23 research outputs found
Oospore germination dynamics and disease forecasting model: an integrated approach for downy mildew management
No full textRecent findings on Flavescence dorée in Franciacorta (North Italy): prevalence of associated phytoplasma genotypes in symptomatic grapevines and in additional plant and insect hosts within and around vineyards
No full textThis study aimed to survey the spread and incidence of Flavescence dorée (FD) in Franciacorta vineyards (North Italy) and study the diffusion of the associated phytoplasmas (FDp) not only in symptomatic grapevines but also in the vineyard agroecosystem. The activities were carried out in 2021 and 2022 in 20 representative vineyards. Average grapevine yellows (GY) incidence in vineyards was around 6% in both 2021 and 2022. Molecular analyses, conducted on 1250 symptomatic vines, identified 16SrV phytoplasmas in 31% (2021) and 34% (2022) of the vines, localized in 14 out of 20 vineyards. In these vineyards, 17 (2021) and 37 (2022) species of known or potential FDp vectors were captured and grouped into 1600 pools for molecular analysis. 16SrV phytoplasmas were identified in 22% (2021) and 6% (2022) of the insect pools. Seven species (S. titanus, Allygidius spp., Dictyophara europaea, Neoaliturus fenestratus, Orientus ishidae, Phogotettix cyclops, Psammotettix spp.) were found to be infected both in 2021 and 2022. Moreover, molecular analyses revealed the presence of 16SrV phytoplasmas in 25 out of 45 wild plant species collected around vineyards. Sequence analyses of map gene identified (i) FDp genotype M54 in symptomatic grapevines (78% and 100% of 16SrV phytoplasma-infected grapevines in 2021 and 2022, respectively), in S. titanus, N. fenestratus, Psammotettix spp. (2021 and 2022), and D. europaea (2021), and in seven wild plant species; (ii) FDp genotype M51 in symptomatic grapevines (22% of 16SrV phytoplasma-infected grapevines in 2021), in D. europaea, N. fenestratus, and P. cyclops (2021 and 2022), and in 22 wild plant species; (iii) FDp genotypes M12, M50, and M122 in other insects. So far, FDp genotype M54, prevalent in northern Italy, is believed to be strictly associated with the closed “grapevine - S. titanus” pathosystem, while the spread of FDp genotype M51 includes additional host plants and vectors (D. europaea and O. ishidae). Obtained results reinforced recent evidence of an increasing FD epidemiological complexity, suggesting that also the prevalent FDp genotype M54, at least in the examined area, can be related to an opened pathosystem, involving additional plant hosts and insect vectors
Evaluation of biostimulant effectiveness in grapevine “bois noir” management
No full textThis work, carried out from 2017 to 2020, aimed to evaluate the effectiveness of four commercial products (Delfan plus, Phylgreen, Phylgreen Kuma, Vegenergy), which use as biostimulants is allowed in organic farming, in the management of ‘bois noir’ (BN), a grapevine disease associated with 'Candidatus Phytoplasma solani'. The field trials were carried out in a Chardonnay BN-affected organic vineyard located in Gussago (Franciacorta, North Italy), monitored since 2012. In September 2017, the vineyard was monitored for grapevine yellows symptoms and a map reporting the phytosanitary state of each plant was created. Based on this map, four treated blocks (each one treated with one biostimulant), and one untreated (control) block were arranged. The activities, conducted from 2018 to 2020, included: (i) applications with the biostimulants from mid-April (10 cm long grapevine shoots) to the beginning of August (every two weeks (7 treatments/year); (ii) mapping and sampling of symptomatic and asymptomatic vines in September; (iii) extraction of total nucleic acids and molecular identification of 'Ca. P. solani' by nested PCR-based amplification of stamp gene; (iv) molecular characterization of phytoplasma strains by means of stamp gene nucleotide sequence analysis; (v) statistical analysis to evaluate any differences in the curative and preventive effect on BN-symptoms. The statistical analysis, conducted on the increase of symptomatic grapevines from 2017 (pre-treatment) to 2020 (cumulative effect of the treatments conducted from 2018 to 20), showed a significant decrease in symptomatic vines in the Delfan plus block (-4.5 percentage points) in comparison to the other blocks. The curative effect (percentage of recovered grapevines) was calculated considering the health status of symptomatic plants in 2017 over the following three years. Percentage of recovered plants in the Delfan plus block was higher than in all the other blocks, although the difference observed towards the block treated with Vegenergy and the untreated one was not statistically significant. The preventive effect was calculated considering the percentage of new symptomatic plants (grapevines showing symptoms for the first time) in the three-year period 2018-20. Statistical analyses did not reveal significant differences on the preventive effect observed in the different blocks. However, the percentage of new symptomatic grapevines in the block treated with Delfan plus was lower than in the other blocks. Molecular and bioinformatics analyses showed the presence of eight distinct 'Ca. P. solani' strains carrying different stamp gene variants (St1, St5, St8, St10, St16, St18, St19, St30). The statistical analysis showed a uniform distribution of such phytoplasma strains within the vineyard, reinforcing the evidence that the effect on BN incidence in the blocks is due to the action of the biostimulants and not to possible differences in the 'Ca. P. solani' strain virulence. Based on the obtained results, it emerged that a reduction in the percentage of symptomatic vines was observed exclusively in the block treated with Delfan plus. Further open field trials carry out in different grape growing areas and on different cultivars are necessary to confirm the effectiveness of biostimulants BN control
Role in “bois noir” epidemiology of inter-row vineyard groundcover vegetation used for green manure
No full text‘Candidatus Phytoplasma solani’ (CaPsol), associated with grapevine ‘bois noir’ (BN), has a broad range of host plants and can be transmitted to grapevine by several insect vectors. Hyalesthes obsoletus Signoret, the main CaPsol vector in European and Mediterranean countries, feeds preferentially and completes its biological cycle on Convolvulus arvensis L. and Urtica dioica L., occasionally transmitting the phytoplasma to grapevine, a dead-end host for the pathogen. Recent studies evidenced that other weeds, naturally present within and around the vineyards, can play a role in BN spreading. This study investigated the role of eight groundcover plant species (Eruca sativa Miller, Sinapis arvensis L., Phacelia tanacetifolia Benth., Vicia sativa L., Vicia faba var. minor Beck, Trifolium incarnatum L., Trifolium alexandrinum L., Polygonum fagopyrum L.), commonly utilized for inter-row vineyard green manure in Franciacorta (North Italy), in BN epidemiology. The activities, conducted in the years 2019 and 2020 in two BN-affected vineyards in Gussago and Provaglio d’Iseo (Franciacorta), included: (i) monitoring and sampling groundcover plant species and C. arvensis (known host plant) in July, and symptomatic grapevines in September; (ii) total nucleic acids extraction followed by CaPsol-specific identification by nested PCR amplification of stamp gene; (iii) sequencing and bioinformatic analyses (comparison with stamp sequence variants dataset available in literature) of stamp amplicons obtained from symptomatic grapevines and groundcover plants. Molecular analyses were carried out on 341, 55, and 108 samples collected during the field surveys from groundcover plants, C. arvensis and symptomatic grapevines, respectively. Nested PCR allowed identifying CaPsol in 7.6% of groundcover plants, 25.5% of C. arvensis plants, and 76.9% of grapevines. Within groundcover plants, only E. sativa, V. sativa, and P. fagopyrum were found CaPsol infected. Based on nucleotide sequence analysis of stamp amplicons, CaPsol strains harboring three stamp sequence variants were identified in grapevines: St5, St19, and St30. The variant St19 was found exclusively in the analyzed grapevines. The variants St5 and St30 were found also in CaPsol strains infecting E. sativa (St5), P. fagopyrum (St5), V. sativa (St5, St30), and C. arvensis (St5), suggesting their possible involvement in CaPsol transmission routes to grapevine. Interestingly, previous study demonstrated that H. obsoletus survival on V. sativa and C. arvensis are comparable, reinforcing its association to BN epidemiology. Results from this and further studies can indicate how to select the groundcover plants for green manure mixture, excluding the species putatively involved in BN diffusion
Role in “bois noir” epidemiology of inter-row vineyard groundcover vegetation used for green manure
No full text‘Candidatus Phytoplasma solani’ (CaPsol), associated with grapevine ‘bois noir’ (BN), has a broad range of host plants and can be transmitted to grapevine by several insect vectors. Hyalesthes obsoletus Signoret, the main CaPsol vector in European and Mediterranean countries, feeds preferentially and completes its biological cycle on Convolvulus arvensis L. and Urtica dioica L., occasionally transmitting the phytoplasma to grapevine, a dead-end host for the pathogen. Recent studies evidenced that other weeds, naturally present within and around the vineyards, can play a role in BN spreading. This study investigated the role of eight groundcover plant species (Eruca sativa Miller, Sinapis arvensis L., Phacelia tanacetifolia Benth., Vicia sativa L., Vicia faba var. minor Beck, Trifolium incarnatum L., Trifolium alexandrinum L., Polygonum fagopyrum L.), commonly utilized for inter-row vineyard green manure in Franciacorta (North Italy), in BN epidemiology. The activities, conducted in the years 2019 and 2020 in two BN-affected vineyards in Gussago and Provaglio d’Iseo (Franciacorta), included: (i) monitoring and sampling groundcover plant species and C. arvensis (known host plant) in July, and symptomatic grapevines in September; (ii) total nucleic acids extraction followed by CaPsol-specific identification by nested PCR amplification of stamp gene; (iii) sequencing and bioinformatic analyses (comparison with stamp sequence variants dataset available in literature) of stamp amplicons obtained from symptomatic grapevines and groundcover plants. Molecular analyses were carried out on 341, 55, and 108 samples collected during the field surveys from groundcover plants, C. arvensis and symptomatic grapevines, respectively. Nested PCR allowed identifying CaPsol in 26 out of 341 (7.6%) groundcover plants, 14 out of 55 (25.5%) C. arvensis plants, and 83 out of 108 (76.9%) grapevines. Within groundcover plants, only E. sativa, V. sativa, and P. fagopyrum were found CaPsol infected. Based on nucleotide sequence analysis of stamp amplicons, CaPsol strains harboring three stamp sequence variants were identified in grapevines: St5, St19, and St30. The variant St19 was found exclusively in the analyzed grapevines. The variants St5 and St30 were found also in CaPsol strains infecting E. sativa (St5), P. fagopyrum (St5), V. sativa (St5, St30), and C. arvensis (St5), suggesting their possible involvement in CaPsol transmission routes to grapevine. Interestingly, previous study demonstrated that H. obsoletus survival on V. sativa and C. arvensis are comparable, reinforcing its association to BN epidemiology. Results from this and further studies can indicate how to select the groundcover plants for green manure mixture, excluding the species putatively involved in BN diffusion
Identification of phytoplasmas associated with grapevine ‘bois noir’ and flavescence dorée in inter-row groundcover vegetation used for green manure in Franciacorta vineyards
No full text‘Bois noir’ (BN) and flavescence dorèe (FD), the two main diseases of the grapevine yellows complex associated with
genetically distinct phytoplasmas, have a complex epidemiology including multiple insect vectors and reservoir plants.
This study investigated the presence of BN and FD phytoplasmas in nine groundcover plant species commonly utilized
for inter-row vineyard green manure in Franciacorta (North Italy). The activities conducted in 2020 included monitoring
and sampling groundcover plant species and symptomatic grapevines in September, and phytoplasma identification and
typing by amplification and sequence analyses of stamp and map genes. Molecular analyses identified BN phytoplasma
(strains carrying the stamp gene sequence variants St5, St19, St30) and FD phytoplasma (strains carrying the map gene
sequence variant M54) in 72% and 28% of symptomatic grapevines, respectively. BN phytoplasma strains St5 and St30
were found also in Eruca sativa, Vicia sativa, and Polygonum fagopyrum. FD phytoplasma strain M54 was found also
in Vicia faba, Trifolium incarnatum, and Polygonum fagopyrum. These results reinforced the evidence of the increasing
range of BN and FD phytoplasma alternative plant hosts and suggested a criterium for the selection of the groundcover
plant species utilized for green manure, excluding the ones putatively involved in BN and FD diffusion
Evaluation of biostimulant effectiveness in grapevine “bois noir” management
No full textThis work, carried out from 2017 to 2020, aimed to evaluate the effectiveness of four commercial products (Delfan plus, Phylgreen, Phylgreen Kuma, Vegenergy), whose use as biostimulants is allowed in organic farming, in the management of ‘bois noir’ (BN), a grapevine disease associated with 'Candidatus Phytoplasma solani'. The field trials were carried out in a Chardonnay BN-affected organic vineyard located in Gussago (Franciacorta, North Italy), monitored since 2012. In September 2017, the vineyard was monitored for grapevine yellows symptoms and a map reporting the phytosanitary state of each plant was created. Based on this map, four treated blocks (each one treated with one biostimulant), and one untreated (control) block were arranged. The activities, conducted from 2018 to 2020, included: (i) applications with the biostimulants from mid-April (10 cm long grapevine shoots) to the beginning of August (every two weeks (7 treatments/year); (ii) mapping and sampling of symptomatic and asymptomatic vines in September; (iii) extraction of total nucleic acids and molecular identification of 'Ca. P. solani' by nested PCR-based amplification of stamp gene; (iv) molecular characterization of phytoplasma strains by means of stamp gene nucleotide sequence analysis; (v) statistical analysis to evaluate any differences in the curative and preventive effect on BN-symptoms. The statistical analysis, conducted on the increase of symptomatic grapevines from 2017 (pre-treatment) to 2020 (cumulative effect of the treatments conducted from 2018 to 20), showed a significant decrease in symptomatic vines in the Delfan plus block (-4.5 percentage points) in comparison to the other blocks. The curative effect (percentage of recovered grapevines) was calculated considering the health status of symptomatic plants in 2017 over the following three years. Percentage of recovered plants in the Delfan plus block was higher than in all the other blocks, although the difference observed towards the block treated with Vegenergy and the untreated one was not statistically significant. The preventive effect was calculated considering the percentage of new symptomatic plants (grapevines showing symptoms for the first time) in the three-year period 2018-20. Statistical analyses did not reveal significant differences on the preventive effect observed in the different blocks. However, the percentage of new symptomatic grapevines in the block treated with Delfan plus was lower than in the other blocks. Molecular and bioinformatics analyses showed the presence of eight distinct 'Ca. P. solani' strains carrying different stamp gene variants (St1, St5, St8, St10, St16, St18, St19, St30). The statistical analysis showed a uniform distribution of such phytoplasma strains within the vineyard, reinforcing the evidence that the effect on BN incidence in the blocks is due to the action of the biostimulants and not to possible difference in the 'Ca. P. solani' strain virulence. Based on the obtained results, it emerged that a reduction in the percentage of symptomatic vines was observed exclusively in the block treated with Delfan plus. Further open field trials carry out in different grape growing areas and on different cultivars are necessary to confirm the effectiveness of biostimulants BN control
Grafting of recovered shoots reduces bois noir disease incidence in vineyard
No full textBois noir (BN) disease of grapevine is associated with ‘Candidatus Phytoplasma solani’ (CaPsol). Due to its multifaceted ecology, BN control is extremely difficult. Several studies showed that BN recovery can be elicited by abiotic stresses and treatment with resistance inducers. In this study, field trials along with molecular analyses have been conducted to evaluate if grafting of recovered shoots can increase the BN recovery rate in symptomatic grapevines and decrease the new CaPsol infection rate on asymptomatic grapevines. Field trials were performed in two vineyards (cv. Chardonnay/Kober 5BB) in Franciacorta (Lombardy Region, northern Italy). Grafting effects were evaluated by symptom observation and CaPsol detection by nested-PCR stamp gene amplification for three consecutive years and compared with non-grafted control vines. Obtained data showed that BN incidence was lower in grafted plants, mainly due to a statistically significant increase of recovery rate, four times higher than in non-grafted plants. These data indicated that grafting of recovered shoots can efficiently induce BN recovery, opening an interesting scenario for its utilization in sustainable strategies of vineyard management
Biology and phytoplasma detection of the newly described Bamboosella dimorpha leafhopper in grapevine yellows-affected vineyards
No full textThe aim of this study was to investigate the biology and the possible role in grapevine yellows epidemiology of the newly described alien species Bamboosella dimorpha in northern Italy regions. The results showed that the bamboo feeding leafhopper is present in the vineyard surroundings where Phyllostachys spp. plants are growing. The flight dynamics confirming its ability to held three generations per year. B. dimorpha can survive a couple of days on grapevine leaves. The specimens collected using sweeping nets from bamboo plants located in vineyard borders carried “flavescence dorée” phytoplasma. Further investigations are needed to evaluate the ability of B. dimorpha to transmit this phytoplasma
