scholarly journals Identification and Characterization of Fungal Pathogens Causing Fruit Rot of Deciduous Holly

Plant Disease ◽  
2018 ◽  
Vol 102 (12) ◽  
pp. 2430-2445 ◽  
Author(s):  
Shan Lin ◽  
Nancy J. Taylor ◽  
Francesca Peduto Hand
Keyword(s):  
Fungal Pathogens ◽  
Disease Incidence ◽  
Phylogenetic Analyses ◽  
Management Strategies ◽  
Morphological Characterization ◽  
Fruit Rot ◽  
Economic Losses ◽  
Yield Reduction ◽  
Inoculum Concentration ◽  
Fruit Samples

Cut branches of deciduous holly (Ilex spp. L.) harboring colorful berries are traditionally used as ornaments in holiday decorations. Since 2012, a fruit rot of unspecified cause has resulted in significant yield reduction and economic losses across Midwestern and Eastern U.S. nurseries. In this study, symptomatic fruit samples collected from nine different locations over five years were analyzed, and several fungal species were isolated. A combination of morphological characterization, multilocus phylogenetic analyses, and pathogenicity assays revealed that Alternaria alternata and Diaporthe ilicicola sp. nov. were the primary pathogens associated with symptomatic fruit. Other fungi including A. arborescens, Colletotrichum fioriniae, C. nymphaeae, Epicoccum nigrum, and species in the D. eres species complex appeared to be minor pathogens in this disease complex. In detached fruit pathogenicity assays testing the role of wounding and inoculum concentration on disease development, disease incidence and severity increased when fruit was wounded and inoculated with a higher inoculum concentration. These findings indicate that management strategies that can protect fruit from injury or reduce inoculum may lower disease levels in the field. This research established the basis for further studies on this emerging disease and the design of research-based management strategies. To our knowledge, it also represents the first report of species of Alternaria, Colletotrichum, Diaporthe, and Epicoccum causing fruit rot of deciduous holly.

scholarly journals Morphological and Molecular Diversity of Ginger (Zingiber officinale Roscoe) Pathogenic Fungi in Chilga District, North Gondar, Ethiopia

2022 ◽  
Vol 2 ◽  
Author(s):  
Sefinew Tilahun ◽  
Marye Alemu ◽  
Mesfin Tsegaw ◽  
Nega Berhane
Keyword(s):  
Causative Agent ◽  
Fungal Pathogens ◽  
Pathogenic Fungus ◽  
Management Strategies ◽  
Infected Plant ◽  
Pathogenic Fungi ◽  
Zingiber Officinale ◽  
Morphological Characterization ◽  
Molecular Techniques ◽  
Diseased Plant

Ginger diseases caused by fungal pathogens have become one of the most serious problems causing reduced production around the world. It has also caused a major problem among farmers in different parts of Ethiopia resulting in a huge decline in rhizome yield. However, the exact causative agents of this disease have not been identified in the state. Although there are few studies related to pathogenic fungus identification, molecular level identification of fungal pathogen was not done in the area. Therefore, this study was undertaken to isolate and characterized the fungal causative agent of ginger disease from the diseased plant and the soil samples collected around the diseased plant from Chilga district, Gondar, Ethiopia. Samples from infected ginger plants and the soil around the infected plant were collected. Culturing and purification of isolates were made using Potato Dextrose Agar supplemented with antibacterial agent chloramphenicol. The morphological characterization was done by structural identification of the isolates under the microscope using lactophenol cotton blue stains. Isolated fungi were cultured and molecular identification was done using an internal transcribed spacer (ITS) of ribosomal DNA (rDNA). A total of 15 fungal morphotypes including 11 Aspergillus spp. (73.3%), 2 Penicillium spp. (13.3%), and single uncultured fungus clone S23 were isolated from the samples representing all the plant organs and the soil. Aspergillus spp. (73.3%) was the most common and seems to be the major causative agent. To the best of our knowledge, this is the first report of ginger pathogenic fungi in Ethiopia identified using ITS rDNA molecular techniques. This study will lay foundation for the development of management strategies for fungal diseases infecting ginger.

scholarly journals Morphological and pathogenic characterization of Fusarium oxysporum in lulo (Solanum spp.)

2021 ◽  
Vol 38 (1) ◽  
pp. 20-37
Author(s):  
Yohana Patricia Anama ◽  
Ricardo Díaz ◽  
David Esteban Duarte-Alvarado ◽  
Tulio Cesar Lagos-Burbano
Keyword(s):  
Growth Rate ◽  
Fusarium Oxysporum ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Morphological Characterization ◽  
Sources Of Resistance ◽  
Randomized Design ◽  
Two Factors ◽  
Height Increase ◽  
Genotype G1

Fusarium oxysporum is one of the most limiting fungal pathogens of lulo crop. To determine its pathogenicity, this work morphologically and pathogenically characterized F. oxysporum isolates from different lulo-growing municipalities of the Department of Nariño. Twenty isolates were evaluated through a completely randomized design with two factors and three replicates per treatment, including a control. The first factor corresponded to 20 isolates of F. oxysporum and the second to 10 lulo genotypes. The morphological characterization involved determining growth rate (GR), color (CO), mycelial type (MT), medium coloration (Mc), shape (Sh), size (S), number (N) of macroconidial (Ma) and microconidial (Mi) septa, presence of chlamydospores (PC), and chlamydospore shape (CS). Moreover, the pathogenic characterization was based on the incubation period (IP), absolute growth rate (AGR), disease severity (DS), disease incidence (I), and vascular discoloration (VD). The morphological characterization demonstrated that all isolates corresponded to F. oxysporum. For IP, genotype G1 showed the lowest average at 18 days. For AGR, genotype G2 had the lowest height increase at 0.05 cm.day-1. For DS, genotype G1 reached the highest severity level (level 9) and a disease incidence of 100%. This study provides the first report of the special form of F. oxysporum f. sp. quitoense in Nariño. Solanum hirtum, Solanum sessiliflorum, and Solanum estramonifolium were resistant to the isolates evaluated, demonstrating that wild species should be considered as sources of resistance for breeding programs aiming to obtain resistant commercial genotypes.

scholarly journals RNAi of a Putative Grapevine Susceptibility Gene as a Possible Downy Mildew Control Strategy

2021 ◽  
Vol 12 ◽  
Author(s):  
Demetrio Marcianò ◽  
Valentina Ricciardi ◽  
Elena Marone Fassolo ◽  
Alessandro Passera ◽  
Piero Attilio Bianco ◽  
...  
Keyword(s):  
Gene Expression ◽  
Downy Mildew ◽  
Disease Severity ◽  
Fungal Pathogens ◽  
Management Strategies ◽  
Susceptibility Gene ◽  
Plasmopara Viticola ◽  
Pinot Noir ◽  
Economic Losses ◽  
Reproductive Structures

Downy mildew, caused by the oomycete Plasmopara viticola, is one of the diseases causing the most severe economic losses to grapevine (Vitis vinifera) production. To date, the application of fungicides is the most efficient method to control the pathogen and the implementation of novel and sustainable disease control methods is a major challenge. RNA interference (RNAi) represents a novel biotechnological tool with a great potential for controlling fungal pathogens. Recently, a candidate susceptibility gene (VviLBDIf7) to downy mildew has been identified in V. vinifera. In this work, the efficacy of RNAi triggered by exogenous double-stranded RNA (dsRNA) in controlling P. viticola infections has been assessed in a highly susceptible grapevine cultivar (Pinot noir) by knocking down VviLBDIf7 gene. The effects of dsRNA treatment on this target gene were assessed by evaluating gene expression, disease severity, and development of vegetative and reproductive structures of P. viticola in the leaf tissues. Furthermore, the effects of dsRNA treatment on off-target (EF1α, GAPDH, PEPC, and PEPCK) and jasmonic acid metabolism (COI1) genes have been evaluated. Exogenous application of dsRNA led to significant reductions both in VviLBDIf7 gene expression, 5 days after the treatment, and in the disease severity when artificial inoculation was carried out 7 days after dsRNA treatments. The pathogen showed clear alterations to both vegetative (hyphae and haustoria) and reproductive structures (sporangiophores) that resulted in stunted growth and reduced sporulation. Treatment with dsRNA showed signatures of systemic activity and no deleterious off-target effects. These results demonstrated the potential of RNAi for silencing susceptibility factors in grapevine as a sustainable strategy for pathogen control, underlying the possibility to adopt this promising biotechnological tool in disease management strategies.

scholarly journals Distribution of stem-end rot on the canopy in ‘Hass’ avocado trees in two coastal areas in Peru

2021 ◽  
Vol 5 (2) ◽  
pp. 60-70
Author(s):  
Alejandro Kepler Llanos Melo ◽  
Walter Eduardo Apaza-Tapia
Keyword(s):  
Disease Incidence ◽  
Management Strategies ◽  
Elongation Factor ◽  
Fungal Species ◽  
Coastal Areas ◽  
Tree Canopy ◽  
Fruit Rot ◽  
Internal Site ◽  
External Site ◽  
Hass Avocado

Stem-end rot (SER) of avocado is caused by several fungal species, and it is presented worldwide. This plant disease currently affects several avocado producer regions in Peru, causing fruit rot, impacting the industry negatively. Research about SER distribution in the canopy of avocado trees is limited. Thus, the present study aimed to compare which areas in the canopy are prone to have more SER in ‘Hass’ avocado harvested fruit in two different coastal areas in Peru. The experiment was conducted in the northern (Barranca) and southern (Cañete) of Lima. ‘Hass’Avocado fruits from both producer areas were collected to identify the causal agent; Lasiodiplodia theobromae was isolated from infected fruits. Identification was conducted based on morphological features and a partial DNA sequence of the translation elongation factor 1-α gene (tef1-α). The results showed that fruits inside the tree canopy were prone to have a higher disease incidence than the fruits located in the external site (P<0.001). Besides, internal-site fruits displayed a higher percentage of infected fruit for each grade disease (P<0.001) than external-site fruits, except for grade 0 (fruits without symptoms) and grade 1. Finally, the results suggested that the altitude where the fruit is positioned on the canopy could influence the incidence of SER, where fruits located in the high part revealed less incidence than the low section. The results are valuable for enhancing management strategies and avoiding postharvest loss of avocado fruits in our region.

ISOLATION, IDENTIFICATION AND CHARACTERIZATION OF BACTERIAL ANTAGONISTS OF THE DRAGON FRUIT FUNGAL PATHOGEN Neoscytalidium dimidiatum

2021 ◽  
Vol 44 (02) ◽  
Author(s):  
NGUYEN NGOC AN ◽  
HUA HUYNH MINH THAO ◽  
HO NGUYEN HOANG YEN ◽  
NGUYEN THI DIEU HANH ◽  
NGUYEN LE HIEN HOA ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Fungal Spore ◽  
Stem Canker ◽  
Antagonistic Effect ◽  
Fruit Rot ◽  
Economic Losses ◽  
Neoscytalidium Dimidiatum ◽  
Dragon Fruit

Dragon fruit or pitahaya (Hylocereus spp.) are famous for their nutrient-rich favourable taste, which brings high economic value to subtropical and tropical countries. However, dragon fruit cultivation all over the world is threatened by fungal pathogens and among them, Neoscytalidium dimidiatum has recently been shown to be responsible for stem canker and fruit rot which cause big economic losses. In order to find an environmentally friendly way to control this pathogen, five out of sixty-nine bacterial isolates used in a screening test for antifungal activity were selected. All five strains appeared to be aerobic Gram positive spore forming bacteria suggesting that they all belong to the Bacillus genus. Cell-free culture supernatants of these strains were found to strongly inhibit both fungal spore germination and mycelia growth in vitro for at least 5 days. The strain D19 which possessed the highest antagonistic effect was further identified to be Bacillus amyloliquefaciens, a well-known species shown to have antifungal effect against several other pathogenic fungi. Thus, the results of this study opened a new promising perspective to prevent Neoscytalidium dimidiatum infection during cultivation of dragon fruit.

Identification and Description of a New Pathogen Causing Flower Dry Rot on Passiflora edulis in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Yue Lian Liu ◽  
Jian Rong Tang ◽  
Yu Han Zhou
Keyword(s):  
Disease Incidence ◽  
Phylogenetic Analyses ◽  
Apical Cell ◽  
Management Strategies ◽  
Morphological Description ◽  
Pathogenicity Test ◽  
New Disease ◽  
Single Spore ◽  
Dry Rot ◽  
Passiflora Edulis

Passiflora edulis Sims (passion fruit) is an economically important fruit crop. A new disease, flower dry rot with an incidence of 30%–40%, has occurred in orchards located in Zhanjiang, China, and led to serious production loss. Disease incidence was about 30%–-40%. A total of 221 isolates of Fusarium sp. were obtained from samples of three types of symptomatic flowers. Three representative single-spore isolates (PaB-1, PaB-2, and PaB-3) from each type were used for pathogenicity test, multi-locus phylogenetic analyses, and morphological description. Pathogenicity test on bud of 5- month-old P. edulis plants reproducedshowed similar symptoms as those observed in nature, and Koch’’s postulates were fulfilledachieved.Results showed that the symptoms were observed on inoculated buds but not on the control, and Koch’s postulates were satisfied in all test isolates. By comparing 36 typical species from the FUSARIUM-ID database, multi-locus phylogenetic analyses showed that the sequences of TEF1, RPB2, and ITS of thethese isolates belong to the Incarnatum clade of the F. incarnatum–-equiseti species complex (FIESC-17-a) with an independent branch. Conidia of the isolates were falcate, smooth walled, curved apical cell, and foot-shaped basal cell, 1-5-septate. The conidial anastomosis tubes were first observed in the FIESC. Therefore, the pathogenic isolates were identifieddescribed as F. pernambucanum (FIESC-17-a). Moreover, in this study, the conidial anastomosis tubes were first observed in the FIESCIt is a new pathogen causing flower dry rot on P. edulis. This study representeds the first report of flower dry rot on P. edulis caused by F. pernambucanum. Further studies should be performed for the selection of effective disease management strategies.This finding provided crucial information on the threats of F. pernambucanum affecting P. edulis in China and management strategies for the new disease, which should be developed.

scholarly journals Potential Application of Propolis Extracts to Control the Growth of Stemphylium vesicarium in “Rocha” Pear

2020 ◽  
Vol 10 (6) ◽  
pp. 1990 ◽  
Author(s):  
Marcella Loebler ◽  
Claudia Sánchez ◽  
Elisabete Muchagato Maurício ◽  
Eugénio Diogo ◽  
Mário Santos ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Brown Spot ◽  
In Vitro Assays ◽  
Economic Losses ◽  
Yield Reduction ◽  
Stemphylium Vesicarium ◽  
Spot Disease ◽  
Brown Spot Disease

Stemphylium vesicarium (Wallr.) E. G. Simmons is the pathogen responsible of brown spot disease in pear and has become one of the main concerns for European pear producers. In Portugal, S. vesicarium is responsible for significant yield reduction and economic losses in “Rocha” pear (Pyrus communis L. cv Rocha) production. Considering the antimicrobial potential of propolis, the high incidence of brown spot in pears and the emergence of fungicides resistance in S. vesicarium, this study aimed to evaluate the potential of Portuguese propolis as an alternative strategy to control brown spot disease in “Rocha” pear. In vitro assays showed that propolis extracts were able to inhibit up to 90% the S. vesicarium mycelial growth. In vivo assays in artificially wounded and inoculated “Rocha” pears showed that, compared to the control, the disease incidence decreased up to 25% and the lesions diameter up to 57%, in fruits treated with propolis. Moreover, propolis seems to be more efficient in reducing the disease incidence when applied after pathogen inoculation (curative assay) than when applied before pathogen inoculation (prophylactic assay). Thus, the results suggest that propolis extracts have potential to be applied as part of an integrated approach for the control of brown spot of pear.

scholarly journals Determining the Sources of Primary and Secondary Inoculum and Seasonal Inoculum Dynamics of Fungal Pathogens Causing Fruit Rot of Deciduous Holly

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 951-958
Author(s):  
Shan Lin ◽  
Francesca Peduto Hand
Keyword(s):  
Leaf Spot ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Fruit Rot ◽  
Plant Production ◽  
Mature Fruit ◽  
Average Temperature ◽  
Leaf Spots ◽  
Maximum Minimum

Fruit rot of deciduous holly, caused by species of the genera Alternaria, Colletotrichum, Diaporthe, and Epicoccum, is affecting plant production in Midwestern and Eastern U.S. nurseries. To determine the sources of inoculum, dormant twigs and mummified fruit were collected, and leaf spot development was monitored throughout the season from three Ohio nurseries over two consecutive years. Mummified fruit was the main source of primary inoculum for species of Alternaria and Epicoccum, whereas mummified fruit and bark were equally important for species of Colletotrichum and Diaporthe. Brown, irregular leaf spots developed in the summer, and disease incidence and severity increased along with leaf and fruit development. Coalesced leaf spots eventually resulted in early plant defoliation. When tested for their pathogenicity on fruit, leaf spot isolates were able to infect wounded mature fruit and induce rot symptoms, which indicated that leaf spots could serve as a source of secondary inoculum for fruit infections. In addition, spore traps were used to monitor seasonal inoculum abundance in the nurseries. Fruit rot pathogens were captured by the spore traps throughout the season, with peak dissemination occurring during flowering. In this study, we also attempted to understand the role of environmental factors on leaf spot development. Although leaf spot incidence and severity were negatively correlated to mean maximum, minimum and average temperature, a decrease in temperature also coincided with leaf senescence. The role of temperature on leaf spot development should be further studied to fully interpret these results.

scholarly journals Effect of Inoculum Concentration and Interrupted Wetness Duration on the Development of Anthracnose Fruit Rot of Strawberry

Plant Disease ◽  
2017 ◽  
Vol 101 (2) ◽  
pp. 372-377 ◽  
Author(s):  
Bruna B. Forcelini ◽  
Fabricio Packer Gonçalves ◽  
Natalia A. Peres
Keyword(s):  
Disease Incidence ◽  
Warning System ◽  
Fruit Rot ◽  
Colletotrichum Acutatum ◽  
Inoculum Concentration ◽  
Immature Fruit ◽  
Different Levels ◽  
Strawberry Cultivars

Anthracnose fruit rot (AFR) of strawberry, caused by Colletotrichum acutatum, greatly affects production if not controlled. Application of fungicides in addition to the use of less susceptible cultivars are important tools for AFR control. The effects of interrupted wetness duration and inoculum concentration on the development of AFR were evaluated on strawberry cultivars with different levels of susceptibility. Fruit rot and flower blight incidence generally increased with increasing inoculum concentration. ‘Camarosa’ and ‘Treasure’ were more susceptible than ‘Strawberry Festival’ and flowers were more susceptible than immature fruit for most cultivars. Interruption in wetness periods had a significant effect on disease incidence when fruit where exposed to dry periods of 6 h or more compared with 24 h of continuous wetness. The results of this study will be used to refine a disease-warning system to predict AFR outbreaks in Florida strawberry production fields.

Molecular and morphological characterization of mealybugs (Hemiptera: Pseudococcidae) from Chilean vineyards

2012 ◽  
Vol 102 (5) ◽  
pp. 524-530 ◽  
Author(s):  
M.C.G. Correa ◽  
J-F. Germain ◽  
T. Malausa ◽  
T. Zaviezo
Keyword(s):  
Management Strategies ◽  
Common Species ◽  
Morphological Characterization ◽  
Economic Losses ◽  
Morphological Examination ◽  
Pseudococcus Longispinus ◽  
Main Production ◽  
Pseudococcus Viburni ◽  
Production Areas

AbstractMealybugs are major pests of grapevines worldwide. They cause economic losses by lowering the cosmetic value of fruits, reducing yields, transmitting viruses and resulting in the quarantine or rejection of produce in international trade. Knowledge of the species present in a vineyard is important for the adjustment of management strategies. We surveyed and accurately characterized the mealybugs infesting vineyards in one of the main production areas of Chile; 164 mealybugs were sampled from 26 vineyards in four regions of Chile and identified by DNA sequencing for two markers (cytochrome oxidase I and internal transcribed spacer 2) and morphological examination.Pseudococcus viburni(Signoret) was the most common species, followed byPseudococcus meridionalisPrado andPseudococcus cribataGonzález. Molecular variability at the COI and ITS2 loci was observed in bothP. viburniandP. cribata. A comparison of haplotypes ofP. viburniworldwide provides support for a recent hypothesis that this species is native to South America, a finding with direct consequences for management. NeitherPseudococcus longispinus(Targioni & Tozzetti) norPlanococcus ficusSignoret were found.

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