Herbicide Use in the Era of Farm to Fork: Strengths, Weaknesses, and Future Implications

Abstract

Climate change mitigation is a major concern of the European Union (EU). In 2019, the EU presented the European Green Deal (EGD), a new environmental strategy that aimed to neutralize climate change by 2050. Within its policy areas, the EGD included the Farm to Fork (F2F) Strategy that aims to reduce pesticide use by 50%, by 2030. This reduction was proposed due to the supposed negative effects of pesticides on the environment and its biota. Among the different pesticide groups (herbicides, fungicides, insecticides, etc.) though, herbicides are perhaps the hardest to reduce. This review aimed to shed light to any factors that might hinder the reduction of herbicide use; thus, the implementation of the Farm to Fork Strategy underlines some of its weaknesses and highlights key points of a viable herbicide reduction-related policy framework. The literature suggests that integrated weed management (IWM) consists perhaps the most suitable approach for the reduction of herbicides in the EU. Even though it is too soon to conclusively assess F2F, its success is not impossible.

Introduction

Herbicides might be the most difficult (among pesticides) to reduce in conventional agriculture (Lechenet et al., 2017). Based on the average pesticide consumption of the EU-27 Member States during 2010–2019, herbicides constitute more than 30% of the total used pesticides within the EU (Fig. 1). This could obstruct the success of the Farm to Fork (F2F) and the European Green Deal (EGD). Sustainability, the core of both the EGD and the F2F strategies, is defined by the techno-economic and the socio-political environment of a country/region (Yunlong & Smit, 1994). This assumption dictates a major obstacle that needs to be addressed: the EU might be in a major “socio-economic crisis.” Within the span of a few years the EU had to cope with Brexit (Choi et al., 2021), refugee influxes (UNICEF, 2021), the COVID-19 pandemic (AGRI Committee, 2021), and the invasion of Ukraine (Osendarp et al., 2022). Some authors suggest that following the 2008 economic crisis, the EU was divided into two groups based on economic development and competitiveness, resulting to the notion of a “two-speed EU” (Kundera, 2019). According to others, the 2008 crisis did not initiate the “disintegration” of EU, rather than promoted it (Dainotto, 2007). The current “crisis” could further boost the heterogeneity of EU and the agricultural-productivity gap among the EU-27 Member States (EAFRD, 2021) might get widened. Subsequently, the horizontal implementation of F2F within a multi-speed EU-27 might ignore the fact that several Member States would adapt faster than the others. Regardless of their share in the total gross agricultural product of EU, Southern European economies are more agriculture-reliant compared to the Northern ones (Esposito et al., 2014). The aspired herbicide reduction could thus have a greater impact on these Member States that are already considered economically fragile (Gopinath et al., 2017).

Fig. 1.

The distribution of pesticides per pesticide group (%) in EU-27, based on the applied kg during 2010–2019. Data retrieved from the FAOSTAT (https://www.fao.org/faostat/en/#home)

Furthermore, the reduction of herbicide use premises the adoption of suitable, alternative weed management strategies. Several non-chemical weed control methods (tillage, mowing, mulching, flaming, the use of cover crops, and many more) have been proposed as alternatives to chemical weed management that could reduce the use of herbicides (Fogliatto et al., 2020). Even though non-chemical weed management complies with F2F, on certain occasions, these practices could be inefficient. Tillage can control annual weeds, but it is not recommended for perennial weed management as it propagates their vegetative underground organs (Romaneckas et al., 2015). Similar to tillage, mowing might not be suitable for controlling perennial weeds as they can produce new shoots (Ringselle et al., 2016).

Mulching affects soil temperature and increases acidity (Dong et al., 2014; Chopra & Koul, 2020). Flaming controls weeds for a short period of time (1–3 weeks), is dangerous for the crop, and is not very effective against perennial weeds (Fogliatto et al., 2020). Intercropping and cover crops suppress weeds but increase the competition for resources (Steenwerth et al., 2013; Peltonen-Sainio et al., 2015). Even though considerable research has been conducted regarding the use of biopesticides and biological control agents, their implementation on field conditions remains challenging (EIP-AGRI, 2022).

Concurrently, the number of new herbicides released in the market is decreasing (Möhring et al., 2020), the rate on which new herbicidal active ingredients and modes of action are being discovered has become low (Qu et al., 2021), and an increasing number of registered herbicides (including glyphosate) could possibly get banned as existing pesticides are constantly being evaluated for their hazardous properties (European Commission, 2020). Regardless of whether the EU will renew the approval of glyphosate or not, some member states of the EU-27 banned, plan to ban, or consider banning glyphosate-based herbicides (CEO, 2021). Replacing glyphosate with other active ingredients could be problematic for F2F. In their majority, the herbicides that could substitute glyphosate are effective against a single group of weeds (e.g., monocots or dicots) (Fogliatto et al., 2020). Replacing glyphosate would not only require the combined application of different herbicides (Fogliatto et al., 2020), but also potentially multiple post- and pre-emergence applications (González and Pedraza, 2021). This could further increase the average herbicide consumption within the EU-27, so how can we sustainably reduce the use of herbicides?

Reducing the Herbicide Use Sustainably

Are There Available Alternatives?

Literature thrives with non-chemical weed management alternatives, yet their efficacy is often debatable. Several of their weaknesses have already been mentioned above. However, the literature also suggests that although each of these alternatives may be insufficient individually, their combination could control weeds sustainably and reliably (Pavlović et al., 2022). Consequently, integrated weed management (IWM) consist perhaps the best candidate among the available weed management strategies. IWM is a widely accepted weed management approach that utilizes chemical and non-chemical control methods (Shaner, 2014; Tataridas et al., 2022). Even though IWM includes the (rational) use of herbicides, its conceptualization was based on the diversification of weed management practices and the promotion of non-chemical alternatives. The success of IWM is further endorsed by its efficacy in controlling invasive (Kruger and Vieira, 2017) and/or herbicide resistant (Perotti et al., 2020) weeds.

In a recent study, Riemens et al. (2022) proposed that an IWM strategy should be designed based on 5 axes: (a) the diversification of cropping systems, (b) the cultivar, (c) soil management, (d) in site weed management, and (e) monitoring. Under the context of each one of these axes, several different techniques and methods have been studied and evaluated within the EU, providing a wide range of management alternatives. The diversification (both in space and in time) of cropping systems includes the adoption of crop rotations, cover crops, intercropping, and landscape arrangement (Błażewicz-Woźniak et al., 2015; Giuliano et al., 2016; Kuht et al., 2017; Weber et al., 2017; Dhima et al., 2018; Royo-Esnal et al., 2018; Scavo et al., 2019, 2021; Butkevičienė et al., 2021). Cultivar selection could be based on certain agronomic traits that enhance competitive abilities and can potentially suppress weeds more efficiently (Kokare et al., 2014; Karkanis et al., 2016; De Vita et al., 2017; Rasmussen et al., 2021). Regarding soil management, tillage, stale seedbed, and dead mulches have been proposed to reduce infestations and seedbank presence (Pinke et al., 2018; Jensen, 2019; Menegat and Nilsson, 2019; Fracchiolla et al., 2021; Nikolić et al., 2021; Zeller et al., 2021). Mowing, hoeing, and flaming (Gerhards et al., 2020;Mainardis et al., 2020;Spaeth et al., 2020;Hofmeijer et al., 2021), as well as the use of beneficial microorganisms, biocontrol agents and bioherbicides (Boari et al., 2016; Giannini et al., 2021; Pinto et al., 2021) could be used in site-specific direct control. Finally, state-of-the-art artificial intelligence technologies, weed mapping, and decision support systems (DSS) facilitate the monitoring of weed communities, and the rapid and informed decision-making (Sønderskov et al., 2015; Halstead et al., 2021; Jurado-Expósito et al., 2021).

At this point, it should also be clarified that the ban of glyphosate in the EU is a possibility, not a certainty. The adverse environmental impact of glyphosate has not yet been proven beyond doubt as several studies suggest that it has a relatively short half-life, it is inactive in soil as it binds to the soil components, it does not significantly affect the soil microbiota (Duke, 2020a, 2020b), and its acute and chronic toxicity on mammals is possibly very low (Duke, 2020b).

Are They Profitable? What Are their Effect on the Yields and Food Security?

Predicting the profitability of IWM is challenging. The economic efficiency of alternative pest management strategies is affected by the recovery-rate of pest populations, the interactions among different pest populations, and their resistance to certain management methods, among others (Tisdell et al., 2017). In addition, the potential ban of glyphosate should also be reckoned. Schulte et al. (2021) stated that banning glyphosate in Germany could decrease the average farmer’s income by 30–130 $ ha⁻¹ and Johansson et al. (2019) estimated that banning glyphosate in Sweden could increase economic losses by 32–165 $ ha⁻¹. Nevertheless, references where IWM was found cost-efficient within the EU-27 do exist in the literature (Delpuech and Metay, 2018; Rajmis et al., 2022). IWM case studies in the EU have also reported similar or insignificantly lower yields, compared to conventional weed management strategies (Verschwele et al., 2016; Adeux et al., 2019; Adeux et al., 2019b). While studying the effects of herbicides on crop production in wheat fields of western France, Gaba et al. (2016) concluded that reducing them even by as far as 50% is possible without compromising the yields.

Maintaining yields while reducing herbicide use would benefit food security. Food security is based upon four pillars: availability, access, utilization, and stability (Gunaratne et al., 2021), ergo it could be ensured not only by maintaining/increasing the yields (food availability), but also via improving household incomes and stabilizing food prices (food access), crop/diet diversification (food utilization), promoting sustainable agricultural/food systems (food stability), etc. (NMFA, 2012). For instance, besides its benefits on the environment, and the maintenance of ecosystem services, reducing herbicides could also improve farmer’s income (Gaba et al. 2016). As the risk of poverty is higher in rural areas in the EU (Eurostat, 2020), and given that poverty and malnutrition are closely correlated (Siddiqui et al., 2020), a better income for farmers could enhance food security in rural areas within the EU-27.

What About Their Environmental Trade-offs?

Soil degradation is a major concern in the EU as it has been estimated to cost European farmers more than € 1.25 billion per year (European Commission, 2021a). Even though tillage constitutes an essential tool in the “IWM arsenal,” it has been suggested that it increases greenhouse gases (GHG) emissions (Rutkowska et al., 2018) that the EGD aims to reduce. Likewise, the new European Soil Strategy (ESS) aims to reduce soil erosion; thus, no-tillage regimes have gained popularity (European Commission, 2021b). Nonetheless, tillage does not necessarily contradict the EGD and the ESS, and vice versa. In a recent meta-analysis by Shakoor et al. (2021), authors compared conventional tillage and no-tillage (NT) regimes and concluded that even though NT reduces the global warming potential, it could increase CO₂, N₂O, and CH₄ emissions, compared to conventional tillage. Moreover, NT relays heavily on the use of herbicides for weed control (Maheswari, 2021). A recent simulation study by Colbach and Cordeau (2022) reported that an herbicide-free approach in NT could be devastating for the yields. However, NT is not the only available tillage alternative. NT is one of the several systems included under the concept of conservation tillage (CT). CT intends to conserve soil and water via a reduction in the intensity of tillage and the retention of plant residues (Carter, 2005). The most commonly accepted definition of CT is “a system that covers 30% or more of the soil surface with crop residue, to reduce soil erosion,” and includes mulch tillage, ridge tillage, zone tillage, NT, minimum tillage, and reduced tillage (Carter, 2005). Especially, the latter has been found beneficial for the health of the soil and has reported sufficient weed management properties when combined with cover crops (Büchi et al., 2020) or other weed management alternatives.

Can All the Member States of the EU-27 Comply?

Provided that its heterogeneity will hinder the unanimous reduction of herbicides within EU, a potential solution could be to divide the EU-27 in clusters of Member States with similar characteristics and adjust F2F accordingly to these clusters. An example of this proposition is presented on Fig. 2 where the EU-27 Member States were divided in three clusters (C1, C2, and C3) based on their average annual herbicide consumption during 2000–2019. The clustering was performed by subjecting data retrieved from FAOSTAT to the k-means clustering method of vector quantization, using R studio (Version 4.2.1), and following the algorithm (Faber, 1994):

$$\text{E}={\sum }_{j=1}^k{\sum }_{i=1}^n∥x_i^{(j)},-,C_j∥$$ 2

Fig. 2.

Results of the k-means clustering. The countries within each cluster are presented on the right of the figure. Dim1 and Dim2 represent a projection of the original data set. Each dimension represents a certain amount of the variation contained in the original data set

where ${∥x_i^{(j)},-,C_j∥}^2$ is a selected distance measure between data point $x_i^{(j)}$ and cluster center C_j. The clustering analysis grouped the EU-27 Member States in three major clusters: cluster C1 includes the Member States with the highest herbicide consumption (France, Italy, Germany, Poland, and Spain), while the clusters C2 and C3 include the ones with moderate and low herbicide consumption respectively. According to the FAOSTAT data, more than half of the total applied herbicides within the EU-27 derive from the C1 (FAOSTAT, 2022). Of course, under no circumstances should these findings inculpate C1 Member States. After all, C1 also produces a significant portion of EU’s agricultural commodities. In fact, in 2018, even though 71.8% of the total EU-27 herbicide consumption corresponded to C1, the state members of this cluster produced 67.6% of the total agricultural gross value of EU-27 (FAOSTAT, 2022b). On the contrary, this clustering would aim to facilitate the implementation of F2F by weighting the contribution of each cluster in the total EU-27 herbicide consumption. Prioritizing the reduction of herbicides in the C1 would be more impactful to the implementation of F2F, as per the above clustering. It should be noted though that the clustering performed in the present study is a mere simplified example.

The agricultural gross value of each cluster, the acreage of agricultural land, the cultivated crops, the applied herbicides and their active ingredients, and the treatment frequency should also be included in such clustering analyses.

Strengths, Weaknesses, and Future Perspectives

On the EU-27 or on a national level, Member States can motivate farmers to adopt IWM either by imposing penalties (e.g., taxation) or by positive reinforcement (e.g., subsidies). Ranaldo et al. (EIP-AGRI, 2022b) proposed that perhaps the simultaneous implementation of both (a “carrot and stick” strategy) is more efficient. Both tactics though bear their risks. Case in point, a 2020 report by the UN environment programme, regarding the effects of taxes and subsidies on pesticide and fertilizer use, found that high taxes may encourage illicit behaviors and low taxes may be ineffective (UN, 2020). In the same report, subsidies were found to be more beneficial for large-scale farms (UN, 2020). The authors also noted that large-scale farms are rarely owned by women, implying an underlying gender bias (UN, 2020). Under no circumstances do these findings establish that taxations and subsidies are pointless. Nevertheless, perhaps it would be preferable to emphasise on raising awareness and educating the public.

Farmers tend to focus on the short-term economic benefits, while the agroecological benefits of herbicide reduction are long-term oriented (EIP-AGRI, 2022). In a study conducted in 2019, Moss (2019) reported 16 “limiting” factors that cause farmers to be reluctant regarding the adaptation of IWM strategies including the economic benefits and feasibility of IWM (e.g., the increased cost of IWM, the higher financial risk, the reduced economic efficiency of IWM, the reduced profits, etc.), farmers’ perceptions and biases on weed management (e.g., IWM is more “complex” and “time-consuming,” expecting upcoming herbicides that can manage noxious weeds, etc.), and the lack of technical know-how. Information and knowledge can be useful to overcome these barriers. Toubou et al. (2020) reported that in Greece, almost half of the cereal farmers that participated in a survey were unaware of what herbicide resistance is, and approximately 40% of them were willing to adopt alternative weed control practices to prevent it. Similarly, Lucchi and Benelli (2018) concluded that knowledge facilitates the adoption of integrated pest management (IPM) strategies in vineyards of Italy. Moreover, farmers’ biases can be heavily influenced by their peers (Niu et al., 2022). EU-27 Member States should invest not only in the development of “farmer-consumer” communication channels, but also in the promotion of national and international “farmer-farmer” ones. Workshops, farming press, seminars, and information dissemination projects (either on national or EU level) are vital and could include farmers/orators that have successfully reduced the use of herbicides in their crops, to share their success stories.

Another important aspect are the extension services (ES). In most European countries, ES have been delegated by governments to private companies (EIP-AGRI 2022c). According to the findings of Wuepper et al. (2021) regarding the advice farmers receive on pest management strategies, farmers were more likely to adopt preventive measures rather than depend on chemical inputs when advised by public ES instead of private ones. This could also be the case for weed management. The reduction of herbicide use might call for independent, public advice to farmers. This does not signify the exclusion of the private sector. On the contrary, private–public collaborations have been proven to be highly effective. In Switzerland, the producer organization IP-SUISSE developed a non-organic, private–public standard for pesticide-free wheat production. This project was based on a combination of public and private compensations (via direct payments and price mark-ups) for farmers (Böcker et al., 2019).

A successful policy framework includes every actor of the value chain (Möhring et al., 2020) (Fig. 3). The title of “Farm to Fork” itself implies everyone’s participation, from farmers to consumers. Consumers play a crucial role in F2Fas their preferences and choices (demand) can force farmers to comply with the proposed herbicide reduction (Saleh et al., 2021). However, a significant portion of EU citizens might not be (or does not feel adequately enough) informed. Recent reports indicate that in their majority, EU citizens are not well informed about soil legislation and protection (Schismenos et al., 2022), more than half of them are unfamiliarized with the loss of biodiversity (European Commission, 2019), and approximately 50% of them do not feel informed regarding pesticides overall (European Commission, 2018). Admittedly, the EU has intensified its efforts to make the dangers of herbicide overuse lucid to the public. Informational initiatives should also target younger ages. The inclusion of lectures in school and university curriculums would result to future consumers with environmental concerns and invest in the agronomists of tomorrow from their early stages.

Fig. 3.

Framework of an herbicide reduction policy. The framework includes every actor of the supply chain (EU Commission, Governments, Corporations of the agri-food sector, Farmers, and Consumers). The arrows represent the beneficial interactions among the actors

Finally, and most importantly, EU should always address the criticism it receives. Prior to the EGD and the F2F, Holt et al. (2016) argued that it is next to impossible for an EU pesticide policy to ensure food security and maintain ecosystem services. Schebesta and Candel (2020) pointed out that F2F does not define “food sustainability” successfully, and many of its goals are not accurately translated into action plans. Similar concerns have been expressed by Monarrez Lachhein (2022) regarding the problems that might arise in the legislation and the national judicial systems of the EU-27, due to the ambiguity of “sustainability” within the F2F. According to Fuchs et al. (2020), the EGD (and the F2F) are responsible for offshoring environmental damage to nations outside the EU. The Commission should take into account these comments and (depending on their validity) re-evaluate its action plans.

Abbreviations

EU

European Union

EGD

European Green Deal

F2F

Farm to Fork

IPM

integrated pest management

IWM

integrated weed management

NT

no-tillage

CT

conventional tillage.

Authors’ Contributions

Conceptualization, V. T., A. M., and D. B.; literature search, V. T., A. M., I. K., C. K., I. K. K., A. Z., G. K., D. Be., I. R., G. E., and D. B.; data analysis, V. T., C. K., I. K. K., A. Z., and G. K.; writing original draft preparation, V. T., A. M., and D. B.; writing review and editing, A.M., and D.B.

Data Availability

All data were retrieved from the official FAOSTAT website (https://www.fao.org/faostat/en/).

Declarations

Conflict of Interest

The authors declare no competing interests.