Search

Simple Summary: The inter-row management strategy in the vineyard influences the diversity of the vegetation and, consequently, the presence and activity of natural enemies of grapevine pests. This study aims to evaluate whether the replacement of periodical tillage with the alternate mowing of the resident herbaceous vegetation in vineyard inter-rows reduces the density of the European leafhoppers Hebata vitis and Zygina rhamni by improving the presence and activity of their natural enemies in the context of conservation biological control. The results show that, on grapevines with ground vegetation, the number of hunting spiders increases, thus reducing the leafhopper population with their predation activity. Green covering also improves hymenopteran parasitoids characterized for their important role in the grapevine pest control. A greater vegetation diversity in the vineyard improves the landscape quality of the agroecosystem and, by supporting the activity of the natural enemies of grapevine pests, reduces the need for insecticide applications in the vineyards. Inter-row management in vineyards can influence the abundance of grapevine pests and their natural enemies. In 2013–2015, in a vineyard in northeastern Italy, the influence of two vineyard inter-row management strategies (i.e., alternate mowing, AM, and periodical tillage, PT) on the population dynamics of grapevine leafhoppers Hebata vitis and Zygina rhamni and their natural enemies, the mymarid Anagrus atomus and spiders (Araneae), and other hymenopteran parasitoids, were studied with different survey approaches. The infestations of both leafhoppers were lower in AM than PT due to the reduced leafhopper oviposition and higher nymph mortality in AM. This occurred although leafhopper egg parasitization by A. atomus was greater in PT than AM according to a density-dependent relationship with the leafhopper egg amount. Hymenopteran parasitoids other than A. atomus were the most abundant in AM, probably due to the higher availability of nectar and pollen than in PM. The significantly higher population densities of hunting spiders in AM than PT can be associated with the higher predation of leafhopper nymphs. Therefore, the study demonstrated that the alternate mowing of vineyard inter-rows enhances the abundance of natural enemies, such as spiders and hymenopteran parasitoids, and can contribute to grapevine leafhopper pest control. [ABSTRACT FROM AUTHOR]

Pierce's disease (PD) is a vector-borne disease caused by the bacteria Xylella fastidiosa, which affects grapevines in the Americas. Currently, vineyards in continental Europe, the world's largest producer of quality wine, have not yet been affected by PD. However, climate change may alter this situation. Here we incorporate the latest regional climate change projections into a climate-driven epidemiological model to assess the risk of PD epidemics in Europe for different levels of global warming. We found a significant increase in risk above + 2 ∘ C in the main wine-producing regions of France, Italy and Portugal, in addition to a critical tipping point above + 3 ∘ C for the possible spread of PD beyond the Mediterranean. The model identifies decreasing risk trends in Spain, as well as contrasting patterns across the continent with different velocities of risk change and epidemic growth rates. Although there is some uncertainty in model projections over time, spatial patterns of risk are consistent across different climate models. Our study provides a comprehensive analysis of the future of PD at multiple spatial scales (country, Protected Designation of Origin and vineyard), revealing where, why and when PD could become a new threat to the European wine industry. [ABSTRACT FROM AUTHOR]

Shiraz disease (SD) is one of the most destructive viral diseases of grapevines in Australia and is known to cause significant economic loss to local growers. Grapevine virus A (GVA) was reported to be the key pathogen associated with this disease. This study aimed to better understand the diversity of GVA variants both within and between individual SD and grapevine leafroll disease (LRD) affected grapevines located at vineyards in South Australia. Amplicon high throughput sequencing (Amplicon-HTS) combined with median-joining networks (MJNs) was used to analyze the variability in specific gene regions of GVA variants. Several GVAII variant groups contain samples from both vineyards studied, suggesting that these GVAII variants were from a common origin. Variant groups analyzed by MJNs using the overall data set denote that there may be a possible relationship between variant groups of GVA and the geographical location of the grapevines. [ABSTRACT FROM AUTHOR]

'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. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases (GTDs) are a substantial challenge to viticulture, especially with a lack of available control measures. The lack of approved fungicides necessitates the exploration of alternative controls. One promising approach is the investigation of disease escape plants, which remain healthy under high disease pressure, likely due to their microbiome function. This study explored the microbiome of grapevines with the disease escape phenotype. DNA metabarcoding of the ribosomal internal transcribed spacer 1 (ITS1) and 16S ribosomal RNA gene was applied to trunk tissues of GTD escape and adjacent diseased vines. Our findings showed that the GTD escape vines had a significantly different microbiome compared with diseased vines. The GTD escape vines consistently harbored a higher relative abundance of the bacterial taxa Pseudomonas and Hymenobacter. Among fungi, Aureobasidium and Rhodotorula were differentially associated with GTD escape vines, while the GTD pathogen, Eutypa, was associated with the diseased vines. This is the first report of the link between the GTD escape phenotype and the grapevine microbiome. [ABSTRACT FROM AUTHOR]

Phaeoacremonium minimum is an important esca and Petri disease pathogen that causes dieback of grapevines in South Africa. Little is known regarding the reproductive strategy of the pathogen. Sexual reproduction could lead to a better adaptation of the pathogen to disease management strategies by combining alleles through recombination. The study aimed to investigate the genetic diversity and recombination potential of eight populations in the Western Cape, from six commercial vineyards and two nursery rootstock mother blocks. This was achieved by developing and applying nine polymorphic microsatellites and mating-type-specific markers. Thirty-seven genotypes were identified from 295 isolates. Populations were characterised by the same dominant genotype (MLG20 occurring 65.43%), low genotypic diversity (H) and high numbers of clones (81.36% of dataset). However, genotypes from the same sampling sites were not closely related based on a minimum spanning network and had high molecular variation within populations (94%), suggesting that multiple introductions of different genotypes occurred over time. Significant linkage disequilibrium among loci (r̅d) further indicated a dominant asexual cycle, even though perithecia have been observed in these four populations. The two rootstock mother blocks had unique genotypes and genotypes shared with the vineyard populations. Propagation material obtained from infected rootstock mother blocks could lead to the spread of more genotypes to newly established vineyards. Based on our results, it is important to determine the health status of rootstock mother blocks. Management strategies must focus on reducing aerial inoculum to prevent repeated infections and further spread of P. minimum genotypes. [ABSTRACT FROM AUTHOR]

The European fruit lecanium, Parthenolecanium corni (Bouché) (Hemiptera: Coccomorpha: Coccidae), is an important grapevine pest in all grape production regions. Due to its hidden way of life, knowing which vine parts to sample when monitoring is important for early infestation detection. Within-plant distribution of this pest was studied throughout the whole vegetative season, in a three-year field trial carried out in Neštin, Serbia. Grapevine trunk and cane were each divided in three equal sections. Reference point was the merging spot of trunk and cane. Canopy was divided in nine equal quadrants. The number of P. corni individuals in each part was estimated. It was recorded that P. corni adult females and nymphs prefer certain grapevine parts for their settlement. A significant difference between the number of adult females recorded on different grapevine woody parts was observed, with the highest number recorded on the first third of cane. The nymphs, which infest canopy, were unevenly distributed. Their number was highest on the leaves nearby preferred adult female settlement spots (first third of cane) throughout the whole season. The number of adult females and nymphs showed a decreasing trend with the increase of distance from the reference point. The information gathered during this research can be useful for early detection and monitoring of P. corni infestations in the vineyards. [ABSTRACT FROM AUTHOR]

The grapevine trunk disease, Eutypa dieback (ED), causes significant vine decline and yield reduction. For many years, the fungus Eutypa lata was considered the main pathogen causing ED of grapevines in Australia. Recent studies showed other Diatrypaceous fungi were also associated with vines exhibiting dieback symptoms but there is limited information on how these fungal pathogens spread in vineyards. Thus, information on the spore dispersal patterns of Diatrypaceous fungi in different wine regions will assist in identifying high-risk infection periods in vineyards. Using more than 6800 DNA samples from airborne spores collected from eight wine regions in south-eastern Australia over 8 years using a Burkard spore trap, this study investigated the diversity and abundance of Diatrypaceous species, using multi-faceted molecular tools. A multi-target quantitative PCR (qPCR) assay successfully detected and quantified Diatrypaceous spores from 30% of the total samples with spore numbers and frequency of detection varying between regions and years. The high-resolution melting analysis (HRMA) coupled with DNA sequencing identified seven species, with E. lata being present in seven regions and the most prevalent species in the Adelaide Hills, Barossa Valley and McLaren Vale. Cryptovalsa ampelina and Diatrype stigma were the predominant species in the Clare Valley and Coonawarra, respectively while Eutypella citricola and Eu. microtheca dominated in the Hunter Valley and the Riverina regions. This study represents the first report of D. stigma and Cryptosphaeria multicontinentalis in Australian vineyards. This study further showed rainfall as a primary factor that triggers spore release, however, other weather factors that may influence the spore release in different climatic regions of Australia still requires further investigation. [ABSTRACT FROM AUTHOR]

Grapevine red blotch virus (GRBV) causes red blotch disease and is transmitted by the three-cornered alfalfa hopper, Spissistilus festinus. GRBV isolates belong to a minor phylogenetic clade 1 and a predominant clade 2. Spatiotemporal disease dynamics were monitored in a 1-hectare 'Merlot' vineyard planted in California in 2015. Annual surveys first revealed disease onset in 2018 and a 1.6% disease incidence in 2022. Ordinary runs and phylogenetic analyses documented significant aggregation of vines infected with GRBV clade 1 isolates in one corner of the vineyard (Z = −4.99), despite being surrounded by clade 2 isolates. This aggregation of vines harboring isolates from a non-prevalent clade is likely due to infected rootstock material at planting. GRBV clade 1 isolates were predominant in 2018–2019 but displaced by clade 2 isolates in 2021–2022, suggesting an influx of the latter isolates from outside sources. This study is the first report of red blotch disease progress immediately after vineyard establishment. A nearby 1.5-hectare 'Cabernet Sauvignon' vineyard planted in 2008 with clone 4 (CS4) and 169 (CS169) vines was also surveyed. Most CS4 vines that exhibited disease symptoms one-year post-planting, likely due to infected scion material, were aggregated (Z = −1.73). GRBV isolates of both clades were found in the CS4 vines. Disease incidence was only 1.4% in non-infected CS169 vines in 2022 with sporadic infections of isolates from both clades occurring via secondary spread. Through disentangling GRBV infections due to the planting material and S. festinus-mediated transmission, this study illustrated how the primary virus source influences epidemiological dynamics of red blotch disease. [ABSTRACT FROM AUTHOR]

Fungal pathogens involved in grapevine trunk diseases (GTDs) may infect grapevines throughout their lifetime, from nursery to vineyard, via open wounds in stems, canes or roots. In vineyards, pruning wound protection products (PWPPs) offer the best means to reduce the chance of infection by GTD fungi. However, PWPPs may affect non-target microorganisms that comprise the natural endophytic mycobiome residing in treated canes, disrupting microbial homeostasis and indirectly influencing grapevine health. Using DNA metabarcoding, we characterized the endophytic mycobiome of one-year-old canes of cultivars Cabernet Sauvignon and Syrah in two vineyards in Portugal and Italy and assessed the impact of established and novel PWPPs on the fungal communities of treated canes. Our results reveal a large fungal diversity (176 taxa), and we report multiple genera never detected before in grapevine wood (e.g., Symmetrospora and Akenomyces). We found differences in mycobiome beta diversity when comparing vineyards (p = 0.01) but not cultivars (p > 0.05). When examining PWPP-treated canes, we detected cultivar- and vineyard-dependent alterations in both alpha and beta diversity. In addition, numerous fungal taxa were over- or under-represented when compared to control canes. Among them, Epicoccum sp., a beneficial genus with biological control potential, was negatively affected by selected PWPPs. This study demonstrates that PWPPs induce alterations in the fungal communities of grapevines, requiring an urgent evaluation of their direct and indirect effects on plants health with consideration of factors such as climatic conditions and yearly variations, in order to better advise viticulturists and policy makers. [ABSTRACT FROM AUTHOR]

Trunk disease is a major problem on grapevine in Zanjan province, causing serious decline, despite which its aetiology remains unknown. The purpose of this study was to investigate factors involved in grapevine decline in vineyards of Zanjan province. Samples were collected from twigs and branches of grapevines in the region between October and November 2018. Fungal isolates were identified based on morphological characteristics and ITS‐rDNA sequence data for selected isolates. The frequency and diversity of the fungal community recovered from grapevines in Darreh Sejin in Zanjan province were higher than in other regions. A total of 112 fungal isolates comprising 22 species were recovered. Phaeoacremonium minimum, Microsphaeropsis olivacea and Kalmusia variispora were identified as the dominant species in the region examined and could be considered the main trunk pathogens of grapevines in Zanjan region. In inoculation tests, M. olivacea was proved to be pathogenic on grapevine for the first time in this study. [ABSTRACT FROM AUTHOR]

Fanleaf degeneration is a complex viral disease of Vitis spp. that detrimentally impacts fruit yield and reduces the productive lifespan of most vineyards worldwide. In France, its main causal agent is grapevine fanleaf virus (GFLV). In the past, field experiments were conducted to explore cross-protection as a management strategy of fanleaf degeneration, but results were unsatisfactory because the mild virus strain negatively impacted fruit yield. In order to select new mild GFLV isolates, we examined two old 'Chardonnay' parcels harbouring vines with distinct phenotypes. Symptoms and agronomic performances were monitored over the four-year study on 21 individual vines that were classified into three categories: asymptomatic GFLV-free vines, GFLV-infected vines severely diseased and GFLV-infected vines displaying mild symptoms. The complete coding genomic sequences of GFLV isolates in infected vines was determined by high-throughput sequencing. Most grapevines were infected with multiple genetically divergent variants. While no specific molecular features were apparent for GFLV isolates from vines displaying mild symptoms, a genetic differentiation of GFLV populations depending on the vineyard parcel was observed. The mild symptomatic grapevines identified during this study were established in a greenhouse to recover GFLV variants of potential interest for cross-protection studies. [ABSTRACT FROM AUTHOR]

A decline of various grapevines (Vitis vinifera L.) in the province of Doukkala in Morocco was observed in 2021. The causal pathogen was identified as Lasiodiplodia viticola based on morphological characteristics and phylogenetic analysis of the internal transcribed region (ITS), the β-tubulin gene (TUB) and calmodulin (cmdA). Koch's postulates were confirmed by successful re-isolation of L. viticola from plants inoculated with the pathogen under controlled conditions. The disease was shown to be prevalent in Bni Hilal (71.43%), Laamria (60%), and Boulaouane (40%) districts, but was quasi-absent in Lmechrek. To understand the dominance of L. viticola as one of the grapevine trunk pathogens, effects of temperature (10–40 °C) and pH (pH 3–pH 12) on growth and sporulation were investigated. The species were able to grow in a range of temperatures ranging from 15 to 40°C and showed a higher growth rate at 35 °C. The fungus were also characterized by a broad optimum pH ranging between 3–12. This study is the first report dealing with L. viticola associated with grapevine trunk diseases in Morocco. Additional studies are therefore required to understand the high occurrence of this disease in vineyards, which is likely due to climate changes. A good understanding of this complex disease might help to develop a reliable and sustainable preventive control strategy. [ABSTRACT FROM AUTHOR]

Grapevine leafroll disease (GLD) constrains wine production worldwide. In New Zealand, the main causal agent of GLD is grapevine leafroll-associated virus 3 (GLRaV-3). To control GLD, an integrated management program is used and includes removing (roguing) GLRaV-3-infected vines from the vineyard. The classical foliar symptoms from virus-infected red-berry cultivars are leaves with dark red intervein, green veins, and downward rolling of margins. Growers use these phenotypic cues to undertake visual symptom identification (VSI) for GLD. However, the influence of the known large genetic variation among GLRaV-3 isolates on the foliar symptoms from different grapevine cultivars remains undescribed, especially in cool-climate growing environments, such as New Zealand. Over three vintages (2015, 2016, and 2017), VSI for GLD was undertaken at three field sites in New Zealand (Auckland, Hawke's Bay, and Marlborough), each including four cultivars (Merlot, Pinot noir, Sauvignon blanc, and Pinot gris) infected with three GLRaV-3 genotypes (Groups I, VI, and X) or GLRaV-3-uninfected control plants. Throughout this study, no visual symptoms were observed on white-berry cultivars infected with GLRaV-3. For red-berry cultivars, the greatest variability in observed foliar symptoms among regional study sites, cultivars, and GLRaV-3 genotypes was observed early in the growing season. In particular, Group X had significantly delayed symptom expression across all three sites compared with Groups I and VI. As the newly infected, young vines matured in years 2 and 3, the GLRaV-3 genotype, cultivar, region, and environmental conditions had minimal influence on the accuracy of VSI, with consistently high (>95%) within-vintage identification by the end of each vintage. The results from this study strongly support the use of VSI for the GLD management of red-berry cultivar grapevines, Merlot and Pinot noir, as a reliable and cost-effective tool against GLD. [ABSTRACT FROM AUTHOR]

Scaphoideus titanus Ball is a major pest of grapevine in Europe, being the main vector of Flavescence dorée phytoplasma (FDp). The North American grapevine leafhopper was identified in neighboring countries, however, the FDp vector was not recorded and there is no available data on its presence in Kosovo. In 2021, initial investigations were conducted and field surveys were carried out in the region of Rahovec in order to evaluate the presence of S. titanus in Kosovarian vineyards. The survey was established in seventeen vineyards in different locations and grapevine varieties. In the middle of June, in each vineyard chosen for investigation were settled yellow sticky traps for surveying and sampling of leafhoppers. All plantations were subjected to fungicide treatment and no insecticide treatment was applied for S. titanus. The captures on the yellow sticky traps indicated that the North American grapevine leafhopper was present in Kosovo. Its population was different in investigated vineyards. Of the seventeen vineyards monitored, in twelve of them was captured the FDp vector, two sticky traps were damaged, and in three vineyards was not captured any specimen of Scaphoideus titanus. An average, of two up to forty-nine specimens of S. titanus per trap were collected over the surveyed period from the beginning of June until the end of September 2021. These results show only the distribution of S. titanus in the surveyed area. Furthermore, the presence of the North American grapevine leafhopper in Kosovo is an alert for urgent phytosanitary control of the quarantine phytoplasma Flavescence dorée (FD). [ABSTRACT FROM AUTHOR]

During field surveys conducted from July to October 2018-2020 in the eastern part of Georgia (Caucasus region), 145 out of 8000 (1.8%) and 147 out of 6600 (2.2%) grapevine plants, respectively, from mother stock/collection fields and commercial vineyards, were found exhibiting typical or suspicious grapevine yellows (GY) symptoms. Most of the symptomatic grapevine plants of Georgian cultivars showed mild symptoms with no berry alterations. Leaf samples from symptomatic plants were analyzed by serological (DAS--ELISA) and molecular (two previously published protocols of TaqMan triplex real-time PCR, here named Set I and Set II) tools for detecting GY-associated phytoplasmas. The presence of GY phytoplasmas was not detected in any examined grapevines by a serological method. GY phytoplasmas were identified in 22.41% and 6.9% symptomatic plants from mother stock and collection vineyards and in 48.3 and 19.0% symptomatic plants from commercial vineyards by Set I and Set II PCRs, respectively. As expected from previous studies reporting the wide presence of bois noir (BN) in Georgian vineyards, 'Candidatus Phytoplasma solani'(CaPsol) was detected in most phytoplasma-infected plants (47.6%), with the highest infection rate in Chardonnay. Phytoplasmas belonging to taxonomic group 16SrV were detected in 45.6% of the phytoplasma-infected grapevines. To the best of our knowledge, this is the first report of 16SrV phytoplasmas in Georgia and in the Caucasus region. Further molecular typing of 16SrV phytoplasma strains is necessary to determine if such strains are associated with flavescence dorée (FD). The knowledge of typical GY symptoms and the utilization of accurate diagnostic tools are crucial for preventing pathogen spread and producing healthy planting material. Based on the results obtained in this study, the presence of BN and 16SrV phytoplasmas should be monitored in the next years using triplex real-time PCR. [ABSTRACT FROM AUTHOR]

This study aimed to survey the occurrence of eight grapevine viruses in commercial vineyards located in the Calchaquíes Valleys in the northwest region of Argentina. A total of 103 samples of mature canes of vines showing either none or some viral-like symptoms were randomly collected. The samples were tested by RT-PCR/PCR-based assays for the screening of the following viruses: Grapevine fanleaf virus (GFLV), Grapevine leafroll-associated viruses (GLRaV-1, -2, -3, -4), Grapevine virus A (GVA), Grapevine rupestris stem pitting-associated viruses (GRSPaV), and Grapevine red blotch virus (GRBV). Sixty percent of the analyzed samples showed infection with some of the analyzed viruses, except GRBV. GLRaV-3 and GFLV were the most frequent viruses, present in 34% and 21% of the positive samples, respectively. This study represents the first survey report of the presence of grapevine viruses in the region of the Calchaquíes Valleys and contributes to the knowledge to maintain the sanitary status of commercial vineyards in Argentina. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases make up a disease complex associated with several vascular fungal pathogenic species. Surveys to characterize the composition of grapevine trunk diseases have been conducted for most major grape growing regions of the world. This study presents a similar survey characterizing the fungi associated with grapevine trunk diseases of cold-hardy interspecific hybrid grape varieties grown nearly exclusively in the atypical harsh winter climate of Northern Midwestern United states vineyards. From the 172 samples collected in 2019, 640 isolates obtained by culturing were identified by ITS sequencing and represent 420 sample-unique taxa. From the 420 representative taxa, opportunistic fungi of the order Diaporthales including species of Cytospora and Diaporthe were most frequently identified. Species of Phaeoacremonium, Paraconiothyrium, and Cadophora were also prevalent. In other milder Mediterranean growing climates, species of Xylariales and Botryosphaeriales are often frequently isolated but in this study they were isolated in small numbers. No Phaeomoniellales taxa were isolated. We discuss the possible compounding effects of winter injury, the pathogens isolated, and management strategies. Additionally, difficulties in researching and understanding the grapevine trunk disease complex are discussed. [ABSTRACT FROM AUTHOR]

The spread of Grapevine trunk diseases (GTDs) such as esca concerns wine growers worldwide. Besides rain-splash and air currents, arthropods may play an additional role in the dissemination of esca-related pathogens such as Phaeomoniella chlamydospora (Pch) and Phaeoacremonium minimum (Pmm). The present study confirms that black garden ants (Lasius niger L., Formicidae: Formicinae) and European earwigs (Forficula auricularia L., Dermaptera: Forficulidae) can, under artificial conditions, efficiently transmit spores of Pch and Pmm to healthy grapevine cuttings, causing new infections. The potential of earwig feces as inoculum source in vineyards is additionally discussed. Spores of Pch and Pmm retained germination ability after earwig gut passage, and infectious feces successfully infected wounded grapevine cuttings under artificial conditions. However, molecular detection frequencies of esca-related pathogens in earwig feces collected from the field were very low. With this, the risk of earwig feces as inoculum source for esca-related pathogens is probably only marginal. However, arthropods carrying esca-related spores on their exoskeletons, such as ants and earwigs, might contribute to the overall spread of esca in vineyards. The invasion of GTDs during the phase of pruning wound susceptibility, either by arthropod vectors or by airborne spores, can efficiently be prevented by adequate pruning wound protection. [ABSTRACT FROM AUTHOR]

The European grapevine moth (EGVM), Lobesia botrana (Lepidoptera: Tortricidae) and the vine mealybug (VMB), Planococcus ficus (Hemiptera: Pseudococcidae), are two important pests of grapevine in Mediterranean vineyards. In the last 20 years, pheromone-based mating disruption (MD) has been successfully developed, with noteworthy reduction in chemical insecticide use and safeguard of non-target insects. In the present study, a dedicated plastic reservoir dispenser (Isonet® L PFX246), releasing simultaneously synthetic pheromone active ingredients of both EGVM and VMB, was evaluated by testing 400, 500 and 600 dispensers/ha in five study sites located in Southern (Sicily), Central (Tuscany) and Northern (Veneto) Italy. Trials were performed by monitoring EGVM and VMB populations in wine and table-grape vineyards managed with MD, and in grower’s standard and untreated control vineyards. One single application per year of MD resulted in a significant reduction of both EGVM and VMB male catches, infested flower clusters and bunches, as well as of EGVM nests and VMB individuals, compared to untreated controls. MD efficacy was comparable to or higher than the efficacy expressed by grower’s standard. In general, no significant differences were found among the three tested rates of Isonet® L PFX246. Overall, our results highlighted that the use of Isonet® L PFX246 for the combined control of EGVM and VMB can contribute in achieving effective management of both pests, with the distinctive trait of this dispenser being the active ingredients: the sex pheromones of two insect species that do not belong to the same Order, i.e. Lepidoptera and Hemiptera. [ABSTRACT FROM AUTHOR]

This research identified arbuscular mycorrhizal fungi (AMF) in rhizosphere soil of grapevines with Grapevine Death and Decline symptoms (GDD) or asymptomatic healthy (H) plants, and characterized the relationship of AMF communities with soil chemical attributes. The AMF spore number ranged from 287 to 432 spores 50 cm-3 in soil with GDD plants, and from 357 to 464 spores 50 cm-3 in H plants, with no differences among vineyards or between GDD and H plants within each vineyard. We detected 42 species and 17 genera, and most taxa belonged to Acaulosporaceae or Glomeraceae. Claroideoglomus etunicatum, Funneliformis mosseae, and Archaeospora trappei were the most frequent species in all vineyards. Soil chemical attributes were not determinant for the occurrence of most fungal species; although, Entrophospora infrequens, Diversispora sp1 and Diversispora sp2 were associated with a vineyard having high soil copper. Vineyards harbor highly diverse AMF communities, which are determined by location. [ABSTRACT FROM AUTHOR]

Phytoplasma strains were sporadically found in specimens of Hishimonus hamatus, Japananus hyalinus and Graphocephala fennahi caught during an entomological survey conducted in Southern Switzerland on the edges and woods surrounding cultivated vineyards in 2017. The subsequent molecular characterization of the pathogens allowed to identify them as strains strictly associated to Flavescence dorée, a serious European grapevine disease, transmitted from vine to vine by the leafhopper Scaphoideus titanus. In particular, M12 and M50 genotypes were found in H. hamatus and J. hyalinus, respectively, while G. fennahi harboured mixed phytoplasma genotypes with at least two different Flavescence dorée isolates. The potential importance of these findings in the frame of the Flavescence dorée epidemics in Europe is discussed. [ABSTRACT FROM AUTHOR]

A search for phytoplasma‐associated diseases was conducted for the first time in the main grapevine‐growing localities of the Dukagjini plain in Kosovo. A total of 144 samples were collected from grapevine cultivars displaying leaf yellowing, reddening, discolouration and irregular wood ripening, and analysed using nested and quantitative PCR assays. These assays showed that 35.4% of samples belonging to eight cultivars were positive to the presence of phytoplasmas in the 16SrXII group. The 16S rDNA phytoplasma sequences obtained from 15 samples shared identity greater than 99.5% with 'Candidatus Phytoplasma solani'. Sequence analysis of the tuf gene showed that the strains found in Kosovar grapevines are in the tuf‐type b1 group, sharing 99.6% to 99.8% identity with 'Ca. P. solani'‐related strains associated with the "bois noir" grapevine disease in many European countries; the secY gene sequences, on the other hand, shared 100% identity with 'Ca. P. solani' strains from Bosnia and Herzegovina, Serbia, Croatia and Turkey. This study constitutes the first report on the presence and molecular characterization of phytoplasmas in Kosovar vineyards. Based on these results, it is recommended that testing for phytoplasma be included in the certification program for grapevine in Kosovo. [ABSTRACT FROM AUTHOR]

Water potential (Ψw) is a fundamental thermodynamic parameter that describes the activity of water and is a key metric of plant water status. In this paper, we evaluate the continuous measurement of water potential in grapevine trunks using a novel in situ sensor known as a 'microtensiometer' under field conditions in two South Australian vineyards. We characterised the seasonal and diurnal dynamics of trunk water potentials (Ψtrunk) obtained from microtensiometers installed in two grapevine cultivars, Shiraz and Cabernet Sauvignon, and compared these values to pressure chamber-derived stem (Ψstem) and leaf (Ψleaf) water potentials. Diurnal patterns of Ψtrunk matched those of Ψstem and Ψleaf under low-vapour pressure deficit (VPD) conditions, but diverged under high-VPD conditions, where Ψtrunk dropped below Ψstem in the late afternoon. Interestingly, under high-VPD conditions, Ψtrunk values consistently dropped below Ψstem values around mid-afternoon with a recovery observed by early evening. The highest diurnal values of Ψtrunk were observed shortly after dawn. Ψstem was better correlated with Ψtrunk than was Ψleaf in both cultivars. Time cross-correlation analysis revealed that Shiraz Ψtrunk lagged Cabernet Ψtrunk in response to changing VPD. Microtensiometer-derived Ψtrunk generally matched the seasonal and diurnal patterns of plant Ψw obtained with a pressure chamber except under high-VPD conditions. To be useful for irrigation scheduling, where absolute values of Ψw are required, crop- and cultivar-specific thresholds of Ψtrunk need to be developed. [ABSTRACT FROM AUTHOR]

The incidence of grapevine virus infections in Korean vineyards was investigated from July to October, 2020. A total of 177 petiole samples were collected from two or three different cultivars in each of four different regions; these were examined by reverse transcription-polymerase chain reaction assay for the presence of 14 major viruses. The overall occurrence of grapevine viruses was 91.0%, and the level of incidence was high irrespective of region or cultivar. The predominant viruses were grapevine leafroll-associated virus 3 (80.2%), grapevine fleck virus (70.6%), and grapevine rupestris stem pitting-associated virus (49.2%). Most grapevines were infected with multiple viruses, suggesting that Korean vineyards are likely to suffer economic losses resulting from viral diseases. This is the first extensive survey performed in Korea to observe the outbreak status of diverse grapevine viruses; surveys of this type can provide important information for the management of grapevine viruses in Korea. [ABSTRACT FROM AUTHOR]

Grapevine leaf mottling and deformation is a novel grapevine disease that has been associated with grapevine Pinot gris virus (GPGV). The virus was observed exclusively inside membrane-bound structures in the bundle sheath cells of the infected grapevines. As reported widely in the literature, many positive-sense single-stranded RNA viruses modify host-cell membranes to form a variety of deformed organelles, which shelter viral genome replication from host antiviral compounds. Morphologically, the GPGV-associated membranous structures resemble the deformed endoplasmic reticulum described in other virus-host interactions. In this study we investigated the GPGV-induced membranous structures observed in the bundle sheath cells of infected plants. The upregulation of different ER stress-related genes was evidenced by RT-qPCR assays, further confirming the involvement of the ER in grapevine/GPGV interaction. Specific labelling of the membranous structures with an antibody against luminal-binding protein identified them as ER. Double-stranded RNA molecules, which are considered intermediates of viral replication, were localised exclusively in the ER-derived structures and indicated that GPGV exploited this organelle to replicate itself in a shelter niche. Novel analyses using focussed ion-beam scanning electron microscopy (FIB-SEM) were performed in grapevine leaf tissues to detail the three-dimensional organisation of the ER-derived structures and their remodelling due to virus replication. Grapevine leaf mottling and deformation (GLMD) is a novel grapevine disease that has been associated with grapevine Pinot gris virus (GPGV). Despite the increase in the number of reports describing GLMD in vineyards worldwide, the literature still lacks information on virus–grapevine interactions at the cytological and molecular level. The results reported in this work contribute to understanding the biology of GPGV in its natural host and to improving knowledge of the novel GLMD disease, whose aetiology is still poorly understood. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases (GTDs) are the most destructive diseases in grape-growing regions worldwide. Black foot is one of the important GTDs affecting young vineyards and nurseries. This disease has not been reported in China. During 2017 and 2019, field surveys were carried out in the Guangxi, Hebei, Ningxia, Shanxi, and Xinjiang provinces of China. Incidence of plants with black foot symptoms was 0.1% to 1% in the surveyed vineyards. Plant samples with poorly developed shoots and canes, chlorotic leaves, and necrotic trunks or roots were collected from the five provinces. In total, 50 fungal isolates were obtained from symptomatic tissues. Based on morphological and multi-gene phylogenetic analyses, five species were identified as Cylindrocladiella lageniformis, Dactylonectria torresensis, D. macrodidyma, D. alcacerensis and Neonectria sp.1. Pathogenicity was assessed using young, healthy detached green shoots of grapevine 'Summer Black' and potted 3-month-old 'Summer Black' cuttings. Inoculated detached shoots developed necroses after 7 d, and inoculated cuttings after 80 d. Fungi were re-isolated from necrotic lesions. Among the five species, D. macrodidyma was the most aggressive. This is the first report of C. lageniformis, D. torresensis, D. macrodidyma, D. alcacerensis, and Neonectria sp. 1 associated with black foot in China. This study has enhanced knowledge of the fungi associated with black foot in China, and will assist development of control measures for this disease. [ABSTRACT FROM AUTHOR]

Copper has been successfully used in the sulfate form as a fungicide to control grapevine diseases since 150 years, yet high Cu accumulation in vineyards may alter soil life. Although actual Cu additions are about tenfold lower than 50 years ago, the use of Cu in the context of the agroecological transition is still debated. Indeed, copper is one of the rare pesticides allowed for organic farming. Therefore, we performed a meta-analysis on Cu ecotoxicity by selecting 19 articles out of 300 articles relevant to copper and soil biological quality. Results show that microbial activity decreased by 30% when more than 400 kg of Cu was applied yearly per ha. Nematodes abundance remained unchanged for copper application up to 3200 kg/ha/year. Collembola and enchytraeid reproduction declined by 50% after application of 400 and 1895 kg Cu/ha/year, respectively. Earthworm biomass was reduced by 15% after application of 200 kgCu/ha/year. For soil Cu levels higher than 200 kg Cu/ha, microbial respiration decreased by 50% and no effect was observed on collembola. Overall, while toxicity is observed, the corresponding literature investigations involved Cu levels that are at least 50 times higher than the dose of 4 kg Cu/ha/year currently authorized by the European Commission for viticulture. As a consequence, applying copper at 4 kg/ha/year should not modify substantially soil biological quality and functions. [ABSTRACT FROM AUTHOR]

The vine mealybug (VMB), Planococcus ficus, is a major grapevine pest worldwide, whose chemical control is often unsatisfactory due to its cryptic behavior, insecticide resistance and high fecundity rate. Recently, increasing restrictions have been applied to insecticides used for managing VMB. This review discusses sustainable VMB management strategies in organic viticulture. Pheromone-mediated mating disruption has been proved to be effective in both organic wine and table-grape vineyards. Biocontrol projects carried out through the release of parasitoids and/or predators have often provided inconclusive results, ranging from effective reduction of mealybug infestation to a marginal impact of parasitoids on VMB density. The latter outcome is likely due to constraints affecting the parasitoid activity, such as the disrupting activity of mealybug-tending ants and broad-spectrum insecticides, or untimely release of parasitoids. Ant suppression should be associated with the release of beneficial organisms, as mealybug-tending ants can severely affect the parasitoid activity. Cultural and physical control and the employment of entomopathogens and natural products mitigate the buildup of VMB populations, but they are not widely applied. VMB control in organic viticulture requires the integration of different strategies, as application of single control tools as a stand-alone treatment may not be effective, especially for high pest infestation. Future research to determine the density action threshold below which sustainable methods are effective and calibrate efforts in relation with pest infestation is needed. A multi-disciplinary approach is required to define the most appropriate sustainable control protocols in different environmental conditions and promote a further spread of organic viticulture. [ABSTRACT FROM AUTHOR]

The state of Sonora is the main grape production area in Mexico. Grapevine trunk diseases (GTD) are serious disease in this region. During the springs of 2017 and 2018, symptoms of yellow and wilted leaves, and necrotic buds, were observed in several vineyards in Sonora. Affected plants had numerous small, black and bright acervuli. This study aimed to identify the causative agent of this disease. Isolates were obtained from small pieces of damaged plant parts, and were cultured on potato dextrose agar. The developing mycelium was white but turned greyish white after 3 d. Multi-shaped black mucilaginous droplets appeared in the cultures after 2 d, and the agar in Petri dishes was completely covered with mycelium after 7 d, and the colonies had five or six rings with large numbers of conidiomata. Conidia were hyaline or light cream, fusiform, oval or ellipsoid, with truncated bases and narrow almost pointed apices, and were 6--10 mm long and 2--3 mm wide. Phylogenetically analysed concatenated sequences of the DNA from two representative isolates, from the internal transcribed spacer region, and large ribosomal subunit, showed they were in a separate clade which aligned with several strains of Greeneria uvicola, confirming the presumptive morphological identity of the isolates. This cosmopolitan ascomycete is responsible for bitter rot of grapes, but the role of this fungus as a cause of grapevine trunk diseases is little known. Pathogenicity tests of the isolates were performed on 1-year-old 'Passion Fire' grapevines plants, one of the new cultivars planted in Sonora. All of strains G. uvicola were pathogenic, and the fungus was recovered from the lesions, fulfilling Koch's postulates. This is the first report on the pathogenicity of G. uvicola in wood tissues of Vitis vinifera in Mexico. [ABSTRACT FROM AUTHOR]

Grapevine Trunk Diseases (GTDs) cause important economic losses in vineyards. Diagnosis of pathogens causing GTDs is usually achieved using culture methods from symptomatic plants, but these methods may not be definitive. This study aimed to detect three fungi associated with GTDs in Chile (Diplodia seriata, Phaeomoniella chlamydospora and Eutypa lata) using qPCR methods, after extracting DNA from asymptomatic woody pruning material taken from 912 grapevine plants and 346 rootstocks. Pathogen incidence and distribution across different regions, vineyards, grape and wine cultivars, plant ages and rootstocks were determined. Forty percent of assessed grapevine plants and 42% of rootstocks were positive for the assayed GTD pathogens. The fungus with the greatest incidence was D. seriata (36% of plants and 30% of rootstocks), followed by E. lata (6% of plants and 20% of rootstocks) and P. chlamydospora (4% of plants and 5% of rootstocks). Positive relationships were detected between the presence of D. seriata and P. chlamydospora and grapevine age. However, the three fungi were randomly distributed across graprevine plants and rootstocks since none of the assessed factors had statistically significant influence in their distribution. This study is the first to assess incidence and distribution of E. lata in Chile. The qPCR-based method described could be used for detecting fungi in asymptomatic nursery plants, and be used to avoid distribution of infected plants into new vineyard plantings. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases (GTDs) are increasing in vineyards in many grape production regions. Among the pathogens causing these diseases, Neofusicoccum parvum, is one of the most frequent and virulent. To control GTDs, biocontrol is being developed using plant beneficial microorganisms. Strains of the oomycete Pythium oligandrum have been shown to naturally colonize grapevine roots in vineyards in several countries in Europe. This study examined the ability of the root-coloniser P. oligandrum to induce grapevine resistance against N. parvum, by deciphering the gene expression changes in a set of 62 genes involved in different grapevine defence pathways. Two greenhouse assays showed that the wood necrosis of vine cuttings caused by N. parvum was reduced by 65% when P. oligandrum colonized root systems of the plants. The relative expression levels of selected genes in the host trunks were studied by real-time PCR. Plant responses were assessed after inoculation by P. oligandrum and/or N. parvum, at three different sampling time points (0, 14 and 150 d after N. parvum inoculation). Sampling time influenced gene expressions for the different inoculation treatments. At each sampling time, specific host responses to the different treatments were also detected, for controls, and for inoculations with P. oligandrum, N. parvum or P. oligandrum + N. parvum. When P. oligandrum colonized grapevine root systems, inoculation with the pathogen was associated with increased up-regulation and over-expression of particular genes, including those regulating Pathogen-Related proteins, cell wall reinforcement proteins and hormone signalling pathways. A priming effect of the grapevine defence system was induced in roots colonized by P. oligandrum. [ABSTRACT FROM AUTHOR]

After the first report of grapevine decline caused by Botryosphaeriaceae in Sicily in 2007, epidemiological studies carried out in mature vineyards until 2011 confirmed the widespread occurrence of "Botryosphaeria dieback" and the "Esca complex" disease. Dieback symptoms were also recently observed in two young vineyards in Partanna and Castellammare del Golfo in western Sicily (Trapani province). Declining vines were inspected for grapevine trunk disease (GTD) symptoms, and were uprooted and submitted for analyses. Fungal isolates were collected and identified using culturing and molecular analyses. One isolate per identified species was inoculated to three grapevine shoots to evaluate pathogenicity and fulfil Koch's postulates. Several GTD Botryosphaeriaceae pathogens in the genera Cadophora, Ilyonectria, Neonectria, Phaeoacremonium and Phaeomoniella were isolated from the symptomatic young vines. Artificial inoculation confirmed the pathogenicity of these fungi. In addition, virulence variability was observed among the isolates, with P. chlamydospora causing the largest lesions. The different species were associated with specific symptoms and/or host vine parts, especially in the roots and around the grafting areas. Several fungi associated with Petri disease and black foot were shown to be responsible of young vine decline. [ABSTRACT FROM AUTHOR]

The three-cornered alfalfa hopper, Spissistilus festinus (Say), was shown to transmit Grapevine red blotch virus (GRBV), the causative agent for Grapevine red blotch disease, in a greenhouse study on grapes. GRBV is a major concern of wine grape growers due to its economic impact on wine quality. Plants in the family Fabaceae are preferred hosts of S. festinus and are commonly planted as cover crops or present in a vineyard's native vegetation. In late winter, during grapevine dormancy, S. festinus migrate into vineyards to feed and reproduce on these cover crop and weed hosts. Tilling vineyard floor vegetation provides growers an opportunity to disrupt the life cycle of early instars that are relatively immobile, reducing the S. festinus first-generation population. Nymphal presence is difficult to detect. First through third instars were not detected in sweep net samples in a 2-yr weekly sampling study, whereas fourth and fifth instars were first found on the same sample date as emerging adults. A degree-day model was developed and successfully predicted when early S. festinus instars are present in the vineyard to aid in exploiting the time period when S. festinus is most susceptible to cultural control measures. [ABSTRACT FROM AUTHOR]

The effect of different management techniques for plant control in the vineyard were compared in the present work, focusing on plant diversity preservation and management efficacy in a two-year experiment on vineyard row weed community. Biomass-fueled flame weeding (with two intensities) was applied as an innovative plant control technique in contrast to tillage and mowing practices. The results showed that flaming was comparable to tillage regarding weed control effectiveness, and was more efficient than mowing. However, species number and functional evenness were not substantially modified by changing the applied management technique. Functional trait analysis demonstrated that row management significantly affected the frequency of annual plants, plant height, root depth index, and the occurrence of plants with storage organs. As for species composition, meaningful differences were found: only the two flaming treatments (i.e. gentle vs intense) and the gentle flaming vs mowing had consistent species composition. Flame wedding showed some potential benefits in plant control in the vineyard by favouring small plant and controlling overall weed abundance. On the other hand, flaming favoured plant species with asexual reproduction, with a potential negative impact on weed-vine competition and species persistence in the vineyard. Further studies are required to investigate such contrasting aspects, also considering other weed control techniques (e.g. cover-crops), considering a sustainable perspective of an herbicide-free environment. [ABSTRACT FROM AUTHOR]

Eighty-six viruses have been isolated to date from grapevines worldwide. Some of these viruses are associated with economically damaging diseases such as leaf mottling and deformation, vein clearing, leafroll, degeneration and red blotch. They belong to the families Betaflexiviridae, Caulimoviridae, Closteroviridae, Secoviridae and Geminiviridae, and are transmitted by diverse vectors such as mealybugs (Hemiptera: Pseudococcidae), soft scale insects (Hemiptera: Coccidae), an aphid (Hemiptera: Aphididae), dagger nematodes (Nematoda: Longidoridae), a treehopper (Hemiptera: Membracidae) and eriophyid mites (Acari: Eriophyidae). Management of these viruses primarily relies on preventive measures to limit their presence in the propagation and planting material. In the vineyard, specific disease scenario-based strategies such as rogueing in combination with agrochemical applications to limit vector populations, if appropriate, and the removal of entire parcels and their replacement with clean planting material, including vector tolerant rootstocks, if opportune, are implemented to reduce their incidence, prevent their spread and mitigate their impact. These solutions are simple but their implementation is often suboptimal and their adoption is largely low. Some of the uncertainties that hinder their endorsement are captured here, and options to refine them and to enhance their adoption are discussed. [ABSTRACT FROM AUTHOR]

Although the fungus Phaeomoniella chlamydospora is the most commonly detected causal agent of Petri disease and esca, two important fungal grapevine trunk diseases, little is known about the dispersal patterns of P. chlamydospora inoculum. In this work, we studied the dispersal of P. chlamydospora airborne inoculum from 2016 to 2018 in two viticultural areas of eastern (Ontinyent) and northern (Logrono) Spain. The vineyards were monitored weekly from November to April using microscope slide traps, and P. chlamydospora was detected and quantified by a specific realtime quantitative (qPCR) method set up in this work. The method was found to be sensitive, and a good correlation was observed between numbers of P. chlamydospora conidia (counted by microscope) and DNA copy numbers (quantified by qPCR). We consistently detected DNA of P. chlamydospora at both locations and in all seasons but in different quantities. In most cases, DNA was first detected in the last half of November, and most of the DNA was detected from December to early April. When rain was used as a predictor of P. chlamydospora DNA detection in traps, false-negative detections were observed, but these involved only 4% of the total. The dispersal pattern of P. chlamydospora DNA over time was best described (R2 = 0.765 and concordance correlation coefficient = 0.870) by a Gompertz equation, with time expressed as hydrothermal time (a physiological time accounting for the effects of temperature and rain). This equation could be used to predict periods with a high risk of dispersal of P. chlamydospora. [ABSTRACT FROM AUTHOR]

Copyright of Yuzuncu Yil Universitesi Journal of Agricultural Sciences (YYU J Agr Sci) is the property of Yuzuncu Yil University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Among all causes of grapevine decline, Grapevine Trunk Diseases (GTDs) are major concerns for grape growers. This paper reviews knowledge and proposes hypotheses on two major GTDs, esca and Botryosphaeria dieback, and assembles a conceptual model. The objective was to collect information into a sequence, from grapevine nursery propagation processes, through foliar symptom expression, to plant death in mature vineyards. Pathogen infection and colonization steps in woody vine tissues, and the hypotheses that have been formulated to explain the outburst of foliar symptoms, are reported and discussed. Factors that could aggravate or repress GTD symptoms and incidence expansion are also addressed. Vine physiology and pathology together could expand understanding of these diseases. Knowledge and hypotheses that need validation are summarized, and a conceptual model is proposed to explain the occurrence of symptoms and the influencing factors. The model could be useful to cope with the complexity of GTDs, and as a starting point for research to unravel knowledge gaps and suggest new disease management strategies. [ABSTRACT FROM AUTHOR]

BACKGROUND: Fungal grapevine trunk diseases (GTDs) represent a threat to viticulture, being responsible for important economic losses worldwide. Nursery and vineyard experiments were set up to evaluate the ability of Trichoderma atroviride SC1 to reduce infections of GTD pathogens in grapevine planting material during the propagation process and to assess the long‐term protection provided by this biocontrol agent on grapevine plants in young vineyards during two growing seasons. RESULTS: Reductions of some GTD pathogen incidence and severity were found on grapevine propagation material after nursery application of T. atroviride SC1 during the grafting process, and also after additional T. atroviride SC1 treatments performed during two growing seasons in young vineyards, when compared with untreated plants. CONCLUSION: Trichoderma atroviride SC1 showed promise to reduce infections caused by some GTD pathogens in nurseries, and also when establishing new vineyards. This biological control agent could possibly be a valuable component in an integrated management approach where various strategies are combined to reduce GTD infections. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Guignardia bidwellii or black rot of vine is one of the most dangerous diseases that occur in vineyards in the center of Transylvania. The objective of this work was the tolerance testing of varieties and clones homologated at SCDVV Blaj to the Guignardia bidwellii attack. The behavior of vine varieties to the Guignardia bidwellii fungus attack was characterized by the analysis of the severity of the symptoms according to a scale in function of the attack degree (AD). The results obtained revealed the tolerance of the tested varieties: ‘Rubin’ (AD=0.13%), ‘Amurg’ (AD=0.25%), ‘Brumariu’ (AD=0.78%), ‘Radames’ (AD=0.96%) and ‘Blasius’ (AD=0.97%), a medium tolerance presented ‘Selena’ (AD=9.28%) variety and ‘Neuburger-10 Bl’ (AD=5.04%), ‘Iordana 9-1 Bl’ (AD=6.40%), ‘Riesling de Rhin 7-2’ (AD=7.2%), ‘Sauvignon-9 Bl’ (AD=9.28%), ‘Traminer roz-60 B’ clones (AD=17.5%) and susceptibility for ‘Astra’ variety (AD=25.56%) and ‘Riesling italian-3 Bl’ (AD=22.4%), ‘Pinot gris-34 Bl’ (AD=30.60%), ‘Feteasca regala-21 Bl’ (AD=31.50%), ‘Muscat Ottonel-12Bl’ (AD=35.30%), ‘Feteasca alba-29 Bl’ clones (AD=38.40%). The results obtained regarding the behavior of grapevine in the climatic conditions specific to the studied area for the 2016-2018 period, show that the lowest values of AD were registered for the ‘Rubin’ (AD=0.13%), ‘Amurg’ (AD=0.25%), ‘Brumariu’ (AD=0.78%), ‘Radames’ (AD=0.96%) and ‘Blasius’ (AD=0.97%) varieties homologated at SCDVV Blaj. [ABSTRACT FROM AUTHOR]

Grapevine 'Pinot gris' virus (GPGV) is a newly emergent virus associated with the appearance of grapevine leaf mottling and deformation disease (GLMD). The worldwide spreading of this virus, and sometimes of the associated disease, that has occurred in the last years, requests further epidemiological studies to verify the progress of natural infection in the field. In the present paper, GPGV infection and spatiotemporal spreading of GLMD, investigated in two vineyards with high disease occurrence, confirmed an elevated presence of the virus in vineyards of Northeastern Italy, and revealed an increasing of symptomatic plants over the time. At the same time, the progress of natural infection was monitored after the placement of new grafted plants near the symptomatic grapevines in the infected vineyards. After three years, 76 % of the plantlets that were initially GPGV-free became GPGV-infected, giving an evidence of the fast transmission of GPGV in the field. Only 14 % of the plantlets, all collocated inside a patch with diseased plants, showed typical GLMD-symptoms. Interestingly, some plantlets, which were already GPGV-infected with the "asymptomatic" GPGV variant before planting in the field, did not become infected with the "symptomatic" viral wild variant after three years and never showed GLMD symptoms. [ABSTRACT FROM AUTHOR]

Bois noir (BN), the most prevalent disease of the grapevine yellows complex, causes considerable yield loss in vineyards. BN is associated with phytoplasma strains of the species 'Candidatus Phytoplasma solani' (taxonomic subgroup 16SrXII‐A). In Europe, the BN phytoplasma is transmitted to grapevine mainly by Hyalesthes obsoletus, a polyphagous cixiid completing its life cycle on stinging nettle and field bindweed. As a result of the complexity of BN epidemiology, no effective control strategies have been developed. In previous studies conducted in the eastern Mediterranean coast of Israel, chaste tree (Vitex agnus‐castus) was found to be the preferred host plant of H. obsoletus but did not harbour BN phytoplasma. Thus, a 'push and pull' strategy was suggested based on the fact that chaste tree plants located at vineyard borders was an effective trap plant for H. obsoletus adults. However, in other studies carried out in the eastern Adriatic coast of Montenegro, chaste tree was found to be a key source plant for BN phytoplasma transmission to grapevine. This study aimed to investigate (i) the interaction between chaste tree and H. obsoletus through survival, attractiveness and oviposition experiments conducted comparing the behaviour of H. obsoletus in chaste tree versus stinging nettle and grapevine and (ii) the capability of chaste tree to harbor 'Ca. P. solani' in northern Italy through transmission trials. H. obsoletus adults were found to survive on chaste tree and grapevine over a 1 week period and prefer chaste tree to grapevine. Moreover, H. obsoletus produced eggs and overwintered as nymphs on chaste tree, even if at a lesser extent than on stinging nettle. H. obsoletus originating from nettle was found able to transmit 'Ca. P. solani' to chaste tree (2 plants of 16 were found infected by the BN phytoplasma strain St5 identified in H. obsoletus specimens). These results increased our knowledge about the role of Vitex agnus‐castus as host plant of H. obsoletus and BN phytoplasma in northern Italy and do not recommend considering chaste tree as trap plant at vineyard borders. [ABSTRACT FROM AUTHOR]

To study the role of wild areas around the vineyards in the epidemiology of flavescence dorée (FD) and track the origin of new foci, two phytoplasma genetic markers, dnaK and malG, were developed for FD phytoplasma (FDp) characterization. The two genes and the vmpA locus were used to genetically characterize FDp populations at seven agroecosystems of a wine-growing Italian region. Vitis vinifera, "gone-wild" V. vinifera and rootstocks, Clematis spp., and Scaphoideus titanus adults were sampled within and outside the vineyards. A range of genotypes infecting the different hosts of the FDp epidemiological cycle was found. Type FD-C isolates were fairly homogeneous compared to type FD-D ones. Most of the FD-D variability was correlated with the malG sequence, and a duplication of this locus was demonstrated for this strain. Coinfection with FD-C and FD-D strains was rare, suggesting possible competition between the two. Similar levels of FDp genetic variation recorded for grapevines or leafhoppers of cultivated and wild areas and co-occurrence of many FDp genotypes inside and outside the vineyards supported the idea of the importance of wild or abandoned Vitis plants and associated S. titanus insects in the epidemiology of the disease. Genetic profiles of FDp found in Clematis were never found in the other hosts, indicating that this species does not take part in the disease cycle in the area. Due to the robustness of analyses using dnaK for discriminating between FD-C and FD-D strains and the high variability of malG sequences, these are efficient markers to study FDp populations and epidemiology at a small geographical scale. IMPORTANCE Flavescence dorée, a threatening disease of grapevine caused by FD phytoplasma (FDp), is distributed within the most important wine-producing areas of Europe and has severe effects on both vineyard productivity and landscape management. FDp is a quarantine pest in Europe, and despite the efforts to contain the pathogen, the disease is still spreading. In this work, new genetic markers for the fine genetic characterization of FDp at local scale are presented. Our findings improve the knowledge of FDp epidemiological cycle and offer the possibility of tracking the route of the FDp infection. In particular, due to its high genetic variability, one of the newly developed markers could be sufficient to track the origin of new infection foci, either from the wild areas or from nurseries. [ABSTRACT FROM AUTHOR]

Disease detection and control is one of the main objectives of vineyard research in France. Manual monitoring of diseases is a time consuming operation especially when fields are large. Current research studies aim to develop automatic in-field systems to detect diseases. This study investigated the optimal spectral bands for the design of a dedicated high-resolution multispectral camera embedded on an unmanned aerial vehicle for identifying infected zones in a grapevine field. The target disease was Flavescence dorée, which is infectious, incurable and can result in considerable yield loss. An in-field spectrometry study was performed on four grapevine varieties in the Provence Alpes Côte d'Azur region in France. Two spectral analysis techniques were proposed for choosing the best spectral bands capable of discriminating healthy from diseased leaves. The first novel approach is a feature selection technique based on the successive projection algorithm (SPA), some spectral pre-processing techniques were jointly investigated. The second approach examines a set of traditional vegetation indices (VI). Support vector machine (SVM) and discriminant analysis (DA) are the two classifiers used in this paper and the accuracy of the results is compared for the two methods of analysis. The best models were computed as a function of the grapevine variety considered. The SPA technique performed better in general with respect to common VIs, the overall classification accuracy was more than 96%. Results demonstrated that employing a feature selection technique based on the SPA algorithm can provide a valid tool for determining the optimal bands that are sensitive to Flavescence dorée grapevine disease and assist in its identification. The benefit behind the presented procedure relies on the possibility of generalizing it for other infections and stresses or even for different crops. [ABSTRACT FROM AUTHOR]