Elsevier

Crop Protection

Volume 170, August 2023, 106266
Crop Protection

Are innovative cropping systems less dependent on synthetic pesticides to treat Septoria leaf blotch (Zymoseptoria tritici) than conventional systems?

https://doi.org/10.1016/j.cropro.2023.106266Get rights and content

Highlights

  • Agricultural practices in innovative cropping systems can reduce pesticide use.

  • Long-term lower pesticide use effect on crop damage and yield has not been studied.

  • Septoria leaf blotch (STB) is a widespread winter wheat foliar disease.

  • Conventional and low-input systems rely more on pesticides than Conservation system.

  • Low-input system has the best trade-off among pesticide use, crop damage, and yield.

Abstract

In recent decades, agriculture has been typified by a reliance on synthetic pesticides, with detrimental effects on human health and the environment. It has therefore become necessary to develop more sustainable pest management strategies. To meet this objective, agricultural practices within innovative cropping systems are designed to reduce synthetic pesticide inputs, while controlling pest and pathogen life cycles. However, knowledge is still needed when it comes to the ways in which consecutive growing seasons characterized by lighter synthetic pesticide inputs affect long term crop damage by pests and pathogens, and how their minimal use can cascade on the harvested yield. This article presents a longitudinal comparison, over five years, of the severity of Septoria leaf blotch and harvested yield of winter wheat cultivated with and without synthetic pesticides among one conventional and three innovative systems – low-input-, conservation-, and organic agriculture. Conventional and conservation agriculture systems showed, respectively, the highest and the lowest difference in Septoria severity between untreated winter wheat and the same crop treated with synthetic pesticides, making them the most and least chemical protection-dependent systems. The four cropping systems produced different yields, which were not significantly influenced by the reduction in synthetic pesticide input. Low-input agriculture proved to be the best trade-off between minimal synthetic pesticide use and Septoria severity, with no effect on yield. Our study provides evidence that adopting innovative cropping systems that are less dependent on synthetic pesticides, and thus contributing to a sustainable agriculture for the future, can be done without missing production targets.

Introduction

Throughout the last few decades, conventional agriculture has characteristically relied on sizeable synthetic pesticide inputs to mitigate crop pest and pathogen damages (Foley et al., 2005). Despite clear benefits (Cooper and Dobson, 2007), the use of synthetic pesticides has come under increasing criticism due to their negative effects on the natural environment – especially biodiversity loss (Geiger et al., 2010; Outhwaite et al., 2022) and air-water pollution (Arias-Estévez et al., 2008; Silva et al., 2019) – and on human health (Budzinski and Couderchet, 2018). Research has shown that synthetic pesticides provide only short-term protection as, in the long term, evolutionary processes make pests and pathogens tolerant toward pesticide toxicity and thus lead to an increase in their dosage and economic cost (Hawkins et al., 2019; Pimentel, 2005). This is compounded by a downturn in new synthetic molecule development in favour of other, more sustainable molecules (Umetsu and Shirai, 2020). These challenges now call for alternative pest management strategies (Barzman and Dachbrodt-Saaydeh, 2011; Lamichhane et al., 2016; Lee et al., 2019). Alternative methods against pests and pathogens, both preventive and curative, have been provided by environmental policies such as the European Parliament and the EU Council's Directive 2009/128/EC (European Parliament, 2009). One suggested solution involves the adoption of innovative cropping systems, which affect the life cycle of pests and pathogens while reducing synthetic pesticide inputs (Jacquet et al., 2022; Lamichhane, 2017; Meynard et al., 2003).

To reduce reliance on synthetic pesticides, innovative cropping systems use mechanisms based on the meticulous design, integration, and management of an array of agricultural practices, such as sowing date, intercropping, N fertilization, sowing plant density, use of genetically resistant crop varieties and soil management (Loyce et al., 2008). Each practice achieves partial control of a targeted pest or pathogen, and their interactions constitute the cropping system's overall agroecological pest management strategy (Belmain et al., 2022). Following the eight principles of IPM (Barzman et al., 2015), instead of disentangling the singular pest control effect of each agricultural practice, this systemic approach evaluates the cropping system for its pest control efficacy as a whole (Drinkwater, 2002; Loyce et al., 2012; Lechenet et al., 2017). For example, Loyce et al. (2008) showed the potential to control fungal winter wheat diseases by means of a technique combining the management of seed sowing density and sowing date, with the use of genetically resistant varieties. By inhibiting fungal spore development and spread, this combination allows for a reduction in synthetic pesticide inputs. Moreover, Chikowo et al. (2009) have shown how to perform efficient weed management on winter cereals and summer crops by adjusting crop rotation, soil tillage and mechanical weeding, thereby reducing the necessity for chemical protection inputs. In order to increase crop tolerance against pest and pathogen damage, it is essential that agricultural practices be combined coherently (Debaeke et al., 2009; Rempelos et al., 2018), to minimize potential yield losses caused by the lack of chemical protections (Hossard et al., 2014).

Septoria leaf blotch, a foliar disease caused by the pathogenic fungus Zymoseptoria tritici (Roberge ex Desm.) Quaedvl. & Crous., is widespread in winter wheat (Triticum aestivum L.) and is responsible for severe yearly yield losses (McDonald and Mundt, 2016; O'Driscoll et al., 2014). The intensive agricultural practices commonly adopted in conventional cropping systems have been proved to foster the onset, development, spread, and severity of Septoria in winter wheat, thus requiring iterative synthetic pesticide inputs (Fones and Gurr, 2015; Loyce et al., 2008). For instance, an earlier sowing date can increase the likelihood of a Septoria infestation due to the prolonged exposure of seedlings to the previous year's debris, which are known to be a reservoir for fungal spores (Morais et al., 2016; Suffert et al., 2011). Higher sowing density can result in a closer canopy, which helps spores spread between neighbouring plants through splash dispersion or leaf-to-leaf contact (Lovell et al., 2004; Morais et al., 2015). A closer canopy can create a microenvironment with higher humidity in the lower layers of the crop vegetation favouring fungus development (Tompkins et al., 1993). Intensive monocultures based on a single winter wheat variety are more prone to severe Septoria (Kristoffersen et al., 2020) and can facilitate the pathogenic fungus' ability to overcome the wheat's genetic resistances (Mahboubi et al., 2022; Makhdoomi et al., 2015). Research has suggested that redesigning and coherently combining these agricultural practices within innovative cropping systems to curtail the viability of Septoria should lead to a partial or total cut in synthetic pesticide inputs (Jørgensen et al., 2014).

Previous research has already compared Septoria leaf blotch severity between innovative winter wheat cropping systems with different synthetic pesticide input regimes (Loyce et al., 2008; Rempelos et al., 2020). What remains to be quantified, however, is innovative cropping systems’ reliance on synthetic pesticides and the extent to which the design of agricultural practices can mitigate the effects of partial or complete synthetic pesticide cuts on Septoria severity. In addition, the long-term effects of lower synthetic pesticide inputs on both crop damage and harvested yield remain unknown. In this article, we set out to: (1) compare Septoria severity and harvested yield between one conventional and three innovative winter wheat cropping systems when treated and not treated with synthetic pesticides during five consecutive growing seasons; (2) identify which innovative cropping system performs best in reducing disease severity during years with higher disease pressure through the use of well-designed agricultural practices; (3) verify if harvested yields is influenced by reductions in synthetic pesticide inputs. Results should provide farmers with information to foster the ongoing trend towards switching from conventional practices towards a sustainable agriculture for the future.

Section snippets

Description of the study site “La Cage”

The study was conducted at the experimental site “La Cage” (Fig. 1), which was established in 1998 by INRAE (Institut national de recherche pour l'agriculture, l'alimentation et l'environment) located 15 km southwest of Paris (48°48′ N, 2°08′ E), France. According to the FAO classification, the experimental site's soil is a deep Luvisol, with a 58% silt, 25% sand and 17% clay average. This soil has a neutral pH and the climate at this site is temperate, with 640 mm mean annual precipitation and

Results

The four cropping systems showed inter-annual variability in Septoria severity, with higher percentages in 2014 and 2016 which were exacerbated by the absence of pesticide treatments (Table 2). The highest degree of severity was recorded in 2014 in the conventional system's NP zone while the lowest degree of severity was measured in 2015, when <5% of Septoria severity were recorded in all cropping systems, specifically in the PT zone of the conventional, low-input and conservation agriculture

Discussion

The prevalent use of synthetic pesticides in agriculture has caused severe detrimental effects on natural environments (Outhwaite et al., 2022). Our study aimed to support a more sustainable pest management strategy, through the design of innovative cropping systems which can mitigate reliance on synthetic pesticides while minimizing yield losses. Besides the relatively low number of replicates, we found that low-input, conservation agriculture and organic systems were able to mitigate the

Conclusion

Overall, this study provides long-term evidence of the ability of two innovative cropping systems, low-input and conservation agriculture, to minimize synthetic pesticide inputs and, to a large extent, control disease pressure in consecutive growing seasons. Conservation agriculture was characterized by a high disease control capacity but failed to translate this into high yield production. In contrast, low-input showed a production similar to the conventional system and a lower susceptibility

Funding sources

This study was funded by Consortium Biocontrôle in the framework of the IBC – Intégration du Biocontrôle – project.

CRediT authorship contribution statement

Bellone Davide: Conceptualization, Investigation, Analysis, Visualization, Writing-original draft; Corentin Barbu and Arnaud Gauffreteau: Investigation, Analysis, Editing; Marie-Hélène Jeuffroy, Michel Bertrand, Muriel Morison-Valantin: Conceptualization, Investigation and Editing; Marie Noel Mistou: Data Curation, Investigation; Elsa Ballini: Editing; Foteini G. Pashalidou: Funding acquisition, Conceptualization, Investigation, Analysis, Editing.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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