Prevalence and Epidemics of Neoscytalidium Stem and Fruit Canker on Pitahaya (Hylocereus spp.) in South Florida

Since the 2000s, production of pitahaya (Hylocereus spp.) has increased significantly in South Florida. However, very limited information is available on the main diseases affecting this crop, particularly in regard to disease epidemiology and economic impact on the commodity. In this study, we surveyed five local pitahaya orchards and documented the most prevalent diseases and their causal agents. Three genera of fungal pathogens (Neoscytalidium, Alternaria, and Colletotrichum) were the major groups associated with symptoms on pitahaya cladodes (stems) during the early growing season. Among these, N. dimidiatum was identified as the most prevalent pathogen, with an overall isolation frequency of 29.8% (range, 13.9 to 47.2%). Hence, the temporal progress of N. dimidiatum stem canker infection was monitored and the relationship between stem canker intensity (incidence and severity) and fruit canker incidence was investigated. A significant positive correlation was found between fruit canker incidence and the standardized area under the disease incidence or severity curve on cladodes, suggesting that high stem canker intensity in the early season may contribute to high fruit canker incidence and thereby impact the aesthetic and market value of fruits. In vitro assays showed that both conidial germination and mycelial growth of N. dimidiatum are positively correlated with increasing temperature, with a maximum growth area at 32°C. This finding suggests a higher risk of infection, under an environment with high temperatures, which is common in South Florida. Data obtained in this study represent baseline knowledge for the future development of integrative management programs for controlling major diseases of pitahaya in South Florida.

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Antagonistic potential of lactobacillus plantarum against some postharvest pathogenic fungi

Zbornik Matice srpske za prirodne nauke ◽

10.2298/zmspn1936079z ◽

2019 ◽

pp. 79-88

Author(s):

Svetlana Zivkovic ◽

Stefan Stosic ◽

Danijela Ristic ◽

Ivan Vucurovic ◽

Milos Stevanovic

Keyword(s):

Lactobacillus Plantarum ◽

Fungal Pathogens ◽

Disease Incidence ◽

Pathogenic Fungi ◽

In Vitro Assays ◽

Colletotrichum Acutatum ◽

Bacterial Suspension ◽

Antagonistic Potential

Lactobacillus plantarum, one of the most widespread lactic acid bacte?ria, exert a strong antagonistic activity against many microorganisms. The present study was conducted to determine in vitro and in situ antagonistic potential of L. plantarum (DSM 20174) for control postharvest decay caused by phytopathogenic fungi: Aspergillus flavus, Colletotrichum acutatum, Colletotrichum gloeosporioides, and Fusarium avenaceum. The results obtained in in vitro assays showed that L. plantarum had a stronger inhibitory effect on spore germination than on mycelia growth of all tested fungi. After 3 days of incubation, the diameter of inhibition zones ranged from 11.67 mm for C. gloeosporioides to 14.67 mm for C. acutatum. The bacterial suspension of L. plantarum significantly inhibited conidial germination of all postharvest pathogens (89.62-97.61%). In situ assays showed that treatment with L. plantarum efficiently inhibited necrosis ranging from 42.54% for C. acutatum to 54.47% for A. flavus. The disease incidence in L. plantarum treated fruits was statistically significantly lower than in the positive control for all fungi tested (P<0.05). The presented data demonstrate the antagonistic potential of L. plantarum (DSM 20174) and indicate the possibility of using this bacterial strain as a biological agent to control postharvest fungal pathogens.

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

Journal of Science and Technology - IUH ◽

10.46242/jst-iuh.v44i02.1036 ◽

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.

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VARIATION IN AGGRESSIVENESS OF FUSARIUM HEAD BLIGHT SPECIES TOWARDS BARLEY PLANTS DETERMINED USING THREE IN VITRO ASSAYS

Pakistan Journal of Phytopathology ◽

10.33866/phytopathol.031.01.0478 ◽

2019 ◽

Vol 31 (1) ◽

pp. 19-33 ◽

Cited By ~ 3

Author(s):

Nachaat Sakr

Keyword(s):

Fusarium Head Blight ◽

Disease Incidence ◽

Germination Rate ◽

Field Conditions ◽

In Vitro Assays ◽

Lesion Length ◽

Head Blight ◽

Coleoptile Length ◽

Progress Curve

Aggressiveness is the most important fungal trait affecting Fusarium head blight (FHB) disease invasion and stability of host resistance. Until recently, in vitro methodologies have proved to be very useful in analyzing disease responses in barley plants to FHB infection. To update our knowledge, the variation in aggressiveness for 16 isolates of four FHB species was assessed towards two barley cultivars varying in resistance to FHB. Nine aggressiveness criteria involved in three in vitro assays were used: incubation period, latent period (LP), lesion length (of detached leaf and clip-dipping inoculations), germination rate reduction, standardized area under disease progress curve (AUDPCstandard), coleoptile length reduction of Petri-dish inoculation, and percentage of infected seedlings (of foliar-spraying and pin-point inoculations). Differences in inoculated treatment were observed on young plant parts relative to water controls. Inter and intraspecific differences in aggressiveness were observed towards barley plants as measured by LP and AUDPCstandard. Nevertheless, the other seven criteria did not differentiate FHB isolates. Results indicted that a cultivar-specific aggressiveness do not exist among barley plants and pathogens for LP and AUDPCstandard. Significant correlation coefficients were obtained between the data of LP and AUDPCstandard. Moreover, the values of LP and AUDPCstandard were significantly correlated with the data of disease incidence generated under controlled and field conditions. It seems that LP and AUDPCstandard are indicators of aggressiveness occurring in the whole plant during FHB infection. To our best knowledge, this is the first in vitro research full analyzing aggressiveness of four FHB species on barley plants. In addition, our study investigates the potential use of in vitro indices in predicting FHB data generated under controlled and field conditions.

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

Applied Sciences ◽

10.3390/app10061990 ◽

2020 ◽

Vol 10 (6) ◽

pp. 1990 ◽

Cited By ~ 1

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.

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Isothiocyanates inhibit fungal pathogens of potato in in vitro assays

Plant and Soil ◽

10.1007/s11104-014-2157-y ◽

2014 ◽

Vol 382 (1-2) ◽

pp. 281-289 ◽

Cited By ~ 9

Author(s):

Fiona Isabelle Taylor ◽

David Kenyon ◽

Susan Rosser

Keyword(s):

Fungal Pathogens ◽

In Vitro Assays

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Fusarium oxysporum (F221-B) as biocontrol agent against plant pathogenic fungi in vitro and in hydroponics

Plant Protection Science ◽

10.17221/59/2016-pps ◽

2017 ◽

Vol 53 (No. 2) ◽

pp. 85-95 ◽

Cited By ~ 8

Author(s):

Thongkamngam Titi ◽

Jaenaksorn Tanimnun

Keyword(s):

Fusarium Oxysporum ◽

Fungal Pathogens ◽

Biocontrol Agent ◽

Disease Incidence ◽

Pathogenic Fungi ◽

Curvularia Lunata ◽

Plant Growth Promoting ◽

Healthy Control ◽

Further Development

Efficacy of non-pathogenic Fusarium oxysporum (F221-B) was assessed as a possible biocontrol agent against fungal pathogens, namely Curvularia lunata (C11, C12), F. semitectum (F113), F. oxysporum f.sp. lactucae (F221-R, F442-G), Rhizoctonia solani (R11, R12), Rhizoctonia sp. (R111, R112, R113) in vitro, while F221-B showed a moderate ability to inhibit the mycelial growth of tested fungi about 36–56%. Then, F221-B was further evaluated for its ability of controlling lettuce root rot and wilt caused by F442-G in hydroponics. It was revealed that F221-B reduced disease incidence and severity about 60–80% compared to the inoculated control and significantly promoted the growth of 3 lettuce varieties. Interestingly, using only F221-B gave the significantly highest fresh weight (twice over the healthy control). Conclusively, this study provides an important suggestion for further development of F221-B since it showed the ability of biocontrol agent and plant growth promoting fungus.

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Regional Evaluation of Fungal Pathogen Incidence in Colombian Cocoa Crops

Agriculture ◽

10.3390/agriculture9030044 ◽

2019 ◽

Vol 9 (3) ◽

pp. 44

Author(s):

Raquel Villamizar-Gallardo ◽

Johann Osma ◽

Oscar Ortíz-Rodriguez

Keyword(s):

Fungal Pathogens ◽

Morphological Variability ◽

Phytopathogenic Fungi ◽

Phytophthora Palmivora ◽

In Vitro Assays ◽

Post Conflict ◽

Solid Media ◽

Black Pod

The production of cocoa (Theobroma cacao L.) in Colombia has a significant environmental and socioeconomic importance as a promissory crop in the post-conflict process. The department of Norte de Santander has cocoa crops that are dramatically affected by fungal pathogens causing important losses during harvest and post-harvest. Therefore, the current study focused on the determination of the incidence of diseases caused by phytopathogenic fungi in cocoa crops, and the identification of primary phytopathogenic fungi found in biological material from different farms of the region. The study was conducted in four municipalities of the department, by sampling fruits infected with frosty pod rot (FPR) and black pod rot (BPR) that presented in situ incidence ranging from 0.37 to 21.58% and from 1.75 to 35.59%, respectively. The studied hybrid materials, together with clone TSH 65, were found to be the most susceptible, while the remaining clones were more tolerant, especially CCN 51, IMC 67, and ICS95. Fifteen strains were isolated using in vitro assays and then morphologically characterized both in solid media and by microscopy. Nine of them corresponded to the pathogen Moniliophthora roreri, and other six to Phytophthora palmivora. The isolated agents showed in vitro morphological variability, as well as the ability to adapt to different environments when growing in situ.

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Antifungal Mechanism of Rhodotorula mucilaginosa and Aureobasidium sp. nov. Isolated from Cerbera manghas L. against the Growth of Destructive Molds in Post Harvested Apples

Recent Patents on Food Nutrition & Agriculturee ◽

10.2174/2212798411666200423101159 ◽

2020 ◽

Vol 11 (3) ◽

pp. 219-228

Author(s):

Dalia Sukmawati ◽

Andisa Shabrina ◽

Reni Indrayanti ◽

Tri Handayani Kurniati ◽

Muktiningsih Nurjayadi ◽

...

Keyword(s):

Disease Incidence ◽

Its Rdna ◽

In Vitro Assays ◽

Postharvest Disease ◽

Dual Culture ◽

Rhodotorula Mucilaginosa ◽

Killer Activity ◽

Aureobasidium Sp ◽

Cerbera Manghas

Background: Apples often experience postharvest damage due to being attacked by mold organisms. Several groups of molds such as Aspergillus sp., Penicilium expansum, Botrytis cinerea, and Venturia sp. can cause a serious postharvest disease exhibited as watery regions where areas of blue-green tufts of spores develop. Current methods using fungicides to control pathogenic fungi can cause resistance if applied in the long term. An alternative procedure using yeast as a biological agent has been found. Objective: The aim of this study is to screen potential yeast, which has the ability to inhibit the growth of Aspergillus brasielensis (isolate A1) and Aspergillus flavus section flavi (isolate A17) isolated from apple fruits. Methods: Antagonism test using YMA dual culture medium using in vitro assays and ITS rDNA identification were performed. Results: The result showed that 3 out of 19 yeast isolated from Cerbera manghas L, T1, T3 and T4, demonstrated the potential ability as a biocontrol agent. ITS rDNA identification demonstrated that T1 has a similarity to Rhodotorula mucilaginosa while T3 and T4 were identified as Aureobasidium sp. nov. The 3 isolates exhibited the ability to reduce the growth of A. brasiliensis sensu lato better than dithane 0.3% with a Disease Incidence (DI) of 100% and a Disease Severity (DS) value of 45%. Only isolate T1 and T3 were able to reduce decay symptoms in apples inoculated with A. flavus sensu lato (with DO and DS were 100% and 25%, respectively) compared to dithane pesticides 0.3%. Conclusion: This study indicated that competition between nutrients occurs between pathogenic molds and under-yeast in vitro and in vivo conditions. However, further studies in the future might be able to elucidate the ‘killer’ activity and interaction with the pathogen cells and the bio-product production using Rhodotorula mucilaginosa and Aureoubasidium namibiae strains to control postharvest diseases.

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Serendipita Species Trigger Cultivar-Specific Responses to Fusarium Wilt in Tomato

Agronomy ◽

10.3390/agronomy9100595 ◽

2019 ◽

Vol 9 (10) ◽

pp. 595 ◽

Cited By ~ 4

Author(s):

Negar Ghezel Sefloo ◽

Krzysztof Wieczorek ◽

Siegrid Steinkellner ◽

Karin Hage-Ahmed

Keyword(s):

Disease Incidence ◽

Dry Mass ◽

In Vitro Assays ◽

Plant Interactions ◽

Inhibitory Effects ◽

Negative Effects ◽

Beneficial Effects ◽

Specific Effects ◽

Tomato Cultivars

The endophytic fungi Serendipita indica and S. vermifera have recently gained increasing attention due to their beneficial effects on plant growth and plant health. Little is known about other species, such as S. williamsii and S. herbamans. To test their biocontrol and growth-promoting potential, susceptible and tolerant tomato cultivars (Kremser Perle and Micro-Tom, respectively) were inoculated with S. williamsii, S. herbamans, S. indica, or S. vermifera and challenged with the soilborne pathogen Fusarium oxysporum f. sp. lycopersici (Fol) in greenhouse experiments. Furthermore, in vitro assays on the direct inhibitory effects of Serendipita spp. against Fol were performed. Negative effects of Fol on phenological growth in the susceptible cultivar were alleviated by all four applied Serendipita spp. Apart from these similar effects on biometric parameters, disease incidence was only reduced by S. herbamans and S. vermifera. In the tolerant cultivar, disease parameters remained unaffected although shoot dry mass was negatively affected by S. vermifera. Direct effects of Serendipita spp. against Fol were not evident in the in vitro assays indicating an indirect effect via the host plant. Our results highlight the importance of identifying cultivar-specific effects in pathogen–endophyte–plant interactions to determine the most beneficial combinations.

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Novel Hit Compounds as Putative Antifungals: The Case of Aspergillus fumigatus

Molecules ◽

10.3390/molecules24213853 ◽

2019 ◽

Vol 24 (21) ◽

pp. 3853 ◽

Cited By ~ 5

Author(s):

Eftichia Kritsi ◽

Minos-Timotheos Matsoukas ◽

Constantinos Potamitis ◽

Anastasia Detsi ◽

Marija Ivanov ◽

...

Keyword(s):

Antifungal Activity ◽

Aspergillus Fumigatus ◽

Fungal Pathogens ◽

Fungal Infections ◽

Pharmacophore Model ◽

Antifungal Drugs ◽

In Vitro Assays ◽

Minimum Fungicidal Concentration ◽

Dynamics Simulations

The prevalence of invasive fungal infections has been dramatically increased as the size of the immunocompromised population worldwide has grown. Aspergillus fumigatus is characterized as one of the most widespread and ubiquitous fungal pathogens. Among antifungal drugs, azoles have been the most widely used category for the treatment of fungal infections. However, increasingly, azole-resistant strains constitute a major problem to be faced. Towards this direction, our study focused on the identification of compounds bearing novel structural motifs which may evolve as a new class of antifungals. To fulfil this scope, a combination of in silico techniques and in vitro assays were implemented. Specifically, a ligand-based pharmacophore model was created and served as a 3D search query to screen the ZINC chemical database. Additionally, molecular docking and molecular dynamics simulations were used to improve the reliability and accuracy of virtual screening results. In total, eight compounds, bearing completely different chemical scaffolds from the commercially available azoles, were proposed and their antifungal activity was evaluated using in vitro assays. Results indicated that all tested compounds exhibit antifungal activity, especially compounds 1, 2, and 4, which presented the most promising minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values and, therefore, could be subjected to further hit to lead optimization.

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