Cadophora Luteo-olivacea Research Articles

Pseudomonas synxantha volatile organic compounds: efficacy against Cadophora luteo-olivacea and Botrytis cinerea of kiwifruit.

Volatile organic compounds (VOCs) are responsible for the antagonistic activity exerted by different biological control agents (BCAs). In this study, VOCs produced by Pseudomonas synxantha strain 117-2b were tested against two kiwifruit fungal postharvest pathogens: Cadophora luteo-olivacea and Botrytis cinerea, through in vitro and in vivo assays. In vitro results demonstrated that P. synxantha 117-2b VOCs inhibit mycelial growth of C. luteo-olivacea and B. cinerea by 56% and 42.8% after 14 and 5 days of exposition, respectively. In vivo assay demonstrated significant inhibitory effects. VOCs used as a biofumigant treatment reduced skin-pitting symptoms disease severity by 28.5% and gray mold incidence by 66.6%, with respect to the untreated control. BCA volatiles were analyzed by solid-phase microextraction coupled with gas chromatography-mass spectrometry (SPME-GC/MS), and among the detected compounds, 1-butanol, 3-methyl and 1-nonene resulted as the most produced. Their efficacy as pure synthetic compounds was assayed against mycelial growth of fungal pathogens by different concentrations (0.34, 0.56, and 1.12 µL mL-1 headspace). The effect of the application of VOCs as a biofumigant was also investigated as the expression level of seven defense-related genes of kiwifruit at different exposition times. The results indicated an enhancement of the expression of almost all the genes starting from 3h of treatment. These results described P. synxantha VOCs characteristics and their potential as a promising method to adopt for protecting kiwifruit from postharvest diseases caused by C. luteo-olivacea and B. cinerea.

Modeling the Effect of Temperature on the Severity of Blueberry Stem Blight and Dieback with a Focus on Neofusicoccum parvum and Cultivar Susceptibility

Stem blight and dieback rank among the most relevant diseases affecting blueberry production worldwide. In Northern Italy, Neofusicoccum parvum, Diaporthe rudis, Cadophora luteo-olivacea and Peroneutypa scoparia have been reported to cause stem blight and dieback in blueberry. Considering that the incidence and severity of these diseases are on the rise in Northern Italy, two of the main aims of the present study were a—to compare the in vitro growth rate of the four fungi at different temperatures and b—to assess the aggressiveness of the same fungi on four commercial blueberry cultivars. Neofusicoccum parvum had the fastest growth rate and was the most aggressive pathogen. A possible effect of temperature on host colonization by N. parvum and disease expression was postulated and tested as a third aim. In planta trials were performed to model and predict the influence of temperature on the severity of blueberry stem blight and dieback caused by N. parvum. Increasing temperatures boosted the aggressiveness of the pathogen, causing higher disease severity and host mortality. Our findings suggest that temperature plays a relevant role in the severity of blueberry stem blight and dieback caused by N. parvum. Given the predictions of a warmer climate, this disease may become increasingly more significant and should be actively managed.

Characterization and Pathogenicity of Fungal Species Associated with Dieback of Apple Trees in Northern Italy.

Severe dieback symptoms were recently observed on apple (Malus × domestica) trees in Northern Italy, representing a growing concern for producers. Surveys were conducted over a 3-year period (2019 to 2021), and five apple orchards, from 5 to 12 years old, were monitored. A total of 33 fungal isolates isolated from symptomatic plants was selected for characterization. The species identification was achieved through multilocus phylogenetic analyses performed on sequences of three genomic loci (ITS, tub2, and tef1). Morphological features were assessed, and the average growth rate at different temperatures was determined. Seven species were identified in association with dieback of apple trees: Botryosphaeria dothidea, Cadophora luteo-olivacea, Diaporthe rudis, Diplodia seriata, Eutypa lata, Kalmusia longispora, and Paraconiothyrium brasiliense. All the species were pathogenic when inoculated on healthy apple plants. B. dothidea resulted in the most aggressive infections. This study provides an insight into the fungal species diversity associated with apple dieback and provides basis for further investigations to assess the phytosanitary status of plant materials to recommend and implement effective management strategies.

Cadophora luteo-olivacea on apple and kiwifruit: characterization of selected strains and evaluation of fungicides for their control

Cadophora luteo-olivacea on apple and kiwifruit: characterization of selected strains and evaluation of fungicides for their control

Health Status of Ready-to-Plant Grapevine Nursery Material in Canada Regarding Young Vine Decline Fungi.

Young vine decline (YVD), caused by several taxonomically different fungi, results in the decline and death of grapevines within a few years after planting. Infection can occur in nursery mother blocks and/or at several stages in the nursery propagation process, but the final plant material may remain asymptomatic. Four nurseries that sell ready-to-plant grapevines in Canada were sampled to evaluate the health status with regard to YVD fungi, including Botryosphaeriaceae spp., Cadophora luteo-olivacea, Dactylonectria macrodidyma, Dactylonectria torresensis, Phaeoacremonium minimum, and Phaeomoniella chlamydospora. Plants representing three cultivars, 'Chardonnay', 'Merlot', and 'Pinot noir', either grafted onto '3309C' rootstock or self-rooted, were provided by the nurseries. Samples from the roots, base of the rootstock or self-rooted cultivar, graft-union, and scion were collected from each plant. DNA was extracted, and the total abundance of each fungus was quantified using Droplet Digital PCR. Results revealed that 99% of plants harbored at least one of the fungi studied, with a mean of three different fungal species that were present per grapevine. Droplet Digital PCR results showed that the abundance of the different fungi significantly varied between different sections of each plant, individual plants for each cultivar, and cultivars from the same nursery. Necrosis measurements were recorded from the base of the rootstock or self-rooted cultivars and did not correlate with fungal abundance recorded in that section for each grapevine, but necrosis was consistent across cultivars within nurseries. Five different rootstocks were compared from one nursery, and results showed no differences between rootstocks and their health status. Among all nurseries, C. luteo-olivacea was the most prevalent fungus (97% of the plants), while D. macrodidyma was the least commonly found (13% of the plants). This study shows that ready-to-plant nursery material sold in Canada is likely to be infected with several YVD fungi and that presence and abundance of fungi vary significantly among individual grapevines and nurseries.

Current status of grapevine trunk disease pathogens on asymptomatic nursery-produced grapevines in Türkiye

Good health of grapevine plants is important for productivity and sustainability of newly established vineyards, and accurate detection of bacterial and fungal pathogens is a prerequisite for managing the diseases they cause in nurseries. This study screened marketable, bare-rooted grapevine plants, obtained from different geographical regions of Türkiye, for fungal pathogens associated with grapevine trunk diseases (GTDs). In 2021, 43 grapevine nurseries located in eight provinces were surveyed to reveal the status of GTD pathogens on asymptomatic marketable plants. Fungal pathogens isolated from the roots and basal parts of asymptomatic dormant grapevines were identified using with morphological characteristics and molecular markers, and were subjected to pathogenicity tests. Six species; Cytospora viticola, Diaporthe ampelina, Diplodia seriata, Lasiodiplodia brasiliensis, Neofusicoccum parvum, and Truncatella angustata (associated with dieback), and six species; Cadophora ferruginea, Cadophora luteo-olivacea, Cadophora malorum, Phaeoacremonium minimum, Phaeoacremonium tuscanicum and Phaeomoniella chlamydospora (associated with Petri disease) were identified based on DNA sequencing of ITS and TEF1-α genes. GTD pathogens were detected in 12 and 14 of the 43 nurseries, respectively. Pathogenicity tests on 1103P vines revealed that all species were pathogenic (N. parvum and C. luteo-olivacea being the most virulent), and caused significant wood necroses when compared to non-inoculated experimental controls. This is the first report of C. ferruginea, C. malorum, L. brasiliensis, and P. tuscanicum associated with GTDs in Türkiye.

Effects of Temperature and Moisture Duration on Spore Germination of Four Fungi that Cause Grapevine Trunk Diseases.

Grapevine trunk diseases (GTDs) are serious threats worldwide and are difficult to control, in part because the environmental requirements for epidemiological processes of the causal fungi are poorly understood. Therefore, we investigated the effects of temperature and moisture duration on spore germination of four fungi associated with two GTDs (esca complex and Eutypa dieback): Phaeomoniella chlamydospora, Phaeoacremonium minimum, Cadophora luteo-olivacea, and Eutypa lata. Conidia of Phaeomoniella chlamydospora, Phaeoacremonium minimum, and C. luteo-olivacea were similar: conidia of these fungi germinated profusely (>90%) between 20 and 30°C; Phaeomoniella chlamydospora and Phaeoacremonium minimum tended to germinate at higher temperatures (up to 40°C for P. minimum), and C. luteo-olivacea at lower temperatures (as low as 5°C). E. lata ascospores germinated between 10 and 30°C. The required duration of moist periods for germination was shortest for C. luteo-olivacea (about 6 h), followed by P. minimum and E. lata (about 12 h) and Phaeomoniella chlamydospora (about 24 h). Further research on the environmental requirements of GTD fungi may increase our ability to predict infection periods and, thereby, improve disease control.

Fibulorhizoctonia psychrophila, causal agent of lenticel spot in pome fruit, rarely detected in Dutch pear and apple orchards

Fibulorhizoctonia psychrophila causes lenticel spot in stored pome fruit. A Dutch survey revealed that damage can be observed regularly in individual lots at low incidence to occasionally incidences above 25% after storage for five months or longer under specific controlled atmosphere storage conditions. The source of inoculum of the psychrophilic pathogen is not known. A species-specific TaqMan PCR assay was developed to quantify the pathogen DNA in orchard litter considered as potential inoculum source. 2008 samples of various litter types such as dead leaves, fallen fruits and mummies and necrotic tissues of grasses and weeds, collected in 2009–2012 in ten apple and twenty pear orchards, were analyzed. Although other fruit rot pathogens such as Neofabraea alba, Cadophora luteo-olivacea and Stemphylium vesicarium were detected in the samples at high incidences in earlier studies, F. psychrophila was only detected in three samples. The results show that F. psychrophila is not ubiquitously present in Dutch orchards at traceable concentrations. The main sources of the disease remain unknown. Possibly, the pathogen is present on storage bins or dust in storage facilities.

Study of the efficacy of bacterial antagonists against Cadophora luteo-olivacea of kiwifruit

Skin pitting currently represents one of the major postharvest diseases of kiwifruit and one of the most difficult to manage in packinghouses due to its latent behavior and the difficulty in predicting its emergence. Our research demonstrates the potential to use different bacterial strains (Pseudomonas synxantha and Bacillus spp.) instead of synthetic compounds to preserve kiwifruit from the development of postharvest skin pitting symptoms, following the momentum towards sustainable strategies. The antagonists tested with in vitro assays showed different efficacy rates against C. luteo-olivacea (strain Cad21) mycelial growth by producing non-volatile metabolites. The biochemical composition of the most active bacterial non-volatile secondary metabolites was described through FT-IR (Fourier-Transform Infrared) spectroscopy. Pseudomonas synxantha strain 117-2b emerged as the most active strain in in vivo experiments, both as a curative and preventive treatment (63% and 84.7% of inhibition, respectively). In addition to its ability to reduce disease incidence, the biological antagonism exerted by P. synxantha strain 117-2b was further demonstrated by qPCR analysis as a reduction in the pathogen's abundance. In view of these results, alternative solutions in the field and during postharvest storage could be considered to control C. luteo-olivacea of kiwifruit.

Characterization and antimicrobial activity of fungal endophytes from Crocus caspius (Iridaceae)

Plant endophytes are known as one of the newest natural sources for producing specialized metabolites and novel antibiotics. In the present study, endophytic fungi isolated from the corms of Crocus caspius Fisch. & C.A.Mey. ex Hohen. (Iridaceae) were characterized for the first time. Six fungal endophytes were isolated and their antibacterial activity was studied against human pathogens including Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Enterococcus faecium (Clinical isolate), and Candida albicans ATCC 10231 by determination of the minimum inhibitory-minimum bactericidal concentration (MIC-MBC) assays. Thin-layer chromatography (TLC)-bioautography technique was applied to investigate the antifungal activity of the methanolic extracts of fungal endophytes against ochratoxin A-producing fungus, Aspergillus ochraceus Strain 168. Based on morphological and ITS1-5.8S-ITS2 sequencing analysis, isolated endophytes from the plant corms were identified as Xenoacremonium falcatus (SBU-1), Fusarium oxysporum (SBU-2), Cadophora luteo-olivacea (SBU-3), Phialocephala sp. (SBU-4) and Talaromyces purpureogenus (SBU-5 and SBU-6). The extracts of T. purpureogenus SBU-6 (MIC = 1 mg/ml) and Phialocephala sp. SBU-4 (MIC = 0.25 mg/ml) showed a considerable antibacterial activity against E. coli and S. aureus, respectively. The obtained extract from SBU-5 showed the highest antifungal activity (MIC = 4 mg/ml) against C. albicans. Furthermore, both SBU-2 and SBU-5 at a concentration of 16 mg/ml showed bactericidal and fungicidal effects against E. coli and C. albicans. The extracts of SBU-2, SBU-4, and SBU-5 showed significant antifungal activity against A. ochraceous. These findings could be interesting for further exploitation of these endophytes to produce antibiotics and biological fungicides.

Preliminary results on Cadophora luteo-olivacea pathogenicity aspects on kiwifruit

Preliminary results on Cadophora luteo-olivacea pathogenicity aspects on kiwifruit

DNA metabarcoding reveals high relative abundance of trunk disease fungi in grapevines from Marlborough, New Zealand

Grapevine trunk diseases (GTDs) are a threat to grape production worldwide, with a diverse collection of fungal species implicated in disease onset. Due to the long-term and complex nature of GTDs, simultaneous detection of multiple microbial species can enhance understanding of disease development. We used DNA metabarcoding of ribosomal internal transcribed spacer 1 (ITS1) sequences, supported by specific PCR and microbial isolation, to establish the presence of trunk pathogens across 11 vineyards (11–26 years old) over three years in Marlborough, the largest wine producing region in New Zealand. Using a reference database of trunk pathogen sequences, species previously associated with GTD, such as Cadophora luteo-olivacea, Diplodia seriata, Diplodia mutila, Neofusicoccum australe, and Seimatosporium vitis, were identified as highly represented across the vineyard region. The well-known pathogens Phaeomoniella chlamydospora and Eutypa lata had especially high relative abundance across the dataset, with P. chlamydospora reads present between 22 and 84% (average 52%) across the vineyards. Screening of sequences against broader, publicly available databases revealed further fungal species within families and orders known to contain pathogens, many of which appeared to be endemic to New Zealand. The presence of several wood-rotting basidiomycetes (mostly Hymenochaetales) was detected for the first time in the Marlborough vineyard region, notably, the native Inonotus nothofagii which was present at 1–2% relative abundance in two vineyards.

Hot Water Treatment Causes Lasting Alteration to the Grapevine (Vitis vinifera L.) Mycobiome and Reduces Pathogenic Species Causing Grapevine Trunk Diseases.

The effective management of grapevine trunk diseases (GTDs) is an ongoing challenge. Hot water treatment (HWT) is an environmentally friendly and economically viable option; however, the short-term effects of HWT on grapevine (Vitis vinifera L.) health and production are not fully understood. The aim of this study was to compare the effects of HWT on plant growth and fungal community structure in nursery stock until plants were completely established in the field. We assessed eleven graft and three rootstock varieties from four local nurseries in a region of Catalonia (NE Spain) where GTDs are a serious threat. After treatment, the plants were left to grow under field conditions for two growing seasons. Metabarcoding of the ITS region was used to study the mycobiomes of plant graft unions and root collars. We also assessed the influence of plant physiological indicators in community composition. Hot water treatment caused lasting changes in GTD communities in both the root collar and graft union that were not always characterized as a reduction of GTD-related fungi. However, HWT reduced the relative abundance of some serious GTD-associated pathogens such as Cadophora luteo-olivacea in graft tissues, and Phaeomoniella chlamydospora and Neofusicoccum parvum in the root collar. Treatment had the greatest influence on the total and GTD-related fungal communities of Chardonnay and Xarel·lo, respectively. Total community variation was driven by treatment and nursery in rootstocks, whereas HWT most significantly affected the GTD community composition in R-110 rootstock. In conclusion, changes in fungal abundance were species-specific and mostly dependent on the plant tissue type; however, HWT did reduce plant biomass accumulation in the short-term.

Lignans Extract from Knotwood of Norway Spruce-A Possible New Weapon against GTDs.

Grapevine trunk diseases (GTDs) pose a major threat to the wine industry worldwide. Currently, efficient biological methods or chemical compounds are not available for the treatment of infected grapevines. In the present study, we used an extract from the knotwood of spruce trees as a biological control against GTDs. Our in vitro trial was focused on the antifungal effects of the extract against the most common GTD pathogens—Cadophora luteo-olivacea, Dactylonectria torresensis, Diaporthe ampelina, Diaporthe bohemiae, Diplodia seriata, Eutypa lata, and Phaeoacremonium minimum. Our in vitro trial revealed a high antifungal effect of the extract against all tested fungi. The inhibition rates varied among the different species from 30% to 100% using 1 mg·mL−1 extract. Subsequently, the efficiency of the extract was supported by an in planta experiment. Commercial grafts of Vitis vinifera were treated with the extract and planted. The total genomic DNA of grapevines was extracted 10 days and 180 days after the treatment. The fungal microbial diversities of the treated/untreated plants were compared using high-throughput amplicon sequencing (HTAS). Treated plants showed 76.9% lower relative abundance of the genus Diaporthe and 70% lower relative abundance of the genus Phaeoacremonium 10 days after treatment. A similar scenario was observed for the genus Cadophora 180 days after treatment, where treated plants showed 76% lower relative abundance of this genus compared with untreated grapevines.

Dissemination of esca-related pathogens in German vineyards: do arthropods play roles in vectoring spores?

Grapevine Trunk Diseases (GTDs) such as esca challenge viticulture. The main fungal agents of Petri disease or young esca, Phaeomoniella chlamydospora (Pch), diverse Phaeoacremonium species (Pm spp.) and Cadophora luteo-olivacea (Clo), are transmitted to pruning wounds of vines by rain splashes and air currents. Arthropod-mediated dispersal is another possibility for the pathogens to reach pruning wounds. The present study was the first to evaluate possible involvement of arthropods in the dissemination process of esca-related pathogens in German vineyards. Diversity of arthropods on grapevine trunks was determined in 2019 and 2020, using cardboard traps mounted on vine trunks. Captured arthropods were surveyed for the presence of esca-related pathogens on their exoskeletons by using a nested multiplex PCR. In total, 2099 arthropods were examined, of which 35% were positive for Phaeomoniella chlamydospora (Pch), 21% for Phaeoacremonium spp. (Pm), and 7% for Cadophora luteo-olivacea (Clo). Earwigs and spiders were the most prevalent trapped arthropods; Pch was detected on 27% of earwigs and 38% of spiders, Pm spp. on 17 and 19%, and Clo on 3 and 8% of these arthropods. In both years, arthropods carrying the pathogens were already present in April, and therefore within the presumed susceptibility phase of pruned vines. These results indicate involvement of arthropods in the dispersal of esca-related pathogens in German vineyards. Further research, particularly to determine the infection potential of insect-borne fungi, is needed to confirm transmission risk. These results underline the importance of protecting vine pruning wounds to prevent host invasion by GTD pathogens.

Occurrence of Canker and Wood Rot Pathogens on Stone Fruit Propagation Material and Nursery Trees in the Western Cape of South Africa.

Dieback and canker of young stone fruit trees can cause suboptimal growth and even death under severe conditions. One source of inoculum of canker pathogens could be through nursery trees harboring latent infections that would not be visible to inspections done according to the deciduous fruit scheme. The objectives of this study were to identify the canker and wood rot fungal pathogens present in nursery stone fruit trees as well as in propagation material and to evaluate their pathogenicity. Isolations were made from scion and rootstock propagation material and from certified nursery stone fruit trees. The plant material sampled did not have any external symptoms. The certified nursery trees when cross-sectioned displayed brown discoloration from the pruning wound, the bud union, and often the crown. Fungal species isolated were identified by sequencing of the relevant barcoding genes and phylogenetic analyses thereof. Canker- and wood rot-associated fungi were identified. Buds used for budding had low levels of infection, with 1.2% of dormant buds infected and 0.4% of green buds infected. The dormant rootstock shoots had a canker pathogen incidence of 6.2% before they were planted in the nursery fields and increased inasmuch as the ungrafted, rooted rootstock plants had 11.1% infection with canker and wood rot pathogens. Out of 1,080 nursery trees, the canker- and wood rot-associated fungi infected 21.8% of trees. The canker-causing pathogens that were isolated the most were Cadophora luteo-olivacea and Diplodia seriata. A low incidence of wood rot fungi was found, with only 1.5% of nursery trees infected. In total, 26 new reports of fungal species on stone fruit in South Africa were made. Of these, 22 have not been found on stone fruit worldwide. The pathogenicity trials' results confirmed the pathogenic status of these newly reported species. All of the isolates tested formed lesions significantly longer than the control, 4 months after wound inoculation of 2-year-old shoots of two plum orchards. Lasiodiplodia theobromae was the most virulent species on both plum cultivars. The results of this research showed that nursery stone fruit trees and propagation material can harbor latent infections. Different management practices need to be evaluated to prevent these infections to ensure healthier stone fruit nursery trees.

Post-Harvest Non-Conventional and Traditional Methods to Control Cadophora luteo-olivacea: Skin Pitting Agent of Actinidia chinensis var. deliciosa (A. Chev.)

Cadophora luteo-olivacea represents a critical problem for kiwifruit in the post-harvest phase, mainly for its little note epidemiology. The study presented some results about the possibility of preserving kiwifruit from skin pitting symptoms using alternative methods to fungicides. By in vitro assays, antagonist mechanisms of action against pathogen isolates were tested. Trichoderma harzianum (Th1) showed the highest inhibitory activity against C. luteo-olivacea isolates by volatile, non-volatile, and by dual culture assay, displaying an inhibition respectively by 90%, 70.6%, and 78.8%, and with respect to Aureobasidium pullulans (L1 and L8) by 23.3% and 25.8%, 50% and 34.7%, and 22.5% and 23.6%, respectively. Further, the sensitivity on CFU and mycelial growth of C. luteo-olivacea isolates to fludioxonil, and CaCl2 was tested, displaying interesting EC50 values (0.36 and 0.92 g L−1, 22.5 g L−1, respectively). The effect of Brassica nigra defatted meal was tested as biofumigation assays and through FT-IR (Fourier-Transform Infrared) spectroscopy. The above-mentioned treatments were applied in vivo to evaluate their efficacy on kiwifruits. Our data demonstrated that alternative solutions could be considered to control postharvest pathogens such as C. luteo-olivacea.

Screening of newly isolated marine-derived fungi for their laccase production and decolorization of different dye types

Six marine-derived fungi (Alternaria sp. D11, Alternaria sp. D21, Cadophora sp. D43, Cadophora luteo-olivacea D51, Phoma sp. K2BR, Phoma sp. K21) were isolated from the Çakalburnu Lagoon, Izmir Bay, Aegean Sea in Turkey. An effective method has been developed for marine-derived fungi isolation and laccase production of the fungi has been studied. This method consisted of immersing a sterile solid substrate containing lignin into the aquatic system under aseptic conditions and removing at the end of 10 days, isolation for laccase producing fungi of marine origin. The decolorization potential of the isolate Alternaria sp. D21 with the highest laccase activity was investigated for dyes containing azo, anthraquinone, triarylmethane and heterocyclic chemical classes. The decolorization rates were determined as 98% for Methyl orange, 93% for Acid green 3, 78% for Methylene blue, 71% for Remazol Brilliant Blue, 58% for Crystal violet, and 53% for Congo red after 144 h at 100 mg/L concentration of dyes. The ability of the marine-derived fungi to remove dyes of different chemical classes is also promising for waste containing mixtures of various pollutants.

Identification and Pathogenicity of Diplodia, Neofusicoccum, Cadophora, and Diaporthe Species Associated with Cordon Dieback in Kiwifruit cultivar Hayward in Central Chile.

Dieback symptoms associated with fungal trunk pathogens cause significant economic losses for farmers of kiwifruit and other woody fruit trees worldwide. This study represents the first attempt to identify and characterize the fungal trunk pathogens associated with cordon dieback disease of kiwifruit in central Chile. Field surveys were conducted throughout the main kiwifruit-growing regions in central Chile to determine the incidence and characterize the fungal trunk pathogens associated with cordon dieback of kiwifruit cultivar Hayward through morphological, molecular, and pathogenicity studies. A total of 250 cordon samples were collected and isolations were performed on 2% acidified potato dextrose agar (APDA) plus antibiotics and Igepal. The incidence of kiwifruit cordon dieback ranged between 5% and 85% in all surveyed areas in central Chile. A total of 246 isolates were isolated and identified using culture and morphological features belonging to three fungal taxa: Diaporthaceae spp. (Diaporthe ambigua and D. australafricana; n = 133 isolates); Botryosphaeriaceae spp. (Diplodia seriata and Neofusicoccum parvum; n = 89 isolates); and Ploettnerulaceae spp. (Cadophora luteo-olivacea and C. malorum; n = 24 isolates). These were identified using phylogenetics studies of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) of the rDNA, part of the β-tubulin gene (tub2), and part of the translation elongation factor 1-α gene (tef1-α). Isolates of N. parvum and D. seriata were the most virulent, causing internal brown lesions and dieback symptoms in attached green shoots, attached lignified canes, and young inoculated kiwifruits. This report is the first to describe D. seriata and C. luteo-olivacea associated with kiwifruit cordon dieback in Chile. It presents the first description of N. parvum causing kiwifruit dieback worldwide.

Vascular Fungi Associated with Branch Dieback of Olive in Super-High-Density Systems in Southern Spain.

Symptoms of branch dieback of olive with internal longitudinal dark streaking were observed during routine surveys in super-high-density systems in southern Spain. Nineteen fungal isolates recovered from wood samples showing internal discoloration and necrotic xylem vessels were selected. Multilocus alignments of the internal transcribed spacer, 28S ribosomal RNA, β-tubulin, or actin were performed, and the following species were identified: Acremonium sclerotigenum, Cadophora luteo-olivacea, Paracremonium sp., Phaeoacremonium italicum, P. minimum, P. scolyti, and Pseudophaeomoniella oleicola. Colony color, mycelial growth, conidial characteristics, and production were defined on potato dextrose agar, malt extract agar (MEA), and oatmeal agar. Phenotypic characteristics and conidial production varied depending on the isolate and culture media. The effect of temperature on mycelial growth was evaluated on MEA. The isolates showed slow mycelial growth (0.5 to 2.0 mm day-1), with the optimum temperature ranging from 23.2 to 33.9°C. Pathogenicity tests were conducted on 9-month-old olive potted plants (Arbequina) inoculated with mycelial plugs. C. luteo-olivacea, Phaeoacremonium minimum, and Phaeomoniella chlamydospora isolates from grapevine were included in the pathogenicity tests for comparative purposes. Prior to inoculation, the effect on the infection by inoculation with conidial suspensions or mycelial plugs was evaluated, with the second method being the most effective. C. luteo-olivacea was the fungus most aggressive to olive, followed by Phaeoacremonium minimum.