Search Results (105)

An isolate of Peniophora lycii was obtained from grapevine, and its interactions with several grapevine-associated fungi and the plant host were examined. The fungus was not able to infect intact leaves, but necrotized the margins of foliar disks and caused necrosis and white rot in woody tissues. In dual cultures, P. lycii and Aureobasidium pullulans showed mutual antagonism. Mycoparsitism of P. lycii was observed on epiphytic Botrytis cinerea, Alternaria sp., and endophytic Botryosphaeria dothidea interaction partners. In contrast, P. lycii showed trophic growth towards endophytic Phaeomoniella chlamydospora without any signs of harmful interactions. Dual inoculations of foliar disks with epiphytic fungi revealed no effects of fungal interactions on necrosis development by pathogens and verified mycoparasitic interactions in planta. Co-infection assays of cuttings with endophytic pathogen fungi showed cumulative effects of fungal interactions on wood symptom expression, with the exclusive contribution of P. lycii to white rot development. In addition to providing the first isolation of P. lycii from grapevine and the description of its mycoparasitic behavior, the present study suggests that the fungus may act as an opportunistic grapevine pathogen, probably as a secondary colonizer in trunk diseases. The observed dual host preference may allow trunk disease pathogens to initially feed on fungi, followed by damage to the grapevine. This may be in connection with the exceptionally long latency of these syndromes. Full article

Water availability represents a major limiting factor for crop production, particularly in Mediterranean agroecosystems. In parallel, water-stressed plants are often more susceptible to diseases, including Grapevine Trunk Diseases (GTDs), such as Botryosphaeria Dieback caused by Botryosphaeriaceae species. In Italy, the increasing prevalence of GTDs in young table grape plants and nursery material highlights the need to better understand the interaction between abiotic stress and pathogen dissemination in woody tissues. This study investigated the relationship between different water regimes (WRs) and infections by Neofusicoccum parvum. Grapevine cuttings (Vitis vinifera ‘Italia’ vines grafted onto the rootstock ‘140 Ruggeri’) were subjected to three WRs (20%, 50%, and 100% of crop evapotranspiration, ET_c) under controlled environmental conditions and, subsequently, inoculated with mycelial plugs of N. parvum at both the scion and rootstock levels. Plant responses were monitored non-destructively using low-cost proximal sensing tools, including leaf temperature (T_leaf) and the Normalized Difference Vegetation Index (NDVI). Disease development was assessed by measuring internal necrotic lesion extension. Reduced irrigation was associated with increased disease severity, while proximal sensing detected differences in plant physiological responses among water regimes. Overall, the results highlight the interplay between water availability, plant physiological status, and disease severity under controlled conditions. Full article

Grapevine trunk diseases, particularly those caused by Neofusicoccum parvum, represent a major threat to vineyard productivity and are increasingly difficult to control with conventional fungicides. Green synthesis of silver nanoparticles (AgNPs) using biocontrol fungi offers a promising alternative, but the factors governing the efficiency and bioactivity of biogenic nanoparticles remain poorly understood. Here, three Trichoderma species (T. harzianum, T. asperellum and T. virens) were evaluated as biological nanofactories for AgNP production. Cell-free fungal filtrates were used to synthesize AgNPs, which were characterized by UV–visible spectrophotometry, Dynamic Light Scattering (DLS) and transmission electron microscopy, while fungal redox metabolism was assessed using DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging assays and HPLC profiling of extracellular metabolites. AgNPs were tested against two isolates of N. parvum in vitro. The Trichoderma strains differed markedly in nanoparticle yield, size and antifungal activity, with T. harzianum T0 producing the highest amounts of small, well-dispersed AgNPs that exerted a strong fungistatic effect on N. parvum. Nanoparticle production correlated with antioxidant capacity and the abundance of redox-active metabolites. Integration of these parameters into a Fungal Nanofactory Efficiency Index (FNEI) revealed that nanoparticle bioactivity depends on both dose and biological origin. These results demonstrate that fungal metabolism is a key determinant of biogenic nanoparticle performance and identify Trichoderma as a platform for sustainable nanotechnology-based control of grapevine trunk pathogens. Full article

Grapevine trunk diseases, particularly Botryosphaeria dieback, pose a major threat to vineyard sustainability, a risk that is further intensified by climate variability and increasing environmental stress. This study evaluated pathogenicity and bacterial biocontrol efficacy against Neofusicoccum parvum and Diplodia seriata under vineyard conditions, analyzing the combined effects of cultivar (Vitis vinifera L. cv. Cabernet Sauvignon and Sauvignon Blanc), tissue type (young shoots and lignified arms), and phenological season (autumn/winter and spring/summer). Pathogenicity assays revealed clear tissue-age specialization: N. parvum was more aggressive in young shoots, whereas D. seriata caused the most severe vascular lesions in lignified wood. Seasonality further modulated disease expression, with higher lesion development during spring/summer, particularly for N. parvum in young shoots, while D. seriata maintained high aggressiveness in lignified tissues across both seasons. Berry assays provided a rapid initial assessment of isolate virulence but did not fully reflect pathogen behavior in woody tissue under field conditions. Biological treatments using native bacterial strains (Pseudomonas sp. AMCR2b, GcR15a, and Rhodococcus sp. PU4) significantly reduced lesion severity in V. vinifera under field conditions, although efficacy varied by tissue type and season. Biocontrol effects were generally more stable in lignified arms, and under high disease pressure, only the most robust strains maintained consistent protection, in some cases matching or surpassing the efficacy of the fungicide tebuconazole. These results show that both pathogenicity and biocontrol performance against Botryosphaeria dieback in V. vinifera under field conditions are strongly influenced by tissue type and season, supporting bacterial biocontrol as a sustainable component of integrated disease management in vineyards. Full article

Esca disease, the most widespread grapevine trunk disease in Europe, is characterized by both chronic and acute forms. In both cases, alterations in the plant’s physiological processes are significant and lead to yield losses and/or plant death. Studies have highlighted the effects of a mixture of foliar fertilizers and seaweeds in reducing foliar symptoms and improving both the quantity and quality of yield. These effects have now been evaluated on additional cultivars and in other vineyard areas. Furthermore, for the first time, the activity of the fertilizer mixture in reducing apoplexy and the resulting vine mortality has been assessed. During the 2022–2023 biennium, in four vineyards of the Lambrusco cultivar in the Province of Reggio Emilia, Northern Italy, affected by both chronic and acute forms of the disease, foliar applications of the mixture were carried out at 10-day intervals starting from the “nine leaves unfolded” BBCH (Biologische Bundesanstalt, Bundessortenamt and Chemical industry) stage 19 up to the “berries developing color” BBCH stage 83. The results confirmed the activity of the fertilizer mixture in reducing chronic symptoms, which appeared particularly pronounced in 2022, when rainfall quantity and distribution allowed regular development of phenological stages. In that year, in all vineyards, a reduction of approximately 50% and 60% in the incidence and severity of chronic leaf symptoms was recorded. Under these optimal growth conditions, treated vines generally showed superior yield and quality. Conversely, in 2023, characterized by heavy rains, smaller effects on foliar symptoms and no improvements in yield were observed. Applications of the mixture resulted in a significant reduction in apoplexy and, consequently, vine mortality, as verified in 2024. This effect did not appear to be influenced by climatic conditions. This study confirms that applications of the mixture aimed at reducing symptom expression and yield damage are a valid addition to the few available control practices. The positive effects observed on the acute form for the first time require further investigation. Full article

This study analyzed the microbiome of three varieties differing in genotype and technical purpose: Cristal, Riesling, and Avgustin, all exhibiting decline symptoms of unknown etiology. A total of 92 symptomatic and asymptomatic grapevines were analyzed using ITS and 16S rRNA amplicon sequencing and molecular genetic methods. Phytoplasmas and the pathogenic bacteria Xylella fastidiosa and Xylophilus ampelinus were not present in the samples. The decline symptoms were associated with a cocktail of fungal pathogens that cause grapevine trunk diseases. In particular, the analysis revealed the causative agents of Botryosphaeria dieback (Sphaeropsis spp. and Botryosphaeria spp.), fungi associated with the Esca complex (Phaeomoniella spp., Phaeoacremonium spp., Inonotus spp., Seimatosporium spp., Stereum spp., and Cadophora spp.), and the causative agents of Phomopsis dieback (Diaporthe spp.). The symptoms of decline may be increased by several facultative grapevine pathogens that have been identified in microbiome (genera Stemphylium, Alternaria, Aspergillus, Penicillium, Talaromyces, and Fusarium). The metagenomic data of the grapevine microbiome provides opportunities for developing disease control strategies, which is important for the sustainable management of vineyards. Full article

Rootstock mother fields supply the cuttings used in the grafted grapevine propagation process, and their productivity is essential for the nursery production. In southern Europe, mother fields are usually managed with a ground-level pruning system, which provides high yields but increases sanitary and management risks. Dense canopies favour humid microclimates and large pruning wounds increase the incidence of trunk diseases. Trellis systems have been proposed as alternatives to mitigate these risks, but their productive performance remains unclear. The aim of this study was to evaluate the vegetative growth of three vertical trellis systems: elevated crown, alternate crown, and vertical axis, in two rootstock mother fields, and to compare their cutting productivity with that of the traditional ground-level system once the trellis vines were fully established. The trial was conducted from 2022 to 2024 in a commercial rootstock mother field in Soria, Spain, using two Vitis berlandieri × V. rupestris hybrids (110 Richter and 140 Ruggeri). The experimental design consisted of three trellis systems arranged in four replicates of 12 vines each, following a randomised block design. Pruning weight increased significantly with vine age but was unaffected by trellis system. Cutting yield differed between rootstocks, with 140 Ruggeri producing about twice as many cuttings as 110 Richter. The comparison between trellis and ground-level systems showed that the former increased labour requirements and reduced cutting yields. Although trellis systems challenge their adoption for commercial rootstock propagation under the dry-summer conditions of this study, their potential to reduce fungal disease incidence and improve canopy management may offer advantages in a transition towards a more sustainable nursery process. Full article

The genus Diaporthe consists of saprobes, endophytes, and important plant pathogens. Members of this genus are widely distributed and have a broad host range, including grapevines. This study aimed to establish a baseline survey to assess the diversity of Diaporthe species infecting propagation material and to explore their dynamics in disease development. Initially, a survey was conducted in a nursery field, and isolations were carried out from 2-month-old symptomatic grafted vines of cv. Agiorgitiko grafted onto rootstock Richter 110. The initial molecular identification of the isolated mycobiome at the genus level was carried out by sequencing the universal internal transcribed spacer (ITS) locus, while subsequent species-level identification of the Diaporthe isolates was performed through phylogenetic approaches coupled with morphological characterization. Based on the combined analysis, five phylogenetically distinct Diaporthe spp. were identified in this study, taxonomically assigned to D. ampelina, D. eres, D. foeniculina, D. serafiniae, and D. novem. Pathogenicity trials demonstrated that the most aggressive species were D. ampelina followed by D. eres, while the remaining species were classified as opportunistic or weak pathogens of grapevine. Overall, accurate identification and monitoring of Diaporthe species involved in propagation material infections are important in order to develop species-specific effective management strategies in grapevine nurseries. Full article

The grapevine microbiome is shaped by a complex interplay of biotic and abiotic factors, affecting microbial community structure and plant health. This study investigates the diversity, composition, and dynamics of fungal communities associated with grapevine (Vitis vinifera) and neighboring cultivated plants, as well as plants from semi-natural vegetation, including pear (Pyrus communis), apricot (Prunus armeniaca), dogrose (Rosa canina), and blackthorn (Prunus spinosa), in a landscape-level habitat matrix. Using metabarcoding techniques, fungal communities from leaves and woody tissues of grapevine and neighboring plants were analyzed over a growing season. Fungal richness and abundance differed significantly among host plants, with woody tissues exhibiting higher diversity. Host plant identity was the primary factor shaping wood-associated fungal communities (15.7% of explained variance), whereas sampling time dominated in leaves (16.3%), with sampling site having a weaker effect in both cases. Pathogenic fungi associated with grapevine trunk diseases, such as Diaporthe, Eutypa, and Phaeomoniella, were identified across grapevine and neighboring plants, suggesting that multiple hosts may act as reservoirs for fungal inoculum. These findings highlight the complex interactions between fungal communities, host plants, and environmental factors, underscoring the need for landscape-level approaches to plant protection that account for both cultivated and surrounding ecosystems. Full article

Fungi of the genus Trichoderma show strong potential as biological control agents (BCAs) against grapevine trunk diseases (GTDs) through mechanisms like antibiotic metabolite production and lytic enzymes. This study evaluated the biocontrol activity of four native Trichoderma strains—T. gamsii T065 and T071, T. carraovejensis T154, and T. harzianum T214—against Phaeoacremonium minimum, Phaeomoniella chlamydospora, and Diplodia seriata. Culture filtrates obtained at 8, 16, and 24 days post-incubation were tested using antibiogram and mycelial inhibition assays. Strains T071, T154, and T214 effectively inhibited D. seriata, while T154 and T214 also suppressed P. chlamydospora. Nevertheless, the limited effectiveness of all filtrates against P. minimum suggests that antibiosis is not the predominant mechanism involved in its control. These findings highlight the potential of specific Trichoderma strains and incubation times to directly control GTD pathogens and support the development of scalable biocontrol solutions. Full article

Innovative applications of high-resolution airborne imaging are explored for detecting grapevine diseases. Driven by the motivation to enhance early disease detection, the method’s effectiveness lies in its capacity to identify isolated cases of grapevine yellows (Flavescence dorée and Bois Noir) and trunk disease (Esca complex), crucial for preventing the disease from spreading to unaffected areas. Conducted over a 17 ha vineyard in the Forlì municipality in Emilia-Romagna (Italy), the aerial survey utilized a photogrammetric camera capturing centimeter-level resolution images of the whole area in 17 minutes. These images were then processed through an automated analysis leveraging RGB-based spectral indices (Green–Red Vegetation Index—GRVI, Green–Blue Vegetation Index—GBVI, and Blue–Red Vegetation Index—BRVI). The analysis scanned the 1.24 · 10⁹ pixels of the orthomosaic, detecting 0.4% of the vineyard area showing evidence of disease. The instances, density, and incidence maps provide insights into symptoms’ spatial distribution and facilitate precise interventions. High specificity (0.96) and good sensitivity (0.56) emerged from the ground field observation campaign. Statistical analysis revealed a significant edge effect in symptom distribution, with higher disease occurrence near vineyard borders. This pattern, confirmed by spatial autocorrelation and non-parametric tests, likely reflects increased vector activity and environmental stress at the vineyard margins. The presented pilot study not only provides a reliable detection tool for grapevine diseases but also lays the groundwork for an early warning system that, if extended to larger areas, could offer a valuable system to guide on-the-ground monitoring and facilitate strategic decision-making by the authorities. Full article

Among grapevine trunk diseases, Eutypa dieback, caused by the fungus Eutypa lata, is one of the most critical ones, due to its widespread infection in vineyards and the lack of effective treatments. This fungus is a vascular pathogen that enters grapevines through pruning wounds. The infection process is associated with phytotoxic metabolites produced by the fungus, and as such, the identification of new metabolites from different culture conditions and broths could provide valuable insights into the fungus’s enzymatic system and help its control. For the purposes of this study, the OSMAC (one strain, many compounds) approach was applied to investigate the secondary metabolism of E. lata strain 311 isolated from Vitis vinifera plants in Spain. A total of twenty metabolites were isolated, including five reported for the first time from E. lata and four that are newly identified compounds in the literature: eulatagalactoside A, (R)-2-(4′-hydroxy-3′-methylbut-1′-yn-1′-yl)-4-(hydroxymethyl)phenol, (S)-7-hydroxymethyl-3-methyl-2,3-dihydro-1-benzoxepin-3-ol, and (3aR,4S,5R,7aS)-4,5-dihydroxy-6-((R)-3′-methylbuta-1′,3′-dien-1′-ylidene)hexahydrobenzo[d][1,3]dioxol-2-one. These compounds were extracted from fermentation broths using silica gel column chromatography and high-performance liquid chromatography (HPLC). Their structures were elucidated through extensive 1D and 2D NMR spectroscopy, along with high-resolution electrospray ionization mass spectrometry (HRESIMS). Compounds were evaluated for phytotoxicity against Phaseolus vulgaris, with only eulatagalactoside A producing white spots after 48 h. Additionally, the antibacterial activity against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae of selected compounds was tested. The compounds (R)-2-(4′-hydroxy-3′-methylbut-1′-yn-1′-yl)-4-(hydroxymethyl)phenol and (S)-7-(hydroxymethyl)-3-methyl-2,3-dihydrobenzo[b]oxepin-3-ol showed the most significant antimicrobial activity against Gram-positive bacteria, inhibiting S. aureus by over 75%, with IC₅₀ values of 511.4 µg/mL and 617.9 µg/mL, respectively. Full article

Grapevine trunk diseases (GTDs) are widespread worldwide, causing serious economic losses to the vitiviniculture industry. The etiology of the complex pathogenic mycobiome associated with this group of diseases is critical to implementing appropriate management strategies. Diseased grapevines exhibiting typical GTD symptoms were collected from vineyards in different provinces of Cyprus, resulting in 19 pycnidial isolates. A subsequent multilocus sequence analysis of six genetic loci (ITS, LSU, SSU, b-tub, tef1-a, and rpb2) identified them as Kalmusia variispora, and twelve representative isolates are included in the phylogenetic analyses. According to pathogenicity trials on two-year-old potted vines (cv. Mavro), all tested isolates were pathogenic, exhibiting light to dark brown discoloration and lesions of varying levels, ranging from 4 to 12.3 cm long. The capacity of K. variispora isolates to produce cell-wall-degrading exoenzymes was qualitatively estimated on solid media. Cellulase, pectinase, and laccase production were evident for all the tested isolates, except isolate CBS 151329, where the latter enzyme was undetected. The severity of the symptoms was consistent with the laccase-producing capacity. The present study confirmed the association of K. variispora with grapevines as a pathogen and represents the first description of this ascomycete as a GTD causal agent in Cyprus. This highly virulent species may play a significant role in the GTD complex, and its biological cycle and epidemiology should be further investigated. Full article

Vegetative propagation of European grapevine (Vitis vinifera L.) requires grafting onto American rootstocks due to susceptibility to phylloxera. However, the grafting yield is compromised by the presence of grapevine trunk diseases (GTDs) such as Esca. This study investigates the phenolic response and enzyme activity in grapevine callus from grafts obtained by scions with different GTD status (healthy, asymptomatic, and symptomatic) treated with different disinfection methods (Beltanol, Beltanol in combination with thermotherapy, Serenade^® ASO, Remedier, BioAction ES, and sodium bicarbonate). Twenty-three phenolic compounds were identified in the graft callus, with flavanols, stilbenes, and condensed tannins predominating. Scion disinfection with BioAction ES led to a significant increase in total phenolic content in the callus, especially in symptomatic scions, for on average 510.3 µg/g fresh weight (FW) higher total phenolic content, compared to grafts where scions were treated with Beltanol. Phenolics such as epicatechin gallate, procyanidin derivatives, and resveratrol hexoside were significantly increased, indicating a strong elicitor effect of BioAction ES. Enzymatic activity analysis showed that the disinfection methods affected the activity of key enzymes involved in the phenylpropanoid metabolic pathway. In particular, BioAction ES significantly increased phenylalanine ammonia lyase (PAL) activity in callus from grafts with healthy scions by 3.4-fold and flavanone 3β-hydroxylase (FHT) activity in callus from grafts with infected scions by 4.9-fold (asymptomatic) and 6.9-fold (symptomatic) compared to callus from grafts with Beltanol-treated scions. The results highlight the potential of environmentally friendly disinfection methods, particularly BioAction ES, in influencing phenolic content and enzymatic activity in graft callus, potentially affecting the success of grapevine grafting. Full article

Botryosphaeria dieback, a significant grapevine trunk disease (GTD) caused by various pathogens, represents a serious threat to viticulture. Biocontrol emerges as a promising sustainable alternative to chemical control, aligning toward environmentally friendly viticultural practices. This study evaluated the in vitro, in vivo, and in situ biocontrol potential of Chilean native bacteria isolated from wild flora and endophytic communities of grapevine against Neofusicoccum parvum. In vitro biocontrol assays screened 15 bacterial strains at 10, 22, and 30 °C, identifying four Pseudomonas strains with >30% mycelial growth inhibition. In diffusible agar and double plate assays, plant growth-promoting bacteria AMCR2b and GcR15a, which were isolated from native flora, achieved significant inhibition of N. parvum growth, with reductions of up to ~50% (diffusible agar) and up to ~46% (double plate). In vivo experiments on grapevine cuttings revealed that strains AMCR2b and GcR15a inhibited mycelial growth (17–90%); younger grapevines (1–5 years) were more susceptible to N. parvum. In situ trials using Vitis vinifera L. cv. Cabernet Sauvignon and Sauvignon Blanc demonstrated higher fungal susceptibility in Sauvignon Blanc. These results highlight the potential of Pseudomonas sp. AMCR2b and GcR15a to be effective biocontrol agents against GTDs at a wide range of temperatures, contributing to sustainable viticulture. Full article