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The first in a series of articles discussing observations and asking important questions about the degradation of agricultural and rural landscapes throughout Australia.
This month, Tim Thompson and I travelled through south-eastern Victoria and southern and central New South Wales, meeting innovators in sustainable farming. The generosity and desire to share knowledge by all involved was humbling. I strongly suggest you subscribe to Tim’s YouTube channel 'Farm Learning' to hear the stories and emerging themes from these visits.
While much of the trip was positive, there was one disturbing aspect: widespread vegetation death in cropping districts, mostly mature trees, in tree belts, long paddocks and paddocks. The phenomenon was notably absent in neighbouring grazing regions, despite similar drought conditions. Even the hardiest of drought-resistant trees – the African peppercorn – was being affected.
We were left wondering about this PARA-normal effect we were seeing throughout the cropping area. WHAT could be causing it?
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The damage wasn’t limited to trees at field edges or within fields but extended to trees not directly adjacent to cropland yet still within cropping districts. This pattern was consistent throughout the cropping areas we surveyed. We observed two distinct types of impact: direct and indirect effects.
Direct effects appeared on trees within or bordering cropped paddocks, showing damage from spray boom drift (killing foliage from the bottom up) or aerial application (killing from the top down).
More concerning however, was the widespread impact of light spray droplets carried by temperature inversions (indirect), which settled considerable distances from the application site.
The destruction of mature trees is undermining entire ecosystems. The most immediate sign is the disappearance of birds. Pesticide spraying and the removal of nesting sites have drastically reduced bird numbers, allowing insect populations to explode. These insects now overwhelm already vulnerable trees, creating a destructive cycle.
Where once birdsong filled the air, silence now prevails. While nearby grazing lands still vibrate with diversity and the distinctive calls of cockatoos and galahs, the cropland is becoming the embodiment of a Silent Spring once again.
In Groundbreaking: Soil Security and Climate Change, we discussed the adverse externalities of production: where profits are private, but the costs—such as increased bush fires and floods, degraded soil, dead trees, and public health risks—are borne by the community. This pattern is clearly evident here, as natural capital in the landscape faces mounting threats from some farmers actions.
During the trip, it was apparent that cropping was associated with PARA-normal tree death.
WHAT were some farmers doing or applying to their crops to cause the tree death?
My conclusion? Herbicide spray drift the most likely answer. In particular, the mix of Paraquat and LVE, or Paraquat and Diqua.
The direct spray drift appears to be a combination of glyphosate, LVE (low volatile ester) paraquat and diquat. LVE is widely used and advertised as a low volatile spray, but low volatile is not non-volatile and does not stop the formation of microdroplet spray drift. LVE is a simple acronym that avoids mentioning what it actually is 2,4-Dicholorphenoxyacetic acid (2,4-D) a component of Agent Orange used with devastating consequences in the Vietnam war. LVE is often combined with Paraquat in a ‘double-knock’ strategy for weed management, with highly effective—and it seems deadly—results.
The use of these four chemicals in non-cotton crops has exploded in the last few years, as the cotton industry has reduced herbicide usage particularly, the use of glyphosate.
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The indirect drift appears to be that associated with droplet burns, almost always associated with winter wheat or cotton. Indirect drift is killing the pepper trees in the stockyards and the birds—and potentially impacting our health. It is an extremely toxic acute poison for humans.
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The Australian Pesticides and Veterinary Medicines Authority (APVMA) is currently reassessing paraquat and diquat, following their 2024 determination that glyphosate is non-hazardous when used according to guidelines. According to APVMA, paraquat is classified as highly toxic to mammals (including humans) and birds, while diquat is highly toxic to birds and moderately toxic to mammals.
The APVMA has restricted application parameters for horticultural use, particularly in viticulture, but their assessment critically assumes perfect adherence to safety protocols. Their technical report on paraquat specifies "ground application only," yet fails to define the maximum permissible height for spray equipment to qualify as ground application.
This raises important questions: Does a spray boom constitute ground application, and at what height does application cease to be classified as ground-based?
Additionally concerning is that current spray drift buffer zones are designated exclusively for livestock protection, with no corresponding safeguards for wildlife or native vegetation. Though there are restrictions on wind strengths for use of sprays, there appears to be no consideration of temperature inversions in late autumn afternoons.
Paraquat exhibits significant persistence in soil, leading to degradation of soil function. It being highly soluble in water could readily explain the widespread diffuse tree mortality observed throughout the cropping districts of western Victoria and southern NSW.
When spraying occurs on still days with temperature inversions (where warm air sits above cooler air), paraquat and 2,4-D (LVE) disperse in air attached to water moisture in the air and will drift across the country, far from where it was applied. As temperatures change, these droplets fall back to earth, following the landscape. This airborne spread is likely what's killing our trees—and potentially putting the health of our rural communities at risk.
APVMA regulatory scope is limited to packaging, labelling and food residue accumulation – not the actual application practices once products leave the controlled environmental of the dealer’s premises. There is no oversight of field application methods, no follow-up on improper usage and no systematic investigation of tree mortality or ecosystem damage. This regulatory gap would be unacceptable in any other industry. Such environmental harm would never be tolerated in waterways or air quality. Why, then do we accept this level of landscape degradation in rural environments? Comprehensive studies of real-world application practices and their ecological impacts are urgently needed.
Visual evidence on the leaves of trees and plants in the cropping industry indicates the application of Paraquat together with 2,4-D—no matter what the labels and studies say—is causing environmental degradation at not just landscape but regional scale. If the agricultural industry and many farmers are advertising they are climate friendly and sustainable, the widespread tree and ecosystem death in cropping areas belies their claims.
As Paraquat is extremely toxic to mammals (including us), could this passive diverse spray drift be affecting our communities? Incorrect use of these herbicides is clearly compromising the environment, so what are they doing to our health? Growing accounts from community suggest these concerns are more than theoretical. What was once a potentiality now appears a reality.
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We have PARA-normal widespread ecological death in our countryside.
WHAT do you think we can do about it?
For those that don’t believe me, take a two-hour drive through the country and look closely at multiple tree deaths and their proximity to cropping areas. Ask, what are we doing now that we didn’t 30 years ago?
I welcome alternate hypotheses, because mine scares me.
Join the discussion on LinkedIn.
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