# How to manage the complexity of deploying microbial biocontrol agents against plant diseases?

Marc Bardin, Thomas Pressecq, Marc Tchamitchian, Philippe C. Nicot

► To cite this version:

Marc Bardin, Thomas Pressecq, Marc Tchamitchian, Philippe C. Nicot. How to manage the complexity of deploying microbial biocontrol agents against plant diseases?. Third international congress of biological control (ICBC3), IOBC, CABI, Jun 2024, San Jose, Costa Rica. hal-04837568

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# How to manage the complexity of deploying microbial biocontrol agents against plant diseases?

Marc Bardin

Thomas Pressecq

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Plant Pathology Research unit
Avignon, France

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# Augmentative biocontrol of diseases with microbials:
increasing number of registered products

At world level, against diseases
(virus, bacteria, oomycetes, fungi)

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**91 microbial strains:**

49 fungi/yeast/oomycetes + 37 bacteria/actinomycetes + 5 virus/phages

BioControl
DOI 10.1007/s10526-017-9801-4

<figure><img src="image_9.png" /></figure>

Biological control using invertebrates and microorganisms:
plenty of new opportunities

Joop C. van Lenteren · Karel Bolckmans · Jürgen Köhl ·
Willem J. Ravensberg · Alberto Urbaneja

**41 microbial strains approved in Europe**
(EU pesticide database, 07/2023)

→ How are these products actually used?
## Survey of French vegetable farmers and farm advisors

* Online questionnaires disseminated to more than 500 professionals (217 answers):

* ✓ Only few biocontrol products known (21/32) and used (15)

* ✓ Efficacy perceived as low

* Face-to-face interviews performed (42 / 217 respondents):

* ✓ Aware of the benefits of applying biocontrol products to manage plant diseases
  But

* ✓ Difficulties in using biocontrol with other cultural practices

* ✓ Unstable efficacy

Using microbial biocontrol for disease control in French vegetable production: An analysis of the perspectives of farmers and farm advisors

Thomas Pressecq<sup>a,b,*</sup>, Philippe C. Nicot<sup>a</sup>, Jean François Bourgeay<sup>a</sup>, Aurélie Rousselin<sup>b</sup>, Claire Goillon<sup>b</sup>, Marc Bardin<sup>a</sup>, Marc Tchamitchian<sup>a</sup>

Commercial microbial biocontrol product

<figure><img src="image_10.png" /></figure>

→ What are the possible causes for this instability in the efficacy of protection?

<footnote><sup>a</sup> INRAE, Pathologie Végétale, 84140, Montfavet, France</footnote>

<footnote><sup>b</sup> Association Provençale de Recherche & d'Experimenter Légumière - APREL, 13210, Saint-Rémy-de-Provence, France</footnote>
# Example of factors that can modulate the efficacy of biocontrol against plant diseases

## Climatic conditions

<figure><img src="image_11.png" /></figure>

Agron. Sustain. Dev. (2014) 34:641-648

DOI 10.1007/s13593-013-0168-3

RESEARCH ARTICLE

## Cultural practices

Nitrogen fertilization impacts biocontrol of tomato gray mold

Manzoor A. Abro • François Lecompte • Marc Bardin

Philippe C. Nicot

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## Other phytosanitary treatments including biocontrol

Biological Control 46 (2008) 476-483

Compatibility between biopesticides used to control grey mould, powdery mildew and whitefly on tomato

M. Bardin<sup>a,n</sup>, J. Fargues<sup>b</sup>, P.C. Nicot<sup>a</sup>

## Resistance of pathogen to biocontrol

<figure><img src="image_15.png" /></figure>

frontiers

in Plant Science

REVIEW
published: 27 July 2015
doi: 10.3389/fpls.2015.00506

Is the efficacy of biological control against plant diseases likely to be more durable than that of chemical pesticides?

Marc Bardin<sup>*</sup>, Sakhr Ajouz<sup>†</sup>, Morgane Comby<sup>‡</sup>, Miguel Lopez-Ferber<sup>¶</sup>, Benoit Graillot<sup>¶,§</sup>, Myriam Siegwart<sup>¶</sup> and Philippe C. Nicot<sup>¶</sup>

## Mode(s) of action and their activation

<figure><img src="image_16.png" /></figure>

## Modes of Action of Microbial Biocontrol Agents against Plant Diseases

ESTELLE TURC<sup>1,2</sup>, THOMAS PRESSECO<sup>1,2</sup>, PHILIPPE C. NICOT<sup>1</sup> AND MARC BARDIN<sup>1*</sup>

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<footnote><sup>a</sup>INRA, Unité de Pathologie Végétale, UR 407, F-84140 Montf岳, France</footnote>

<footnote><sup>b</sup>INRA, Centre de Biologie et de Gestion des Populations, Campus international de Baillarguet, CS 30 016, 34988 Montferrier-sur-Lez cédex, France</footnote>

<footnote><sup>¶</sup>Plant Pathology Unit, Institut National de la Recherche Agronomique, UR407, Montf岳, France, <sup>†</sup>Laboratoire de Génie de l'Environnement Industriel, Ecole des Mines d'Alles, Institut Mines-Télécom, Alles, France, <sup>‡</sup>Natural Plant Protection, Arysta LifeScience Group, Pau, France, <sup>§</sup>Parigi et Systèmes de Culture Horticoles Unit, Institut National de la Recherche Agronomique, UR115, Avignon, France</footnote>

<footnote n="1"><sup>1</sup>INRAE, Pathologie Végétale, Montf岳, France</footnote>

<footnote n="2"><sup>2</sup>Groupe Éléphant Vert France, Serris, France</footnote>

<footnote n="3"><sup>3</sup>INRAE, Ecodéveloppement, Avignon, France</footnote>
# Classification of efficacy factors for a biocontrol microbial strain

* Efficacy factors organized into 4 groups

* Each group includes a number of related factors

* Possible interactions between factors

* Cultural practices

* Plant species, genotype

* Fertirrigation

* Phytosanitary treatments

* Type of disease

* Inoculum pressure

* Level of sensitivity

Pathogen

Cropping practices

Efficacy

Biocontrol

Environnement

* Ecological competence

* Mode of action

* Dose / quality / formulation of product

* Method / condition of use

* Physical (T°C, humidity, light...)

* Chemical (pH, O₂, CO₂...

* Biochemical (nutrients)

* Microbial

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How to deal with this
complexity and help farmers
use biocontrol correctly?

BURLEIGH DOODS SERIES IN AGRICULTURAL SCIENCE

Improving integrated
pest management in
horticulture

Edited by Professor Colin Waterhouse, University of UK

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by burleigh dodds

Advances in bioprotectants for plant
disease control in horticulture

Philippe C. Nicot, Thomas Pressecq and Marc Bardin, INRAE, Pathologie Végétale, France
# How to deal with this complexity and help farmers?

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* Develop practical guidelines helping to choose the most adequate products for specific situations

* Obtain information about the most efficient way to use a biocontrol solution

→ **Where to find this information ?**

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→ **the data available in scientific articles will make it possible to obtain this information**

* ✓ Is there a substantial amount of published knowledge on the factors governing the efficacy of microbial biocontrol agents?

* ✓ Is it possible to gather suitable information to develop guidelines for the practical application of these products by farmers?

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ELSEVIER

Contents lists available at ScienceDirect

Crop Protection

journal homepage: www.elsevier.com/locate/crop

Using microbial biocontrol for disease control in French vegetable production: An analysis of the perspectives of farmers and farm advisors

Thomas Pressegq<sup>a,b,c</sup>, Philippe C. Nicot<sup>a</sup>, Jean François Bourgeay<sup>b</sup>, Aurélie Rousselin<sup>b</sup>, Claire Goillon<sup>b</sup>, Marc Bardin<sup>c</sup>, Marc Tchamitchian<sup>a</sup>

<footnote><sup>a</sup> INRAE, Laboratoire Végétal, 04140, Montpellier, France</footnote>

<footnote><sup>b</sup> Association Prévocat de Recherche d'Exposition et de Prévention - APRÉL, 13210, Saint Béry-de-Prévalois, France</footnote>
# Analysis of published knowledge on the factors governing the efficacy of microbial biocontrol agents

* Collect relevant peer-reviewed articles

All publications on the **41 biocontrol microbial strains registered in Europe**
(excluding reviews)

Research equation : Full name of biocontrol agent (**species + strain name**)
OR current (and possibly previous) commercial name

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WEB OF SCIENCE

* ✓ 808 publications collected on European registered microbial strains

* ✓ Great majority of publications concerned strains in species *Bacillus* (255) and *Trichoderma* (263)

* ✓ Most studied strains: *B. amyloliquefaciens* QST 713 (133 publications) and *T. afroharzianum* T-22 (115)
# Analysis of published knowledge on the factors governing the efficacy of microbial biocontrol agents

* Collect relevant peer-reviewed articles

* Review of scientific information on the efficacy factors

* ✓ 37% of articles with information on efficacy factors (296)

* ✓ Certain articles can include results for different factors of efficacy

* ✓ No information for 13 of the 41 strains registered in Europe
# Analysis of published knowledge on the factors governing the efficacy of microbial biocontrol agents

* Collect relevant peer-reviewed articles

* Review of scientific information on the efficacy factors

* In-depth analysis of publications: extraction of data on efficacy factors

Every publication analyzed according to the following framework:

**Context**

* Biocontrol name
  (strain, commercial product)

* Crop

* Pathogen targeted

* ...

**Experimental conditions**

* Experimental method
  (in vitro, controlled condition, in field...)

* Biocontrol treatment (type, dose, timing, frequency)

* Pathogen inoculation (natural or artificial, conditions)

* ...

**Data on efficacy factors**
# Analysis of published knowledge on the factors governing the efficacy of microbial biocontrol agents

* Collect relevant peer-reviewed articles

* Review of scientific information on the efficacy factors

* In-depth analysis of publications: extraction of data on efficacy factors

Every publication analyzed according to the following framework:

<figure><img src="image_25.png" /></figure>

## Data on efficacy factors

* Efficacy factor(s) tested (group and sub-group)

* Protective efficacy value

* Effect of factor(s) tested on efficacy (quantitative data if available)

* ...

✓ For a given article, several relevant information can be obtained
# Analysis of published knowledge on the factors governing the efficacy of microbial biocontrol agents

* Collect relevant peer-reviewed articles

* Review of scientific information on the efficacy factors

* In-depth analysis of publications: extraction of data on efficacy factors

Every publication analyzed according to the following framework:

**Context**

* Biocontrol name
  (strain, commercial product)

* Crop

* Pathogen targeted

* ...

**Experimental conditions**

* Experimental method
  (in vitro, controlled condition, in field...)

* Biocontrol treatment (type, dose, timing, frequency)

* Pathogen inoculation (natural or artificial, conditions)

* ...

**Data on efficacy factors**

* Efficacy factor(s) tested (group and sub-group)

* Protective efficacy value

* Effect of factor(s) tested on efficacy
  (quantitative data if available)

* ...

Build a database on efficacy factors of microbial biocontrol agents against plant diseases

* ✓ Few quantitative data available

* ✓ Very heterogenous distribution of information among strains and among types of efficacy factors
Example of *Trichoderma* strains: lot of data but...

* Some data not relevant (e.g. strain name not indicated)

* Little information available / commercial strain / efficacy factor

* Information not directly applicable (e.g. data obtained under artificial conditions)

Trichoderma strains used as active substances

<figure><img src="image_26.png" /></figure>

Groups and sub-groups of efficacy factors

: Information not directly applicable
(e.g. *in vitro* studies, no direct effect on efficacy, ...)

Number of information on efficacy factors, sorted by groups
Conclusion

* Is there a substantial amount of published knowledge on the factors governing the efficacy of microbial biocontrol agents?

→ **Most of the data currently published on microbial biocontrol agents in scientific journal do not involve commercial strains or efficacy factors**

* Is it possible to gather suitable information to develop guidelines for the practical application of these products by farmers?

→ **Tremendous amount of additional data required for the development of guidelines for farmers**
# What's next ?

* Increase the availability of data in future published articles for integration into the database

* ✓ Clearly indicate the strain name of the biocontrol agent used in the study

* ✓ Share data more widely, including “negative” results

* Obtain more data on biocontrol agent efficacy factors

* ✓ Make agreements with companies (in progress)

* ✓ Carry out experiments under production conditions, recording as many variables as possible (climatic conditions in particular)

* Translate this scientific knowledge into decision rules

* ✓ Transform the data collected in the database into operational information

* ✓ Integrate this information into a decision support system useful to farmers

DeciControl

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http://ephytia.inra.fr/fr/P/175/DeciControl

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SynDev
L'orchestration des biosolutions
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IOBC-WPRS

XVII

Meeting of the Working Group

**Biological and
integrated control
of plant pathogens**

From single microbes
to microbiomes targeting
One Health

https://www.iobctorino2025.org/

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**SAVE THE DATE**
**June 11-14, 2025**

Università degli Studi di Torino
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Thank you !

INRAE

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NIVIGION
PATHOLOGIE
VEGETALE

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<figure><img src="image_36.png" /><figcaption>Thomas
PRESSECQ</figcaption></figure>

<figure><img src="image_37.png" /><figcaption>Philippe
NICOT</figcaption></figure>

<figure><img src="image_38.png" /><figcaption>Marc
TCHAMITCHIAN</figcaption></figure>

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ADOPT
IPM

EU-China joint action
to increase the development
and adoption of IPM tools

The project has received funding from the Horizon Europe Framework
Programme of the European Union under grant agreement No 101060430

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RÉPUBLIQUE
FRANÇAISE

Liberté
Légitiè
Fraternité

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FRANCE

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anr

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INRAE

CULTIVER
PROTÉGER
autrement

CAP

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PHYTO

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biocontrôle

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RÉGION
SUD

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Liberté • Égalité • Fraternité
RÉPUBLIQUE FRANÇAISE

MINISTÈRE
DE LA TRANSITION
ÉCOLOGIQUE ET SOLIDAIRE

MINISTÈRE
DE L'AGRICULTURE
ET DE L'ALIMENTATION