Novel sustainable strategies to control Plasmopara viticola in grapevine unveil new insights on priming responses and arthropods ecology

Abstract

BACKGROUND Reduction of fungicide consumption in agriculture is globally recognized as a priority. Government authorities are fostering research to achieve a reduction of risks associated with conventional pesticides and promoting the development of sustainable alternatives. To address these issues, in the present study, alternative protocols for the control of downy mildew infection in grapevine were compared to the standard protocol. In the first protocol, only resistance inducers were used, comprising a single formulation with Acibenzolar S‐methyl, laminarin and disodium‐phosphonate. The second and third protocols followed the standard protocol but substituted phosphonates with phosphorus pentoxide and Ecklonia maxima extract. RESULTS The results showed that at veraison downy mildew incidence and severity in all tested protocols were significantly reduced compared to nontreated controls on both canopy and bunches. Expression analysis of key genes involved in plant stress response, indicated that the two protocols for phosphites substitution induced a remodulation of salicylic acid (SA) and jasmonic acid (JA), with positive impact on yields. Analysis of the first protocol revealed that the primed state induced a short delay in bunch ripening, with a shift of carbohydrate metabolism to boost the plant defences, involving an upregulation of defence related‐gene, SAR response and a decreased ROS detoxification. Additionally, analysis on the arthropods populations, in parallel with the positive results achieved using alternatives to conventional fungicides, were enriched by those showing the potential of naturally occurring predators of spider mites. CONCLUSION This study provides practical solutions to reduce the environmental impact of treatments for the control downy mildew in viticulture. © 2022 Society of Chemical Industry.

Effects of fungicide application on physiological and molecular responses of grapevine (Vitis vinifera L.): a comparison between copper and sulfur fungicides applied alone and in combination with novel fungicides

“…Nonetheless, in our conditions the expression of these genes was greatly affected by genotype‐mediated responses, as both VvBgluc and VvPR1 were induced in ‘Nebbiolo’ and downregulated in ‘Arneis’ upon antifungal compounds. Similar changes were previously observed in grapevine following the application of other resistance inducers 55,31 . It is therefore conceivable that the antifungal protection induced by these compounds is only partially based on SAR mechanisms.…”

“…Among those, lipoxygenases (LOX) catalyse the oxygenation of polyunsaturated fatty acids and are at the first step of fatty acid signaling pathways, which include the production of jasmonate (JA). Remarkably, VvLOX transcription increased in response to B. cinerea, 61 antifungal products in the vineyard 55 and ozone treatment. 62 In 2020, the modulation of VvLOX expression was exclusively based on the sampling time, highlighting a sharp transcript reduction in both cultivars at D4-M, while no statistically significant changes were detected in relation to T or D × T (Fig.…”

“…Similar changes were previously observed in grapevine following the application of other resistance inducers. 55,31 It is therefore conceivable that the antifungal protection induced by these compounds is only partially based on SAR mechanisms. Furthermore, the higher concentration of glucanases in infected leaf tissues compared to non-infected ones from the same plant 56 could explain the greater expression of VvBgluc and VvPR1 in the CTR samples of 'Arneis', which in both years had significantly higher levels of fungal infections in comparison to the treated samples (Table 2).…”

Tagatose Suppresses Grapevine Powdery Mildew and Downy Mildew under Field Conditions with No Severe Impacts on Grape Must Fermentation

“…Moreover, several active substances are under scrutiny for substitution in the EU, including molecules that are currently used against powdery mildew and downy mildew (e.g., copper, metalaxyl, fuopicolide, triazoles, and quinoxyfen) [14]. Te issue of fnding an effective alternative against these two diseases is particularly relevant in organic production [15]. Copper, which is widely used to suppress downy mildew in organic viticulture [16], is currently allowed in the EU up to a maximum of 28 kg/ha in 7 years (EU regulation 2018/1981) [19], and further limitations in copper use are expected in the future [18,19].…”

“…In conventional agriculture, several synthetic chemical fungicides are applied for downy mildew and powdery mildew control (e.g., ametoctradin, captan, dimethomorph, fenarimol, folpet, kresoxim-methyl, quinoxyfen, and penconazole), and they may have a negative impact on S. cerevisiae fermentation [24,[26][27][28] and on sensory wine characteristics [29,30], indicating that their use should be concluded sufciently in advance before harvest. Although several potential alternatives to sulfur, copper, and synthetic chemical fungicide have been studied [7,15,31,32], their potential side efects on must fermentations have seldom been investigated.…”