in cotton, what does it look like in 2022?

Research Agronomist Eric Koetz and WeedSmart Northern Extension Agronomist Paul McIntosh discuss key weed control challenges cotton growers are facing. Read More...

Factsheets

View all
Fact Sheet

Windrow burn chute for CASE harvester

CAD designs for a narrow windrow burning chute suited to a CASE header – suitable for adaptation to other harvester makes. Read More...
Fact Sheet

Wild radish factsheet

Increasing resistance to multiple herbicide modes of action is forcing growers to adopt diverse strategies to control wild radish. Read More...
Fact Sheet

Farm Practices Survey Report 2021

The report provides information on the adoption of a range of weed management practices on Australian grain farms. Read More...

Subscribe to the WeedSmart Newsletter