With the foreseeable discontinuation of the PFAS plant protection product flufenacet, new solutions must be developed to control weed grasses. The degradation product trifluoroacetic acid, which can be formed during the degradation of all PFAS plant protection products, has proven to be so toxic that essential authorisation criteria are no longer met.  Sustainable and forward-looking development of agricultural technology based on the precautionary principle is becoming increasingly important in order to give farmers security when combating weeds. After all, good alternatives require innovations in the field and several years of testing and optimisation.

Flufenacet is a very important component for soil herbicides, especially against weeds such as foxtail – and will soon be discontinued at least in Germany. (Link)

EFSA concluded that flufenacet no longer meets the criteria for authorisation of plant protection products set out in Regulation (EC) No 1107/2009 due to concerns about its effects on the human endocrine system and the possible contamination of water by harmful degradation products such as trifluoroacetic acid. (Link)

Like a number of other crop protection products, flufenacet belongs to the group of polyfluorinated alkyl substances (PFAS). These are substances in which three fluorine atoms are bound to at least one carbon atom of the active ingredient molecule.  Such substances are generally either hardly or not at all degradable in the environment (so-called perpetuants) or they break down into substances that are no longer degradable, such as trifluoroacetic acid (TFA). Other important TFA-releasing pesticides include diflufenican, fluazinam, tritosulfuron, tembotrione, fluopyram, fluaziflop-P, trifloxystrobin, fluopicolide, lambda-cyhalothrin and flonicamid. (Link)

And it is precisely this non-degradable trifluoroacetic acid that is the current problem molecule with flufenacet. Trifluoroacetic acid is highly soluble in water and leaches from the soil into the groundwater. It can also be easily absorbed and accumulated by plants. As a result, it also reaches humans via the food chain or is spread back onto the fields in the nutrient cycle, e.g. with liquid manure and fermentation residues. Even the most modern sewage treatment plants cannot remove it from the water cycle. If trifluoroacetic acid gets into the air, it rains back onto the fields and into the water. TFA no longer disappears. (Link) (Link2)

With a good 400 tonnes of potential TFA generation per year in Germany, pesticides are the largest source from agriculture, pharmaceuticals, municipal sewage treatment plants and precipitation. At just under 200 tonnes, flufenacet accounts for almost half of the potential input quantities of the “forever chemical” TFA. (LInk)

Trifluoroacetic acid was long rated as a harmless degradation product.  This changed fundamentally when Bayer informed the EU Commission in 2021, based on its own very high-quality study, that severe malformations of the skeleton and intestines had occurred in tests on rabbits during pregnancy. (Link)

As a result, TFA was classified as “toxic for reproduction Cat. 1 B”, i.e. likely to cause prenatal, non-heritable health effects and foetal damage in humans.(Link)

This toxicological finding is the often mentioned exclusion criterion according to the authorisation regulation (EC) No. 1107/2009 for plant protection products.

However, long before 2021, many groups and decision-makers wanted to limit the use of PFAS to absolutely necessary areas on the basis of the precautionary principle. (TRIFLUORESSIGSÄURE)

Some state offices for agriculture began developing plant protection concepts without flufenacet as early as 2016 (!). With clear results:

– the elimination of flufenacet makes autumn treatment of foxtail and ryegrass more difficult….

– Weeds … can no longer be controlled in the long term with chemicals alone…

– Various arable measures should definitely be tried out and integrated on the farm

(Link)

As is so often the case with technical developments, falling back on old, familiar techniques and processes is often not the breakthrough to efficient problem solving. The ‘return’ to old solutions (which have usually been replaced for good reasons) is often only a stopgap solution or no solution at all. This is particularly true when a previously very efficient measure or technology, such as chemical plant protection, is no longer available. Therefore, completely new solutions must be sought and integrated into the required applications in a customised manner.

With electrophysical plant control, crop.zone is presenting a new mode of action for broad application that can also help to get a better grip on resistance problems or the strong dependence of other methods on the weather, for example.

For this reason, crop.zone is also working on strategies for integrating the pre-sowing and pre-emergence treatment of foxtail and windthale into arable farming measures. This is particularly interesting where additional soil movement is undesirable or not possible.

Only together and with foresight with all partners in the value chain can we feed more and more people sufficiently and sustainably despite climate change and threatened biodiversity. Innovative agricultural technology with new active principles must be integrated even more strongly into new arable farming measures on the ground.

In the case of fluorinated PFAS plant protection products in particular, considerable further restrictions are to be expected, which are likely to affect not only, but also soil herbicides. On the other hand, agriculture has always thrived on innovations in agricultural technology.

crop.zone is working on bringing electrophysical innovations in agricultural technology to the fields.