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A field experiment was conducted between mid-August 2016 and mid-October 2017 in four table-grape vineyards in the Siriji Valley, Pernambuco State (Northeastern Brazil), to study the conidial dispersal dynamics of Botryosphaeriaceae fungi, causing grapevine trunk diseases (GTDs). Conidial dispersal was assessed by exposing microscope slides coated with Vaseline close to symptomatic plants and pruning debris. The slides were replaced every 2 weeks for a total of 30 sampling periods. Conidia of the genera Diplodia, Lasiodiplodia and Neofusicoccum were enumerated based on morphological characters. Conidia were collected from all four table-grape vineyards, confirming that these fungi are present as aerial inoculum and could be associated with GTDs in the region. Conidia of Diplodia and Lasiodiplodia were present in all the sampling periods, and those of Lasiodiplodia were the most abundant. Conidia of Neofusicoccum were found less frequently, and in less numbers than the other genera. Significant correlation between the number of conidia sampled and the amount of rain was observed for Diplodia only. Greater numbers of conidia were collected from pruning debris than from symptomatic plants. For Diplodia and Lasiodiplodia, the numbers of conidia gradually increased in September, increased sharply between March and June, and then decreased. These dynamics were described by a logistic equation, with hydro-thermal time (i.e., a combination of degree-days and relative humidity) as the independent variable (R2 > 0.998). [ABSTRACT FROM AUTHOR]

Black foot disease (BFD) and crown and root rot (CRR) are important soilborne diseases that affect young grapevines in nurseries and vineyards. A 3-year survey (2013-2015) of five open-field grapevine nurseries was conducted in the Western Cape Province of South Africa. The survey involved the isolation of BFD and CRR pathogens from grafted rootstocks (ten plants per nursery, per year) that were rooted in soil for 1 year. In 2013 and 2015, grapevines were sampled, while in 2014, sampling was focused on rotation crops and weeds (ten plants each). The rotation crops included white mustard, lupins, canola, triticale and forage radish. The weed species sampled included Johnson grass, ryegrass, winter grass, Cape marigold and corn spurry. Soil samples from ten sites per nursery were also collected in close proximity to the sampled plants, at depths of 0-30 cm and 30-60 cm (ten samples per depth). Isolations were made from the grapevines, rotation crops and weeds. Pathogen detection and quantification in the soil were determined using quantitative real-time polymerase chain reaction technology. The predominant BFD pathogens isolated from grapevines were Campylocarpon fasciculare, Ca. pseudofasciculare and Dactylonectria macrodidyma. The predominant CRR pathogens were Pythium irregulare and Phytopythium vexans. Dactylonectria macrodidyma, D. novozelandica, D. pauciseptata, Py. irregulare, Py. ultimum var. ultimum and Py. heterothallicum were isolated from triticale roots. Dactylonectria spp. were also isolated from corn spurry, while Py. irregulare and Py. ultimum var. ultimum were isolated from numerous weeds and rotation crops. Mean soil DNA concentrations of Ilyonectria and Dactylonectria were from 0.04 to 37.14 pg μL-1, and for Py. irregulare were between 0.01 and 3.77 pg μL-1. The Phytophthora mean soil DNA concentrations ranged from 0.01 to 33.48 pg μL-1. The qPCR protocols successfully detected and quantified BFD and CRR pathogens in grapevine nursery soil. This is the first report of D. pauciseptata and D. alcacerensis in South African grapevine nurseries. [ABSTRACT FROM AUTHOR]

Nineteen species of Phaeoacremonium have been associated with grapevines in South Africa, of which only six species have been confirmed as pathogens through pathogenicity tests conducted on field-grown grapevines. This study determined the pathogenic status of ten Phaeoacremonium spp. recently found for the first time on South African grapevines. These were: Pm. australiense, Pm. austroafricanum, Pm. fraxinopennsylvanicum, Pm. griseo-olivaceum, Pm. griseorubrum, Pm. iranianum, Pm. italicum, Pm. prunicolum, Pm. scolyti and Pm. sicilianum. In the pathogenicity tests, Ph. parasiticum was used as the positive control, and sterile water as the negative control. Up to three isolates were used per species, depending on isolate availability. Freshly cut pruning wounds in a 9-yearold Cabernet Sauvignon vineyard in Stellenbosch, South Africa, were inoculated with 200 conidia of each fungus per wound. Inoculated pruning wounds were removed after 18 months, cut longitudinally and lesion lengths were measured. Re-isolation proportions were determined by conducting isolations from inoculated spurs. All the inoculated isolates successfully colonized pruning wounds, and caused lesions that were significantly different from the negative control. All isolates were re-isolated at proportions varying from 28.6 to 85.7%. Phaeoacremonium griseo-olivaceum STE-U 7859 produced the longest lesions (mean = 79.5 mm) and Pm. iranianum STE-U 6998 the shortest (62.0 mm). No statistically significant differences in mean lesion lengths were observed between the inoculated species. There were also no significant differences between isolates of the same species, except in Pm. prunicolum where isolate STE-U 5968 produced longer lesions (mean = 77.3 mm) than STE-U 7857 (62.3 mm). This study confirmed the capabilities of all the tested Phaeoacremonium spp. to infect grapevine pruning wounds and cause lesions. The study also confirmed the importance of pruning wounds as ports of entry by these pathogens into host plants. [ABSTRACT FROM AUTHOR]

Two vineyards in the Abruzzo Region, central Italy, affected by grapevine leaf stripe disease (GLSD), were monitored for incidence and severity of foliar symptoms of the disease for 21 consecutive years (1994 to 2014). Each year, rainfall and temperature were recorded. Correlations between symptom incidence or severity and rainfall or temperature of different periods of the year or single months were assessed. July rainfall and temperature were highly correlated with incidence and severity of leaf symptoms. The vineyards were characterized by high longevity, vigour and yields, and a particular dynamic of GLSD. In the period following 2005, the year of peak vine mortality, there was a decrease of the expression of foliar symptoms, which was not correlated with both of the climate parameters. Greater mortality occurred for vines showing severe symptoms at the first appearance of GLSD than for vines with low severity. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases (GTD) are one of the most important constraints for grapevine and wine production worldwide. Most of the published studies on these diseases in Europe relate to the major vine growing regions mainly located in southern Europe. This is the first study of GTD incidence and associated fungal pathogens in Czech vineyards, as an example of the north-eastern European grape-growing region. Annual incidence of GTD symptoms in vineyards of cvs. 'Chardonnay' and 'Cabernet Sauvignon' in three Czech locations was surveyed. On average, 3.7% of the 'Chardonnay' plants showed GTD symptoms and 0.7% suddenly collapsed each year. Within the 'Cabernet Sauvignon' vineyards, 10.1% of the plants showed GTD symptoms and 2.5% suddenly collapsed. Several fungal pathogens were associated with the suddenly collapsed grapevines, and the most frequent was Phaeomoniella chlamydospora (77% of analyzed grapevines), followed by Eutypa lata (62%), Diaporthe ampelina (31%), Botryosphaeria dothidea (15%) and Fomitiporia mediterranea (15%). [ABSTRACT FROM AUTHOR]

Grapevine leaf stripe disease (GLSD) is the most important syndrome of the esca disease complex. GLSD foliar symptoms are associated with grapevine yield losses and decline in vigour of host plants. Relationship between incidence and severity of GLSD symptoms and reductions grape quantity and quality has been demonstrated. In 2010-2012, foliar applications of mixtures of fertilizers based on calcium, magnesium and seaweed reduced symptom expression and increased yield quantity and quality. In the present study, mixture applications were carried out in 2013-2015 in different vineyards located in Abruzzo and Emilia-Romagna Regions (north-central Italy). These treatments reduced GLSD symptom incidence and severity, and applications of seaweed without calcium and magnesium was not effective. This confirmed involvement of the nutrients in the reduction of leaf symptom expression. Mechanical properties and absorbance difference measurements demonstrated increased berry quality from vines treated with the mixture. In trials carried out in 2015, the efficacy of the mixture applied in tank mix with other pest and disease control products was not reduced. We conclude that applications of calcium, magnesium and seaweed mixtures are effective for reducing the impacts of GLSD in vineyards. [ABSTRACT FROM AUTHOR]

The pathogens Phaeomoniella chlamydospora and Phaeoacremonium minimum are associated with different syndromes of the esca disease complex affecting grapevine propagation material, and young and adult plants. Infections by these fungi occur in grapevine nurseries and in vineyards, with disease control strategies providing limited protection in both cases. Several chemicals are effective in vitro against these two pathogens, but treatment of infected plants, especially endotherapy, has not yet proven satisfactory. Five chemicals (elemental silver, fosetyl- Al, glutaraldehyde, hydrogen peroxide and Blad-containing oligomer) were tested in vitro, with the first four also tested in planta, by means of endotherapy, against Pa. chlamydospora and Pm. minimum. All chemicals were effective in vitro for preventing growth of both pathogens, at different concentrations. Endotherapy of rooted grapevine cuttings (cv. Touriga Nacional) was effective against Pa. chlamydospora for all the tested chemicals, with reductions in the frequency of re-isolation of this pathogen of 91-95% (glutaraldehyde), 68-96% (hydrogen peroxide), 68-77% (elemental silver) and 58-59% (fosetyl-Al) when compared with the water-treated experimental controls. The only treatment that was effective against Pm. minimum was glutaraldehyde, providing a 75-83% reduction in re-isolation frequency. These results indicate that endotherapy of young grapevines during early stages of infection may be an effective control strategy, especially against the wood pathogen Pa. chlamydospora. [ABSTRACT FROM AUTHOR]

Grapevine Trunk Diseases (GTDs), particularly esca, are major concerns in Spain. This study characterized the fungal and bacterial communities in a 30-year-old ‘Cabernet Sauvignon' vineyard in Catalonia, Spain. Six symptomatic vines expressing esca-foliar symptoms and six additional asymptomatic plants were surveyed. Non-necrotic and necrotic tissues were sampled from rootstocks, trunks and cordons of the selected vines. Fungal isolations and molecular techniques were used in combination to investigate the endophytic microflora and to characterize the fungal and bacterial diversity of the vines. Pathogenic fungi involved in GTDs were identified, and the associations were assessed between all the isolated fungal taxa and the health status of vines, host parts and tissue types. Phaeomoniella chlamydospora and Diplodia seriata were found in non-necrotic tissues, whereas Fomitiporia mediterranea was mainly found in soft-rot tissues, and Neofusicoccum parvum and Eutypa cf. lata in hard necrotic tissues. Several Alternaria and Trichoderma species were isolated, mainly from non-necrotic tissues. The single strand conformation polymorphism fingerprinting method showed differences in bacterial and fungal communities between the different types of tissue in healthy and diseased vines. However, no differences were detected in these microbial communities between non-necrotic tissues from asymptomatic and symptomatic vines. Two frequently-isolated species of Paraconiothyrium were tested for pathogenicity, but their pathogenic roles on grapevines was unclear. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases (GTDs) are one of the most important groups of fungal diseases affecting grapevine plants worldwide. One of the main causes of GTDs infection occur during nursery plant production processes. The phytosanitary status was determined for 150 young grapevine plants (two varieties grafted onto different rootstocks) that were produced in three European nurseries. Some plants were analyzed upon submission, while others were assessed after up to 12 months growth in a greenhouse. Fungal species associated with GTDs were identified and characterized from the scions, graft unions, rootstocks, or roots. A total of 449 fungal isolates associated with GTDs were obtained, and 20 species were identified by morphological characteristics and DNA analyses. Five species were involved in Botryosphaeria dieback, six in black foot disease, six in Diaporthe dieback, and three in Petri disease. Incidence of GTDs on grapevine plants was between 81 and 100%, with different diseases varying between rootstocks and grapevine varieties. Isolates of other fungal genera not involved in the GTD complex were also detected, including Colletotrichum, Fusarium, and Rhizoctonia. The high presence of GTDs during nursery production of grapevine plants raises the need to implement effective control methods that could prevent the spread of these diseases to vineyards. [ABSTRACT FROM AUTHOR]

Since the early 1990s, grapevine trunk diseases (GTDs) have posed threats for viticulture. Esca complex, Eutypa- and Botryosphaeria- diebacks, mostly detected in adult vineyards, are currently responsible for considerable economic losses in the main vine-growing areas of the world. Other GTDs, such as Petri- (Esca complex) and Black-foot diseases, are emerging problems in grapevine nurseries (resulting in grafting failures and/or loss of saleable plants) and in young vineyards. The impacts of GTDs in modern viticulture depend on several factors, some related to their complexity, and others linked to host plant characteristics, changes in vineyard management and to the scarcity of simple tools for their control. For these reasons control of GTDs remains difficult, also depending on knowledge transfer from research to field and vice versa. This paper outlines the main preventive and curative techniques currently applied, scientifically tested or not that have resulted from the outcomes of "Winetwork", a European Union funded project with special emphasis on the promising and innovative approaches. [ABSTRACT FROM AUTHOR]

Sour rot, a disease affecting berries of cultivated Vitis spp. worldwide, has not been clearly defined. Reported symptoms of the disease include browning of the berry skin, oozing of disintegrated berry pulp, and the smell of acetic acid, all in the presence of fruit flies (Drosophila spp.). We determined acetic acid concentrations in multiple collections of symptomatic berries, isolated and identified microbes from them, and inoculated commonly isolated organisms into healthy berries with and without concurrent exposure to wild-type or axenic Drosophila melanogaster. Coinoculations combining one of several yeasts (Metschnikowia spp., Pichia spp., and a Saccharomyces sp.) plus an acetic acid bacterium (an Acetobacter sp. and Gluconobacter spp.) reproduced sour rot symptoms, defined here as decaying berries with a loss of turgor and containing acetic acid at a minimum of 0.83 g/liter, based on observed field levels. Symptoms developed only in the presence of D. melanogaster, either wild type or axenic, indicating a nonmicrobial contribution of these insects in addition to a previously suggested microbial role. We conclude that sour rot is the culmination of coinfection by various yeasts, which convert grape sugars to ethanol, and bacteria that oxidize the ethanol to acetic acid, and that this process is mediated by Drosophila spp. [ABSTRACT FROM AUTHOR]

The distribution and diversity of grapevine red blotch virus (GRBV) and wild Vitis virus 1 (WVV1) (genus Grablovirus; family Geminiviridae) were determined in free-living Vitis spp. in northern California and New York from 2013 to 2017. Grabloviruses were detected by polymerase chain reaction in 28% (57 of 203) of samples from California but in none of the 163 samples from New York. The incidence of GRBV in free-living vines was significantly higher in samples from California counties with high compared with low grape production (χ² = 83.09; P < 0.001), and in samples near (<5 km) to compared with far (>5 km) from vineyards (χ² = 57.58; P < 0.001). These results suggested a directional spread of GRBV inoculum predominantly from vineyards to freeliving Vitis spp. WVV1 incidence was also significantly higher in areas with higher grape production acreage (y2 = 16.02; P < 0.001). However, in contrast to GRBV, no differential distribution of WVV1 incidence was observed with regard to distance from vineyards (χ² = 0.88; P = 0.3513). Two distinct phylogenetic clades were identified for both GRBV and WVV I isolates from free-living Vitis spp., although the nucleotide sequence variability of the genomic diversity fragment was higher for WWV1 (94.3 to 99.8% sequence identity within clade 1 isolates and 90.1 to 100% within clade 2 isolates) than GRBV (98.3% between clade 1 isolates and 96.9 to 100% within clade 2 isolates). Additionally, evidence for intraspecific recombination events was found in WVV 1 isolates and confirmed in GRBV isolates. The prevalence of grabloviruses in California free-living vines highlights the need for vigilance regarding potential grablovirus inoculum sources in order to protect new vineyard plantings and foundation stock vineyards in California. [ABSTRACT FROM AUTHOR]

Grapevine red blotch virus (GRBV) is the causal agent of grapevine red blotch, an emerging disease that affects cultivated grapevine such as Vitis vinifera. The ability to detect viruses in grapevine is often hindered by low virus titers compounded by a variable distribution in the plant and seasonal variations. In order to examine these two variables in relation to GRBV, we developed a quantitative polymerase chain reaction (qPCR) method that incorporates both internal and external references to enhance assay robustness. In greenhouse-grown vines infected with GRBV, qPCR identified highest virus titers in the petioles of fully expanded leaves and significantly reduced levels of virus in the shoot extremities. In vineyard-grown vines infected with GRBV, the virus titer in July and October 2016 followed a pattern similar to that found for the greenhouse-grown plants but, most strikingly, close to half (44%) of the samples analyzed in June 2015 tested negative for infection. The technique presented and results obtained highlight the variability of virus distribution in its host and provide a useful guide for selecting the best tissues for optimal GRBV diagnosis. [ABSTRACT FROM AUTHOR]

Vineyard surveys were conducted for three consecutive seasons in eastem Washington State, the major grapevine-growing region in the state, to document the occurrence of Grapevine leafroll-associated virus 3 (GLRaV-3) and Grapevine red blotch virus (GRBV). The majority of samples were collected from red-berried wine grape (Vitis vinifera) cultivars exhibiting symptoms of or suspected for grapevine leafroll (GLD) and red blotch (GRBD) diseases. A limited number of samples from white-berried cultivars were collected randomly due to the lack of visual symptoms. Samples were collected from a total of 2.063 grapevines from 18 red-berried cultivars and seven white-berried cultivars planted in eight American Viticultural Areas and tested for GLRaV-3 and GRBV using RT-PCR and PCR, respectively. The results showed 67.77% and 6.01% of total samples positive for GLRaV-3 and GRBV, respectively, and 9.06% of samples positive for both viruses. About 17% of samples tested negative for the two viruses, but some of these samples were positive for GLRaV-2 and GLRaV-4. Overall results indicated that GLRaV-3 was more common than GRBV, independent of cultivars and the geographic origin of samples. Due to variability in symptoms in redberried cultivars, virus-specific diagnostic assays were deemed necessary for reliable identification of GLRaV-3 and GRBV and to differentiate GLD and GRBD symptoms from those induced by biotic and abiotic stresses in vineyards. A multiplex PCR protocol was developed for simultaneous detection of GLRaV-3 and GRBV in grapevine samples. A global phylogenetic analysis of GRBV genome sequences revealed segregation of virus isolates from Washington State vineyards into two distinct clades, with the majority of isolates belonging to clade II. [ABSTRACT FROM AUTHOR]

Grapevine yellows diseases occur in cultivated grapevine (Vitis vinifera L.) on several continents, where the diseases are known by different names depending upon the identities of the causal phytoplasmas. In this study, phytoplasma strains associated with grapevine yellows disease (North American grapevine yellows [NAGY]) in vineyards of Pennsylvania were characterized as belonging to 16S ribosomal RNA (rRNA) gene restriction fragment length polymorphism group l6Srl (aster yellows phytoplasma group), subgroup I6S1I-B (l-B), and variant subgroup l-B*. The strains (NAGYI strains) were subjected to genotyping based on analyses of 16S rRNA and secY genes, and to in silico three-dimensional modeling of the SecY protein. Although the NAGYI strains are closely related to aster yellows (AY) phytoplasma strains and are classified like AY strains in subgroup I-B or in variant subgroup I-B*, the results from genotyping and protein modeling may signal ongoing evolutionary divergence of NAGYI strains from related strains in subgroup 16Srl-B. [ABSTRACT FROM AUTHOR]

Botryosphaeria dieback, caused by species of Botryosphaeriaceae, is an important grapevine trunk disease in Australia. Inocula produced by the pathogens are primarily dispersed by rain splash and wind and infect pruning wounds leading to cankers, dieback. and eventually death of vines. The objective of this study was to develop molecular tools to detect and quantify Botryosphaeriaceae inocula from the environment. These tools are essential for investigating spore dispersal patterns of Botiyosphaeriaceae pathogens in Australian vineyards. DNA extraction protocols were evaluated and one modified protocol was found suitable for extracting Botiyosphaeriaceae DNA from artificially and naturally inoculated Burkard volumetric spore sampler tapes. Multispecies primers and a hydrolysis probe for quantitative PCR (qPCR) were further developed to detect and quantify Botryosphaeriaceae inocula from environmental samples. Specificity tests showed that the multispecies primers were able to amplify the DNA of 10 Botiyosphaeriaceae species (58 isolates) found in Australia while none of the 27 nontarget fungal species (90 isolates) tested were amplified. The qPCR assay was suitable for amplifying purified DNA, synthetic DNA fragments (gBlocks). and mixed DNA from spore trap tapes. The qPCR method developed in this study was shown to be rapid and sensitive in detecting Botryosphaeriaceae inocula from the environment using spore traps. [ABSTRACT FROM AUTHOR]

The soil-borne nepovirus Grapevine fanleaf virus (GFLV), causal agent of grapevine fanleaf degeneration disease, spreads mainly via the nematode vector Xiphinema index . Since the arbuscular mycorrhizal (AM) fungus Rhizophagus intraradices can induce local and systemic protection against X. index (Hao et al., 2012), therefore, the objective of the present study was to investigate if AM may represent a means for limiting GFLV infection by reducing nematode vector attack. Three-week-old mycorrhizal or nonmycorrhizal grapevine rootstock SO4 ( Vitis berlandieri  ×  V. riparia ) plants were inoculated with 10 or 100 viruliferous nematodes per plant under glasshouse conditions. Plants were harvested 35 and 90 days after inoculation with X. index (DAIN), prior to and after the appearance of fanleaf degeneration symptoms, respectively. Both levels of viruliferous X. index inhibited root growth of nonmycorrhizal plants at 90 DAIN, while the presence of arbuscular mycorrhizal colonization significantly decreased gall formation on roots at both time points and reduced nematode reproduction in soil at 90 DAIN. GFLV was not detected by one-step reverse transcription PCR in the roots of any plant at 35 DAIN after viruliferous X. index inoculation. At 90 DAIN with 10 viruliferous nematodes per plant, the virus was present in nonmycorrhizal roots but absent from mycorrhizal grapevine. The virus was detected in both mycorrhizal and nonmycorrhizal plants 90 DAIN. It is suggested that inhibition of X. index proliferation and penetration by AM may protect grapevine against GFLV at a low abundance of the viruliferous nematode in soils and so contribute to virus control under these conditions. [ABSTRACT FROM AUTHOR]

Bois noir (BN), caused by 'Candidatus Phytoplasma solani', is a serious disease of grapevines in Europe. During the 2010-2012 survey in Perná vineyard (South Moravia, Czech Republic) a total of 4854 insect individuals were collected and among these, 95 insect species belonging to Auchenorrhyncha (77 species), Heteroptera (12), and Psylloidea (62) were indentified. The nested polymerase chain reaction-restriction fragment length polymorphism analyses confirmed Hyalesthes obsoletus as the main BN vector with 43.8% of phytoplasma positive individuals on average. A significant role of Anaceratagallia ribauti (22.6% of phytoplasma positive specimens) should be taken into account based on its occurrence and incidence of infected individuals. Eleven insect species were identified as new carriers of 'Ca. P. solani' or suggested as potential BN vectors in this work. [ABSTRACT FROM AUTHOR]

Aster yellows phytoplasma (AY), only recently reported in South Africa and still limited in its distribution in the country, causes a serious disease of grapevine. A leafhopper, Mgenia fuscovaria (Stål)(Hemiptera: Cicadellidae), was shown to transmit AY to grapevine (Vitis vinifera L.) locally. A second Mgenia species, identified as Mgenia angusta (Theron), has also been found in vineyards in South Africa but has not been shown to transmit AY. M. angusta is morphologically similar to M. fuscovaria, but does differ regarding the size of the male sex organ and in the number of teeth of the blades making up the ovipositor. In this study, we determined the nucleotide sequence of the mitochondrial cytochrome oxidase I gene (cox1), commonly used in insect bar-coding, of a number of specimens of males, females and nymphs of both M. fuscovaria and M. angusta. No differences were observed between the cox1 sequences of the male, female and nymph specimens putatively assigned to any specific species, but some nucleotide sequence differences were observed between specimens of M. fuscovaria and M. angusta. These differences, however, were insufficient to allow the development of PCR systems specific to each species. [ABSTRACT FROM AUTHOR]

The article discusses the use of chemicals and biocontrol agents to control grapevine trunk diseases (GTDs). It mentions that GTDs are diseases of grapevine caused by several fungal pathogens that live in and colonize the wood of the perennial organs. It cites Esca which is considered as the oldest GTDs and considered as the white to caused by basidiomycetes.

Grapevine red blotch virus (GRBV) has a monopartite single-stranded DNA genome and is the type species of the genus Grablovirus in the family Geminiviridae. To address the etiological role of GRBV in the recently recognized red blotch disease of grapevine, infectious GRBV clones were engineered from the genome of each of the two previously identified phylogenetic clades for Agrobacterium tumefaeiens-mediated inoculations of tissue culture-grown Vitis spp. plants. Following agroinoculation and one or two dormancy cycles, systemic GRBV infection was detected by multiplex polymerase chain reaction (PCR) in Vitis vinifera exhibiting foliar disease symptoms but not in asymptomatic vines. Infected rootstock genotype S04 (V. berlandieri x V riparia) exhibited leaf chlorosis and cupping, while infection was asymptomatic in agroinoculated 110R (V. berlandieri x V. rupestris), 3309C (V. riparia x V rupestris), and V. rupestris. Spliced GRBV transcripts of the replicaseassociated protein coding region accumulated in leaves of agroinfected vines, as shown by reverse-transcription PCR: this was consistent with systemic infection resulting from virus replication. Additionally, a virus progeny identical in nucleotide sequence to the infectious GRBV clones was recovered from agroinfected vines by rolling circle amplification, cloning, and sequencing. Concomitantly, subjecting naturally infected grapevines to microshoot tip culture resulted in an asymptomatic plant progeny that tested negative for GRBV in multiplex PCR. Altogether, our agroinoculation and therapeutic experiments fulfilled Koch's postulates and revealed the causative role of GRBV in red blotch disease. [ABSTRACT FROM AUTHOR]

Water plays an essential role in fungal decay of wood, and limiting the cell wall moisture content by chemical modification can effectively improve the durability of the material. Investigating the wood-water relations of modified material under climatic conditions relevant for fungal decay are, however, experimentally challenging. Most studies in literature therefore focus on moisture sorption under conditions outside those of importance for fungal decay. This review discusses the validity of such data for characterising the wood-water relations at very humid climatic conditions, relevant for fungal decay. Moreover, the review attempts to cover the basics of fungal decay, the important role of water, and how controlling water content by modification can improve durability. [ABSTRACT FROM AUTHOR]

The antifungal activity of an aqueous extract (AE) and the solid fraction of a chloroform-methanol fruit pericarp extract (CME) of Sapindus mukorossi resolved in water was tested for the first time against Venturia inaequalis and Botrytis cinerea--two important fungal pathogens worldwide. In the greenhouse, a CME (1 % vol/vol) spray significantly reduced V. inaequalis symptoms and sporulation (99%) on apple seedling leaves (P ≤ 0.05). In field trials, applications of AE (1% vol/vol) reduced the disease severity of B. cinerea on grape, on average, by 63%. Extracts were fractionated by high-performance liquid chromatography and the bioefficacy of the fractions was tested in vitro. Some components of the most fungicidal fraction were identified by liquid chromatographyhigh resolution mass spectrometry as saponins: sapindoside B (accounting for ≥98% of the total constituents), hederagenin-pentosylhexoside, and oleanolic acid-hexosyl-deoxyhexosyl-hexoside. This fraction inhibited the mycelial growth of V. inaequalis and B. cinerea by 45 and 43%, respectively. [ABSTRACT FROM AUTHOR]

Summary: Xylella fastidiosa is a Gram‐negative bacterial plant pathogen with an extremely wide host range. This species has recently been resolved into subspecies that correlate with host specificity. This review focuses on the status of X. fastidiosa pathogenic associations in plant hosts in which the bacterium is either endemic or has been recently introduced. Plant diseases associated with X. fastidiosa have been documented for over a century, and much about what is known in the context of host–pathogen interactions is based on these hosts, such as grape and citrus, in which this pathogen has been well described. Recent attention has focused on newly emerging X. fastidiosa diseases, such as in olives. Taxonomy: Bacteria; Gammaproteobacteria; family Xanthomonadaceae; genus Xylella; species fastidiosa. Microbiological properties: Gram‐negative rod (0.25–0.35 × 0.9–3.5 μm), non‐flagellate, motile via Type IV pili‐mediated twitching, fastidious. Host range: Xylella fastidiosa has a broad host range that includes ornamental, ecological and agricultural plants belonging to over 300 different species in 63 different families. To date, X. fastidiosa has been found to be pathogenic in over 100 plant species. In addition, it can establish non‐symptomatic associations with many plants as a commensal endophyte. Here, we list the four distinct subspecies of X. fastidiosa and some of the agriculturally relevant diseases caused by them: X. fastidiosa ssp. fastidiosa causes Pierce's disease (PD) of grapevine (Vitis vinifera); X. fastidiosa ssp. multiplex causes almond leaf scorch (ALS) and diseases on other nut and shade tree crops; X. fastidiosa ssp. pauca causes citrus variegated chlorosis (CVC) (Citrus spp.), coffee leaf scorch and olive quick decline syndrome (OQDS) (Olea europaea); X. fastidiosa ssp. sandyi causes oleander leaf scorch (OLS) (Nerium oleander). Significant host specificity seemingly exists for some of the subspecies, although this could be a result of technical biases based on the limited number of plants tested, whereas some subspecies are not as stringent in their host range and can infect several plant hosts. Disease symptoms: Most X. fastidiosa‐related diseases appear as marginal leaf necrosis and scorching of the leaves. In the case of PD, X. fastidiosa can also cause desiccation of berries (termed ‘raisining’), irregular periderm development and abnormal abscission of petioles. In olive trees affected with OQDS, leaves exhibit marginal necrosis and defoliation, and overall tree decline occurs. Plants with ALS and OLS also exhibit the characteristic leaf scorch symptoms. Not all X. fastidiosa‐related diseases exhibit the typical leaf scorch symptoms. These include CVC and Phony Peach disease, amongst others. In the case of CVC, symptoms include foliar wilt and interveinal chlorosis on the upper surfaces of the leaves (similar to zinc deficiency), which correspond to necrotic, gum‐like regions on the undersides of the leaves. Additional symptoms of CVC include defoliation, dieback and hardening of fruits. Plants infected with Phony Peach disease exhibit a denser, more compact canopy (as a result of shortened internodes, darker green leaves and delayed leaf senescence), premature bloom and reduced fruit size. Some occlusions occur in the xylem vessels, but there are no foliar wilting, chlorosis or necrosis symptoms . Useful websites: http://www.piercesdisease.org/; https://pubmlst.org/xfastidiosa/; http://www.xylella.lncc.br/; https://nature.berkeley.edu/xylella/; https://ec.europa.eu/food/plant/plant_health_biosecurity/legislation/emergency_measures/xylella-fastidiosa_en [ABSTRACT FROM AUTHOR]

Grapevines exhibiting general decline symptoms were observed in July 2012 in Arbatan, a region in Marand county, north-western Iran. Leaf necrosis symptoms were also observed in affected grapevines. Dark brown necrotic lesions and wood discoloration were observed in the vascular tissues of affected cordons. Fungal isolates, all with similar cultural and morphological features, were obtained from symptomatic tissues. Morphological characteristics indicated that the isolates were Macrophomina phaseolina. Sequence analysis of the elongation factor (EF-1α) gene from isolates confirmed this identification, with 100% similarity to the reference M. phaseolina sequences obtained from GenBank. Pathogenicity assays of two M. phaseolina isolates on 2-year-old potted vines (cv. 'Keshmeshi') demonstrated that M. phaseolina was pathogenic on grapevine. This study confirmed the association of M. phaseolina with grapevine decline symptoms, and represents the first report of this fungus associated with grapevine trunk diseases in Iran. [ABSTRACT FROM AUTHOR]

Grapevine red blotch virus (GRBV) is a recently described virus that infects grapevine. Little information is available on the possible occurrence and distribution outside North America. Therefore, we surveyed commercial vineyards from the three major grape-growing regions in Switzerland to determine the presence or absence of GRBV. In total, 3,062 vines were analyzed by polymerase chain reaction. None of the vines tested positive for GRBV, suggesting the absence of GRBV from Swiss vineyards. We also investigated whether GRBV was present in 653 grapevine accessions in the Agroscope grapevine virus collection at Nyon, including dominantly Swiss (457) but also international accessions. Only six referential accessions were infected by GRBV, all originating from the United States, whereas all others from 10 European and 8 non-European origins tested negative. High-throughput sequencing analysis of Zinfandel A2V13, in the collection since 1985, confirmed close similarity of GRBV isolate Z_A2V 13 to American isolates according to genomes deposited in GenBank. Because the Zinfandel A2V13 reference was also maintained grafted on the leafroll virus indicator Vitis vinifera 'Gamay', we evaluated the effect of GRBV on viticultural performance over a 3-year period. Our results showed clear detrimental effects of GRBV on grapevine physiology (vine vigor, leaf chlorophyll content, and gas exchange) and fruit quality. These findings underscore the importance of implementation of GRBV testing worldwide in certification and quarantine programs to prevent the dissemination of this virus. [ABSTRACT FROM AUTHOR]

Bois noir (BN) is the most widespread disease of the grapevine yellows complex in the Euro-Mediterranean area. BN is caused by 'Candidatus Phytoplasma solani' (BNp), transmitted from herbaceous plants to grapevine by polyphagous insect vectors. In this study, genetic diversity among BNp strains and their prevalence and possible association with grapevine symptom severity were investigated in a Sangiovese clone organic vineyard in the Chianti Classico area (Tuscany). Field surveys over 2 years revealed a range of symptom severity on grapevine and an increase of BN incidence. A TaqMan allelic discrimination assay detected only tufB type b among BNp strains, suggesting the prevalence of the bindweed-related ecology. Nucleotide sequence analyses of vmp1 and stamp genes identified 12 vmp1 and 16 stamp sequence variants, showing an overall positive selection for such genes. The prevalent genotype was Vm43/St10, reported for the first time in this study and closely related to strains identified only in the French Eastern Pyrenees. BNp strains identified in the examined vineyard and mostly grouped in separate bindweed-related phylogenetic clusters showed statistically significant differences in their distribution in grapevines exhibiting distinct symptom severity. These results suggest the possible occurrence of a range of virulence within BNp strain populations in the Chianti Classico area. [ABSTRACT FROM AUTHOR]

Botrytis cinerea, the causal agent of Botrytis bunch rot and gray mold, is the number one postharvest disease of fresh grapes in the United States. Fungicide applications are used to manage the disease, but fungicide-resistant isolates are common and postharvest losses occur annually. Host resistance is needed for long-term management of the disease. Sources of resistance in grape have been identified, but often have poor fruit quality. In this study, 27 grape lines (cultigens and species), including high fruit-quality Vitis vinifera, were evaluated for fruit and leaf susceptibility to two isolates of B. cinerea. No significant differences in virulence or pathogenicity were detected between the two isolates, but differences in disease incidence were evident among lines in leaves and berries. Most V. vinifera cultivars evaluated had high disease incidence in berries, whereas complex hybrids, Vitis aestivalus and Vitis arizonica, had low- to moderate disease incidence. Two V. vinifera breeding lines had moderate susceptibility (<50% disease) to Botrytis bunch rot when inoculated with either isolate. Only one V. vinifera line had little (<5%) to no berry or leaf disease when inoculated with either isolate. Moderate resistance (10% to 25%) was detected in Vitis spp., and a single V. vinifera line. Correlations were examined among soluble solids, leaf susceptibility, and fruit susceptibility. No correlations between soluble solids and disease susceptibility (leaves or berries) were identified, but moderate correlations between leaf and berry susceptibility were observed. Moderate resistance to Botrytis bunch rot and leaf spot were detected in Vitis breeding lines, suggesting these may be useful for developing grape cultivars with high fruit quality and resistance to B. cinerea. [ABSTRACT FROM AUTHOR]

The effects of tumorigenic and nontumorigenic strains of Agrobacterium vitis on graft strength and growth of grapevines was studied. A procedure was developed for inoculating graft interface surfaces with A. vitis and for measuring the force required to break grafts at different time points. Cuttings were soaked in an aqueous suspension of bacteria, about 106 CFU/ml, and bacteria were spread onto the graft interface during the grafting procedure. Tumorigenic strain CG49 caused reduced bud germination and increased callus (crown gall) at the graft union and at the base of cuttings at 30 days postinoculation (dpi) and significantly reduced shoot growth by 60 dpi whereas, at the same time points, nontumorigenic strain F2/5 inhibited callus formation but did not affect bud germination or shoot growth. Graft strength was enhanced at 30 dpi with CG49, presumably because the crown gall callus served to secure the union; graft strength was weakened by F2/5 over the same period. Between 30 and 60 dpi, the greatest increase in graft strength was observed in the water control. Following graft union inoculations, the A. vitis population increased more than 1,000-fold within 5 days. [ABSTRACT FROM AUTHOR]

Summary: Grapevines, like other perennial crops, are affected by so‐called ‘trunk diseases’, which damage the trunk and other woody tissues. Mature grapevines typically contract more than one trunk disease and often multiple grapevine trunk pathogens (GTPs) are recovered from infected tissues. The co‐existence of different GTP species in complex and dynamic microbial communities complicates the study of the molecular mechanisms underlying disease development, especially under vineyard conditions. The objective of this study was to develop and optimize a community‐level transcriptomics (i.e. metatranscriptomics) approach that could monitor simultaneously the virulence activities of multiple GTPs in planta. The availability of annotated genomes for the most relevant co‐infecting GTPs in diseased grapevine wood provided the unprecedented opportunity to generate a multi‐species reference for the mapping and quantification of DNA and RNA sequencing reads. We first evaluated popular sequence read mappers using permutations of multiple simulated datasets. Alignment parameters of the selected mapper were optimized to increase the specificity and sensitivity for its application to metagenomics and metatranscriptomics analyses. Initial testing on grapevine wood experimentally inoculated with individual GTPs confirmed the validity of the method. Using naturally infected field samples expressing a variety of trunk disease symptoms, we show that our approach provides quantitative assessments of species composition, as well as genome‐wide transcriptional profiling of potential virulence factors, namely cell wall degradation, secondary metabolism and nutrient uptake for all co‐infecting GTPs. [ABSTRACT FROM AUTHOR]

This paper reports the susceptibility to powdery mildew of 41 grapevine genotypes growing in the north and northwest of Spain over a three-year period. Although the humid climate of these vine-growing areas is not particularly favourable to the development of this disease, serious damages appears in some years when dry weather alternates with times of some rain. All the examined genotypes belonged to the collection of the Misión Biológica de Galicia (CSIC) (Pontevedra, Galicia, Spain). The incidence and severity of powdery mildew were determined on leaves three weeks after the onset of flowering and on clusters at harvest. The values for both variables were smaller than those recorded for other fungal diseases, although great differences in susceptibility between the different genotypes were observed. The most susceptible was Castañal (recently included in the Spanish Registry of Commercial Varieties), a genotype native to the O Rosal subzone of the Rias Baixas denomination of origin area. The present results could help viticulturalists grow different grapevine genotypes more successfully in regions with climatic conditions similar to those where the study was undertaken. [ABSTRACT FROM AUTHOR]

Summary: Herbivorous insects use olfactory cues to locate their host plant within a complex olfactory landscape. One such example is the European grapevine moth Lobesia botrana, a key pest of the grape in the Palearctic region, which recently expanded both its geographical and host plant range. Previous studies have showed that a synthetic blend of the three terpenoids, (E)‐β‐caryophyllene, (E)‐β‐farnesene and (E)‐4,8‐dimethyl‐1,3,7‐nonatriene (DMNT), was as attractive for the moth as the complete grape odour profile in laboratory conditions. The same studies also showed that the specific ratio of these compounds in the grape bouquet was crucial because a percentage variation in any of the three volatiles resulted in almost complete inhibition of the blend's attractiveness. Here, we report on the creation of stable grapevine transgenic lines, with modified (E)‐β‐caryophyllene and (E)‐β‐farnesene emission and thus with an altered ratio compared to the original plants. When headspace collections from these plants were tested in wind tunnel behavioural assays, they were less attractive than control extracts. This result was confirmed by testing synthetic blends imitating the ratio found on natural and transformed plants, as well as by testing the plants themselves. With this evidence, we suggest that a strategy based on volatile ratio modification may also interfere with the host‐finding behaviour of L. botrana in the field, creating avenues for new pest control methods. [ABSTRACT FROM AUTHOR]

The article discusses the individual diseases and pathogens that lead to grapevine trunk diseases (GTDs), the importance of understanding disease etiology and epidemiology to design control programs, and the future prospects for proper disease management. Topics discussed include management of GTDs nurseries and newly established vineyards, crop rotation in nursery fields, and the potential of the biofumigant Indian mustard seed meal.

Recently incidence of Tetranychus urticae is a widespread issue in grape orchards in India. The possibility of a pesticide induced resurgence of mites was explored by applying field recommended doses of commonly used pesticides. The field trial revealed no resurgence with respect to dicofol, abamectin, spiromecifen, dichlorovos + fish oil resin soap, and dinocap usage consecutively. Sulphur induced heavy resurgence (16.55%) with resurgence ratio of 1.05, followed by thiamethoxam (8.89%), acetamiprid (6.97%), imidacloprid (6.15%) and buprofezin (5.46%) with resurgence ratios of 0.81, 0.89, 0.87, and 0.88 respectively. [ABSTRACT FROM AUTHOR]

Management of agricultural landscapes can influence the biodiversity and the ecological services provided by these ecosystems, such as natural biological pest control. Viticulture is a very important economic activity in most countries with Mediterranean climate, often shaping their landscapes and culture. Grape production is affected by a number of pests and diseases, and farmers use prophylactic and response-driven pesticides to control these pests. Here we quantified the main biotic causes of crop losses in four grape castes, two red (Touriga Nacional and Baga) and two white (Arinto and Chardonnay), and evaluated the potential effect of native biodiversity to provide biotic resistance to pest outbreaks and grape losses. Specifically, the diversity and abundance of bird and insect communities in these vineyards were quantified and divided into functional guilds (pest, neutral or auxiliary), to test whether these natural communities hold the potential to naturally control grape pests (biotic resistance hypothesis) under normal vineyard management (including pesticide application regimes). A potential association between distance to the vineyard edge and grape losses was also evaluated. We recorded a very small proportion of grape losses (mean D0.6 %; maxD7.5 %), with insect pests showing a preference for the castes Baga (red) and Chardonnay (white), while bird pests avoided the caste Arinto (white). Grape color did not influence losses caused by insect pests, but birds showed a preference for red castes. The caste Baga was also more vulnerable to losses caused by fungi. Despite their low impact on grape production, most insects and birds detected in the six vineyards were pests, which entails a potentially low level of biotic resistance in this highly managed agricultural ecosystem. Further research is necessary to fully evaluate the role of functional biodiversity in vineyards, particularly if alternative production processes, such as organic farming, can increase the potential of native biodiversity to protect against grape losses from pests under lower regimes of chemical spraying. [ABSTRACT FROM AUTHOR]

The ascomycete Neofusicoccum parvum, one of the causal agents of Botryosphaeria dieback, is a destructive wood-infecting fungus and a serious threat to grape production worldwide. The capability to colonize woody tissue, combined with the secretion of phytotoxic compounds, is thought to underlie its pathogenicity and virulence. Here, we describe the repertoire of virulence factors and their transcriptional dynamics as the fungus feeds on different substrates and colonizes the woody stem. We assembled and annotated a highly contiguous genome using single-molecule real-time DNA sequencing. Transcriptome profiling by RNA sequencing determined the genome-wide patterns of expression of virulence factors both in vitro (potato dextrose agar or medium amended with grape wood as substrate) and in planta. Pairwise statistical testing of differential expression, followed by co-expression network analysis, revealed that physically clustered genes coding for putative virulence functions were induced depending on the substrate or stage of plant infection. Co-expressed gene clusters were significantly enriched not only in genes associated with secondary metabolism, but also in those associated with cell wall degradation, suggesting that dynamic co-regulation of transcriptional networks contributes to multiple aspects of N. parvum virulence. In most of the co-expressed clusters, all genes shared at least a common motif in their promoter region, indicative of co-regulation by the same transcription factor. Co-expression analysis also identified chromatin regulators with correlated expression with inducible clusters of virulence factors, suggesting a complex, multi-layered regulation of the virulence repertoire of N. parvum. [ABSTRACT FROM AUTHOR]

Limited information is available on the spread of Grapevine reel blotch virus (GRBV, genus Grablovirus, family Geminiviridae) in vineyards. To investigate ecological aspects of red blotch disease spread, sticky cards to catch flying insects were placed in 2015 (April to November) and 2016 (March to November) in a vineyard study site in California where disease incidence increased by nearly 20% between 2014 and 2016. Subsets of insect species or taxa were removed from sticky card traps and individual specimens were tested for the presence of GRBV by multiplex polymerase chain reaction. GRBV was consistently detected in Spissistilus festinus (Membracidae), Colladonus reductus (Cicadellidae), Osbomellus borealis (Cicadellidae), and a Melanoliarus sp. (Cixiidae). Populations of these four candidate vectors peaked from June to September, with viruliferous S. festinus peaking from late June to early July in both years. An assessment of co-occurrence and covariation between the spatial distribution of GRBV-infected vines and viruliferous insects identified a significant association only with viruliferous S. festinus. These findings revealed the epidemiological relevance of S. festinus as a vector of GRBV in a vineyard ecosystem. Sequencing coat protein and replicaseassociated protein gene fragments of GRBV isolates front newly infected vines and viruliferous vector candidates further suggested secondary spread primarily from local sources and occasionally from background sources. [ABSTRACT FROM AUTHOR]

Grapevine trunk diseases: Eutypa dieback, esca and Botryosphaeria dieback, which incidence has increased recently, are associated with several symptoms finally leading to the plant death. In the absence of efficient treatments, these diseases are a major problem for the viticulture; however, the factors involved in disease progression are not still fully identified. In order to get a better understanding of Botryosphaeria dieback development in grapevine, we have investigated different factors involved in Botryosphaeriaceae fungi aggressiveness. We first evaluated the activity of the wood-degrading enzymes of different isolates of Neofusicoccum parvum and Diplodia seriata, two major fungi associated with Botryosphaeria dieback. We further examinated the ability of these fungi to metabolize major grapevine phytoalexins: resveratrol and δ-viniferin. Our results demonstrate that Botryosphaeriaceae were characterized by differential wood decay enzymatic activities and have the capacity to rapidly degrade stilbenes. N. parvum is able to degrade parietal polysaccharides, whereas D. seriata has a better capacity to degrade lignin. Growth of both fungi exhibited a low sensitivity to resveratrol, whereas δ-viniferin has a fungistatic effect, especially on N. parvum Bourgogne S-116. We further show that Botryosphaeriaceae are able to metabolize rapidly resveratrol and δ-viniferin. The best stilbene metabolizing activity was measured for D. seriata. In conclusion, the different Botryosphaeriaceae isolates are characterized by a specific aggressiveness repertory. Wood and phenolic compound decay enzymatic activities could enable Botryosphaeriaceae to bypass chemical and physical barriers of the grapevine plant. The specific signature of Botryosphaeriaceae aggressiveness factors could explain the importance of fungi complexes in synergistic activity in order to fully colonize the host. [ABSTRACT FROM AUTHOR]

Spectral measurements are employed in many precision agriculture applications, due to their ability to monitor the vegetation's health state. Spectral vegetation indices are one of the main techniques currently used in remote sensing activities, since they are related to biophysical and biochemical crop variables. Moreover, they have been evaluated in some studies as potentially beneficial for detecting or differentiating crop diseases. Flavescence Dorée (FD) is an infectious, incurable disease of the grapevine that can produce severe yield losses and, hence, compromise the stability of the vineyards. The aim of this study was to develop specific spectral disease indices (SDIs) for the detection of FD disease in grapevines. Spectral signatures of healthy and diseased grapevine leaves were measured with a non-imaging spectro-radiometer at two infection severity levels. The most discriminating wavelengths were selected by a genetic algorithm (GA) feature selection tool, the Spectral Disease Indices (SDIs) are designed by exhaustively testing all possible combinations of wavelengths chosen. The best weighted combination of a single wavelength and a normalized difference is chosen to create the index. The SDIs are tested for their ability to differentiate healthy from diseased vine leaves and they are compared to some common set of Spectral Vegetation Indices (SVIs). It was demonstrated that using vegetation indices was, in general, better than using complete spectral data and that SDIs specifically designed for FD performed better than traditional SVIs in most of cases. The precision of the classification is higher than 90%. This study demonstrates that SDIs have the potential to improve disease detection, identification and monitoring in precision agriculture applications. [ABSTRACT FROM AUTHOR]

P. oxalicum is known as plant pathogen, mycotoxin producer and was suggested to be involved in the induction of champagne gushing. Early detection of the fungus enforces decision making in the wine industry as to how grapes will be further processed. A loop-mediated isothermal amplification (LAMP) assay for P. oxalicum was established with a detection limit of 100 pg genomic DNA per reaction. The assay was highly specific for P. oxalicum DNA. The assay was applied for the detection of the fungus on artificially infected grapes using surface washings as target for the LAMP reaction. Screening of grape samples from different European countries revealed the (rare) presence of P. oxalicum on grapes harvested in Italy and Portugal. We suggest the developed LAMP assay as a promising new tool for the rapid, robust, highly specific and sensitive as well as cost efficient detection of P. oxalicum on grapes used in the wine and champagne industry. [ABSTRACT FROM AUTHOR]

In 2016, grape fruits showing ripe rot symptom were found in fields of Korea. The fungus was isolated and identified as Colletotrichum viniferum based on morphological characteristics and nucleotide sequence data of the internal transcribed spacer, glyceraldehyde-3-phosphate dehydrogenase and ß-tubulin. To our knowledge, this is the first report of C. viniferum causing grape ripe rot disease of grape fruits in Korea. [ABSTRACT FROM AUTHOR]

In 2014, disease symptoms of yellowing, foot rot and drying of leaves were observed in vineyards in Hormozgan province, Iran. The goal of the present study was to characterise fungal isolates associated with black foot of grapevines (Vitis spp.) using multi-gene DNA analysis (partial translation elongation factor-1 [tef1], internal transcribed spacers [ITS rDNA] and ß-tubulin) and pathogenic characteristics of the isolates from the grapevines. Twenty-five isolates were obtained from diseased plants and identified as Campylocarpon fasciculare (14), Fusarium solani (7) and F. decemcellulare (4) through morphological characteristics. The three DNA regions analysed supported the morphological concept. All fungal isolates were evaluated for their pathogenicity on one-year-old rooted grapevine cultivar Askari in the planthouse. Typical root rot symptoms were observed within 90 days after inoculation. Campylocarpon fasciculare and an unnamed phylogenetic species of FSSC 20 were reported for the first time for Iranian mycoflora, indicating that grapevine vineyards have become the new host plants for F. decemcellulare. [ABSTRACT FROM AUTHOR]

A two-year survey was conducted to identify fungi associated with wood decay in a range of tree species and grapevine. Fifty-eight fungal strains isolated from plants of 18 species showing typical wood decay symptoms were characterized by morphological, physiological, and molecular analyses. By 5.8S rRNA gene-ITS sequencing analysis, these isolates were classified into 25 distinct operational taxonomic units, including important phytopathogenic species of the phyla Pezizomycotina and Agaricomycotina, such as Fomitiporia, Inonohis, Phellinus, lnocutis, Fuscoporia, Trametes, Fusarium, Eurypa, Phaeomoniella, Phaeoacremonium, and Pleurostomophora spp. The white rot basidiomycetes Fomitiporia mediterranea (20 isolates, 34.5%) and Inonotus hispidus (6 isolates, 10.3%) were the most prevalent. Pathogenicity tests revealed for the first time that certain fungal species of the genera Fomitiporia, Inonotus, Phellinus, Pleurostomophora, and Fusarium caused wood infection of various tree species in Greece and worldwide. To the best of our knowledge, this is the fust report of F. mediterranea as the causal agent of wood decay in pear, pomegranate, kumquat, and silk tree. This is also the first record of Inonotus hispidus, Phellinus pomaceus, Pleurostomophora richardsiae, and Fusarium solani in apple, almond, avocado, and mulbeny tree, respectively, whereas P. richardsiae was associated with wood infection of olive tree for the first time in Greece. Cross pathogenicity tests with F. mediterranea strains originated from grapevine applied on other woody hosts and from olive on grapevine demonstrated partial host specificity of the fungus. The potential of F. mediterranea to transinfect hosts other than those originated, along with the host range extension of the fungus, is discussed. [ABSTRACT FROM AUTHOR]

Phyllosticta ampelicida causes black rot disease of Vitis spp. Genetic homogeneity of pathogen populations was investigated by analyzing the number of haplotypes present in infected samples from Europe and America. The fungus was identified from an analysis of the internal transcribed spacer (ITS) 1-ITS2 region, and partial sequences of (3-tubulin and calmodulin genes. The analysis of nuclear microsatellites applied to strains from Vitis spp. confirmed the existence of a high degree of genetic variability in the fungal populations, revealed four subpopulations, and showed that strains from America are distinct from the European ones. Furthermore, toe results obtained by landscape genetics showed that there were different introductions of the pathogen in the main vine areas of Europe, confirming what was observed in the first reports of the disease. The genetic variability of the fungus revealed by this study confirms the ability to generate new haplotypes by sexual reproduction. The difference found between the European populations and the American one confirms that the pathogen originated from America. [ABSTRACT FROM AUTHOR]

Grapevine Red Globe virus ( GRGV) is a member of family Tymoviridae tentatively assigned to genus Maculavirus. There is evidence that the distribution of this virus may be widespread. In a recent report, the authors of the present study described the presence of GRGV in Spain. To further estimate its incidence, a survey was carried out that allowed the detection of the virus using RT- PCR in a germplasm collection in northern Spain. In the present study, three isolates were selected to obtain full-length genome sequences using high-throughput sequencing ( HTS) of RNA combined with Sanger sequencing. The GRGV complete genome consists of 6850 nucleotides, excluding the polyA tail. Two ORFs could be identified as the putative replicase and coat protein. Although comparison of the complete genomes provided no evidence for the presence of the additional ORF previously described, another ORF was identified within the coat protein ORF, but it probably lacks functional significance. Phylogenetic analysis supported the ascription of GRGV to genus Maculavirus. The profile of vsi RNA (virus-derived small interfering RNA) distribution along the GRGV genomes suggested the presence of a subgenomic RNA corresponding to the coat protein ORF. To improve detection of GRGV, new primer sets were designed based on consensus sequences. HTS revealed a frequent co-infection of GRGV and grapevine rupestris vein feathering virus ( GRVFV). Biological indexing by grafting two GRGV-infected vines on indicator plants and the visual inspection of symptoms in other infected plants revealed that the virus has a negligible impact on grapevine. [ABSTRACT FROM AUTHOR]

Improving natural pest control by promoting high densities of predatory mites (Acari: Phytoseiidae) is an effective way to prevent damage by pest mites (e.g., Eriophyidae, Tetranychidae) and other arthropod taxa that can cause serious damage to vineyards. Here, we investigate the influence of innovative management on predatory mite densities. We compare (i) full versus reduced fungicide applications and (ii)minimal pruning versus a traditional trellis pruning systemin four fungus-resistant grapevine varieties. As predatory mites also feed on fungus mycelium, we assessed fungal infection of grapevine leaves in the experimental vineyard. Predatory mites were significantly more abundant in both minimal pruning and under reduced plant protection. Increases in predatory mites appeared to be independent of fungal infection, suggesting mostly direct effects of reduced fungicides and minimal pruning. In contrast to predatory mites, pest mites did not increase under innovative management. Thus, conditions for natural pest control are improved in fungus-resistant grapevines and underminimal pruning, which adds to other advantages such as environmental safety and reduced production cost. [ABSTRACT FROM AUTHOR]

Grey mould, caused by Botrytis cinerea, is a disease severely affecting grape production in northern Italy. However, little information is available on the variability of B. cinerea populations associated with grapevine. The mode of reproduction, sensitivity to fungicides, and for the first time in Italy, the genetic structure of B. cinerea populations isolated from grapevine in a northern Italian region are reported. Botrytis cinerea isolates (317) were completely genotyped for six microsatellite loci and characterized for the presence of the transposable elements Boty and Flipper, for the mating type and for resistance to cyprodinil, fludioxonil, boscalid and fenhexamid. All the isolates were found to belong to B. cinerea Group II, indicating the absence of B. pseudocinerea in the investigated areas. The populations possess a high genotypic diversity, different frequencies of transposable elements and a mixed mode of reproduction. At a regional level, B. cinerea populations belong to a large and interconnected pathogen population that includes the major grape-growing districts. The populations were generally sensitive to fungicides, with a low proportion (8%) of isolates resistant to cyprodinil, fludioxonil and boscalid. A small genetic distance was found between B. cinerea populations. However, the populations geographically isolated from the others by a mountain range showed a small but statistically significant genetic differentiation and a different pattern of fungicide resistance. The results show that northern Italian B. cinerea populations possess a high evolutionary potential and adaptive capacity. [ABSTRACT FROM AUTHOR]

The present work was carried out in order to verify the possible association between a new grapevine disease, characterized by leaf mottling and deformation, and the genetic variability and concentration of Grapevine Pinot gris virus ( GPGV), a recently identified virus tentatively associated with the pathology. After vineyard surveys and the establishment of real-time qPCR assays, characterization of GPGV isolates and evaluation of GPGV titre were assessed in more than 100 samples of grapevine Glera, collected from plants regardless of whether or not they showed the symptomatology. Results showed that there was an important association between the GPGV variants and manifestation of the symptoms, and that grapevines with symptoms harboured significantly higher GPGV titre than symptomless vines. Moreover, an interesting relationship among the phylogenetic clustering of the isolates originating from plants with symptoms and some epidemiological characteristics of the disease was found. The current study confirmed the role of GPGV in the emergent disease characterized by grapevine leaf mottling and deformation. [ABSTRACT FROM AUTHOR]

Background: Bois noir is an important disease of grapevine (Vitis vinifera L.), caused by phytoplasmas. An interesting, yet elusive aspect of the bois noir disease is "recovery", i.e., the spontaneous and unpredictable remission of symptoms and damage. Because conventional pest management is ineffective against bois noir, deciphering the molecular bases of recovery is beneficial. The present study aimed to understand whether salicylate- and jasmonate-defence pathways might have a role in the recovery from the bois noir disease of grapevine. Results: Leaves from healthy, bois noir-diseased and bois noir-recovered plants were compared, both in the presence (late summer) and absence (late spring) of bois noir symptoms on the diseased plants. Analyses of salicylate and jasmonate contents, as well as the expression of genes involved in their biosynthesis, signalling and action, were evaluated. In symptomatic diseased plants (late summer), unlike symptomless plants (late spring), salicylate biosynthesis was increased and salicylate-responsive genes were activated. In contrast, jasmonate biosynthesis and signalling genes were up-regulated both in recovered and diseased plants at all sampling dates. The activation of salicylate signalling in symptomatic plants might have antagonised the jasmonate-mediated defence response by suppressing the expression of jasmonate-responsive genes. Conclusions: Ourresultssuggestthatgrapevinereacts to phytoplasma infection through salicylate-mediated signalling, although the resultant full activation of a salicylate-mediated response is apparently ineffective in conferring resistance against bois noir disease. Activation of the salicylate signalling pathway that is associated with the presence of bois noir phytoplasma seems to antagonise the jasmonate defence response, by failing to activate or suppressing both the expression of some jasmonate responsive genes that act downstream of the jasmonate biosynthetic pathway, as well as the first events of the jasmonate signalling pathway. On the other hand, activation of the entire jasmonate signalling pathway in recovered plants suggests the potential importance of jasmonate-regulated defences in preventing bois noir phytoplasma infections and the subsequent development of bois noir disease. Thus, on one hand, recovery could be achieved and maintained over time by preventing the activation of defence genes associated with salicylate signalling, and on the other hand, by activating jasmonate signalling and other defence responses. [ABSTRACT FROM AUTHOR]

A survey was conducted on nine autochthonous grapevine cultivars grown along the Croatian coastal region. In total, 48 vines (44 from germplasm collection, 4 from vineyards) originating from 23 sites were tested for 26 viruses using molecular methods. Results revealed high infection rates with Grapevine leafroll-associated virus 3 (GLRaV-3); Grapevine virus A (GVA, both 91.7%); Grapevine fleck virus (GFkV, 87.5%); and Grapevine rupestris stem pitting-associated virus (GRSPaV, 83.3%). Other detected viruses were: Grapevine fanleaf virus (GFLV); Grapevine leafroll-associated viruses 1, 2, and strains of 4 (GLRaV-1, GLRaV-2, GLRaV-4); Grapevine viruses B, D, F (GVB, GVD, GVF); Grapevine red globe virus (GRGV); Grapevine vein feathering virus (GVFV); Grapevine Syrah virus 1 (GSyV-1); and Grapevine Pinot gris virus (GPGV). No virus-free vine was found. Mixed infections were determined in all vines, the number of viruses in a single vine ranged from three to nine. GLRaV-3 variant typing confirmed presence of group I, II, and III. Four vines with leaf deformation and mottling were positive for GPGV. Seven viruses (GLRaV-4-like group, GVD, GVE, GVF, GRGV, GSyV-1, and GVFV) were detected for the first time in Croatia. This survey confirmed the deteriorated sanitary status of autochthonous Croatian grapevine cultivars. [ABSTRACT FROM AUTHOR]