# Biocontrol of grey mould of greenhouse tomatoes

Véronique Decognet, Yannie Trottin-Caudal, Christine Fournier, Jean-Michel Leyre, Philippe C. Nicot

► To cite this version:

Véronique Decognet, Yannie Trottin-Caudal, Christine Fournier, Jean-Michel Leyre, Philippe C. Nicot. Biocontrol of grey mould of greenhouse tomatoes. 12. International Botrytis Symposium, Jul 2000, Reims, France. hal-02770684

HAL Id: hal-02770684

https://hal.inrae.fr/hal-02770684v1

Submitted on 28 May 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
Véronique Decognet<fnref n="1" />, Yannie Trottin-Caudal<fnref n="2" />, Christine Fournier<fnref n="2" />, Jean-Michel Leyre<fnref n="2" />, Philippe Nicot<fnref n="1" />

In earlier work, a collection of microorganisms isolated from the epiphytic micro-flora of greenhouse tomatoes was screened for its ability to prevent the development of *Botrytis cinerea* on tomato leaf disks and the infection of pruning wounds on potted plants in growth chamber tests (Nicot *et al.*, 1996). A fungal strain, provisionally identified as *Fusarium* sp., was selected and further evaluated for its potential as a biocontrol agent (BCA).

The efficacy of the BCA as a wound protectant on greenhouse tomatoes was tested in 17 crop-level trials conducted in southern France between 1994 and 1998 in conditions close to a commercial situation. Three means of delivering the BCA (as a spore suspension in water) were assessed: (i) as a localised spray on pruning wounds with a hand-held sprayer, (ii) by application on the whole de-leafed area of the plants with a back-pack sprayer and (iii) with pruning shears equipped with a small spray device. To insure the development of disease, inoculum of *B. cinerea* was applied with one hour after leaf removal onto the wounds. This usually resulted in a high incidence of stem lesions on control plants (15 to 78%; average ± standard error of the mean = 54 ± 4%). In most trials, the level of protection afforded by the BCA (73 ± 4% - range: 30 to 97%) was lower but close to that of the reference fungicide (93 ± 2% - range: 70 to 100%) and was significant despite wide differences in environmental conditions and severity of inoculum pressure. The protective effect of the BCA lasted over the whole duration of the trials (10-12 weeks after inoculation) and did not appear to be affected by the tomato cultivar or the method used to deliver the antagonist.

The efficacy of the BCA to suppress leaf infections was investigated at crop level in three greenhouse trials in 1999. The antagonist, water or the fungicide (Sumico L) were applied with a back-pack sprayer just prior to inoculation with *B. cinerea* delivered as dry airborne inoculum. The number of infected leaves was reduced by 64-75% on plants treated with the BCA and by 84-93% on those treated with the fungicide.

The alternation or combination of biological and chemical methods may provide better control of *Botrytis* infections than the antagonist alone. On the other hand, the pesticides used to control other fungal diseases in greenhouse tomatoes may hinder biocontrol. Investigations were consequently conducted to test the effect of active ingredients registered in France on the BCA. Among 23 chemicals tested as commercial formulations, only hexaconazol and dichlofluanid inhibited strongly the germination and the radial and germ tube growth of the BCA across the tested concentrations (0,1-100 mg active ingredient/l). However, the efficacy of the antagonist in protecting pruning wounds was not affected when these two active ingredients were sprayed on plants at the field rate.

<footnote n="1">¹ INRA, Station de pathologie végétale, Domaine Saint Maurice, F-84143 Montfavet, France</footnote>

<footnote n="2">² CTFL, Centre de Balandran, F-30127 Bellegarde, France</footnote>
XIIth International Botrytis Symposium
July 3-7, 2000

<figure><img src="image_2.png" /></figure>

Reims -France