About

Dr. Marc Fuchs is a Principal Investigator and Professor whose research and extension program at Cornell University focuses on translational research related to virus diseases affecting fruit and vegetable crops. Born and raised in the grape growing region of Alsace, France, he earned his master's and doctoral degrees from Université Louis Pasteur in Strasbourg. With over 35 years of experience as a virologist, Dr. Fuchs has concentrated much of his work on viruses of fruit and vegetable crops, particularly those affecting grapevine. His research program aims to characterize virus populations and the interactions between viruses, their vectors, and host plants. Additionally, he develops robust detection methodologies and explores innovative strategies for disease management in these crops.

Research topics

• Biology
• Virology
• Biotechnology
• Genetics
• Botany
• Ecology
• Horticulture
• Business

Selected publications

• Detection of Grapevine Red Blotch Virus at the Plant Level in Vineyards: An Uav-Based Approach Using a Vis/Nir Hyperspectral Camera, Machine Learning, and the Prospect Inversion Model

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• A decade of grapevine red blotch disease epidemiology reveals zonal roguing as novel disease management

  npj Viruses · 2025-04-15 · 3 citations

  articleOpen accessSenior author

  Red blotch disease, a threat to the grape industry, is caused by grapevine red blotch virus. This work is the first to study epidemiological patterns in a vineyard over the course of a decade, revealing an increase in disease incidence from 3.9% in 2014 to 36.4% in 2023 with rapid virus spread proximal to a transmission hotspot. Logistic and exponential models provided the best fit of spread in areas of high and low disease incidence and aggregation, respectively. An inverse spatial incidence of virus strains 1 and 2 suggested secondary spread mostly from diseased to neighboring vines and virus influx from background sources. Precipitation (3-4 years later) and air temperature (the same or 1 year later) significantly influenced epidemic parameters. Finally, asymptomatic infections contributed to spatial aggregations at increasing lags. These findings were salient for considering zonal roguing, the removal of diseased and surrounding vines, as a disease management option.

  PublisherOA PDFDOI

• Rearing of <i>Spissistilus festinus</i> [Say, 1830] (Hemiptera: Membracidae) on snap bean to facilitate studies on the transmission biology of grapevine red blotch virus

  Journal of Economic Entomology · 2025-07-11 · 1 citations

  articleOpen accessSenior author

  Spissistilus festinus [Say, 1830] (Hemiptera: Membracidae) is a well-known pest of leguminous crops and a more recently described pest of grapevine due to its ability to transmit grapevine red blotch virus, an economic threat to grape production. Legumes (family Fabaceae), unlike grapevines (Vitis vinifera L.), are preferred feeding and reproductive hosts for S. festinus. Here, we analyzed the development and behavior of S. festinus on snap beans (Phaseolus vulgaris) in comparison to alfalfa (Medicago sativa) and grapevines, with an emphasis on colony establishment and population growth. Snap beans supported all stages of S. festinus development, promoting feeding, reproduction, and colony establishment, as well as supporting a faster life cycle, particularly on detached trifoliates in controlled environmental chambers, compared with alfalfa. Moreso, social aggregation of S. festinus adults was observed on snap bean plants with the petiole as a preferred feeding site. A preference toward grapevine petioles was also seen, though their survival and aggregation behaviors drastically declined on this nonlegume host. Dissecting the alimentary canal of S. festinus revealed more orange, refractive oil droplets, and air bubbles in specimens from grapevine compared to specimens from snap bean or alfalfa, suggesting possible disruptions in digestive processing or nutritional deficiencies with the former host. Together, our findings highlight snap bean as an ideal host for rearing populations of S. festinus to be used in grapevine red blotch virus transmission studies.

  PublisherOA PDFDOI

• Summary of taxonomy changes ratified by the International Committee on Taxonomy of Viruses from the Plant Viruses Subcommittee, 2025

  Journal of General Virology · 2025-07-25 · 6 citations

  articleOpen access

  In March 2025, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote, newly proposed taxa were added to those under the mandate of the Plant Viruses Subcommittee. In brief, 1 new order, 3 new families, 6 new genera, 2 new subgenera and 206 new species were created. Some taxa were reorganized. Genus Cytorhabdovirus in the family Rhabdoviridae was abolished and its taxa were redistributed into three new genera Alphacytorhabdovirus , Betacytorhabdovirus and Gammacytorhabdovirus . Genus Waikavirus in the family Secoviridae was reorganized into two subgenera ( Actinidivirus and Ritunrivirus ). One family and four previously unaffiliated genera were moved to the newly established order Tombendovirales . Twelve species not assigned to a genus were abolished. To comply with the ICTV mandate of a binomial format for virus species, eight species were renamed. Demarcation criteria in the absence of biological information were defined in the genus Ilarvirus (family Bromoviridae ). This article presents the updated taxonomy put forth by the Plant Viruses Subcommittee and ratified by the ICTV.

  PublisherDOI

• Impacts of viruses on horticultural and fruit traits of young apple trees in a high-density production system in New York

  Journal of Plant Pathology · 2025-09-03

  articleOpen accessSenior author

  The impacts of viruses on horticultural and fruit traits of apple trees were first characterized half a century ago, yet the responses to viruses of contemporary apple cultivars and rootstocks in high-density planting systems remains largely unknown. The aim of our study was to evaluate the effects of apple chlorotic leaf spot virus (ACLSV), apple stem pitting virus (ASPV), apple green crinkle-associated virus (AGCaV), and citrus concave gum-associated virus (CCGaV) on horticultural and fruit traits of young apple trees representing six commercially relevant scion-rootstock combinations in a high-density experimental orchard in New York. Analyses of horticultural traits showed statistically significant differences between infected and uninfected trees in trunk diameter (CCGaV) and terminal shoot growth (CCGaV, AGCaV); however, differences in means were small and inconsistent. Analyses of fruit traits revealed a statistically significant yield reduction of ‘Baigent’ Gala trees on ‘Geneva 935’ (G.935) rootstocks associated with ACLSV (-27%), ASPV (-16%) and CCGaV (-24%) in 2021, but not in 2022. Additionally, the number of concurrent virus infections per tree, as determined by multiplex PCR-based amplicon sequencing, was significantly negatively correlated with the yield of ‘Baigent’ Gala trees on G.935 in 2021 and significantly positively correlated with the firmness of fruits collected from trees on G.935 in both years. Together, these highly variable effects suggest that apple cultivars, rootstock genotypes, or combinations thereof, as well as variable environmental conditions, may influence the impacts of viruses in a high-density production system.

  PublisherOA PDFDOI

• Comparative Acquisition, Transmission, and Retention of Distinct Grapevine Red Blotch Virus Isolates in Relation to the Genotype and Sex of Spissistilus festinus, the Treehopper Vector

  Viruses · 2025-09-20

  articleOpen accessSenior author

  Grapevine red blotch virus (GRBV), the causal agent of red blotch disease of grapevines, is transmitted by Spissistilus festinus, the threecornered alfalfa hopper. Isolates of GRBV belong to two phylogenetic clades (I and II) and S. festinus is a dimorphic insect, with two genotypes found in the western (California, CA) and the southeastern (SE) regions of the United States. The transmission of GRBV by S. festinus is circulative and nonpropagative, yet some parameters of transmission remain to be characterized. Here, we compared the acquisition, transmission, and retention of GRBV isolates from phylogenetic clades I and II by S. festinus males and females of the two genotypes. Results indicated that the SE genotype acquired GRBV more efficiently (72.5%, 29/40) than the CA genotype (22.5%, 18/80), with differences in acquisition observed between males (32.5%, 26/80) and females (52.5%, 21/40) of the two S. festinus genotypes and between GRBV isolates of phylogenetic clades I (29%, 23/80) and II (60%, 24/40). Following acquisition, both S. festinus genotypes and sexes retained GRBV isolates of phylogenetic clades I and II for at least 60 days without access to an infected plant. For transmission, the GRBV isolate of phylogenetic clade II was more efficiently transmitted by the SE genotype (54%, 13/24) than the CA genotype (17%, 4/24) and SE females (75%, 12/16) were significantly more efficient transmitters of GRBV than CA females (19%, 3/16). Together, our findings revealed that S. festinus genotype, sex, and virus isolate influence GRBV acquisition and transmission but not retention. This research addressed important knowledge gaps in S. festinus-mediated transmission of GRBV that are essential for advancing red blotch disease epidemiology and developing appropriate disease management responses.

  PublisherOA PDFDOI

• Ecological Connectivity of Plant Communities for Red Blotch Disease Dynamics Revealed by the Dietary Profiles and Landscape-Level Movement of <i>Spissistilus festinus</i>

  Phytobiomes Journal · 2025-01-07 · 5 citations

  articleOpen accessSenior author

  The epidemiological relationship between arthropod dispersal and plant communities is poorly understood at the landscape level. We investigated the connectivity of natural and cultivated plants in vineyard ecosystems for red blotch disease dynamics by characterizing the dietary history of Spissistilus festinus, a treehopper vector of grapevine red blotch virus. Molecular analysis of the gut content of 205 S. festinus caught in 71 vineyard sites and the flora proximal to vineyards in Napa Valley, California, revealed a total of 171 genera from 60 plant families with a preeminence of Asteraceae, Fabaceae, and Vitaceae over two growing seasons, illustrating dietary profiles composed primarily of natural vegetation. An indicator species analysis identified the strength of ecological associations by showing distinct seasonal feeding trends related to weather patterns and host repertoires unique to some vineyard sites with estimated S. festinus travel distances of up to 2 km. Potential reproductive and overwintering hosts of S. festinus were identified in natural habitats, and an ecological relatedness between free-living vines in riparian corridors and vineyards for grapevine red blotch virus transmission was documented. Together, our findings on landscape vegetation connectivity and S. festinus dispersal transformed our understanding of red blotch disease ecology and informed disease management options. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

  PublisherDOI

• A Soilborne Virus Modifies the Root System Architecture of a Plant Host via a Single Amino Acid and Influences Nematode Transmission

  Phytopathology · 2025-05-15 · 1 citations

  articleOpen accessSenior author

  Grapevine fanleaf virus (GFLV) is the main causative agent of fanleaf degeneration disease. Transmission of GFLV is exclusively accomplished by the ectoparasitic dagger nematode Xiphinema index in a noncirculative, nonpropagative mode. Previous studies of GFLV–host interactions revealed strain- and viral amino acid-specific changes to the root system architecture (RSA) in Nicotiana benthamiana. Here, a two-step assay first revealed the suitability of N. benthamiana in comparison with Vitis spp. for the transmission of GFLV by X. index. Then, a novel one-step assay revealed strain- and viral amino acid-specific differences in transmission between wild-type GFLV strains F13 and GHu and their respective mutants, with a single residue change to position 802 of the putative RNA-dependent RNA polymerase (protein 1E Pol*/Sd ). Higher transmission rates were obtained with asymptomatic mutant GFLV-GHu 1E K802G (33.33%, 16/48) versus symptomatic wild-type GFLV-GHu (25.53%, 12/47) and with asymptomatic wild-type GFLV-F13 (75%, 30/40) versus symptomatic mutant GFLV-F13 1E G802K (51.28%, 20/39). These results indicate that X. index-mediated transmission is influenced by the GFLV strain and the identity of the amino acid in position 802 of protein 1E Pol*/Sd , with a glycine favoring transmission and a lysine reducing transmission. As expected, GFLV transmission was significantly correlated with differences in RSA traits, such as the number of root tips and total root length, but not with GFLV titer in X. index or in the roots of donor plants. This is the first report of a soilborne virus modifying both the RSA of a plant host and transmission by its dagger nematode via a single viral amino acid. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

  PublisherOA PDFDOI

• Utilize VIS/NIR hyperspectral imaging to detect leafroll and red blotch-infected vines in your vineyard

  IVES Technical Reviews vine and wine · 2025-10-17

  articleOpen access

  Grapevines face many threats, with viral diseases like grapevine leafroll and red blotch viruses being particularly challenging due to their elusive nature and lack of cures. Traditional containment methods involve identifying and replacing infected vines, a laborious and costly process. This highlights the need for innovative detection solutions. Advances in technology offer hope, promising more efficient methods. Since 2019, a research project at CSU Fresno has been investigating the use of hyperspectral imagery to improve the detection of leafroll and red blotch.

  PublisherDOI

• A list of eclectic viruses, virus-like diseases and viroids of grapevines that should not be considered for regulatory oversight: a global plea from virologists

  Journal of Plant Pathology · 2025-02-25 · 8 citations

  articleOpen access1st authorCorresponding

  Abstract Grapevine ( Vitis spp.) propagation material is profusely exchanged across geographic and regulatory boundaries. Trading germplasm increases the diversity of cultivars and rootstocks with enhanced viticultural attributes but also risks the dissemination of pests and detrimental pathogens such as viruses in new grape production areas. Therefore, regulations are established to facilitate the safe trade of Vitis propagation material with desirable traits. Regrettably regulations are sometimes inadequate. Consequently, the accessibility of desired germplasm for growers might be unduly delayed, providing opportunities to circumvent regulations by illegally introducing germplasm of interest, amidst risking epidemics of viruses of concern, including quarantined agents, and jeopardizing the health of vineyards. To address some of the regulatory limitations, scientists from around the world recently defined phantom agents in fruit crops, including grapevines, and provided a compelling case for their exclusion from regulatory oversight. Simultaneously, a group of virologists realized the need to complement the list of phantom agents in grapevines by considering additional viruses, virus-like diseases and viroids that should not be subject to regulatory oversight. Here, we present a list of nine viruses, 14 virus-like diseases, nine viroids, and 129 presumed viruses of the grapevine, that are not phantom agents but should be excluded from regulation or should not be regulated. Our list is anticipated to assist policy makers adopt regulations that expedite the safe exchange of Vitis germplasm across regulatory boundaries while reducing incentives for illicit introductions.

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Frequent coauthors

• Keith L. Perry

  Cornell University

  150 shared

• Jeremy R. Thompson

  Ministry for Primary Industries

  99 shared

• Heather McLane

  Cornell University

  93 shared

• Dennis Gonsalves

  65 shared

• Elizabeth Cieniewicz

  Clemson University

  51 shared

• Maher Al Rwahnih

  Plant (United States)

  46 shared

• Corinne Schmitt‐Keichinger

  Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement

  41 shared

• Fevziye Celebi-Toprak

  41 shared

Labs

• Fuchs LabPI

Awards & honors

• Research award (2016) New York Wine and Grape Foundation