Read time: 5 minutes

John Stevenson, Lockhart NSW

Corporate farming and weed control

At Warakirri Cropping Trusts’ ‘Orange Park’, manager John Stevenson has set up a crop rotation that is profitable and able to combat herbicide resistance in weeds.

Orange Park is an 8200 ha corporate dryland cropping operation with eight main blocks, all within a 30 km radius of Lockhart, NSW where John introduced the use of the double break from cereals 10 years ago.



To get the best result possible from OP canola, ‘Orange Park’ manager John Stevenson (left) has their seed professionally graded and only plants seed sized over 2 mm diameter. Karl Grocke (right) has joined the team at Orange Park on their graduate program, making the most of the opportunity to learn from great operators like John.

“Our rotation is driven by herbicide resistant weed management,” he says. “A double break, such as hay/canola, pulse/canola, fallow/canola, is implemented once in a 7-year rotation. The rotation is flexible but we do what we can to avoid growing three cereal crops in a row because the result is inevitably a weed blow-out.”

The main weeds on Orange Park are annual ryegrass in-crop and fleabane in summer, which has been increasing since 2005, particularly in wet years. Wild oats is a lesser but persistent weed.

“We have low level glyphosate resistance and varying levels of Group A resistance to contend with,” says John. “We don’t use much Group B chemistry either, except occasionally in imi-tolerant crops, partly because of decontamination issues with canola, but mainly because of poor efficacy.”

The wettest September on record in 2016 saw about 10% of the crop across the Orange Park operation inundated – compromising their weed control and nitrogen management.

“Essentially we lost a year of weed control with ryegrass blow outs due to poor crop competition and not being able to do timely herbicide applications,” says John. “We also saw a shift in the weed spectrum with more carryover of weeds that thrive in wet conditions, such as toad rush and lesser loosestrife.”

Crop rotation and double break cropping

The rotation that is working well on Orange Park since 2008 consists of two cereals followed by canola, then another two cereals and finally a double break before returning to cereals.

John incorporates as much diversity within the system as possible to maximise returns and keep pressure on weed numbers. Canola, wheat, barley, pulses (including faba bean, lentils and vetch hay), oaten hay for export, and strategic fallowing to conserve moisture, all feature in the list of options. The diversity in crops enables the rotation of herbicide groups, including pre-emergent herbicides ahead of each crop.

Imi-tolerant crops such as Hurricane lentils, IT-canola, possibly barley in the future add to the mix although John often grows hybrid IT-canola conventionally simply for its inherent yield advantage.

“The price of lentils is attractive however logistics are difficult, as grain needs to get to Horsham, over 6 hours away,” he says. “Realistically, canola and feed grain for poultry and feedlots are our mainstay crops.”

To maximise the competitiveness of canola crops John grows some hybrid crops and also grades OP canola to 2 mm diameter as a cost-effective way to improve crop establishment and early vigour that also suppresses early weed growth.

John uses TT canola when weeds become a problem issue and Clearfield canola in low weed population paddocks where he can also apply atrazine on volunteer faba beans.

This year John planted 650 ha trial of lentils in a block that would normally have been fallowed. “There was good residual soil moisture from last year’s wet winter and we tried a late planting system to reduce the density of the lentil crop to keep air flowing through canopy, hopefully reducing the incidence of disease,” he says. “Weed control in the Hurricanes XT lentils has been exceptional although the crop has demonstrated the need for better pH amelioration at depth.”

“Including lentils will spread the workload and we can target a different weed germination cohort,” he says. “Having a different group of herbicides available will also help add diversity to our control program.”

Row spacing, CTF and stubble management

John manages Orange Park as eight 1000 ha management units, where a unit may consist of several blocks in close proximity. He is looking at opportunities to implement east–west sowing in suitable blocks to maximise yield and reduce weed pressure.

While on a Nuffield Scholarship trip to New Zealand, John saw crops grown on 125 mm (5 inch) row spacing where farmers were able to include ryegrass as a crop in their rotation, without concern over future weed problems.

“Historically, our seeding has been on a 300 mm row spacing but we are in the process of investing in a full disc seeding system, which will allow us to narrow the row spacing to 175 mm (7 inches),” says John.

The disc seeder will enable John to retain stubble from their 1.7 t/ha pulses, 3.4 t/ha wheat and 4 t/ha barley crops within their 18 m system with 3 m CTF tramlines.

Harvest weed seed control

John and his team have been narrow windrow burning for three years. Having tried this harvest weed seed control tactic in canola, wheat and barley crops they have found the safest and best results are achieved in canola.

“Realistically, narrow windrow burning is not very compatible with the council’s fire regulations so we are looking at alternatives,” says John. “Cereal stubble burns for 4 or 5 hours, and whirlwinds can easily shift burning chaff 300 m into a neighbour’s stubble.”

A downside to narrow windrow burning is that more moisture is stored under the narrow windrows, which can cause uneven crop germination the following season.

John has been successfully using narrow windrow burning in canola for several years. Twelve days after sowing, this Lancer wheat crop shows the variability in germination where the rows under the narrow windrow have access to more moisture.

John is looking into other options for harvest weed seed control and will probably phase out narrow windrow burning over the next few years. Chaff deck systems suit CTF and although John thinks they have merit, there are limitations on the options available when using contract harvesters. Chaff lining seems easier to implement and is likely to feature in the near future.

“Narrow rows help push weed seed heads to the top of the canopy,” says John. “Two plants per m2 is too many, especially if the weed is able to adopt a prostrate habit and evade collection at harvest. The big challenge is getting inexperienced header drivers to harvest low, even though we pay the contractor a premium to have this happen.”

John uses spray topping in canola, and sometimes wheat and barley, along with hay production to take out late germinating weeds.

Fallow management

Over summer, John uses a contractor with an optical (camera) sprayer to treat survivors with paraquat following a broadacre spray of glyphosate. He says the optical sprayer is also a valuable tool to help manage cud weed, which is becoming more prevalent.

There is no routine cultivation in the system however John does incorporate lime with a speed tiller before planting and a full tillage using a flexicoil is done when there is levelling work required.

“When we change over to the disc seeder we will probably need to cultivate to remove the ridges left by the tined system,” he says. “The disc seeders can’t handle too much chaff on the ground either, so burning is still an option for weed control, or when slugs and mice are a problem.”

Soil fertility and weeds

Across the Orange Park operation John has acidic (pH 4.5) red soil ridges and some sodic vertosols to contend with. He is using variable rate technology (VRT) to apply lime to the red ridges using rates ranging from 1 to 3 t/ha to lift the pH to 5.5.

“We saw an immediate response of lower ryegrass population in low pH blocks after lime application due to stronger crop competition,” he says. “Variable rate application and soil testing has been very cost effective for us and has helped reduce weed numbers and improves herbicide efficacy. Fixing soil pH gives the best return on investment through improved nutrient availability, which supports higher yield and better weed control.”

John is also using soil sensing and VRT to address constraints in nitrogen and phosphorus.

The red soil ridges on ‘Orange Park’ are acidic (pH 4.5) so John is using variable rate lime applications to lift the average pH in these soils to 5.5. In doing so he has observed an immediate reduction in ryegrass numbers due to the improved crop competitiveness.



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Ask an Expert column with Colin McMaster
GRDC Summer Fallow Weed Management Manual

 
Part 2: Increase pre-em efficacy through a mix and rotate strategy
We’ve done a good job of promoting herbicide rotation over the years. And whilst this advice still stands, recent research shows the benefits of mixing herbicides as well.
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Post emergent herbicides

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Part 2:When is it worth rotating from clethodim (Select®) to butroxydim (Factor®)?
Is there any value in rotating the post-emergent herbicides clethodim (Select®) and butroxydim (Factor®)? The research suggests that Factor® will sometimes kill plants that are moderately-resistant to Select® that could help in driving down the weed seed bank. Dr Peter Boutsalis from the University of Adelaide discusses his latest research and observations using both products with AHRI’s Peter Newman.

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WeedSmart Shorts: What considerations should be made for glyphosate tolerant canola?

 
Jump to a section

Simon’s client experience with RR Canola and decision-making process 00:27
What’s the decision-making process when it comes to growing a glyphosate tolerant variety over conventional/TT canola? 01:36
Herbicide strategy & resistance testing: 02:44
Timing of glyphosate sprays 05:02
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Desiccation & windrowing 13:48
GM canola marketing 14:46
On-farm storage 15:14

In this new segment, WeedSmart Shorts, our expert agronomists around the country interview experts on topics in a ‘Question and Answer’ video format.
Simon was kind enough to be our first guest and Jana covers lots of important points with him throughout the interview. Above, you can find what questions are covered if you’d like to jump to one of the specific topics highlighted.
Simon says there has been uptake by his clients of glyphosate tolerant canola in South Australia, but there has been a varied response.

“We are finding that some are wanting to try a paddock, some are wanting to sit back and see how it goes. So, it is probably very similar to what happened in Victoria when it rolled out there as an option,” he says.
South Australian farmers in the past have been able to control the weeds with the existing canola options they have, says Simon, but what they are finding now is there is an increase in clethodim resistance, particularly at higher rates and so that is what is likely to be driving the decision-making process around what other canola options are available, such as RR canola.
While it is exciting to have another option for SA growers, Simon says it is critical that growers know their ryegrass resistance status before committing to planting glyphosate tolerant canola.
“Testing is the backbone behind the decision making around canola options and so once we’re aware of what herbicides still work effectively, that’s where we’re able to make a good, informed decision.”
Simon said it was important to know what works on ryegrass across the whole spectrum of herbicide groups.
“An example is, I did some testing for a new client recently and one of his populations came back as 80% resistant to glyphosate. Now, had we not done that test and put glyphosate resistant canola into that paddock, we would’ve been facing a disaster, but because we had that information on hand, we knew what our options were and what they weren’t,” Simon says.
 
 

Video
Webinar

Considerations for pre-emergent herbicides with dry sowing

In this webinar, we focus on what factors influence the residual control of weeds by pre-emergent herbicides with a focus on Trifluralin, Sakura and new-to-market herbicides.
Join Chris Davey, YPAG and WeedSmart Extension Agronomist and Mark Congreve, ICAN Senior Agronomist as they assess the sowing issues in South Australia and discuss strategies on using pre-emergents.
Factors covered include

Soil type/texture
Rainfall forecast (after application)
Characteristics of the herbicide
Characteristics of the crop
Sowing time (tine vs disc) – sowing depth, speed, soil throw, stubble
Resistance status

GRDC Spray Application Manual
This Spray Application GrowNotes™ manual provides information on how various spraying systems and components work, along with those factors that the operator should consider to ensure the sprayer is operating to its full potential.
This manual focuses on issues that will assist in maintaining the accuracy of the sprayer output while improving the efficiency and safety of spraying operations. It contains many useful tips for your spray operations.

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Double breaks – a double shot at annual ryegrass

Perhaps you’re a ‘short black’ wheat-canola type, strong on inputs?
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Fact Sheet

Farm Business Management Factsheet

Key points

Effective decision-making is at the core of successful farm business management.
Making informed, logical and timely business decisions is crucial to achieving business objectivess.
Understand the different elements that influence how decisions are made and the possible outcomes.
Consider who is responsible for the final decisions in the different areas of your farm business.
Ensure the decision is finalised and implemented in a timely manner.

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Full article can be found here

Fact Sheet

Stewardship First SprayBest Guide

The application of herbicides late in the season to prevent weeds setting seed or to desiccate crops must be carried out with caution and in line with herbicide label recommendations.
It is essential to check if these practices are acceptable to buyers, as in some situations markets have extremely low or even zero tolerance to some pesticide and herbicide residues.

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