Pathogen threats in BD vines
Posted: 27 Nov 2022, 20:12
Responses to climatic and pathogen threats differ in biodynamic and conventional vines
Isabelle Soustre-Gacougnolle1, Marc Lollier, Carine Schmitt, Mireille Perrin, Estelle Buvens, Jean-François Lallemand, Mélanie Mermet, Mélanie Henaux, Christelle Thibault-Carpentier, Doulaye Dembelé, Damien Steyer, Céline Clayeux, Anne Moneyron & Jean E. Masson
Viticulture is of high socio-economic importance; however, its prevalent practices severely impact the
environment and human health, and criticisms from society are raising. Vine managements systems are
further challenged by climatic changes. Of the 8 million hectares grown worldwide, conventional and
organic practices cover 90% and 9% of acreage, respectively. Biodynamic cultivation accounts for 1%.
Although economic success combined with low environmental impact is widely claimed by biodynamic
winegrowers from California, to South Africa, and France, this practice is still controversial in viticulture
and scientific communities. To rethink the situation, we encouraged stakeholders to confront
conventional and biodynamic paradigms in a Participative-Action-Research. Co-designed questions
were followed up by holistic comparison of conventional and biodynamic vineyard managements.
Here we show that the amplitude of plant responses to climatic threats was higher in biodynamic than
conventional management. The same stood true for seasonal trends and pathogens attacks. This was
associated with higher expression of silencing and immunity genes, and higher anti-oxidative and antifungal
secondary metabolite levels. This suggests that sustainability of biodynamic practices probably
relies on fine molecular regulations. Such knowledge should contribute to resolving disagreements
between stakeholders and help designing the awaited sustainable viticulture at large.
Of the 8 million hectares devoted to viticulture worldwide, conventional and organic practices cover 90%
and 9% of acreage, respectively. Biodynamic cultivation accounts for only ca. 1% (http://www.demeter.net/
contacts-di), and this practice is still controversial. Studies on biodynamic or/and organic cultivation focused
on economy and soil composition1, on soil structure, soil biodiversity and microbiological activity2, and on
fertilizer effects3. Studies of grape yield and quality4,5, microbial communities in grapes and leaves6,7, and wine
biochemistry8 have also been reported. However, the results have not resolved the controversy9 about the ‘anthroposophical
paradigm’10 at the heart of biodynamics practice. To date, the dissenting viticulture communities
have not reached a collective plan to reduce the impact of viticulture practices on the environment and human
health11,12. We have tentatively addressed this problem holistically, bringing together the different stakeholders in
a Participative-Action-Research13. The workshops highlighted the dissensus among biodynamic and conventional
winegrowers, as well as among the non-government organizations Alsace Nature/France Nature Environment,
viticulture advisors, technicians, and research scientists. The dissensus stems from lack of distinct proof of the
claims made, and from epistemic conflicts13,14. Relying on a collective epistemology13, the group arrived at the
most sensitive and controversial issues. Biodynamic winegrowers lacked experimental evidence for their claim
that their practices stimulate plant defense mechanisms. The conventional winegrowers have shown that synthetic
pesticides deter pathogens (albeit with a high environmental impact) but there were no data on possible effects on plant defenses. Focusing on plant responses to pathogen and climatic threats, we chose a holistic approach to compare the consequences of the differing practices. We chose Pinot Noir as it is used worldwide for wines and champagne, its genome has been fully sequenced15, and its sensitivity to climatic disorders is well documented.
Our trial consisted of 14 plots of Pinot Noir vines grafted onto the SO4 rootstock that had been grown
under conventional management (8 winegrowers, 8 plots of 21,413 m2) or biodynamic management (3 winegrowers,
6 plots of 9,756 m2) for more than 20 years in the same climatic conditions (Fig. S1). Over a 4-year period,
we monitored vine management, plant physiology, and the levels of infection with virus, downy mildew, and
powdery mildew. For plant defense responses, we analyzed secondary metabolite content as well as steady-state
mRNA levels of 30 immunity and silencing genes.
Results and Discussion
Soils, climatic conditions and vine management. When comparing soils in conventional/biodynamic
management, after chemical and physical analysis, values were higher for pH, Calcium and soil components
above 2 mm in conventional, and higher for Manganese and penetrometer assays in Biodynamic, suggesting
steeper horizons (Mann-Whitney at *P ≤ 0.05; Table S1). Still, there was no clear-cut picture between soils from
biodynamic and conventional plots, in contrast to other studies1,2,4. The conclusions of the latter authors, however,
were based on additional biochemical and biological parameters, and here, we cannot exclude that further
analysis, such as in microbiology, may reveal differences as illustrated in organic and conventional management7.
We characterized pest management practices after interviews with winegrowers13. All winegrowers in the
study relied on copper and Sulfur treatments. In addition, conventional viticulture employed synthetic fungicides,
whereas biodynamic cultures were complemented with preparations such as cow manure (500, 500 P),
minerals such as finely ground silica (501), decoctions of nettle (504), willow, horsetail, valerian, and lemon oil.
Conventional growers followed the guidelines of suppliers, and biodynamic growers followed the Demeter principles
(4, www.demeter.net). To better compare the two managements, we modified TFI18 by subtracting Copper
and Sulfur from conventional products and built up a modified index (mTFI) (Fig. 1). The mTFI values and
application timing changed significantly in response to high pathogen pressure, as in summer 2016 (Fig. 1). As
synthetic fungicides are often systemic, they persist within plants for about 2 weeks. In contrast, all biodynamic
preparations sprayed on plants were washed off by rains and were repeated. This may explain (though not completely)
the higher mTFI for biodynamic cultures (7, 10, and 13.3) in 2014, 2015, and 2016, respectively (Fig. 1).
In addition, biodynamic applications began earlier in the spring and stopped earlier in the summer (Fig. S2), with
more Sulfur than conventional cultures (with the exception of 2014). When summed up for all years, mTFI and
Sulfur applications were higher in biodynamic management. For copper, beside 2016, the mean quantities applied
did not differ in conventional and biodynamic, remaining lower than the norm of 4 kg/hectare/year (Demeter).
Isabelle Soustre-Gacougnolle1, Marc Lollier, Carine Schmitt, Mireille Perrin, Estelle Buvens, Jean-François Lallemand, Mélanie Mermet, Mélanie Henaux, Christelle Thibault-Carpentier, Doulaye Dembelé, Damien Steyer, Céline Clayeux, Anne Moneyron & Jean E. Masson
Viticulture is of high socio-economic importance; however, its prevalent practices severely impact the
environment and human health, and criticisms from society are raising. Vine managements systems are
further challenged by climatic changes. Of the 8 million hectares grown worldwide, conventional and
organic practices cover 90% and 9% of acreage, respectively. Biodynamic cultivation accounts for 1%.
Although economic success combined with low environmental impact is widely claimed by biodynamic
winegrowers from California, to South Africa, and France, this practice is still controversial in viticulture
and scientific communities. To rethink the situation, we encouraged stakeholders to confront
conventional and biodynamic paradigms in a Participative-Action-Research. Co-designed questions
were followed up by holistic comparison of conventional and biodynamic vineyard managements.
Here we show that the amplitude of plant responses to climatic threats was higher in biodynamic than
conventional management. The same stood true for seasonal trends and pathogens attacks. This was
associated with higher expression of silencing and immunity genes, and higher anti-oxidative and antifungal
secondary metabolite levels. This suggests that sustainability of biodynamic practices probably
relies on fine molecular regulations. Such knowledge should contribute to resolving disagreements
between stakeholders and help designing the awaited sustainable viticulture at large.
Of the 8 million hectares devoted to viticulture worldwide, conventional and organic practices cover 90%
and 9% of acreage, respectively. Biodynamic cultivation accounts for only ca. 1% (http://www.demeter.net/
contacts-di), and this practice is still controversial. Studies on biodynamic or/and organic cultivation focused
on economy and soil composition1, on soil structure, soil biodiversity and microbiological activity2, and on
fertilizer effects3. Studies of grape yield and quality4,5, microbial communities in grapes and leaves6,7, and wine
biochemistry8 have also been reported. However, the results have not resolved the controversy9 about the ‘anthroposophical
paradigm’10 at the heart of biodynamics practice. To date, the dissenting viticulture communities
have not reached a collective plan to reduce the impact of viticulture practices on the environment and human
health11,12. We have tentatively addressed this problem holistically, bringing together the different stakeholders in
a Participative-Action-Research13. The workshops highlighted the dissensus among biodynamic and conventional
winegrowers, as well as among the non-government organizations Alsace Nature/France Nature Environment,
viticulture advisors, technicians, and research scientists. The dissensus stems from lack of distinct proof of the
claims made, and from epistemic conflicts13,14. Relying on a collective epistemology13, the group arrived at the
most sensitive and controversial issues. Biodynamic winegrowers lacked experimental evidence for their claim
that their practices stimulate plant defense mechanisms. The conventional winegrowers have shown that synthetic
pesticides deter pathogens (albeit with a high environmental impact) but there were no data on possible effects on plant defenses. Focusing on plant responses to pathogen and climatic threats, we chose a holistic approach to compare the consequences of the differing practices. We chose Pinot Noir as it is used worldwide for wines and champagne, its genome has been fully sequenced15, and its sensitivity to climatic disorders is well documented.
Our trial consisted of 14 plots of Pinot Noir vines grafted onto the SO4 rootstock that had been grown
under conventional management (8 winegrowers, 8 plots of 21,413 m2) or biodynamic management (3 winegrowers,
6 plots of 9,756 m2) for more than 20 years in the same climatic conditions (Fig. S1). Over a 4-year period,
we monitored vine management, plant physiology, and the levels of infection with virus, downy mildew, and
powdery mildew. For plant defense responses, we analyzed secondary metabolite content as well as steady-state
mRNA levels of 30 immunity and silencing genes.
Results and Discussion
Soils, climatic conditions and vine management. When comparing soils in conventional/biodynamic
management, after chemical and physical analysis, values were higher for pH, Calcium and soil components
above 2 mm in conventional, and higher for Manganese and penetrometer assays in Biodynamic, suggesting
steeper horizons (Mann-Whitney at *P ≤ 0.05; Table S1). Still, there was no clear-cut picture between soils from
biodynamic and conventional plots, in contrast to other studies1,2,4. The conclusions of the latter authors, however,
were based on additional biochemical and biological parameters, and here, we cannot exclude that further
analysis, such as in microbiology, may reveal differences as illustrated in organic and conventional management7.
We characterized pest management practices after interviews with winegrowers13. All winegrowers in the
study relied on copper and Sulfur treatments. In addition, conventional viticulture employed synthetic fungicides,
whereas biodynamic cultures were complemented with preparations such as cow manure (500, 500 P),
minerals such as finely ground silica (501), decoctions of nettle (504), willow, horsetail, valerian, and lemon oil.
Conventional growers followed the guidelines of suppliers, and biodynamic growers followed the Demeter principles
(4, www.demeter.net). To better compare the two managements, we modified TFI18 by subtracting Copper
and Sulfur from conventional products and built up a modified index (mTFI) (Fig. 1). The mTFI values and
application timing changed significantly in response to high pathogen pressure, as in summer 2016 (Fig. 1). As
synthetic fungicides are often systemic, they persist within plants for about 2 weeks. In contrast, all biodynamic
preparations sprayed on plants were washed off by rains and were repeated. This may explain (though not completely)
the higher mTFI for biodynamic cultures (7, 10, and 13.3) in 2014, 2015, and 2016, respectively (Fig. 1).
In addition, biodynamic applications began earlier in the spring and stopped earlier in the summer (Fig. S2), with
more Sulfur than conventional cultures (with the exception of 2014). When summed up for all years, mTFI and
Sulfur applications were higher in biodynamic management. For copper, beside 2016, the mean quantities applied
did not differ in conventional and biodynamic, remaining lower than the norm of 4 kg/hectare/year (Demeter).