The current Australian discussion about the toxicity of the herbicide paraquat is almost a repeat of the ban on this highly toxic substance in the EU around 15 years ago. Even then, EU courts were so critical of the link with Parkinson’s disease and the toxicity to humans and animals that the EU Commission had to withdraw the authorisation. The Australian authorities are currently severely restricting the quantities used and making paraquat worthless, for example in potato siccation, due to long waiting periods. Only the acceptance of scientific risk assessments and the early development of sustainable alternatives can maintain weed control and siccation.

There is currently an intense debate in Australia as to whether the non-selective herbicide paraquat is a cause of the increased incidence of Parkinson’s disease. Scientists assume that the causal link can be proven with certainty in animals. (Link)

In its latest report, the Australian Pesticide Management Authority (APVMA) still does not see these links as clearly. (Link)

However, it recommends stopping applications with high application rates if they pose a high risk to the environment or an acute risk of poisoning. (Link)

For those Australians who live or have lived in rural areas, and for those who currently have Parkinson’s disease, the situation remains uncertain and less than reassuring.

In a very extensive evaluation process that was reviewed by the EU courts, the EU Commission finally had to withdraw the previous authorisation of paraquat in 2010 following complaints from several countries because the data on which the authorisation was based did not correspond to the full state of scientific knowledge and its appropriate evaluation. The key points of the toxicological assessment at the time, which then led to the ban, were the sufficiently clear link between paraquat and Parkinson’s disease, life-threatening risks for users and excessive effects on animal health (rabbits, birds). (Link)

Paraquat is the most commonly used pesticide for suicide. Just 20 ml can be fatal. Even the addition of emetics has not significantly reduced the risk of death. (Link)

For these reasons, paraquat is now banned in 67 countries, but is still authorised in Australia and the USA, for example. In China, the owner of the world’s largest paraquat producer, but banned its use in the whole country in 2016. (Link)

Despite this, agricultural productivity in these countries has not fallen.(Link) However, this is not due to the ban without replacement, but to work on alternatives, as weed control and siccation cannot simply be dispensed with.

European agriculture is lagging far behind Australia when it comes to no-till and drought management. In the current wet year (in Germany), risks of drought are often overlooked, but climate change is here to stay. Weed control concepts with multiple cultivations, however shallow and precise they may be, can then cost the crucial leftover water for the next sowing and wind erosion the soil itself.

But perhaps Australia can learn from Europe when it comes to PPP risk management. Glufosinate, paraquat and diquat have been banned by the EU for years and decades on the basis of scientific risk assessments (also and especially with regard to Parkinson’s disease). The early ban has also led to the development of innovative agricultural technology. 

Paraquat is currently authorised in Australia for use 3-7 days before potato uprooting. Surprisingly, according to the latest APVMA report, there is no data to support safe use during this period. Even the available residue data for a 14-day waiting period showed unacceptable levels of paraquat intake for children. The new recommendation for further use is therefore ‘4-5 weeks before uprooting’). (Link)

This stricter recommendation shows that toxicity for humans has obviously been considerably underestimated without any scientific basis. At the same time, however, the example also shows that the new recommendation makes paraquat practically worthless for many farmers who, for a variety of reasons, cannot or do not want to leave their potatoes in the ground for so long.

Cultivation time means yield and money. In many regions of the world, the aim is to allow potatoes to grow actively for a defined period of time in order to achieve high quality and a high price (size, starch content, not too long a pest load in the soil, predictable weather conditions at harvest). Once potato growth is complete, the fields must be available for rapid replanting with a catch crop or the following crop. Even the current waiting period of 14 days is often a considerable difficulty for farmers. Particularly in years with later planting dates, every day of active growth, especially for industrial potatoes, is a significant economic gain. This is why more and more farmers are turning to modern non-chemical methods.

The APVMA report contains a lengthy list of restrictions, from a ban on high application rates to longer waiting periods. For more than 10 crops and fallow land, this means that innovative solutions will have to be found if the restrictions are implemented. Resistance is strong. For example, legume growers in some regions fear very severe wind breakage if they are no longer allowed to apply paraquat early enough. (Link)

The winegrowing sector also sees paraquat as a tried-and-tested component in the herbicide toolbox. (Link)

The same applies to grain and cotton producers, who fear for their future if they can no longer control weeds and desiccate as before. (Link) (Link)

The historical development and current examples show that the general trend towards the use of chemical herbicides is the ever-increasing restriction due to scientifically recognised, unacceptable side effects. Ignoring toxicological studies is also never successful in the medium term in constitutional states. But there will be no going back to the hoe and plough.

So alternatives must be found through innovation. This takes time and must always be started proactively. Non-chemical innovations can be developed much faster than chemical active ingredients, for which the pipeline is also definitely empty. The last new mechanisms of action were discovered more than 30 years ago. Today, only the number of resistant weeds is increasing.

The crop.zone electrophysical process is one of the innovations that is driving progress and is being used in several areas. In Europe, for example, after the long-standing ban on paraquat and, for some years now, diquat, many farmers are happy that crop.zone has no waiting times. Unlike the herbicides that are still available, it does not need sunlight to develop its effect. This means that even in difficult climatic conditions, farmers can desiccate potato haulm and harvest as required for potato quality and logistics. This means that the potato harvest in Germany can continue into November and the following crop are sown immediately afterwards.

crop.zone is using its technology in a rising number of crops areas such as potatoes, cover crops, cereals and, in future, in pre-emergence treatment, legumes and more. This is because crop.zone makes the mode of action of electrophysical treatment usable for large-scale agriculture. This will help any progressive agriculture, whether organic, regenerative or ‘just’ future-orientated, forward-looking and responsible.