A thorough understanding of how herbicides work can assist agronomists and growers in achieving optimal performance from herbicides.

It is a fact recognised by the GRDC, which has started rolling-out another series of herbicide behaviour workshops across the Australian grainbelt.

Commencing in January in Western Australia, and continuing in the eastern states into February - and delivered by Independent Consultants Australia Network (ICAN) - the popular workshops are addressing the science underpinning how herbicides work.

A total of 25 herbicide behaviour workshops were conducted in 2019, with more than 500 agronomists and growers participating.

ICAN weed specialist Mark Congreve says last year's workshops were very well received and the positive feedback from participants influenced the scheduling of 14 additional workshops in early 2020.

"This year's workshops will be mostly in locations different to those chosen in 2019, to cater for those agronomists and growers who may not have been able to attend previous events due to distance," Mr Congreve says.

The workshops have been endorsed by many of the participants who attended workshops in 2019, including one grower who commented: "As a farmer with 30 years' experience managing and operating our spraying program, I found this course excellent. There was a huge amount of information that answered a lot of questions."

Making the most of herbicides

Mr Congreve says participants in the 2020 workshops will gain a better understanding of the key factors dictating herbicide performance and what can be done in the paddock to ensure maximum weed control.

"Weeds are a significant burden to growers in terms of cost of control and impact on their farming systems and productivity," Mr Congreve says.

"And herbicide resistance is a key driver of increasing costs being incurred by growers."

Mr Congreve says that when confronted with a range of weed problems and environmental conditions, the challenge is to optimise the results in the field.

"Knowing what weeds will be controlled from a herbicide application is the easy bit - that information is on the label," he says.

"More challenging questions are around why herbicides perform or fail in some situations, why there are critical comments on the label and how they were developed."

Other challenging questions include:

• what happens in the tank, and in the plant, when we tank-mix different herbicides;
• how do adjuvants and water conditioning agents work - what should be used, when and why;
• how does resistance affect different herbicides and what strategies can be used as resistance emerges; and
• how do residual herbicides work and what influences their breakdown.

Regional focus

Mr Congreve says workshops - targeting experienced agronomists but open to interested growers - will be customised for each location to focus on regionally important herbicides and management issues, covering the following:

• How herbicides work - disruption of key enzyme systems within the plant
• Leaf entry of post-emergent herbicides, including the influence of environmental conditions and the importance of adjuvants
• Post-emergent herbicide translocation and metabolism
• Herbicide resistance and resistance mechanisms
• Maximising performance of the key post-emergent modes of action (MOAs)
• Pre-emergents - stubble, volatilisation, photodegradation and incorporation; relationship with soil type and soil moisture; degradation, plantbacks and crop safety; impacts of tillage and planter type; and maximising performance of key pre-emergent herbicides.

Workshops will be held at the following locations:

• Rich River Golf Club, Moama, NSW - February 6 and 7
• Griffith Exies Club, NSW - February 4 and 5
• Narrogin Club, WA - February 11 and 12
• Ingot Hotel Perth, WA - February 13 and 14
• Launceston Conference Centre, Tasmania - February 27 and 28
• Mayfair Ridge Tavern, Emerald, Queensland - March 17 and 18
• Copper Coast Sports & Leisure Centre, Kadina, South Australia - March 24 and 25
• Rydges Adelaide, SA - March 26 and 27
• Parkes Services Club, NSW - March 31 and April 1
• Wagga Wagga RSL, NSW - April 2 and 3
• Horsham RSL, Victoria - April 21 and 22
• Agriculture Victoria, Hamilton, Victoria - April 23 and 24

These small group workshops are conducted over one-and-a-half days. Numbers are limited to ensure active participation and discussion. Previous workshops have been fully subscribed, so early registration is essential.

The cost is $165 (including GST) per workshop and the events start at 9am on day one and finish by lunchtime on day two.

GRDC Research Code ICN 1811-001SAX

More information and registrations are available through ICAN: https://www.icanrural.com.au/registration/herbicideworkshops.html