Citrus Fungal and Oomycete Diseases

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Plant Protection and Biotic Interactions".

Deadline for manuscript submissions: closed (30 April 2023) | Viewed by 38698

Special Issue Editors


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Guest Editor
Department of Agriculture, Food and Enviroment, University of Catania, Via S. Sofia 100, 95123 Catania, Italy
Interests: plant pathology; detection and characterization of fungal and oomycete diseases of Mediterranean, tropical and subtropical crops; integrated pest management strategies; fungicide resistance

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AGROINNOVA, Centre for Innovation in the Agro-Environmental Sector, University of Torino, Largo Braccini 2, 10095 Grugliasco (TO), Italy
Interests: plant pathology; fungal pathogens phylogeny; tropical and subtropical crop diseases; fruit crop diseases; berry fruit diseases; molecular diagnostics and early detection
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Agriculture, Food and Enviroment, University of Catania, Via S. Sofia 100, 95123 Catania, Italy
Interests: plant pathology; morphological and molecular diagnosis of bacteria and fungi; development of diseases control strategies; soil and substrate disinfestation against soil-borne pathogens; fungicides resistance
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Citrus crops are affected by several diseases caused by fungi and oomycetes. Disease causes economic loss in all the continents where Citrus spp. are cultivated. Oomycetes cause serious and widespread soil-borne diseases. Phytophthora spp. are also responsible for brown rot in several citrus species. Moreover, a broad range of fungal species cause diseases affecting roots, foliage, fruits and wood. Interesting case studies demonstrate how citrus pathogens are in continuous evolution: Alternaria alternata (tangerine pathotype) has been considered a key pathogen for the mandarin group and related hybrids, but recently this species has been described as responsible for brown rot in several sweet orange and lemon clones. Similarly, Colletotrichum spp. have been treated for decades as post-harvest pathogens, though they have been recently reported as major field pathogens in Europe, North Africa and California.

Globalization and changes in cultural practices act with unavoidable consequences such as pathogen movement and abiotic stress for plants. Furthermore, global warming and climate change are affecting plant health by modifying the interactions between hosts, pathogens and the environment. Agrochemicals represent a relevant component for citrus disease control. Their negative effects on the environment and human health address future efforts to develop sustainable and eco-friendly strategies in pre- and post-harvest conditions.

In light of these enormous changes, we highly encourage experts and researchers to contribute with original scientific articles, reviews, and communications addressing the etiology, epidemiology, detection and control strategies on citrus diseases caused by the above-mentioned pathogens, as well as species members of other families and genera such as Botryosphaeriaceae, Mycosphaerellaceae, Diaporthe, Fusarium, Neocosmospora, Phytopythium, Plenodomus, Pythium, Phyllosticta, etc.

Prof. Dr. Giancarlo Polizzi
Dr. Vladimiro Guarnaccia
Dr. Dalia Aiello
Guest Editors

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Keywords

  • fungal and oomycete diseases
  • detection
  • molecular characterization
  • epidemiology
  • disease control

Published Papers (11 papers)

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Research

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17 pages, 2274 KiB  
Article
Efficacy of Biological Control Agents and Resistance Inducer for Control of Mal Secco Disease
by Giuseppa Rosaria Leonardi, Giancarlo Polizzi, Alessandro Vitale and Dalia Aiello
Plants 2023, 12(9), 1735; https://doi.org/10.3390/plants12091735 - 22 Apr 2023
Cited by 5 | Viewed by 1337
Abstract
Mal secco, caused by Plenodomus tracheiphilus, is an economically important fungal vascular disease in citrus-growing countries of the Mediterranean basin. Preventing fungal infections usually requires a high number of copper treatments but European legislation imposes the minimization of their accumulation in soil. In [...] Read more.
Mal secco, caused by Plenodomus tracheiphilus, is an economically important fungal vascular disease in citrus-growing countries of the Mediterranean basin. Preventing fungal infections usually requires a high number of copper treatments but European legislation imposes the minimization of their accumulation in soil. In our study, biological control agents (BCAs) and a plant resistance inducer (PRI), tested in four different experiments on citrus seedlings under controlled conditions, have resulted in promising strategies to control mal secco disease. Foliar (Experiment I) and soil (Experiment II) applications of two formulations of Bacillus amyloliquefaciens strain D747 (Amylo-X® LC and Amylo-X® WG) provided similar performances in reducing the disease amount (incidence and symptoms severity) over time compared to the untreated control, whereas copper hydroxide (Kocide Opti®) used as standard was the most effective treatment over time. In the third experiment, Pythium oligandrum strain M1 (Polyversum®) and Trichoderma asperellum strain ICC012 + Trichoderma gamsii strain ICC080 (Remedier®) were able to reduce disease incidence and symptoms severity compared to the untreated control. Remedier® provided the best performances in reducing the disease amount, whereas the Polyversum® application was the least effective treatment over time. The effectiveness of the Trichoderma spp. formulation in reducing P. tracheiphilus infections did not significantly differ from the standard copper compound (Kocide Opti®). Comprehensively, in the last experiment (IV), acibenzolar-S-methyl (ASM) alone and in mixture with metalaxyl-M proved as effective as B. amyloliquefaciens strain FZB24, with no dose–response relationships observed. These findings provide important insight for the integrated management of mal secco disease. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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16 pages, 2591 KiB  
Article
Assessing Copper-Alternative Products for the Control of Pre- and Postharvest Citrus Anthracnose
by Monia Federica Lombardo, Salvina Panebianco, Antonino Azzaro, Vittoria Catara and Gabriella Cirvilleri
Plants 2023, 12(4), 904; https://doi.org/10.3390/plants12040904 - 16 Feb 2023
Cited by 3 | Viewed by 1595
Abstract
Citrus production is worldwide threatened by Colletotrichum spp., causal agents of pre- and postharvest anthracnose. The recent limitation on the use of copper-based antimicrobials, due to its demonstrated noxious effect on the environment, makes the control of this pathogen difficult. Thus, alternative products [...] Read more.
Citrus production is worldwide threatened by Colletotrichum spp., causal agents of pre- and postharvest anthracnose. The recent limitation on the use of copper-based antimicrobials, due to its demonstrated noxious effect on the environment, makes the control of this pathogen difficult. Thus, alternative products able to reduce/phase out copper in organic citrus farming are needed. In this study, the efficacy of 11 commercial alternative products were evaluated in vitro, in growth chamber, in open field and in postharvest environments. In vitro, mineral fertilizers, basic substances, essential oils, plant defense stimulators and biological control agents were able to inhibit the mycelial growth with variable efficacy. On artificially infected citrus fruit, almost all tested products significantly reduced disease incidence and severity, but with lower efficacy than copper. The efficacy of mineral fertilizers-based Kiram and Vitibiosap 458 Plus, citrus essential oil-based Prev-Am Plus and chitosan-based Biorend was confirmed in open field trials, in naturally infected citrus fruits. In these trials Biorend was the best alternative product, significantly reducing disease incidence (71% DI reduction) with better results than copper (47.5%). Field treatments reduced the incidence and severity of the disease in postharvest conditions, especially in fruits field-treated three times. Overall, selected products tested in open field can represent a good alternative to copper compounds in the view of future limitation of its use. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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14 pages, 2514 KiB  
Article
A New Strategy to Improve Management of Citrus Mal Secco Disease Using Bioformulates Based on Bacillus amyloliquefaciens Strains
by Dalia Aiello, Giuseppa Rosaria Leonardi, Chiara Di Pietro, Alessandro Vitale and Giancarlo Polizzi
Plants 2022, 11(3), 446; https://doi.org/10.3390/plants11030446 - 06 Feb 2022
Cited by 7 | Viewed by 2590
Abstract
The effectiveness of biological commercial products based on Bacillus amyloliquefaciens strains was evaluated through in vitro and in vivo experiments against Plenodomus tracheiphilus. The activity of bacterial cells, volatile organic compounds (VOCs), and culture filtrates of bacteria were tested in vitro against [...] Read more.
The effectiveness of biological commercial products based on Bacillus amyloliquefaciens strains was evaluated through in vitro and in vivo experiments against Plenodomus tracheiphilus. The activity of bacterial cells, volatile organic compounds (VOCs), and culture filtrates of bacteria were tested in vitro against different isolates of P. tracheiphilus. Afterwards, the virulence of these isolates was evaluated on Citrus volkameriana plants to select the most virulent isolate to use in the in vivo experiments. To evaluate the effectiveness of products, C. volkameriana seedlings were pre-treated, twice with biological products and once with standard fungicides, before pathogen inoculation. Moreover, in order to determine the endophytic ability of the bacteria, the population density within the treated citrus stem was determined. Comprehensively, bacterial cells, filtrates, and VOCs were able to significantly reduce the average mycelial diameter of P. tracheiphilus, with some variability according to pathogen isolate. In planta experiments showed that the biological products on average were less effective than fungicides, although all formulates were able to significantly reduce disease incidence and symptom severity, except B. amyloliquefaciens strain D747 (Amylo-X) for symptom severity (SS) 20 days after inoculation. Bacteria were re-isolated from the internal woody tissue of treated plants, showing strong endophytic ability. This work is important as commercial biological products based on B. amyloliquefaciens strains could represent a promising and sustainable alternative for the integrated management of mal secco disease. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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10 pages, 9375 KiB  
Article
Sensitive and Rapid Detection of Citrus Scab Using an RPA-CRISPR/Cas12a System Combined with a Lateral Flow Assay
by Kihye Shin, Soon-Hwa Kwon, Seong-Chan Lee and Young-Eel Moon
Plants 2021, 10(10), 2132; https://doi.org/10.3390/plants10102132 - 08 Oct 2021
Cited by 18 | Viewed by 4172
Abstract
Citrus is the most extensively produced fruit tree crop in the world and is grown in over 130 countries. Fungal diseases in citrus can cause significant losses in yield and quality. An accurate diagnosis is critical for determining the best management practices and [...] Read more.
Citrus is the most extensively produced fruit tree crop in the world and is grown in over 130 countries. Fungal diseases in citrus can cause significant losses in yield and quality. An accurate diagnosis is critical for determining the best management practices and preventing future losses. In this study, a Recombinase polymerase amplification (RPA)-clustered regularly interspaced short palindromic repeats (CRISPR)/associated (Cas) system was established with the integration of a lateral flow assay (LFA) readout system for diagnosis of citrus scab. This detection can be completed within 1 h, is highly sensitive and prevents cross-reactions with other common fungal citrus diseases. Furthermore, the detection system is compatible with crude DNA extracted from infected plant tissue. This RPA-CRISPR/Cas12a-LFA system provides a sensitive, rapid, and cost-effective method with promising and significant practical value for point-of-care diagnosis of citrus scab. To our knowledge, this is the first report to establish an RPA- and CRISPR-based method with LFA for fungal diseases in plants. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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7 pages, 933 KiB  
Communication
Unusual Stylar-End Breakdown and Sour Rot on Key Lime (Citrus aurantiifolia) in Pre-Harvest Condition in Italy
by Giorgio Gusella, Alberto Fiorenza, Dalia Aiello and Giancarlo Polizzi
Plants 2021, 10(5), 989; https://doi.org/10.3390/plants10050989 - 16 May 2021
Cited by 1 | Viewed by 2581
Abstract
Key lime (Citrus aurantiifolia) is an emerging crop in Italy, especially in the Southern regions, where the environmental conditions are suitable for its cultivation. A field survey in Sicily in a commercial orchard of Key lime revealed the widespread presence of [...] Read more.
Key lime (Citrus aurantiifolia) is an emerging crop in Italy, especially in the Southern regions, where the environmental conditions are suitable for its cultivation. A field survey in Sicily in a commercial orchard of Key lime revealed the widespread presence of water-soaked spots and sunken/dry lesions at the stylar-end, mainly in pre-harvest condition. Water-soaked spots were attributed to Geotrichum citri-aurantii, an agent of sour rot on Citrus spp., whereas the sunken/dry lesion was attributed to the physiological disorder known as stylar-end breakdown. Sour rot and stylar-end breakdown are usually considered post-harvest diseases and rarely found in the field on fruit still attached to the tree. Although Geotrichum citri-aurantii is not responsible for the stylar-end breakdown, its association with this alteration reveals the importance of the environmental conditions and the agronomic practices in diseases/disorders development. In addition, to our knowledge, this is the first report of Geotrichum citri-aurantii on Key lime in Europe. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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25 pages, 3208 KiB  
Article
Potential Role of Rhizobacteria Isolated from Citrus Rhizosphere for Biological Control of Citrus Dry Root Rot
by Said Ezrari, Oumayma Mhidra, Nabil Radouane, Abdessalem Tahiri, Giancarlo Polizzi, Abderrahim Lazraq and Rachid Lahlali
Plants 2021, 10(5), 872; https://doi.org/10.3390/plants10050872 - 26 Apr 2021
Cited by 29 | Viewed by 5759
Abstract
Citrus trees face threats from several diseases that affect its production, in particular dry root rot (DRR). DRR is a multifactorial disease mainly attributed to Neocosmospora (Fusarium) solani and other several species of Neocosmospora and Fusarium spp. Nowadays, biological control holds [...] Read more.
Citrus trees face threats from several diseases that affect its production, in particular dry root rot (DRR). DRR is a multifactorial disease mainly attributed to Neocosmospora (Fusarium) solani and other several species of Neocosmospora and Fusarium spp. Nowadays, biological control holds a promising control strategy that showed its great potential as a reliable eco-friendly method for managing DRR disease. In the present study, antagonist rhizobacteria isolates were screened based on in vitro dual culture bioassay with N. solani. Out of 210 bacterial isolates collected from citrus rhizosphere, twenty isolates were selected and identified to the species level based on the 16S rRNA gene. Molecular identification based on 16S rRNA gene revealed nine species belonging to Bacillus, Stenotrophomonas, and Sphingobacterium genus. In addition, their possible mechanisms involved in biocontrol and plant growth promoting traits were also investigated. Results showed that pectinase, cellulose, and chitinase were produced by eighteen, sixteen, and eight bacterial isolates, respectively. All twenty isolates were able to produce amylase and protease, only four isolates produced hydrogen cyanide, fourteen isolates have solubilized tricalcium phosphate, and ten had the ability to produce indole-3-acetic acid (IAA). Surprisingly, antagonist bacteria differed substantially in their ability to produce antimicrobial substances such as bacillomycin (five isolates), iturin (ten isolates), fengycin (six isolates), surfactin (fourteen isolates), and bacteriocin (subtilosin A (six isolates)). Regarding the PGPR capabilities, an increase in the growth of the bacterial treated canola plants, used as a model plant, was observed. Interestingly, both bacterial isolates Bacillus subtilis K4-4 and GH3-8 appear to be more promising as biocontrol agents, since they completely suppressed the disease in greenhouse trials. Moreover, these antagonist bacteria could be used as bio-fertilizer for sustainable agriculture. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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31 pages, 3200 KiB  
Article
Genetic Diversity and Pathogenicity of Botryosphaeriaceae Species Associated with Symptomatic Citrus Plants in Europe
by Jadson Diogo Pereira Bezerra, Pedro Wilhelm Crous, Dalia Aiello, Maria Lodovica Gullino, Giancarlo Polizzi and Vladimiro Guarnaccia
Plants 2021, 10(3), 492; https://doi.org/10.3390/plants10030492 - 05 Mar 2021
Cited by 32 | Viewed by 3379
Abstract
This study represents the first survey studying the occurrence, genetic diversity, and pathogenicity of Botryosphaeriaceae species associated with symptomatic citrus species in citrus-production areas in five European countries. Based on morphological features and phylogenetic analyses of internal transcribed spacer (ITS) of nuclear ribosomal [...] Read more.
This study represents the first survey studying the occurrence, genetic diversity, and pathogenicity of Botryosphaeriaceae species associated with symptomatic citrus species in citrus-production areas in five European countries. Based on morphological features and phylogenetic analyses of internal transcribed spacer (ITS) of nuclear ribosomal DNA (nrDNA), translation elongation factor 1-alpha (TEF1) and β-tubulin (TUB2) genes, nine species were identified as belonging to the genera Diplodia, Dothiorella, Lasiodiplodia, and Neofusicoccum. Isolates of Neofusicoccum parvum and Diplodia pseudoseriata were the most frequently detected, while Dothiorella viticola had the widest distribution, occurring in four of the five countries sampled. Representative isolates of the nine Botryosphaeriaceae species used in the pathogenicity tests caused similar symptoms to those observed in nature. Isolates assayed were all re-isolated, thereby fulfilling Koch’s postulates. Isolates of Diplodia pseudoseriata and Diplodia olivarum are recorded for the first time on citrus and all species found in our study, except N. parvum, are reported for the first time on citrus in Europe. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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13 pages, 2996 KiB  
Article
The Effects of Postharvest Treatments and Sunlight Exposure on the Reproductive Capability and Viability of Phyllosticta citricarpa in Citrus Black Spot Fruit Lesions
by Providence Moyo, Paul H. Fourie, Siyethemba L. Masikane, Régis de Oliveira Fialho, Lindokuhle C. Mamba, Wilma du Plooy and Vaughan Hattingh
Plants 2020, 9(12), 1813; https://doi.org/10.3390/plants9121813 - 21 Dec 2020
Cited by 4 | Viewed by 2913
Abstract
Citrus black spot (CBS) is caused by Phyllosticta citricarpa, which is classified as a quarantine organism in certain countries whose concerns are that CBS-infected fruit may be a pathway for introduction of the pathogen. This study evaluated the reproductive capability and viability [...] Read more.
Citrus black spot (CBS) is caused by Phyllosticta citricarpa, which is classified as a quarantine organism in certain countries whose concerns are that CBS-infected fruit may be a pathway for introduction of the pathogen. This study evaluated the reproductive capability and viability of P. citricarpa under simulated conditions in which the whole fruit, peel segments, or citrus pulp with CBS lesions were discarded. Naturally infected ‘Midknight’ Valencia orange and ‘Eureka’ lemon fruit, either treated using standard postharvest sanitation, fungicide, and wax coating treatments or untreated, were placed into cold storage for 5 weeks (oranges at 4 °C and lemons at 7 °C). Thereafter, treated and untreated fruit were incubated for a further 2 weeks at conditions conducive for CBS symptom expression and formation of pycnidia. The ability of pycnidia to secrete viable pycnidiospores after whole fruit and peel segments or peel pieces from citrus pulp were exposed to sunlight at warm temperatures (±28 °C) and ±75% relative humidity levels was then investigated. The combination of postharvest treatments and cold storage effectively controlled CBS latent infections (>83.6% control) and pycnidium formation (<1.4% of lesions formed pycnidia), and the wax coating completely inhibited pycnidiospore release in fruit and peel segments. Pycnidiospores were secreted only from lesions on untreated fruit and peel segments and at low levels (4.3–8.6%) from peel pieces from pulped treated fruit. However, spore release rapidly declined when exposed to sunlight conditions (1.4% and 0% after 2 and 3 days, respectively). The generally poor reproductive ability and viability of CBS fruit lesions on harvested fruit, particularly when exposed to sunlight conditions, supports the conclusion that citrus fruit without leaves is not an epidemiologically significant pathway for the entry, establishment, and spread of P. citricarpa. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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Review

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16 pages, 5706 KiB  
Review
Biotechnological Approaches for Genetic Improvement of Lemon (Citrus limon (L.) Burm. f.) against Mal Secco Disease
by Chiara Catalano, Mario Di Guardo, Gaetano Distefano, Marco Caruso, Elisabetta Nicolosi, Ziniu Deng, Alessandra Gentile and Stefano Giovanni La Malfa
Plants 2021, 10(5), 1002; https://doi.org/10.3390/plants10051002 - 17 May 2021
Cited by 13 | Viewed by 4397
Abstract
Among Citrus species, lemon is one of the most susceptible to mal secco disease, a tracheomycosis caused by the mitosporic fungus Plenodomus tracheiphilus, which induces chlorosis followed by leaf drop and progressive desiccation of twigs and branches. Severe infection can cause the death [...] Read more.
Among Citrus species, lemon is one of the most susceptible to mal secco disease, a tracheomycosis caused by the mitosporic fungus Plenodomus tracheiphilus, which induces chlorosis followed by leaf drop and progressive desiccation of twigs and branches. Severe infection can cause the death of the plant. Since no effective control strategies are available to efficiently control the pathogen spread, host tolerance is the most desirable goal in the struggle against mal secco disease. To date, both traditional breeding programs and biotechnological techniques were not efficient in developing novel varieties coupling tolerance to mal secco with optimal fruit quality. Furthermore, the genetic basis of host resistance has not been fully deciphered yet, hampering the set-up of marker-assisted selection (MAS) schemes. This paper provides an overview of the biotechnological approaches adopted so far for the selection of mal secco tolerant lemon varieties and emphasizes the promising contribution of marker-trait association analysis techniques for both unraveling the genetic determinism of the resistance to mal secco and detecting molecular markers that can be readily used for MAS. Such an approach has already proved its efficiency in several crops and could represent a valuable tool to select novel lemon varieties coupling superior fruit quality traits and resistance to mal secco. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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Other

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19 pages, 3699 KiB  
Brief Report
Morphology Characterization, Molecular Phylogeny, and Pathogenicity of Diaporthe passifloricola on Citrus reticulata cv. Nanfengmiju in Jiangxi Province, China
by Chingchai Chaisiri, Xiang-Yu Liu, Wei-Xiao Yin, Chao-Xi Luo and Yang Lin
Plants 2021, 10(2), 218; https://doi.org/10.3390/plants10020218 - 23 Jan 2021
Cited by 7 | Viewed by 4309
Abstract
The Nanfengmiju (Citrus reticulata cv. Nanfengmiju), a high-quality local variety of mandarin, is one of the major fruit crops in Jiangxi Province, China. Citrus melanose and stem-end rot, two common fungal diseases of Nanfengmiju, are both caused by Diaporthe spp. (syn. Phomopsis [...] Read more.
The Nanfengmiju (Citrus reticulata cv. Nanfengmiju), a high-quality local variety of mandarin, is one of the major fruit crops in Jiangxi Province, China. Citrus melanose and stem-end rot, two common fungal diseases of Nanfengmiju, are both caused by Diaporthe spp. (syn. Phomopsis spp.). Identification of the Diaporthe species is essential for epidemiological studies, quarantine measures, and management of diseases caused by these fungi. Melanose disease was observed on Nanfengmiju fruit in Jiangxi Province of China in 2016. Based on morphological characterization and multi-locus phylogenetic analyses, three out of 39 isolates from diseased samples were identified as D. passifloricola. Since these three isolates did not cause melanose on citrus fruit in the pathogenicity tests, they were presumed to be endophytic fungi present in the diseased tissues. However, our results indicate that D. passifloricola may persist as a symptom-less endophyte in the peel of citrus fruit, yet it may cause stem-end if it invades the stem end during fruit storage. To the best of our knowledge, this is the first report of D. passifloricola as the causal agent of the stem-end rot disease in Citrusreticulata cv. Nanfengmiju. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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8 pages, 2170 KiB  
Brief Report
Identification of Lasiodiplodia pseudotheobromae Causing Fruit Rot of Citrus in China
by Jianghua Chen, Zihang Zhu, Yanping Fu, Jiasen Cheng, Jiatao Xie and Yang Lin
Plants 2021, 10(2), 202; https://doi.org/10.3390/plants10020202 - 21 Jan 2021
Cited by 17 | Viewed by 3055
Abstract
Considering the huge economic loss caused by postharvest diseases, the identification and prevention of citrus postharvest diseases is vital to the citrus industry. In 2018, 16 decayed citrus fruit from four citrus varieties—Satsuma mandarin (Citrus unshiu), Ponkan (Citrus reticulata Blanco [...] Read more.
Considering the huge economic loss caused by postharvest diseases, the identification and prevention of citrus postharvest diseases is vital to the citrus industry. In 2018, 16 decayed citrus fruit from four citrus varieties—Satsuma mandarin (Citrus unshiu), Ponkan (Citrus reticulata Blanco cv. Ponkan), Nanfeng mandarin (Citrus reticulata cv. nanfengmiju), and Sugar orange (Citrus reticulata Blanco)—showing soft rot and sogginess on their surfaces and covered with white mycelia were collected from storage rooms in seven provinces. The pathogens were isolated and the pathogenicity of the isolates was tested. The fungal strains were identified as Lasiodiplodia pseudotheobromae based on their morphological characteristics and phylogenetic analyses using the internal transcribed spacer regions (ITS), translation elongation factor 1-α gene (TEF), and beta-tubulin (TUB) gene sequences. The strains could infect wounded citrus fruit and cause decay within two days post inoculation, but could not infect unwounded fruit. To our knowledge, this is the first report of citrus fruit decay caused by L. pseudotheobromae in China. Full article
(This article belongs to the Special Issue Citrus Fungal and Oomycete Diseases)
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