Physical and Ecological Weed Management Workshop

The Physical and Ecological Weed Management workshop was developed and is presented by myself Dr Charles 'Merf' Merfield. It has expanded from an hours presentation in the early 2000s to a full day workshop giving a comprehensive overview of physical and ecological weed management. If you want to be notified of the next workshop please email me at and I will notify you when the next one is announced. The information below gives an outline of the workshop.

I am an international academic and practitioner of non-chemical weed management and the leading scientist and consultant in Aotearoa New Zealand. I am also head of the BHU Future Farming Centre and Merfield Agronomy Ltd. plus co-owner and director of PhysicalWeeding. I have over 50 publications on non-chemical weed management including peer reviewed papers and book chapters, conference proceedings and extension publications including though leader articles on the future of weed management. For example, 'Redefining weeds for the post-herbicide era' and 'Could the dawn of Level 4 robotic weeders facilitate a revolution in ecological weed management?' See my research page and the FFC website for more examples and additional information. I was also the OrganicNZ 2024 Organic Leader of the year for excellence in science communication.

I have more than 30 years practical experience in non-chemical weed management. I started my weed management journey helping re-establish Sunnyfields organic vegetable farm in the UK after the previous manager had walked off having lost his war with the weeds. In a sink or swim moment, I devised a new weed management strategy which turned around the weed problem in just two years. From the UK I came to Aotearoa New Zealand for a working holiday from which I am very unlikely to return. In NZ I worked extensively at Harts Creek Farm in Canterbury developing their organic weed management systems across multiple farms.

I have also invented, designed and built a wide range of weeding machinery including an optimised naturally aspirated flame weeder, re-invented the direct-fired steam boiler and repurposed it for ag / horticultural use, the 4 Wheel Hoe, false seedbed cultivators, interrow hoes, basket weeders and even a new toolbar clamp!

Who should attend?

The primary audience is horticultural and cropping / arable farmers & growers as it is these production systems that have the largest challenge with weeds. Perennial crop (e.g. vines, apples) producers will also benefit with one section dedicated to perennial crops (see below). There is some benefit for livestock / pasture systems in terms of the overall concepts of non-chemical and integrated weed management plus herbicide resistance. Consultants and advisors working with farmer and grower clients, particularly in cropping, will gain considerable benefit, especially regarding the latest technologies. Scientists, especially those working on the transition away from agrichemicals, will gain valuable insights.

The content assumes a reasonable level of understanding and practical experience of commercial agriculture and horticulture systems including weed management.

This is a really full on and intense workshop - bring your thinking head!

Please note the workshop is In person only there is no online version.

The primary audience is cropping (horticulture and arable) farmers & growers as it is these production systems that have the largest challenge with weeds. Perennial crop (e.g. vines, apples) producers will also benefit with one section dedicated to perennial crops (see below). For anyone dealing with herbicide resistant weeds, this workshop is the start of your solution. There are also some benefits for livestock / pasture systems in terms of the overall concepts of non-chemical and integrated weed management. Consultants and advisors working with farmer and grower clients, particularly in cropping, will gain considerable benefit, especially regarding the latest technologies. Scientists, especially those dealing with herbicide resistance and working on the transition to non-chemical weed management, will gain valuable insights.

The content assumes a reasonable level of understanding and practical experience of commercial agriculture and horticulture systems including weed management.

This is a really full on and intense workshop - bring your thinking head! Plenty of caffeine is provided!

The benefits of attending.

The day gives a systematic overview of non-chemical weed management, providing information on the changing context of weed management, the fundamentals of weed biology and ecology as they relate to weed management, through to practical know-how of tools and techniques that farmers and growers can use themselves. See below for more detail on the topics covered. Due to the huge size of the topic this is 'only' an overview and cannot get into the detailed of non-chemical weed management in every crop. Specific issues can be discussed in the many Q&A sessions.

Attendees will be given a colour hardcopy booklet containing all the presentation slides (in handout format). Attendees can also download PDF versions of the presentations after the workshop.

Some comments from the previous weed management workshop participants

"Great overview and backed up by robust science"
"Highly useful, time to implement theory into practice"
"At the cutting edge"
"Enthusiastic presenter"
"Great discussions"

Topics covered

Below are the topics covered. There are lots of Q&A and discussion breaks throughout and between the main sessions.

The workshop is theory only. Unless any machinery companies have some weeders they want to display at the workshop.

Part 1: The Big Picture: A Little Context

Context - changing face of weed farming
The new soil health paradigm of plant root exudates
Rethinking weed management
Redefining weeds for the post-herbicide era
Non-chemical vs. Integrated pest and weed management
Biological weed control

Part 2: Herbicide resistance

Global herbicide resistance
NZ herbicide resistance
How herbicide resistant weeds occur
Where do they come from?
Herbicide resistance risk factors
Beating herbicide resistance
How do I know if I have herbicide resistant weeds?

Part 3: Think like a weed: key biological and ecological knowledge

Lifecycles and morphology
Seeds, seeding and dormancy
Discussion / questions and answers
The weed seed bank - the ‘root’ of the problem
The ‘bud based perspective’
Dedifferentiation - zombie plants
Therophytes
Discussion / questions and answers

Part 4: Doing it in the field - the weed management hierarchy

Just how good it can get!
The non-chemical weed management hierarchy
Weed seed rain - stopping it
Harvest weed seed control (HWSC)
Rotations what they can and can’t do for weed management
The relevance, and lack of relevance, of soil conditions inc nutrient status for weed management
The role of crop and pasture choice and grazing management

Part 5: Ecological weed management - Plants vs. weeds

Substitution vs. system redesign
Ecological weed management
Diversity is the answer
Plant mixtures - intercropping
Service (cover) crops for weeds and more

Part 6: Electrical weed management

Mode of action
EWM origins
EWM theory
1st, 2nd and 3rd generation electrical weeders
The future potential

Part 7: Pasture, livestock and perennial weeds

How to graze
Grazers vs. browsers
Spot sprayers and electrical weeders
True roots and shoots and bud based perspective
Shallow and deep creeping, taproots and crowns

Part 8: Perennial crops

"The death zone has gotta go"
Ecological approaches
The alleyway / interrow
The crop row / intrarow
Plant-plant interactions
A Lighter Touch ecological example
Physical approaches
Mowers and cultivators
Flame and steam
Electricals

Part 9: Annuals - Pre-emergence

Pre-crop-emergence weeding (tillage)
Strategic ploughing
Q&A session
False seedbed, blind harrowing and stale seedbeds
Q&A session
Sowing, planting & related techniques
Nutrient placement and timings

Part 10: Annuals - Post-emergence, Tine and spoon weeders (contiguous)

Some preamble to the weeders
Spring tine weeders
Rotary tine weeder
Spoon weeder / rotary hoe T

Part 11: Annuals - Post-emergence, Row hoes (incontiguous)

Jethro Tull
Guidance systems
Machine design
Row hoes
Intrarow weeders
Misc

Part 12: Annuals - Post emergence robotic weeders and Harvest weed seed control (HWSC)

Four levels of robotic weeders
Harvest weed seed control (HWSC)

Part 13: Pulling annual row crop weeding together and herbicide integration

Weeder selection based on crop type and farm system
Q&A session
Integrating mechanical and herbicides
Q&A session
Conclusions