scholarly journals Premature Apple Fruit Drop: Associated Fungal Species and Attempted Management Solutions

Horticulturae ◽  
2020 ◽  
Vol 6 (2) ◽  
pp. 31 ◽  
Author(s):  
Khamis Youssef ◽  
Sergio Ruffo Roberto
Keyword(s):  
Fungal Pathogens ◽  
Fruit Set ◽  
Phytopathogenic Fungi ◽  
Apple Fruit ◽  
In Vitro Tests ◽  
Variable Effect ◽  
Thiophanate Methyl ◽  
Fruit Drop ◽  
Naturally Occurring

The aim of this research was to determine the incidence and possible causal pathogen(s) of premature apple fruit drop (PAFD), and also to assess some fungicides for controlling the disease organisms, in order to promote a sustainable system in orchards. The prevalence and natural incidence of apple fruit drop in cv. Anna was assessed during the 2017–2018 growing seasons in Nubaria and Cairo–Alexandria regions, Egypt. Phytopathogenic fungi were isolated from dropped fruit, and four fungicides, pyraclostrobin + boscalid, difenoconazole, carbendazim, and thiophanate methyl, were tested against the diseases in vitro and under naturally occurring infections in the field. Several phytopathogenic fungi, including Alternaria alternata, Cladosporium cladosporioides, Fusarium semitectum, and Penicillium spp., were associated with apple fruit drop. A. alternata was the most frequently isolated fungus occurring during the investigation. Pathogenicity tests confirmed that the maximum percentage of apple fruit drop was noted when petioles and fruits were inoculated with mixed fungal pathogens using branch sections with fruit. In vitro tests showed that the fungicides had a variable effect against the fungal isolates depending on the concentration used. All fungicides completely inhibited the growth of A. alternata, C. cladosporioides, and F. semitectum at 400 mg·L−1. Under naturally occurring infections, thiophanate methyl applied at fruit set had the greatest effect (81.68%) against PAFD, followed by difenoconazole (73.76%), pyraclostrobin + boscalid (70.29%), and carbendazim (66.34%). The results indicated that PAFD may in part be a result of diseases caused by certain phytopathogenic fungi, which could be controlled using a number of fungicides applied at the beginning of fruit set.

scholarly journals Bacteria Belonging to Pseudomonas typographi sp. nov. from the Bark Beetle Ips typographus Have Genomic Potential to Aid in the Host Ecology

Insects ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 593
Author(s):  
Ezequiel Peral-Aranega ◽  
Zaki Saati-Santamaría ◽  
Miroslav Kolařik ◽  
Raúl Rivas ◽  
Paula García-Fraile
Keyword(s):  
Bark Beetle ◽  
Fungal Pathogens ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Ips Typographus ◽  
In Vitro Tests ◽  
Defense Compounds ◽  
Genes Encoding ◽  
Host Ecology

European Bark Beetle Ips typographus is a secondary pest that affects dead and weakened spruce trees (Picea genus). Under certain environmental conditions, it has massive outbreaks, resulting in the attacks of healthy trees, becoming a forest pest. It has been proposed that the bark beetle’s microbiome plays a key role in the insect’s ecology, providing nutrients, inhibiting pathogens, and degrading tree defense compounds, among other probable traits yet to be discovered. During a study of bacterial associates from I. typographus, we isolated three strains identified as Pseudomonas from different beetle life stages. A polyphasic taxonomical approach showed that they belong to a new species for which the name Pseudomonas typographi sp nov. is proposed. Genome sequences show their potential to hydrolyze wood compounds and synthesize several vitamins; screening for enzymes production was verified using PNP substrates. Assays in Petri dishes confirmed cellulose and xylan hydrolysis. Moreover, the genomes harbor genes encoding chitinases and gene clusters involved in the synthesis of secondary metabolites with antimicrobial potential. In vitro tests confirmed the capability of the three P. typographi strains to inhibit several Ips beetles’ pathogenic fungi. Altogether, these results suggest that P. typographi aids I. typographi nutrition and resistance to fungal pathogens.

scholarly journals Baseline Sensitivities of Fungal Pathogens of Fruit and Foliage of Citrus to Azoxystrobin, Pyraclostrobin, and Fenbuconazole

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1186-1194 ◽  
Author(s):  
S. N. Mondal ◽  
Alka Bhatia ◽  
Turksen Shilts ◽  
L. W. Timmer
Keyword(s):  
Mycelial Growth ◽  
Fungal Pathogens ◽  
Fungal Species ◽  
Brown Spot ◽  
Colletotrichum Acutatum ◽  
Fungicide Sensitivity ◽  
Fruit Drop ◽  
Coefficients Of Variation ◽  
Foliar Pathogens

The baseline sensitivities for mycelial growth of foliar fungal pathogens of citrus, Colletotrichum acutatum, Alternaria alternata, Elsinoe fawcettii, Diaporthe citri, and Mycosphaerella citri, the causal agents of postbloom fruit drop, brown spot of tangerine, citrus scab, melanose, and greasy spot, respectively, were determined in vitro for azoxystrobin, pyraclostrobin, and fenbuconazole. The effective dose to reduce growth by 50% (ED50 values) was determined for each pathogen-fungicide combination using five isolates from different citrus areas of Florida and eight fungicide concentrations. A discriminatory dose for each combination was selected near the ED50, and the range of sensitivity of 50 to 62 isolates of each fungal species was determined. The effect of salicylhydroxamic acid (SHAM) on the sensitivity of the five fungal species to azoxystrobin and pyraclostrobin was determined. Since mycelial growth of A. alternata was insensitive to azoxystrobin, the effect of that fungicide with and without SHAM on spore germination was assessed. The ED50 values for most fungal pathogens of citrus were relatively high compared with foliar pathogens of other tree crops. Values for azoxystrobin ranged from a low of 0.06 μg/ml with E. fawcettii to a high of >100 μg/ml with A. alternata. With pyraclostrobin, the values ranged from a low of 0.019 μg/ml with D. citri to a high of 0.87 μg/ml with A. alternata. With fenbuconazole, the lowest ED50 value was 0.21 μg/ml with M. citri and the highest was 1.01 μg/ml with C. acutatum, but A. alternata and D. citri were not tested. SHAM was inhibitory to all species and reduced growth of D. citri greatly. Inclusion of SHAM in the medium did not greatly affect the sensitivity of mycelial growth of these fungi to azoxystrobin or pyraclostrobin, nor did it affect the ED50 values for conidial germination of A. alternata. The coefficients of variation for the sensitivity of 50 to 62 isolates of each species to these fungi ranged from 7.3% with the pyraclostrobin-C. acutatum combination to a high of 55.0% with the fenbuconazole- M. citri combination. Discriminatory doses have been established for these pathogen- fungicide combinations that should be useful for detecting major shifts in fungicide sensitivity.

scholarly journals Heterologous Expression of Septoria lycopersici Tomatinase in Cladosporium fulvum: Effects on Compatible and Incompatible Interactions with Tomato Seedlings

1998 ◽  
Vol 11 (3) ◽  
pp. 228-236 ◽  
Author(s):  
Rachel E. Melton ◽  
Lynda M. Flegg ◽  
James K. M. Brown ◽  
Richard P. Oliver ◽  
Michael J. Daniels ◽  
...  
Keyword(s):  
Heterologous Expression ◽  
Fungal Pathogens ◽  
Phytopathogenic Fungi ◽  
Cladosporium Fulvum ◽  
Tomato Plants ◽  
Septoria Lycopersici ◽  
Tomato Pathogen ◽  
Anti Fungal ◽  
Incompatible Interactions

The anti-fungal, steroidal, glycoalkaloid saponin, α-tomatine, is present in uninfected tomato plants in substantial concentrations, and may contribute to the protection of tomato plants against attack by phytopathogenic fungi. In general, successful fungal pathogens of tomato are more resistant to α-tomatine in vitro than fungi that do not infect this plant. For a number of tomato pathogens, this resistance has been associated with the ability to detoxify α-tomatine through the action of enzymes known as tomatinases. In contrast, the biotrophic tomato pathogen Cladosporium fulvum is sensitive to α-tomatine and is unable to detoxify this saponin. This paper describes the effects of heterologous expression of the cDNA encoding tomatinase from the necrotroph Septoria lycopersici in two different physiological races of C. fulvum. Tomatinase-producing C. fulvum transformants showed increased sporulation on cotyledons of susceptible tomato lines. They also caused more extensive infection of seedlings of resistant tomato lines. Thus, α-tomatine may contribute to the ability of tomato to restrict the growth of C. fulvum in both compatible and incompatible interactions.

scholarly journals Regional Evaluation of Fungal Pathogen Incidence in Colombian Cocoa Crops

Agriculture ◽  
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.

scholarly journals Fungi pathogenic to the corm of arracacha (Arracada xanthorrhiza) in Puerto Rico

1969 ◽  
Vol 84 (1-2) ◽  
pp. 53-64
Author(s):  
Evelyn Rosa-Márquez ◽  
Lydia I. Rivera ◽  
Carlos E. Ortiz ◽  
Arcángel Rodríguez
Keyword(s):  
Puerto Rico ◽  
Phytophthora Palmivora ◽  
In Vitro Tests ◽  
Fusarium Spp ◽  
Thiophanate Methyl ◽  
Pathogenicity Tests

Phytophthora palmivora, Rhizoctonia sp. and two isolates of Fusarium spp. were identified and associated with the arracacha (Arracada xanthorrhiza) corm rot in pathogenicity tests conducted in vitro and in vivo. In vitro tests revealed that these fungi were pathogenic to the corm. Fungi caused lesions to the corm under greenhouse conditions. Three major symptoms were observed: necrotized roots; necrotized roots with a dry, brown, hard injury to the internal corm tissue; and wet lesions with brown shades. The highest incidence of affected corms occurred with P. palmivora in combination with Rhizoctonia sp., and the lowest was observed in corms inoculated with Rhizoctonia sp. alone. The most severe symptoms were caused by P. palmivora alone and in combination with Rhizoctonia sp. In vitro tests were conducted to evaluate the efficacy of metalaxyl, etridiazofe thiophanate-methyl, and fosetyl-al against the isolated fungi at doses of 5 to 200 mg ai/kg. Among the fungicides tested, etridiazole thiophanate-methyl was effective against all fungi associated with corm rot. Micelial growth of P. palmivora was completely inhibited with metataxyl at all doses and by etridiazole thiophanate-methyl with doses of 20 or more mg ai/kg.

scholarly journals Postharvest Treatments with Three Yeast Strains and Their Combinations to Control Botrytis cinerea of Snap Beans

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2736
Author(s):  
Mingfang Feng ◽  
You Lv ◽  
Tiantian Li ◽  
Xinmao Li ◽  
Jiayin Liu ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Botrytis Cinerea ◽  
Fungal Pathogens ◽  
Postharvest Disease ◽  
In Vitro Tests ◽  
Cryptococcus Albidus ◽  
Snap Beans ◽  
Yeast Strains

Three yeast strains, namely Cryptococcus albidus (Ca63), Cryptococcus albidus (Ca64), and Candida parapsilosis (Yett1006), and their combinations, including single yeast agent, two combined yeast strains, single yeast agent + NaHCO3, single yeast agent + chitosan, single yeast agent + ascorbic acid, and single yeast agent + konjac powder, were evaluated for their activity against Botrytis cinerea, the most economically important fungal pathogens causing postharvest disease of snap beans. In in vitro tests, no inhibition zone was observed in dual cultures of three yeast strains and B. cinerea. The mycelial growth inhibition rates of B. cinerea for Ca63, Ca64, and Yett1006 were 97%, 95%, and 97%, respectively. In in vivo tests, the optimal combination of the lowest disease index of snap beans with B. cinerea was Ca63 + Ca64, with a preventing effect of 75%. The decay rate and rust spots index of Ca64 + ascorbic acid combination were 25% and 20%, respectively, which were the lowest. The activities of defense-related enzymes increased, while malondialdehyde (MDA) content was suppressed in snap beans after different treatments. Our results highlight the potential of the three yeast strains and their combinations as new nonpolluting agents for the integrated control of B. cinerea on snap beans.

scholarly journals Antagonistic effect of volatile and non-volatile compounds from Streptomyces strains on cultures of several phytopathogenic fungi

2020 ◽  
pp. 879
Author(s):  
Daniel Alonso Pérez Corral ◽  
José de Jesús Ornelas Paz ◽  
Guadalupe Isela Olivas Orozco ◽  
Carlos Horacio Acosta Muñiz ◽  
Miguel Ángel Salas Marina ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Fungal Pathogens ◽  
Culture Medium ◽  
Plant Pathogens ◽  
Aerial Mycelium ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
Fresh Culture Medium

Fungi and oomycetes are important plant pathogens that constantly attacked plants, thus compromising the production of foods worldwide. Streptomyces strains might be useful to control fungal pathogens by different mechanism. The in vitro antagonistic activity of non-volatile and volatile metabolites from four Streptomyces strains was evaluated over cultures of phytopathogenic fungi and oomycetes. The non-volatile compounds from Streptomyces strains significantly reduced (44.2 to 92.1%) the growth of aerial mycelium of pathogens. The volatile compounds (VOCs) from Streptomyces strains reduced both aerial mycelium (22.5 to 96.7%) and mycelium growing inside of culture medium (0.0 - 9.4%). The pathogens maintained their capacity to grow normally in fresh culture medium without antagonists after confrontations with antagonist VOCs. The analysis of VOCs by gas chromatography coupled to mass spectrometry revealed different kinds of VOCs included alcohols, aldehydes, ketones, esters, terpenes, terpenoids, thioethers, among others. The most abundant VOCs were trans-1,10-dimethyl-trans-9-decalol (geosmin), 2-methylisoborneol, 2-methyl-2-bornene, 1,4-dimethyladamantane, and 4-penten-1-ol, trifluoroacetate. The antipathogenic activity of nine pure VOCs that had been identified in cultures of the Streptomyces strains alone was evaluated in vitro against phytopathogenic fungi and oomycetes. Trans-2-hexenal was the most effective of these VOCs, inhibiting completely the growth of tested phytopathogens. The volatile and non-volatile compounds from Streptomyces strains effectively reduced the in vitro growth of phytopathogens and they might be used as biological control. Further studies are required to demonstrate this activity on open field conditions.

scholarly journals Study of compatibility and determination of the suitable pollinizer for Argane tree (Argania spinosa L.)

2021 ◽  
Author(s):  
Naima Ait Aabd ◽  
Abdelghani Tahiri ◽  
Abdelaziz Mimouni ◽  
Rachid Bouharroud
Keyword(s):  
Fruit Set ◽  
Pollen Viability ◽  
Breeding Program ◽  
In Vitro Tests ◽  
Pollen Donor ◽  
Cross Compatibility ◽  
Hand Pollination ◽  
Flowering Rate ◽  
First Time

During the breeding program studies, the pollen donor parents (pollinizers) were observed to be characterized by a strong flowering rate and very low fruit set, even after hand pollination. Then the notion of pollinizers in the argane species was born, first mentioned, checked, documented and confirmed like other conventional tree species. Since the argane tree is completely self-incompatible, the presence of compatible pollinizers is necessary for the fruit set. Indeed, pollinizers need to be selected accurately based on the synchronization of bloom periods and compatibility to receiver trees (female). The pollinizer is essential in any breeding program and for new orchard plantations. The current study was conducted on 13 argane genotypes including two pollinizers. The flowering period, bloom phenology, floral structure and fruit set of crossed genotypes were monitored, illustrated and a season phenogram was established. The pollen viability and germination were also evaluated. In order to test compatibility, the hand pollination using two selected pollinizer pollens was compared to open pollination. Then, the compatibility system was monitored and evaluated through analysis of crossing diallel programs and through the index of self-incompatibility. The flowering periods are genotype depending and one to three blooms have been observed during the two years study (2018-2019) and the argane tree is a tristylous species (Mesostylous, brevistylous and longistylous flowers). The in vitro tests showed that the pollen originated from crossed genotypes were viable and able to germinate. The cross-compatibility rate depends on cross associations and it varies from 39 to 84 %. In fact, this study showed that the effect of pollen-parent (xenia) occurs in all fruit components of argane tree. It was observed, for the first time, that both compatible pollinizers and xenic effects of pollen on argane fruit have occurred. Artificial pollination is currently feasible for breeding programs and the screening of elite genotypes. Then the selected pollinizer is quite required for the development of argane tree cropping.

scholarly journals Effect of the Chloro-Substitution on Electrochemical and Optical Properties of New Carbazole Dyes

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3091
Author(s):  
Przemysław Krawczyk ◽  
Beata Jędrzejewska ◽  
Klaudia Seklecka ◽  
Joanna Cytarska ◽  
Krzysztof Z. Łączkowski
Keyword(s):  
Optical Properties ◽  
Fluorescent Probes ◽  
Quantum Chemical ◽  
Biological Properties ◽  
Biologically Active ◽  
In Vitro Tests ◽  
Naturally Occurring ◽  
Active Substances

Carbazole derivatives are the structural key of many biologically active substances, including naturally occurring and synthetic ones. Three novel (E)-2-(2-(4-9H-carbazol-9-yl)benzylidene)hydrazinyl)triazole dyes were synthesized with different numbers of chlorine substituents attached at different locations. The presented research has shown the influence of the number and position of attachment of chlorine substituents on electrochemical, optical, nonlinear, and biological properties. The study also included the analysis of the use of the presented derivatives as potential fluorescent probes for in vivo and in vitro tests. Quantum-chemical calculations complement the conducted experiments.

scholarly journals Investigation of host-specificity of phytopathogenic fungi isolated from woody plants

2020 ◽  
pp. 155-160
Author(s):  
Andrea Zabiák ◽  
Györk Milán Károlyi ◽  
Erzsébet Sándor
Keyword(s):  
Host Specificity ◽  
Fungal Pathogens ◽  
Apple Tree ◽  
Weather Conditions ◽  
Phytopathogenic Fungi ◽  
Botryosphaeria Dothidea ◽  
New Host ◽  
Diplodia Seriata ◽  
New Hosts

Host-specificity is an important characteristic of fungal pathogens. Changing climate could create more appropriate environmental conditions for phytopathogens, thus formerly host-specify fungi could be able to colonize new hosts. Noxious plant pathogen fungi, which can infect several plant species are well-known worldwide. These genera may expand their range of hosts because of the appearance in new geographic areas due to climate change. This new exposure can result in serious problems in agriculture because of the lack of immunity. The susceptibility of apple tree was studied through testing pathogenicity in vitro with species isolated from walnut twigs and nuts, and identified by ITS sequences. Three of four tested species, Botryosphaeria dothidea, Diaporthe eres and Diplodia seriata colonized and necrotized the infected apple branches, while Juglanconis juglandina was not able to infect the twigs. Members of Botryosphaeriaceae were the most virulent, causing the largest lesions in the fastest way. This experiment draws attention to the threat of new host-pathogen connections, which can arise because of the favourable weather conditions and can spread between neighbouring cultures. 

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