When a Plant Resistance Inducer Leaves the Lab for the Field: Integrating ASM into Routine Apple Protection Practices.

Brice Marolleau,Arnaud Lemarquand,Marie-Noëlle Brisset,Matthieu Gaucher,Romain Warneys,Gilles Orain,Christelle Heintz,Alexandre Degrave

doi:10.3389/fpls.2017.01938

Abstract

Plant resistance inducers, also called elicitors, could be useful to reduce the use of pesticides. However, their performance in controlling diseases in the field remains unsatisfactory due to lack of specific knowledge of how they can integrate crop protection practices. In this work, we focused on apple crop and acibenzolar-S-methyl (ASM), a well-known SAR (systemic acquired resistance) inducer of numerous plant species. We provide a protocol for orchard-effective control of apple scab due to the ascomycete fungus Venturia inaequalis, by applying ASM in combination with a light integrated pest management program. Besides we pave the way for future optimization levers by demonstrating in controlled conditions (i) the high influence of apple genotypes, (ii) the ability of ASM to prime defenses in newly formed leaves, (iii) the positive effect of repeated elicitor applications, (iv) the additive effect of a thinning fruit agent.

Highlights

Numerous pathogens and pests attack apple trees (Malus × domestica), causing important losses in yield and quality harvest
Scheduled applications of ASM superimposed to a light application of fungicides during the natural apple scab primary infection period was compared to a classical Integrated Pest Management (IPM) and to the light IPM
Few apple scab symptoms were observed on leaves in the IPM strategy in which incidence and severity reached 8% and 11% respectively (Figure 2A)

Summary

Introduction

Numerous pathogens and pests attack apple trees (Malus × domestica), causing important losses in yield and quality harvest. Among strategies to reduce pesticides, the use of plant resistance inducers (PRIs, called elicitors or plant defense activators) appears as a potential option to face the phytosanitary issues of conventional agricultural practices (Thakur and Sohal, 2013; Walters et al, 2013). These agents include a variety of chemical (Bektas and Eulgem, 2015) or biological (Wiesel et al, 2014) stimulators able to activate plant defenses by exogenous application. Depending on their very nature, they either act as non-self determinants (mimicking MAMP – Microbe Associated Molecular Patterns – or DAMP – Damage Associated Molecular Patterns – general elicitors) perceived by pattern recognition receptors (PRR) present at the cell

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Conclusion