"Biocontrol" Products: Of relative efficiency in combating botrytis. Original language of the article: French.
Botrytis effects the yield and the quality of grape musts. To protect again these damaging effects, winegrowers target their combat against this disease with the application of phytosanitary products and prophylactic interventions. In an oceanic climate, one or two costly annual treatments are commonly applied using products that are both dangerous to the environment and to the health of the machine operator. The biocontrol products represent an interesting alternative to the latter products, but as this study finds, they are neither as effective nor as efficient as classical fungicides.
Botrytis, or grey rot, brings about a reduction of yield and even more importantly affects the quality of the grape musts
A new “biocontrol” product touted to be equally as effective as the traditionally used reference fungicides
In 2014, several Bordeaux wine estates were approached to use this product against botrytis where the efficiency was “said to be” similar to conventional fungicide products but with a “biocontrol” product profile. This product was never officially approved in France as a phytosanitary product
Disappointing results
The 2015 vintage year was not favorable for the development and spread of the fungus
Significantly lower attack frequency was noted on the modality treated with traditional reference anti-botrytis fungicide as compared to the biocontrol modalities. Only the referenced anti-botrytis presented significantly lower attack frequency by the fungus as compared to the NTC and at the same time only one treatment had been applied. However, the attack frequency of this modality had still reached 15 % of the bunches. Compared to the NTC, this difference was more marked on the Merlot grape variety than on the Cabernet-Sauvignon. We note that the combination of the 2 “biocontrol” products (potassium bicarbonate and the foliar fertilizer) presented an attack frequency that was far superior to the NTC, which is surprising to say the least.
Figure 2. % of average bunch attack frequency on 16 parcels for the different modalities (A = Non treated control, B = Conventional referenced anti-botrytis (one treatment only during flowering or at bunch closure), C = foliar fertilizer / CaO+MgO+B (depending on the recommendations of the prescriber ; 4 to 5 applications with a dose of 4 kg/ha from the bunch separation phase to the harvest), D = potassium bicarbonate (2 treatments; at flowering and at veraison (color change), E = modalities C+D).
In terms of impact, with attack frequencies being equal and for a lower attack intensity, the use of a less efficient type of “biocontrol” product could be an interesting complement to prophylaxis. Effectively it is preferable to have very few berries per bunch affected than a botrytis outbreak that is broadly spread.
Figure 3 presents the results obtained for the intensity of botrytis attacks. As a result of weather conditions that were unfavorable for the fungus propagation in August and September
Figure 3. % of average bunch attack intensity on 16 parcels for the different modalities (A = Non treated control, B = Conventional referenced anti-botrytis (one treatment only during flowering or at bunch closure), C = foliar fertilizer / CaO+MgO+B (depending on the prescriber recommendations; 4 to 5 applications with a dose of 4kg/ha from the bunch separation phase to the harvest), D = potassium bicarbonate (2 treatments; at flowering and at veraison (color change), E = modalities C+D).
What to retain?
No efficiency of the foliar fertilizer (CaO+MgO+B) was observed either regarding the frequency or the attack intensity of the grey rot. Considering these inconclusive results, the winegrowers decided not to continue with the experimentation in other vintages. It is, therefore, difficult to definitively conclude with only one year of trials since the epidemic profile of the disease is very variable from one year to the next
It must be noted however, that the use of conventional anti-botrytis products in this trial, only modestly reduced the attacks of this fungus, confirming that prophylaxis remains the most efficient means to fight the damaging impacts of botrytis. The treatment with the anti-botrytis product, whether conventional or “biocontrol”, will only improve the results obtained by prophylaxis methods (good vigor management, the micro-climate of the bunch, the attacks of grape worms etc.) This was outlined during this experiment, notably with the confirmation of the link between the vigor and the intensity of the botrytis attack
Notes
- Ky, I., Lorrain, B., Jourdes, M., Pasquier, G., Fermaud, M., Gény, L., Rey, P., Doneche, B. And Teissedre, P. (2012), Assessment of grey mould (Botrytis cinerea) impact on phenolic and sensory quality of Bordeaux grapes, musts and wines for two consecutive vintages. Australian Journal of Grape and Wine Research, 18: 215-226. https://doi.org/10.1111/j.1755-0238.2012.00191.x
- Agreste (2010). http://agreste.agriculture.gouv.fr/recensement-agricole-2010/
- https://ephy.anses.fr/
- A set of cultural protection methods based on the use of living organisms or of natural substances; A category specific to France.
- Calvo-Garrido, C., Roudet, J., Aveline, N., Davidou, L., Dupin, S., Fermaud, M. (2019) Microbial antagonism toward Botrytis Bunch Rot of grapes in multiple field tests using one Bacillus ginsengihumi strain and formulated biological control products. Front. Plant Sci., 10. https://doi.org/10.3389/fpls.2019.00105
- Butault, J.-P., Dedryver, C.-A., Gary, C., Guichard, L., Jacquet, F., Meynard, J. M., Nicot, P., Pitrat, M., Reau, R., Sauphanor, B., Savini, I., Volay, T. (2010). Synthèse du rapport d'étude Écophyto R&D : quelles voies pour réduire l’usage des pesticides ? Paris, FRA : INRA Editions. 90 p.
- https://ephy.anses.fr/
- Butault, J.-P., Dedryver, C.-A., Gary, C., Guichard, L., Jacquet, F., Meynard, J. M., Nicot, P., Pitrat, M., Reau, R., Sauphanor, B., Savini, I., Volay, T. (2010). Synthèse du rapport d'étude Écophyto R&D : quelles voies pour réduire l’usage des pesticides ?. Paris, FRA : INRA Editions. 90 p.
- Geny, L. & Dubourdieu, D. Le millésime 2015 à Bordeaux (2015).
- Geny, L. & Dubourdieu, D. Le millésime 2015 à Bordeaux (2015).
- Calvo-Garrido, C., Roudet, J., Aveline, N., Davidou, L., Dupin, S., Fermaud, M. (2019) Microbial antagonism toward Botrytis Bunch Rot of grapes in multiple field tests using one Bacillus ginsengihumi strain and formulated biological control products. Front. Plant Sci., 10. https://doi.org/10.3389/fpls.2019.00105
- Ky, I., Lorrain, B., Jourdes, M., Pasquier, G., Fermaud, M., Gény, L., Rey, P., Doneche, B. And Teissedre, P. (2012), Assessment of grey mould (Botrytis cinerea) impact on phenolic and sensory quality of Bordeaux grapes, musts and wines for two consecutive vintages. Australian Journal of Grape and Wine Research, 18: 215-226. https://doi.org/10.1111/j.1755-0238.2012.00191.x
References
- Ky, I., Lorrain, B., Jourdes, M., Pasquier, G., Fermaud, M., Gény, L., Rey, P., Doneche, B. And Teissedre, P. (2012), Assessment of grey mould (Botrytis cinerea) impact on phenolic and sensory quality of Bordeaux grapes, musts and wines for two consecutive vintages. Australian Journal of Grape and Wine Research, 18: 215-226. https://doi.org/10.1111/j.1755-0238.2012.00191.x
- Calvo-Garrido, C., Roudet, J., Aveline, N., Davidou, L., Dupin, S., Fermaud, M. (2019) Microbial antagonism toward Botrytis Bunch Rot of grapes in multiple field tests using one Bacillus ginsengihumi strain and formulated biological control products. Front. Plant Sci., 10. https://doi.org/10.3389/fpls.2019.00105
- Butault, J.-P., Dedryver, C.-A., Gary, C., Guichard, L., Jacquet, F., Meynard, J. M., Nicot, P., Pitrat, M., Reau, R., Sauphanor, B., Savini, I., Volay, T. (2010). Synthèse du rapport d'étude Écophyto R&D : quelles voies pour réduire l’usage des pesticides ?. Paris, FRA : INRA Editions. 90 p. https://prodinra.inra.fr/record/38087
- Geny, L. & Dubourdieu, D. Le millésime 2015 à Bordeaux (2015). http://bordeauxraisins.fr/images/millesimes/millesime_2015.pdf
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