Phytopathologia Mediterranea 2020-12-31T14:13:33+00:00 Editorial Office Open Journal Systems <p><em>Phytopathologia Mediterranea</em> is an international open-access, peer-reviewed journal edited by the <a title="Mediterranean phytopathological union" href="" target="_blank" rel="noopener">Mediterranean Phytopathological Union</a>. The journal deals with the main areas of plant pathology as epidemiology, control, biochemical and physiological aspects, application of molecular biology techniques, applied to fungi, bacteria, phytoplasmas, viruses, viroids, nematodes, etc. Special attention is given to phytopathological problems of the Mediterranean area. The journal includes 3 issues per year in which a review paper, original research papers, short notes and new disease reports are published. It also includes Book reviews of interest for Mediterranean phytopathologists. Papers are published in English. Phytopathologia Mediterranea is covered by CAB, BIOSIS, AGRIS, Chemical Abstracts, CSA, JSTORE.</p> <p><em>Phytopathologia Mediterranea</em> is printed with the financial support of the Ministero per i Beni Culturali, Roma, Italy.</p> Preface to the 11th Special issue on Grapevine Trunk Diseases 2020-12-30T18:37:54+00:00 José Ramón ÚRBEZ-TORRES Florence FONTAINE <p class="p1"><em>Grapevine trunk diseases (GTDs) are a complex caused by many taxonomically unrelated fungi. Diseases in this complex are responsible for different vascular and foliar symptoms, which cause overall decline and eventual death of grapevines. Though GTDs have been known since the late 19th Century their significance and impacts on vine health have been fully recognized much more recently. Today, GTDs are considered major biotic factors reducing grapevine yields and vineyard lifespans, which cause substantial economic losses to grape and wine industries worldwide.</em></p> <p class="p1"><em>Emergence of these diseases in the early 1990s, and the urgent need for effective disease management strategies by growers and industry, focused scientific attention. As a result, a meeting in California took place in July of 1998, organized by the viticulturist Lucie Morton, who saw the potential threats posed by fungus infections of grapevine trunks. On that occasion, participants and founding members developed the structure and objectives of the International Council on Grapevine Trunk Diseases (ICGTD). Since then, the primary goal of the ICGTD has been to promote relevant research, and encourage collaboration and knowledge exchange among scientists and industry partners, on issues pertaining to GTDs.</em></p> <p class="p1"><em>Every two years, since 1999, the ICGTD has organized the International Workshop on Grapevine Trunk Diseases (IWGTD), where scientists and industry members from around the world present, share and discuss the latest research findings on different areas concerning this increasingly important disease complex.</em></p> <p class="p1"><em>This 11th Special Issue of </em><span class="s1">Phytopathologia Mediterranea </span><em>on GTDs collects together presentations given at the 11th IWGTD, which was held on July 7-12, 2019, in Penticton, British Columbia, Canada. This conference marked the 20th Anniversary of the Workshop. The Workshop was attended by 151 participants from 21 countries. A total of 64 oral and 48 poster papers were presented in four sessions, covering Pathogen Detection and Identification, Epidemiology, Host-Pathogen Interactions, and Disease Management. In addition, a special session on GTD control provided the local grapevine industry with a practical summary and overview of the current GTD management options and the economic impacts they cause.</em></p> <p class="p1"><em>A student competition, with awards for best oral and poster presentations, was held for the first time at IWGTDs, with 20 graduate students participating. For Best Poster presentations, first place was awarded to Pierluigi Reveglia (Charles Sturt University, Wagga, New South Wales, Australia), second to Edelweiss Rangel Montoya (Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California, Mexico), and third to Daina Grinbergs (Instituto Nacional de Investigaciones Agropecuarias, Chillán, Chile). For Best Oral Presentation, first place was awarded to Jinxz Pollard-Flamand (Agriculture and Agri-Food Canada Summerland RDC, British Columbia, Canada), second to Clément Labois (Université de Haute-Alsace, Colmar, France), and third to María del Pilar Martínez-Diz (Estación de Viticultura e Enoloxía de Galicia, Ourense, Spain).</em></p> <p class="p1"><em>The ICGTD Council Members have determined that these Workshops will now be convened at 3 year intervals. </em><strong><em>The 12th IWGTD will be held in the Czech Republic in 2022</em></strong><em>.</em></p> <p class="p1"><strong><em>The editorial team of this Journal is indebted to all authors of papers presented in this Special Issue, for their support and contributions.</em></strong></p> 2020-12-12T00:00:00+00:00 Copyright (c) 2020 Laura Mugnai Grapevine trunk disease fungi: their roles as latent pathogens and stress factors that favour disease development and symptom expression 2020-12-30T18:38:22+00:00 José Ramón ÚRBEZ-TORRES Jared HRYCAN Miranda HART Patricia BOWEN Thomas FORGE <p class="p1">Grapevine trunk diseases (GTDs) are major biotic factors reducing yields and limiting vineyard economic life spans. Fungi in the GTD complex cause a range of symptoms in host plants, although these pathogens are slow wood colonizers and potentially latent pathogens. Understanding has recently increased on the possible roles that GTD fungi may play as latent pathogens, and how this can be translated into disease management. This paper summarizes evidence for the latent nature of infections by these fungi in grapevines and other hosts. Abiotic and biotic stressors have been associated with symptom expression in many hosts, but limited information is available regarding their roles in symptom development in grapevines. Based on research conducted in other pathosystems, this review discusses how abiotic and/or biotic stress factors may influence the transition from the endophytic to the pathogenic phases for GTD fungi. Potential methods for stress mitigation are also outlined as alternative GTD control strategies to minimize the economic impacts that that these diseases have on grape production.</p> 2020-10-10T00:00:00+00:00 Copyright (c) 2020 Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada Characterization of Trichoderma isolates from southern Italy, and their potential biocontrol activity against grapevine trunk disease fungi 2020-12-30T18:38:43+00:00 José Ramón ÚRBEZ-TORRES Eugenia TOMASELLI Jinxz POLLARD-FLAMAND Julie BOULÉ Donato GERIN Stefania POLLASTRO <p class="p1">Grapevine trunk diseases (GTDs) are one of the most economically important diseases of grapevines, causing yield reductions and limiting vineyard lifespans. Fungal pathogens responsible for GTDs primarily infect grapevines through pruning wounds. The lack of systemic fungicides to stop the advance of fungi in vine vascular systems makes the use of pruning wound protection with either synthetic chemicals or biological control agents (BCAs) the main available GTD control strategy. Demands for sustainable grape production and increasing limitations on pesticide usage have raised interest in potential use of BCAs as pruning wound protectants against GTDs. The objectives of this study were to characterize 16 <span class="s1"><em>Trichoderma</em></span> isolates from southern Italy using molecular methods, and to evaluate their potential activity as BCAs <span class="s1"><em>in vitro</em></span> against the GTD canker-causing fungi <span class="s1"><em>Diplodia seriata</em></span>, <span class="s1"><em>Eutypa lata </em></span>and <span class="s1"><em>Neofusicoccum parvum</em></span>. Molecular studies along with phylogenetic analyses identified eight species, including <span class="s1"><em>Trichoderma atroviride</em></span>, <span class="s1"><em>T. guizhouense</em></span>, <span class="s1"><em>T. harzianum</em></span>, <span class="s1"><em>T. koningiopsis</em></span>, <span class="s1"><em>T. longibrachiatum</em></span>, <span class="s1"><em>T. paratroviride</em></span>, <span class="s1"><em>T. paraviridescens</em></span>, <span class="s1"><em>T. spirale</em></span>, and one unidentified <span class="s1"><em>Trichoderma</em></span> sp. All these species had optimum mycelium growth between 25 and 35°C. <span class="s1"><em>In vitro</em></span> dual culture experiments assessed antagonistic capabilities of all the<span class="s1"><em> Trichoderma</em></span> isolates against <span class="s1"><em>D. seriata</em></span>, <span class="s1"><em>E. lata</em></span> and <span class="s1"><em>N. parvum</em></span>, and showed that the isolates inhibited mycelial growth of the pathogens by up to 70%. The most inhibitory isolates were tested <span class="s1"><em>in planta</em></span> for capability to protect pruning wounds against <span class="s1"><em>D. seriata</em></span> and <span class="s1"><em>N. parvum</em></span> in a detached cane assay. All the selected <span class="s1"><em>Trichoderma</em></span> isolates gave &gt;80% control of <span class="s1"><em>D. seriata</em></span> and 60% control of <span class="s1"><em>N. parvum</em></span>, and protected pruning wounds for up to 21 d after treatment.</p> 2020-07-17T00:00:00+00:00 Copyright (c) 2020 Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada Precise nondestructive location of defective woody tissue in grapevines affected by wood diseases 2020-12-30T18:39:03+00:00 Ana Teresa VAZ Giovanni DEL FRARI Ricardo CHAGAS António FERREIRA Helena OLIVEIRA Ricardo BOAVIDA FERREIRA <p class="p1">Grapevine trunk diseases are major threats to viticulture. A diverse array of Ascomycetes and Basidiomycetes can affect perennial and, indirectly, annual organs of grapevines. Early infections produce wood discolouration, brown wood streaking, black spots and wood necroses. However, all wood symptoms are internal, making nondestructive identification of infected plant material very difficult. To date, there are no nondestructive methods for detecting the presence of developing wood infections, neither in nursery nor field conditions. This means that infected propagation material is planted into new vineyards. Three technologies, magnetic resonance imaging (MRI), computed tomography scan (CT scan) and X-Ray microtomography (Micro-CT), were assessed for determining presence, location and extent of grapevine wood defects caused by fungal infections. Results indicated that MRI lacked resolution to differentiate between asymptomatic and defective wood. CT scan analyses revealed substantial differences in radiodensity when comparing asymptomatic wood to wood with black spots, necroses, and decay. Greatest resolution was achieved with micro-CT (6 μm). This technology precisely distinguished asymptomatic from defective wood, for wood symptoms including necrosis, decay, black spots and brown wood streaking affecting individual xylem vessels, in perennial wood and canes. Micro-CT was thus the best method for nondestructive identification of wood defects resulting from infections. Further work is required to make this technology feasible for the rapid screening of grapevine nursery stock, both in nurseries and at planting.</p> 2020-08-05T00:00:00+00:00 Copyright (c) 2020 Ana Teresa Vaz, Giovanni Del Frari, Ricardo Chagas, António Ferreira, Helena Oliveira, Ricardo Boavida Ferreira Fungal pathogens associated with grapevine trunk diseases in young vineyards in Sicily 2020-12-31T14:13:33+00:00 Vincenzo MONDELLO Selene GIAMBRA Gaetano CONIGLIARO Nicola FRANCESCA Santella BURRUANO <p class="p1">After the first report of grapevine decline caused by <span class="s1"><em>Botryosphaeriaceae</em></span> in Sicily in 2007, epidemiological studies carried out in mature vineyards until 2011 confirmed the widespread occurrence of “Botryosphaeria dieback” and the “Esca complex” disease. Dieback symptoms were also recently observed in two young vineyards in Partanna and Castellammare del Golfo in western Sicily (Trapani province). Declining vines were inspected for grapevine trunk disease (GTD) symptoms, and were uprooted and submitted for analyses. Fungal isolates were collected and identified using culturing and molecular analyses. One isolate per identified species was inoculated to three grapevine shoots to evaluate pathogenicity and fulfil Koch’s postulates. Several GTD <span class="s1"><em>Botryosphaeriaceae</em></span> pathogens in the genera <span class="s1"><em>Cadophora, Ilyonectria, Neonectria</em></span>, <span class="s1"><em>Phaeoacremonium </em></span>and <span class="s1"><em>Phaeomoniella </em></span>were isolated from the symptomatic young vines. Artificial inoculation confirmed the pathogenicity of these fungi. In addition, virulence variability was observed among the isolates, with <span class="s1"><em>P. chlamydospora</em></span> causing the largest lesions. The different species were associated with specific symptoms and/or host vine parts, especially in the roots and around the grafting areas. Several fungi associated with Petri disease and black foot were shown to be responsible of young vine decline.</p> 2020-08-12T00:00:00+00:00 Copyright (c) 2020 Vincenzo Mondello, Selene Giambra, Gaetano Conigliaro, Nicola Francesca, Santella Burruano In vitro screening of Trichoderma isolates for biocontrol of black foot disease pathogens 2020-12-30T18:39:28+00:00 Wynand Jacobus VAN JAARSVELD Francois HALLEEN Lizel MOSTERT <p class="p1">Management of black foot disease (BFD) of grapevines is difficult due to limited control options. Biological control fungi, in particular <span class="s1"><em>Trichoderma</em></span> spp., hold potential as part of integrated management of BFD. <span class="s1"><em>Trichoderma</em></span> <span class="s1"><em>atroviride</em></span>, <span class="s1"><em>T.</em></span> <span class="s1"><em>fertile</em></span>,<span class="s1"><em> T. harzianum</em></span> and <span class="s1"><em>T.</em></span> <span class="s1"><em>virens</em></span> were evaluated <span class="s1"><em>in vitro</em></span> against four common BFD pathogens in South Africa, including <span class="s1"><em>Campylocarpon fasciculare</em></span>, <span class="s1"><em>C. pseudofasciculare</em></span>,<span class="s1"><em> Dactylonectria macrodidyma</em></span> and<span class="s1"><em> Ilyonectria liriodendri</em></span>. Effects of <span class="s1"><em>Trichoderma</em></span> volatile organic and diffusible antifungal compounds (VOCs and DACs) and direct antagonistic effects were determined in Petri dish assays. Pathogen growth inhibition was determined in the VOC and DAC assays. Macro- and microscopic observations of fungus interaction zones were made in dual culture plate assays. Greater BFD pathogen growth inhibition occurred with the DACs than the VOCs. For both classes of compounds, <span class="s1"><em>D. macrodidyma</em></span> was the most sensitive pathogen (100% inhibition by DACs and 65% by VOCs). In some cases, depending on the <span class="s1"><em>Trichoderma</em></span> spp. isolate, growth stimulation occurred for <span class="s1"><em>I. liriodendri</em></span>, <span class="s1"><em>C</em></span>. <span class="s1"><em>fasciculare</em></span> and <span class="s1"><em>C</em></span>. <span class="s1"><em>pseudofasciculare. </em></span>Macroscopically observed <span class="s1"><em>Trichoderma</em></span> and BFD pathogen interactions included total or partial overgrowth, often associated with sporulation of the <span class="s1"><em>Trichoderma</em></span> spp., and arrested growth or the formation of inhibition zones. Microscopic interactions included adhesion of the <span class="s1"><em>Trichoderma</em></span> to pathogen hyphae, pathogen hyphae swelling, malformation and disintegration. In general, <span class="s1"><em>in vitro</em></span> efficacy was isolate-dependent, both for <span class="s1"><em>Trichoderma</em></span> spp. and the BFD pathogen.</p> 2020-08-05T00:00:00+00:00 Copyright (c) 2020 Lizel Mostert, Wynand Van Jaarsveld, Francois Halleen Synergistic effects of water deficit and wood-inhabiting bacteria on pathogenicity of the grapevine trunk pathogen Neofusicoccum parvum 2020-12-30T18:39:42+00:00 Rana HAIDAR Amira YACOUB Antoine PINARD Jean ROUDET Marc FERMAUD Patrice REY <p class="p1">Grapevine trunk diseases (GTDs), including Esca and Botryosphaeria dieback, are major factors limiting grapevine productivity and longevity in France. The influence of combined biotic and abiotic stress factors on GTD development is not well understood. This study evaluated individual and combined effects of a biotic factor (bacterium occurrence) and abiotic stress (water deficit), on the pathogenicity to grapevine of the GTD pathogen <span class="s1"><em>Neofusicoccum parvum</em></span>. Co-inoculation of 46 different bacterium strains with <span class="s1"><em>N. parvum </em></span>into growing grapevine-cuttings showed synergistic relationships between several of the strains and the pathogen. <span class="s1"><em>Bacillus pumilus </em></span>(strain S35) and<span class="s1"><em> Xanthomonas </em></span>sp<span class="s1"><em>.</em></span> (strain S45), which cause canker lesions, were selected for testing bacterial and fungal interactions in grapevine, under individual and combined stress conditions. <span class="s1"><em>In vitro</em></span>, each of the bacterium strains neither inhibited <span class="s1"><em>N. parvum </em></span>nor the co-inoculated bacterium strain. None of the three microorganisms degraded lignin, but all three degraded cellulose and hemicellulose. In a greenhouse experiment, 9 months after microbial inoculations in plants under normal and water-restricted conditions, effects on canker formation of water deficit combined with the bacteria and <span class="s1"><em>N. parvum</em></span> interactions were assessed and on <span class="s1"><em>N. parvum </em></span>DNA contents. Synergistic effects of biotic and abiotic stresses were demonstrated. The bacterial infection stress influenced the grapevine/<span class="s1"><em>N. parvum </em></span>interaction by increasing canker lesions and <span class="s1"><em>N. parvum </em></span>DNA contents in plants co-inoculated with <span class="s1"><em>B. pumilus </em></span>and/or<span class="s1"><em> Xanthomonas </em></span>sp. qPCR assays showed that high contents of <span class="s1"><em>N. parvum </em></span>DNA occurred in water-restricted potted vines inoculated with <span class="s1"><em>N. parvum</em></span>, especially in the inoculation zones<span class="s1"><em>. </em></span>These results provide insights into the relative roles of biotic and abiotic stress factors in <span class="s1"><em>Botryosphaeriaceae</em></span> symptom expression, which could assist development of future GTD management.</p> 2020-10-10T00:00:00+00:00 Copyright (c) 2020 Rana HAIDAR Spore dispersal of Eutypella species under desert grape-growing conditions of southern California 2020-12-30T18:40:01+00:00 José Ramón ÚRBEZ-TORRES Carmen GISPERT Florent Pierre TROUILLAS <p class="p1">The seasonal abundance of <span class="s1"><em>Diatrypaceae</em></span> spores was studied in southern California’s desert table grape-growing region of Coachella Valley. Glass microscope slides covered with petroleum jelly were placed in a mature cv. Mid-Night Beauty® vineyard, and collected weekly from September 2006 to May 2009 (1400 samples for 140 consecutive weeks). Overall, <span class="s1"><em>Diatrypaceae</em></span>-like colonies were recorded from Petri plates after processing spore traps in 93 (66%) of 140 weeks. Phylogenetic analyses showed <span class="s1"><em>Eutypella citricola </em></span>and <span class="s1"><em>Eutypella microtheca </em></span>to be the <span class="s1"><em>Diatrypaceae</em></span> spp. captured from the spore traps. Though spores were captured throughout each year, their incidence varied among the different seasons. The greatest number of <span class="s1"><em>Eutypella</em></span> spores were captured in autumn (38.7% of the total) followed by winter (30.6%), summer (19.7%), and spring (11%). The greatest numbers of spores were captured in October each year (15.7%) and least in June (1%). <span class="s1"><em>Eutypella</em></span> spore release was correlated with rainfall only in 26 (28%) of the 93 weeks that spores were captured during the study. Analysis of diseased samples collected from the cv. Mid-Night Beauty® vineyard showed that <span class="s1"><em>E. citricola</em></span>, <span class="s1"><em>E. microtheca </em></span>and<span class="s1"><em> E. scoparia</em></span> were the most prevalent fungi isolated from cankers. A pathogenicity study showed that <span class="s1"><em>E. citricola</em></span> and <span class="s1"><em>E. microtheca</em></span> isolates collected from spore traps caused larger vascular necrosis than the non-inoculated controls, indicating their role as pathogens on grapevines. This study has demonstrated <span class="s1"><em>Eutypella</em></span> spp. to play an important role in grapevine health under desert growing conditions of southern California. In addition, and contrary to what it is largely accepted, results from this research suggest that <span class="s1"><em>Diatrypaceae</em></span> spore release can occur in the absence of precipitation. This study expands current knowledge on epidemiology of <span class="s1"><em>Diatrypaceae</em></span> spp. other than <span class="s1"><em>Eutypa lata</em></span>, and provides important information for enhancing control strategies against grapevine trunk diseases under desert growing conditions.</p> 2020-08-15T00:00:00+00:00 Copyright (c) 2020 Her Majesty the Queen in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada Distribution of three grapevine trunk pathogens in Chilean vineyards, determined using molecular detection from asymptomatic woody pruning material 2020-12-30T18:40:16+00:00 Felipe GAÍNZA-CORTÉS Rosa ROA-ROCO Paulina ARRAÑO-SALINAS Pablo RODRÍGUEZ-HERRERA Mauricio A. LOLAS José Carlos CARIS-MALDONADO Patricia SILVA-FLORES Álvaro GONZÁLEZ <p class="p1"><span class="s1">Grapevine Trunk Diseases (GTDs) cause important economic losses in vineyards. Diagnosis of pathogens causing GTDs is usually achieved using culture methods from symptomatic plants, but these methods may not be definitive. This study aimed to detect three fungi associated with GTDs in Chile (</span><span class="s2"><em>Diplodia seriata</em></span><span class="s1">, </span><span class="s2"><em>Phaeomoniella chlamydospora</em></span><span class="s1"> and </span><span class="s2"><em>Eutypa lata</em></span><span class="s1">) using qPCR methods, after extracting DNA from asymptomatic woody pruning material taken from 912 grapevine plants and 346 rootstocks. Pathogen incidence and distribution across different regions, vineyards, grape and wine cultivars, plant ages and rootstocks were determined. Forty percent of assessed grapevine plants and 42% of rootstocks were positive for the assayed GTD pathogens. The fungus with the greatest incidence was </span><span class="s2"><em>D. seriata </em></span><span class="s1">(36% of plants and 30% of rootstocks)</span><span class="s2"><em>, </em></span><span class="s1">followed by </span><span class="s2"><em>E. lata </em></span><span class="s1">(6% of plants and 20% of rootstocks)</span> <span class="s1">and </span><span class="s2"><em>P. chlamydospora </em></span><span class="s1">(4% of plants and 5% of rootstocks). Positive relationships were detected between the presence of </span><span class="s2"><em>D. seriata </em></span><span class="s1">and </span><span class="s2"><em>P. chlamydospora </em></span><span class="s1">and grapevine age. However, the three fungi were randomly distributed across graprevine plants and rootstocks since none of the assessed factors had statistically significant influence in their distribution. This study is the first to assess incidence and distribution of </span><span class="s2"><em>E. lata</em></span><span class="s1"> in Chile. The qPCR-based method described could be used for detecting fungi in asymptomatic nursery plants, and be used to avoid distribution of infected plants into new vineyard plantings.</span></p> 2020-11-14T00:00:00+00:00 Copyright (c) 2020 Felipe Gaínza-Cortés, Rosa Roa-Roco, Paulina Arraño-Salinas, Pablo Rodríguez-Herrera, Mauricio A. Lolas, Patricia Silva-Flores, Álvaro González Aerial inoculum patterns of Petri disease pathogens in South African vineyards and rootstock mother blocks 2020-12-30T18:40:34+00:00 Francois HALLEEN Mahlatse A. BALOYI Michael C. BESTER Lizel MOSTERT <p class="p1"><span class="s1">Petri disease is caused by the xylem inhabiting fungi </span><span class="s2"><em>Phaeomoniella </em></span><span class="s1">(</span><span class="s2"><em>Pa.</em></span><span class="s1">)</span><span class="s2"><em> chlamydospora</em></span><span class="s1"> and several </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> (</span><span class="s2"><em>Pm.) </em></span><span class="s1">species. Pruning wounds are known host ports of entry for aerial spores of these pathogens. However, knowledge is lacking on occurrence of these pathogens as aerial inoculum within South African vineyards. This study determined when spores of Petri disease pathogens are released in Western Cape Province vineyards and how these spore release events coincided with pruning activities when infections could occur. The research was conducted for two seasons from mid-May to early December 2012 and from mid-March to early December 2013. Microscope slide spore traps were affixed to arms of infected vines in six vineyards and mother vines in two rootstock mother vine nurseries. The slides were replaced weekly and fungal spores were retrieved from them, cultured, counted and identified. Colonies resembling those of </span><span class="s2"><em>Pa. chlamydospora</em></span><span class="s1"> and </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> spp. were subcultured for further molecular identification. Species of </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> were identified by amplification of the partial beta-tubulin gene. Taqman probes and primers were developed to facilitate fast detection of the most frequently occurring species (</span><span class="s2"><em>Pm. minimum</em></span><span class="s1">, </span><span class="s2"><em>Pm. parasiticum</em></span><span class="s1"> and </span><span class="s2"><em>Pm. sicilianum</em></span><span class="s1">), using real-time PCR. Petri disease pathogens occurred throughout the periods investigated. </span><span class="s2"><em>Phaeomoniella chlamydospora</em></span><span class="s1"> and </span><span class="s2"><em>Pm. minimum </em></span><span class="s1">were trapped in all vineyards. A total of 14 </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> species were identified, with the greatest diversity ever recorded in vineyards, including </span><span class="s2"><em>Pm. australiense, Pm. griseo-olivaceum, Pm. griseorubrum, Pm. inflatipes</em></span><span class="s1">,</span><span class="s2"><em> Pm. iranianum, Pm. italicum, Pm. minimum, Pm. parasiticum, Pm. prunicola, Pm. scolyti, Pm. sicilianum, Pm. subulatum, Pm. venezuelense </em></span><span class="s1">and</span><span class="s2"><em> Pm. viticola</em></span><span class="s1">. Of these, only </span><span class="s2"><em>Pm. minimum </em></span><span class="s1">and</span><span class="s2"><em> Pm. inflatipes </em></span><span class="s1">have been reported as aerial inoculum within vineyards. Spore release coincided with winter and spring pruning activities. The occurrence of six </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> species in rootstock mother vine nurseries highlights the high risk of pathogen spread through infected nursery material. This is the greatest </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> species diversity ever recorded in vineyards and the first detection of </span><span class="s2"><em>Phaeoacremonium</em></span><span class="s1"> species aerial inoculum in grapevine rootstock mother vine nurseries. The high species diversity and frequency of spore release in vineyards and rootstock mother vine nurseries coinciding with traditional pruning practices emphasizes the need to develop effective wound protection strategies to avoid infection of unprotected grapevine pruning wounds.</span></p> 2020-10-11T00:00:00+00:00 Copyright (c) 2020 Francois Halleen, Michael Bester, Lizel Mostert Yield loss estimation and pathogen identification from Botryosphaeria dieback in vineyards of Central Chile over two growing seasons 2020-12-30T18:40:58+00:00 Alejandra LARACH Carolina TORRES Natalia RIQUELME Miryam VALENZUELA Eduardo SALGADO Michael SEEGER Ximena BESOAIN <p class="p1">Dieback symptoms have been increasingly reported in Chilean vineyards over recent years. Although there have been studies on <span class="s1"><em>Botryosphaeriaceae</em></span> species and associated trunk disease incidence and severity in table grape-producing vineyards, their impacts on ‘Cabernet Sauvignon’, the most planted red wine grape in Chile, is unknown. This study determines the fungus species, incidence, disease severity, and yield losses associated with Botryosphaeria dieback in Chilean ‘Cabernet Sauvignon’ vineyards. Nine vineyards were surveyed during two growing seasons (2010 and 2018), and symptomatic wood samples were taken. Total potential production and yield losses were estimated from spur counts (2010) from harvested vines (2018) with different degrees of infection. Overall disease incidence was 87% in 2010 and 84% in 2018. Severity was 49% in 2010 and 47% in 2018. Yield losses were 39% in 2010 and 46% in 2018. <span class="s1"><em>Diplodia seriata </em></span>was the most prevalent fungus isolated from symptomatic plants in both growing seasons. This study highlights the impacts of grapevine trunk diseases in vineyards in Central Chile, and indicates the need for improved disease management strategies.</p> 2020-12-25T19:44:05+00:00 Copyright (c) 2020 Alejandra LARACH, Carolina TORRES, Natalia RIQUELME, Miryam VALENZUELA, Eduardo SALGADO, Michael SEEGER, Ximena BESOAIN The role of melanin in the grapevine trunk disease pathogen Lasiodiplodia gilanensis 2020-12-30T18:41:11+00:00 Edelweiss Airam RANGEL-MONTOYA Marcos PAOLINELLI Philippe ROLSHAUSEN Rufina HERNANDEZ-MARTINEZ <p class="p1"><span class="s1"><em>Lasiodiplodia</em></span> (<span class="s1"><em>Botryosphaeriaceae</em></span>) includes fungi that are considered among the most aggressive to grapevine, capable of causing cankers and necrotic lesions which eventually lead to death of host plants. A common characteristic of this genus is the presence of melanin in conidia and mycelium. Melanin is produced by the oxidation of phenolic and/or indolic compounds. For some fungi, this pigment is an essential factor for pathogenicity. This study characterized the types and the roles of melanin produced by <span class="s1"><em>Lasiodiplodia gilanensis</em></span>. Using specific melanin inhibitors, <span class="s1"><em>L. gilanensis</em></span> was shown to synthesize DOPA-melanin, DHN-melanin, and pyomelanin. DOPA-melanin was shown to be involved in production of aerial mycelium and protection against enzymatic lysis and oxidative stress; DHN-melanin to be involved in ramification of mycelium when exposed to nutrient deficiency; and pyomelanin to be related with hyphae development. The fungus used tyrosine as a precursor of DOPA-melanin and as carbon and nitrogen sources, and produced melanin inside the piths of infected plants. Genes involved in melanin synthesis were conserved among the <span class="s1"><em>Botryosphaeriaceae</em></span>, highlighting the importance of melanin in this family.</p> 2020-10-10T00:00:00+00:00 Copyright (c) 2020 Edelweiss Airam Rangel-Montoya, Marcos Paolinelli, Philippe Rolshausen, Rufina Hernandez-Martinez Pythium oligandrum induces grapevine defence mechanisms against the trunk pathogen Neofusicoccum parvum 2020-12-30T18:41:26+00:00 Amira YACOUB Rana HAIDAR Jonathan GERBORE Clementine MASSON Marie-Cécile DUFOUR Remy GUYONEAUD Patrice REY <p class="p1">Grapevine trunk diseases (GTDs) are increasing in vineyards in many grape production regions. Among the pathogens causing these diseases, <span class="s1"><em>Neofusicoccum parvum</em></span>, is one of the most frequent and virulent. To control GTDs, biocontrol is being developed using plant beneficial microorganisms. Strains of the oomycete <span class="s1"><em>Pythium oligandrum</em></span> have been shown to naturally colonize grapevine roots in vineyards in several countries in Europe. This study examined the ability of the root-coloniser <span class="s1"><em>P. oligandrum</em></span> to induce grapevine resistance against <span class="s1"><em>N. parvum</em></span>, by deciphering the gene expression changes in a set of 62 genes involved in different grapevine defence pathways. Two greenhouse assays showed that the wood necrosis of vine cuttings caused by <span class="s1"><em>N. parvum </em></span>was reduced by 65% when <span class="s1"><em>P. oligandrum </em></span>colonized root systems of the plants. The relative expression levels of selected genes in the host trunks were studied by real-time PCR. Plant responses were assessed after inoculation by <span class="s1"><em>P. oligandrum</em></span> and/or <span class="s1"><em>N. parvum</em></span>, at three different sampling time points (0, 14 and 150 d after <span class="s1"><em>N. parvum</em></span> inoculation). Sampling time influenced gene expressions for the different inoculation treatments. At each sampling time, specific host responses to the different treatments were also detected, for controls, and for inoculations with <span class="s1"><em>P. oligandrum</em></span>, <span class="s1"><em>N. parvum</em></span> or <span class="s1"><em>P. oligandrum </em></span>+<span class="s1"><em> N. parvum</em></span>. When <span class="s1"><em>P. oligandrum</em></span> colonized grapevine root systems, inoculation with the pathogen was associated with increased<span class="Apple-converted-space">&nbsp; </span>up-regulation and over-expression of particular genes, including those regulating Pathogen-Related proteins, cell wall reinforcement proteins and hormone signalling pathways. A priming effect of the grapevine defence system was induced in roots colonized by <span class="s1"><em>P. oligandrum</em></span>.</p> 2020-10-30T00:00:00+00:00 Copyright (c) 2020 Amira Yacoub, Rana Haidar Cross pathogenicity of Neofusicoccum australe and Neofusicoccum stellenboschiana on grapevine and selected fruit and ornamental trees 2020-12-30T18:41:50+00:00 Kabo MOJEREMANE Palesa LEBENYA Ihan L. DU PLESSIS Marieta VAN DER RIJST Lizel MOSTERT Josep ARMENGOL Francois HALLEEN <p class="p1"><span class="s1"><em>Neofusicoccum australe</em></span> is one of the most important <span class="s1"><em>Botryosphaeriaceae </em></span>pathogens occurring on fruit and vine crops. This fungus was recently taxonomically reassessed, identifying <span class="s1"><em>N. stellenboschiana </em></span>as a separate species. Previous pathogenicity studies used <span class="s1"><em>N. stellenboschiana</em></span> and <span class="s1"><em>N. australe</em></span> isolates as <span class="s1"><em>N. australe</em></span>, so assessment of the pathogenicity of these two species on grapevine and other hosts was required. A pathogenicity trial was conducted on detached shoots of grapevine, plum, apple, olive and Peruvian pepper tree. Shoots were individually inoculated with 11 <span class="s1"><em>N. australe</em></span> and eight <span class="s1"><em>N. stellenboschiana </em></span>isolates originally isolated from grapevine, plum, apple, olive, Peruvian pepper and fig. Both species formed lesions on all five hosts and were re-isolated 5 weeks post-inoculation. In general, the largest lesions were formed on plum and smallest on Peruvian pepper. Isolate host origin did not influence ability to cause lesions on other hosts. Isolates of <span class="s1"><em>N. australe</em></span> and <span class="s1"><em>N. stellenboschiana</em></span> differed in virulence on the various hosts, ranging from those that caused the largest lesions, a group causing intermediate lesions, and another causing lesions similar to uninoculated controls. The study demonstrates that<span class="s1"><em> N. australe</em></span> and <span class="s1"><em>N. stellenboschiana</em></span> isolates originating from various fruit hosts can infect alternative hosts including grapevine and other major fruit crops.</p> 2020-12-11T00:00:00+00:00 Copyright (c) 2020 Francois Halleen Metabolite fingerprints of Chardonnay grapevine leaves affected by esca is both clone- and year-dependent 2020-12-30T18:42:04+00:00 Florian MORET Gilles CLÉMENT Claire GROSJEAN Christelle LEMAÎTRE-GUILLIER Guillaume MORVAN Sophie TROUVELOT Marielle ADRIAN Florence FONTAINE <p class="p1">Esca is one of the most widespread grapevine trunk diseases affecting vineyards. This complex disease leads to leaf alterations, wood necrosis and eventually to plant death. Esca symptoms are caused by several fungi inhabiting the xylem of host plants and degrading the wood structure. The main pathogens causing the disease are <span class="s1"><em>Phaeomoniella chlamydospora</em></span>, <span class="s1"><em>Phaeoacremonium minimum</em></span>, <span class="s1"><em>Fomitiporia mediterranea </em></span>and other wood-rotting basidiomycetes. Grapevine susceptibility to esca can be predisposed by several factors, especially climate, vine age, and cultivar. An experiment was carried out (in 2015) to assess if esca expression on leaves could also be clone-dependent. Chardonnay clones 76 and 95 grown in the same plot were compared according to their developmental and physiological traits, metabolome, and foliar symptom expression. Leaves were sampled during summer on visually healthy vines as controls (C), and from asymptomatic (D-) and symptomatic (D+) shoots of esca-affected vines. Analysis of their metabolomes highlighted a clone-dependent metabolite fingerprint associated to esca expression. Opposite variations of specific metabolites were found between C and D+ leaves of both clones. The experiment was repeated (in 2018). Leaf samples could be discriminated, especially the C and D+ samples for each clone, but the differences were less marked than in the first experiment. Discriminant compounds were all different between the two experiments, and showed no opposite variations between C and D+ samples of both clones, which indicated variable metabolite responses from year to year for both clones. These results confirm that the leaf metabolite fingerprint associated to esca expression is clone-dependent, and is year-dependent in intensity and nature.</p> 2020-08-05T00:00:00+00:00 Copyright (c) 2020 Florian Moret, Gilles Clément, Claire Grosjean, Christelle Lemaître Guillier, Guillaume Morvan, Sophie Trouvelot, Marielle Adrian, Florence Fontaine Greeneria uvicola associated with dieback in vineyards of Sonora, Mexico 2020-12-30T18:42:18+00:00 Jesús Manuel ÁVILA SALAZAR Sergio Francisco MORENO SALAZAR Mario Alberto ÁVILA LUZANÍA Juan Manuel GUZMÁN ORTÍZ Freyman Humberto NAVARRO NAVA María Eugenia RENTERÍA MARTÍNEZ <p class="p1">The state of Sonora is the main grape production area in Mexico. Grapevine trunk diseases (GTD) are serious disease in this region. During the springs of 2017 and 2018, symptoms of yellow and wilted leaves, and necrotic buds, were observed in several vineyards in Sonora. Affected plants had numerous small, black and bright acervuli. This study aimed to identify the causative agent of this disease. Isolates were obtained from small pieces of damaged plant parts, and were cultured on potato dextrose agar. The developing mycelium was white but turned greyish white after 3 d. Multi-shaped black<span class="Apple-converted-space">&nbsp; </span>mucilaginous droplets appeared in the cultures after 2 d, and the agar in Petri dishes was completely covered with mycelium after 7 d, and the colonies had five or six rings with large numbers of conidiomata. Conidia were hyaline or light cream, fusiform, oval or ellipsoid, with truncated bases and narrow almost pointed apices, and were 6–10 mm long and 2–3 mm wide. Phylogenetically analysed concatenated sequences of the DNA from two representative isolates, from the internal transcribed spacer region, and large ribosomal subunit, showed they were in a separate clade which aligned with several strains of <span class="s1"><em>Greeneria uvicola</em></span>, confirming the presumptive morphological identity of the isolates. This cosmopolitan ascomycete is responsible for bitter rot of grapes, but the role of this fungus as a cause of grapevine trunk diseases is little known. Pathogenicity tests of the isolates were performed on 1-year-old ‘Passion Fire’ grapevines plants, one of the new cultivars planted in Sonora. All of strains <span class="s1"><em>G</em></span>. <span class="s1"><em>uvicola</em></span> were pathogenic, and the fungus was recovered from the lesions, fulfilling Koch’s postulates. This is the first report on the pathogenicity of <span class="s1"><em>G</em></span>. <span class="s1"><em>uvicola</em></span> in wood tissues of <span class="s1"><em>Vitis vinifera</em></span> in Mexico.</p> 2020-12-25T20:06:23+00:00 Copyright (c) 2020 María Eugenia Rentería Martínez, Jesús Manuel Ávila Salazar, Sergio Francisco Moreno Salazar , Mario Alberto Ávila Luzanía, Juan Manuel Guzmán Ortíz, Freyman Humberto Navarro Nava Host defence activation and root colonization of grapevine rootstocks by the biological control fungus Trichoderma atroviride 2020-12-30T18:42:34+00:00 Elodie STEMPIEN Romain Jean, Gaston PIERRON Ilka ADENDORFF Wynand Jacobus VAN JAARSVELD Francois HALLEEN Lizel MOSTERT <p class="p1">Several <span class="s1"><em>Trichoderma</em></span> species can act as biocontrol agents and hold the potential to control soilborne diseases through different modes of action. Little is known about the colonization pattern of <span class="s1"><em>Trichoderma atroviride</em></span> in grapevine roots and activation of induced systemic resistance <span class="s1"><em>in planta</em></span>. A laboratory model was developed to assess root colonization and its impact on grapevine defence activation. Rootstock cuttings from 1-year-old dormant canes were inoculated with conidium suspensions of <span class="s1"><em>T. atroviride</em></span> T-77 or <span class="s1"><em>T. atroviride</em></span> USPP T1, and host and inoculum colonisation were assessed after 21 d. The two strains of <span class="s1"><em>T. atroviride</em></span> were re-isolated from the treated plants (from 70% of the roots and 20% of crowns). Colonization rates did not depend on the <span class="s1"><em>Trichoderma </em></span>strain or rootstock cultivar. However, up-regulation of targeted defence genes was dependent on the inoculated <span class="s1"><em>Trichoderma</em></span> strain and rootstock cultivar. Furthermore, in leaves of rootstock cultivars ‘US 8-7’ and ‘Paulsen 1103’, genes were up-regulated which encode for PR proteins involved in plant defence or production of stilbenic phytoalexins. <span class="s1"><em>Trichoderma</em></span> <span class="s1"><em>atroviride</em></span> T-77 was transformed with tdTomato fluorescent protein to allow visualization by confocal laser scanning microscopy. These results give new insights into the mechanisms of grapevine-<span class="s1"><em>Trichoderma</em></span> interactions, and allow detection of establishment of potential biocontrol agents within host tissues.</p> 2020-11-14T00:00:00+00:00 Copyright (c) 2020 Elodie Stempien, Romain, Jean, Gaston Pierron, Ilka Addendorf, Wynand Jacobus van Jaarsveld, Francois Halleen, Lizel Mostert