Southern Alberta Weed workshop - Transdisciplinary approaches to better weed research and management?

In June 2016 Sally Peltzer & I attended Andina III – a 5 day weed workshop in southern Alberta organised by a range of weedies including the notable Roger Cousens, University of Melbourne and Sonia Graham, a social scientist from the University of NSW.

The workshop was held at the Gladstone Ranch near Pincher Creek, in the eastern foothills of the Canadian Rockies and was attended by 32 ‘natural’ and 'social' scientists, agronomists and consultants, from seven countries. Australians and North Americans made up the bulk of the participants.

 Gladstone Ranch homestead

This was the third Andina workshop, with the first 2 taking place in Yellowstone National Park and Spain. Each conference has had a different theme. The theme for Andina III was “the transdisciplinary approach” to weed research and management and a few social scientists were thrown into the mix.

The general principle behind these get-togethers is to fill a perceived void left by traditional conferences by fostering international dialogue, collaboration and mentoring in a relaxed atmosphere. By spending 5 days together and doing a wide range of activities trust and relationships are built between the participants which will continue into the future once everyone has returned home to their normal lives and jobs.

So what is a "transdisciplinary approach"?

This was an interesting question because we asked “what is the difference between transdisciplinarity and a good research and extension program?” This was discussed at some length, for better or worse over the five days.

Integrative multidisciplinary research is thought to address complex real-world problems addressed systemically rather than as isolated problems.  It involves harnessing scholarly and practical knowledge across many stakeholder groups such as scientists from different disciplines, private sector players, farmers, and extensionists at a range of geographic and political levels e.g. local, regional, landscape-wide.

Some of the participants in a 'break-out' session.

Multiple parties bring:

  • a wide range of knowledge to address a complex problem.
  • AND a diverse and often conflicting range of interests and views

Normally what happens in research is that researchers concentrate on research directions and objectives and tack on some publicity, such as a dry press release, or ill-planned extension at the completion of the research. This is the old top-down approach to research - we know what’s good for you so you should use our research findings....... and be grateful while you’re at it.

We tried to test the multi-disciplinary approach in southern Alberta by doing a fair amount of pre-workshop communication between workshop members as well as reading up on the issues facing the diverse range of land users in southern Alberta.

For us the most interesting case study we investigated was the Waldron Grazing Cooperative which:

  • Is a collection of commercial cattle ranches  (over 16,000 ha) under a single progressive manager
  • It is a prime wildlife corridor for bears, cougars, elk, deer, coyote and moose
  • Accesses land management funds for projects from Alberta Province and Federal Government, private donors and the co-operative.
  • Has an agreement with the Nature Conservancy of Canada to protect the land in a state similar to that prior to white settlement, except running beef instead of bison.
  • Makes the Waldron Coop an outlier with other beef ranchers in the area because they are seen as different because of their size and the way they access a range of external funds. This is then seen as the major reason why they can run above district average numbers of beasts and obviously has nothing to do with the pasture and grazing management being practised.
  • Has leafy spurge (Euphorbia esula) as its major weed species. Leafy Spurge is a perennial with a spreading root system that isn’t eaten by cattle and has been spreading across North America since the early 1900s.

Mike the Walrond manager’s approach

Mike, manager of the Waldron Cooperative, outlining his approach to range management.

  • Manage the grass first and the cattle second because without the grass you can’t fatten the cattle. Mike tries to emulate the grazing patterns of the bison with rotational grazing and lets the perennial grasses seed before winter to maintain species diversity in his pastures. Like in Australia most cattle ranchers set stock their pastures over summer leading to an increased density of leafy spurge, and a decline in species diversity and cattle weight gain.
  • To manage the leafy spurge Mike uses a biocontrol agent that is a root-feeding beetle. Many other ranchers have also established this beetle on their leafy spurge infestations while others use an ‘unplanned’ herbicide program in an attempt to contain weed infestations.
  • What is different with the Waldron Co-op is that they graze  sheep (leased) on the spurge as well. We were told that the reason why the combination of biocontrol and grazing with sheep works so well was that the sheep disperse biocontrol agent. Interestingly no research has been conducted looking at the influence of defoliation in combination with the root feeding biocontrol. We thought that this is probably the reason why this combination works so well not the dispersal of the beetles. This is an excellent example where a multi-disciplinary approach to a problem would have paid off rather than leaving it to biocontrol specialists.

  • It is interesting to note that there also is a VERY negative attitude towards the grazing of sheep in the general ranching community going back to the time when homesteaders moved into the Canadian rangelands leading to ‘range wars’.  
  • We thought that if you hate sheep, why not try a combination of slashing and biocontrol?

Unfortunately we did not meet any other ranchers that would be considered “typical”. The ranchers we sat down and discussed a weed management with were all organic beef growers. What all ranchers do seem to like doing is sit on a horse.

Canada has also experienced contraction of provincial agriculture departments with a reduction in production research and extension being available to landholders.

So what did we take home from Andina III?

  • Andina is a great opportunity to meet a range of international researchers and get to know them having a great time while you’re at it.
  • Multi-disciplinary approaches (which are hard to define – just read the peer reviewed papers on the subject) have merit because a number of the researchers we met did not work with anyone from outside their technical silo. Hmmmm. Several researchers said that they would not look at multi-disciplinary cooperation because it would not progress their career objectives i.e. pump out papers.
  • Multidisciplinary teams seem an obvious approach for someone with an extension/research background but was a new concept for a number of the researchers.

If you get the opportunity to attend an Andina workshop it is well worth the effort. The next workshop is in Agentina in January 2018. This time the topic will be fundamental molecular biology through to mathematical modelling. For more information go to

Which herbicide caused that injury? We put some scientists to the test.

As part of the 20th Australian Weeds Conference Agronomy Field Tour in September 2016, the tour participants tested their ability to recognise herbicide damage symptoms across a range of crops and pasture species with the trial funded by Department of Agriculture & Food WA and Royalties for Regions™. To make it not too difficult, the guinea pigs (sorry, particpants) pre-downloaded the new GRDC Ute Guide herbicide Injury app to assist them in their quest. To sharpen their wits we also made it into a competition with extravagant prizes to be had. 

Herbicide injury demonstration at Muresk InstituteAfter saying I would never ever go on another Conference field tour, I had to put my money where my mouth was when Sally Peltzer and I were approached early in 2016 to organise the agronomy tour for the Weeds Conference to be held in Perth, WA.

We had to make the day interesting so decided to base it at or close to the Muresk Institute, just outside Northam, Western Australia. This is an easy 1.5 hour bus trip from Perth.

So back to the issue of herbicide injury of crops. We know herbicide damage is caused by herbicide drift, poor sprayer hygiene, adding the wrong product or spraying the wrong paddock. So how can growers and their advisers know what which herbicides are causing the problem? They can:

  • pinpoint the herbicide and therefore hopefully decipher how it happened
  • estimate a level of potential yield loss
  • determine harvest or grazing withholding periods that could affect marketing of produce through exceeding maximum residue levels

GRDC has recently released an app to enable growers and agronomists more easily identify which herbicides are damaging the crop. Sally and I decided to establish a herbicide injury demonstration to test the Agronomy tour participants’ brains, as well as evaluate the app.

The treatments in Table 1 were sprayed across 18 crop and pasture types 15 days before the field day. No tank-mixes were used as this would have “muddied the water”.

Table 1. Herbicides and rates used in the demonstration.

Trade name

Active Ingredient

MOA Group



MCPA ester


1 L/ha

Amitole® T



5 L/ha

Verdict® + Uptake™



100 mL/ha


metsulfuron methyl


5 g/ha


urea + ammonium nitrate


50 L/ha

Atrazine + Uptake



1.1 kg/ha




200 mL/ha




40 mL/ha




0.5 L/ha


paraquat (200 g/L)


500 mL/ha


So how did the competition go?

There were 8 ‘stations’ for the contest and we split the participants into groups of 3 or 4.  We wanted the modes of action causing crop damage at the 8 stations and those in the “herbicide business” also had to name the actual herbicide to help level the playing field.

As can be seen from the photos the groups were busy competing.

Various groups busy trying to identify the 8 herbicide modes of action

What this exercise highlighted was how difficult it can be to identify the herbicide causing crop damage. It is important to not just look at the crop, but the weeds and other species and observe how they are reacting. Knowing the time elapsed since herbicide application also makes a huge difference in assessing the symptoms as symptoms change with time and dose. For example with cool low light intensity conditions paraquat (Group L) damage to cereals can look like a number of other herbicides during the first 2 weeks before desiccation has properly commenced. Even some of the 'herbicide experts' were fooled.

 Catherine Borger, DAFWA, with Kerry Harrington, NZ, and two international visitors.

Besides the fun, some great feedback has also been supplied to the GRDC to improve the Herbicide Injury app.

Rest of the day

After the herbicide injury competition Peter Vella and Dave Rogers from Hardi Australia discussed how modern spray technology, as used on their Saritor 5500, improves spray efficiency and efficacy through lighter booms and accurate height control .

The group fascinated by the high tech Hardi Saritor 5500.

Next we inspected the exhibition model of the iHSD – integrated Harrington Seed Destructor – with Devon Gilmour, McIntosh & Son, along with Ray Harrington, the inventor.

 Inventor and farmer Ray Harrington explaining how the iHSD kills weed seeds.

After lunch Andrew Guzzomi, University of Western Australia, demonstrated his selective cultivating tine. The tines are activated when the sensors detect a weed, digging it out. This shows lots of promise for low density fallow weed control.

Andrew Guzzomi explaining the complicated path to developing a new concept in tillage.Then it was back on the bus to head out to Andrew Boultbee’s farm nearby to look at his approach to harvest seed management with chaff dumps. Andrew has a number of approaches to dealing with the dumps. He sows through them and may or may not burn them depending on the season and amount of rain received. Everyone was fascinated by Andrew’s adaptation of the dump and burn approach.

Farmer Andrew Boultbee explaining how he manages weed seed production in cereal crops.

After that it was back to Perth via York.

We are pleased to say that the feedback was all positive from the day and a great deal of thanks goes to:

  • Peter Vella and Dave Rogers at Hardi Australia
  • Devon Gilmour at McIntosh & Son
  • Ray Harrington
  • Andrew Boultbee
  • Andrew Guzzomi, UWA
  • the staff at Muresk Institute, Northam, Western Australia
  • Bridget & the team from Kalyx Australia
Paraquat resistance is gaining momentum in Australia

Another three weed species in Australia have just confirmed resistant to paraquat – Cudweed (Gamochaeta pensylvanica), blackberry nightshade (Solanum nigrum) and crowsfoot grass (Eleusine indica) taking the total number of species to 9 in Australia (Table 1).

Paraquat resistant crowsfoot grass regrowing following spraying. Image: P. Boutsalis & C. Preston

Overseas there are now 24 species resistant to paraquat, from the Middle East through to New Zealand, comprising of 6 grass and 18 broadleaf species.

Table 1 Species that have developed paraquat resistance in Australia
(Australian Glyphosate Sustainability Working Group)


Common name

Year first confirmed



Resistance to other herbicides / MOAs

Arctotheca calendula





Diquat (L)

Hordeum glaucum

Northern barley grass




Diquat (L)

Hordeum leporinum

Barley grass




Diquat (L)

Vulpia bromoides

Silver grass




Diquat (L)



Small square weed




Diquat (L)

Lolium rigidum

Annual ryegrass


South Australia

Pasture seed

A / M - 2 populations

Gamochaeta pensylvanica




Tomatoes, peanuts, sugar cane, avocados


Solanum nigrum

Blackberry nightshade



Tomatoes, peanuts, sugar cane, avocados


Eleusine indica

Crowsfoot grass



Tomatoes, peanuts, sugar cane, avocados



As can be seen from Table 1, paraquat resistance hasn’t developed in broadacre cropping yet and the listed rotations, or lack of them, were highly reliant on paraquat for weed control.  However the widespread adoption of paraquat either as a second knock or an alternative to glyphosate over the past 10 years we probably don’t have long to wait. There are rumours of a glyphosate-paraquat resistant population of annual ryegrass (L. rigidum) about to confirmed from southern Western Australia.

In 2013 we confirmed a ryegrass population from a Great Southern vineyard that is strongly resistant to both glyphosate and paraquat which was the result of a vineyard manager rotating between these two important herbicides. Rotating herbicide modes of action buys you time, but doesn’t prevent resistance.

The answer?

The only way to stop herbicide resistance in its tracks is ensure no survivors of a herbicide application are allowed to set fertile seed.

This means drive weed numbers down and use diverse crop rotations, which in turn gives you plenty of options to use a range of non herbicide weed tactics. Combined with competitive crops, good timing of operations and effective spray practices you are on the way to putting herbicide resistance well into the future.

While tank mixing solid rates of different modes of action can be effective, many growers will be too late for this tactic as they already have resistance to at least one of these modes of action. For tank-mixing to work as a resistance management strategy both herbicides MUST BE fully effective on the weeds in question.

Mixing glyphosate and paraquat is not a viable option because of antagonism (biological) in the plant. When mixed together these products are not complementary and the paraquat works too rapidly for the glyphosate to be effectively translocated. This is the reason the double knock is utilised. Both products can be utilised on the same weed population without antagonism of the mix.

But before you go, ask yourself the question, “How do I know which of my herbicides still work?”

Blackberry nightshade Image: AGRONOMO

Being aware of sensitive crops and (geographical) areas when spraying

There has been rain and that means it’s weeds and spraying time. This time of year also lends itself to extremely risky spray conditions. Beautiful autumn weather is when surface temperature inversions are most common. For more information on inversions read my previous blogs here and here.

Strong inversion conditions March 2016. Image: AGRONOMORemember that all pesticides drift, it is just that some, such as Group I herbicides like 2,4-D, have a recognisable odour and produce unique symptoms on sensitive vegetation.


So what is the problem with off-target movement of pesticide? The most obvious agricultural issue is damage to sensitive crops. For example in the 2007-08 cotton growing season it was estimated that 10 per cent of the Australian cotton crop has some level of herbicide damage costing $5 million.

The second agricultural issue is pesticide residues. Organic farmers certainly don’t want anyone else’s pesticides. Drift is a particular problem when a crop is getting close to harvest. Signing a vendor declaration that you haven’t used certain pesticides gets complicated when the purchaser tests the product and it is ‘contaminated’.

Some of our major trading partners also have zero tolerance for certain pesticides. Ship loads of grain have been turned around and sent back for such breeches. The wine grape industry is particularly aware of the potential effects of unwanted residues on their markets.

Contamination of the natural and human environments is also a major concern.

Sensitive areas

Other than showing a duty of care, reading and following the label, using buffer zones and using best practice application, we need to be aware of sensitive areas in the vicinity of the farm when spraying. Talk to your neighbours and find out what crops they will have in, particularly in paddocks along the boundary. Be aware of state restrictions on pesticide use and spraying.

Some Australian states have restrictions on spraying in or near ‘sensitive’ areas. Western Australia has listed most Group I herbicides as ‘Scheduled’ meaning they cannot be used within certain distances of sensitive crops and high volatile 2,4-D ester is banned within 5 km of a commercially sensitive crop (vineyards or tomatoes), within 19 km of the Geraldton post office and within the Swan Valley, or within 10 km of the Kununurra Post Office. High volatile ester is not registered any other state or territory.

Victoria has nine designated areas where the type of pesticide and its application is regulated.

Agricultural Chemical Control areas in Victoria. Source: Agriculture VictoriaThe cotton industry has led the way with on online mapping with 95% of cotton crops mapped.  There is no excuse to say you didn’t know there is cotton nearby.

Cotton field awareness map for the western Riverina. Source: Cotton Australia & Cotton CRDCWestern Australia also has a voluntary system of registering your pesticide sensitive crop with the Department of Agriculture & Food WA.

DAFWA sensitive areas map 2015The map highlights organic farms, vineyards, tree crops, vegetable, bee hives and aquaculture sites. Being voluntary not all WA sensitive crops are mapped and a quick comparison with Google Earth will show additional vineyards and orchards. Another problem is that most broadacre farmers I have spoken with are unaware that this map of sensitive crops exits.  This is ironic because much of the potential drift affecting these sensitive crops could come from cropping country.

When it is spray time, do some planning, look at the weather forecast and for any potential risks, talk to your neighbours, use the right gear and get that pesticide where it is meant to be.