Articles de revues : « Foliar fungal pathogens »

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Çelik Oğuz, Arzu, et Aziz Karakaya. « Genetic Diversity of Barley Foliar Fungal Pathogens ». Agronomy 11, n^o 3 (27 février 2021) : 434. http://dx.doi.org/10.3390/agronomy11030434.

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Powdery mildew, net blotch, scald, spot blotch, barley stripe, and leaf rust are important foliar fungal pathogens of barley. Fungal leaf pathogens negatively affect the yield and quality in barley plant. Virulence changes, which can occur in various ways, may render resistant plants to susceptible ones. Factors such as mutation, population size and random genetic drift, gene and genotype flow, reproduction and mating systems, selection imposed by major gene resistance, and quantitative resistance can affect the genetic diversity of the pathogenic fungi. The use of fungicide or disease-resistant barley genotypes is an effective method of disease control. However, the evolutionary potential of pathogens poses a risk to overcome resistance genes in the plant and to neutralize fungicide applications. Factors affecting the genetic diversity of the pathogen fungus may lead to the emergence of more virulent new pathotypes in the population. Understanding the factors affecting pathogen evolution, monitoring pathogen biology, and genetic diversity will help to develop effective control strategies.

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Allan, Eric, Jasper van Ruijven et Michael J. Crawley. « Foliar fungal pathogens and grassland biodiversity ». Ecology 91, n^o 9 (septembre 2010) : 2572–82. http://dx.doi.org/10.1890/09-0859.1.

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Fang, Kai, Jie Zhou, Lin Chen, Yu-Xuan Li, Ai-Ling Yang, Xing-Fan Dong et Han-Bo Zhang. « Virulence and community dynamics of fungal species with vertical and horizontal transmission on a plant with multiple infections ». PLOS Pathogens 17, n^o 7 (15 juillet 2021) : e1009769. http://dx.doi.org/10.1371/journal.ppat.1009769.

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The virulence evolution of multiple infections of parasites from the same species has been modeled widely in evolution theory. However, experimental studies on this topic remain scarce, particularly regarding multiple infections by different parasite species. Here, we characterized the virulence and community dynamics of fungal pathogens on the invasive plant Ageratina adenophora to verify the predictions made by the model. We observed that A. adenophora was highly susceptible to diverse foliar pathogens with mixed vertical and horizontal transmission within leaf spots. The transmission mode mainly determined the pathogen community structure at the leaf spot level. Over time, the pathogen community within a leaf spot showed decreased Shannon diversity; moreover, the vertically transmitted pathogens exhibited decreased virulence to the host A. adenophora, but the horizontally transmitted pathogens exhibited increased virulence to the host. Our results demonstrate that the predictions of classical models for the virulence evolution of multiple infections are still valid in a complex realistic environment and highlight the impact of transmission mode on disease epidemics of foliar fungal pathogens. We also propose that seedborne fungi play an important role in structuring the foliar pathogen community from multiple infections within a leaf spot.

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Brown, Alexander, et Robert W. Heckman. « Light alters the impacts of nitrogen and foliar pathogens on the performance of early successional tree seedlings ». PeerJ 9 (8 juillet 2021) : e11587. http://dx.doi.org/10.7717/peerj.11587.

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Light limitation is a major driver of succession and an important determinant of the performance of shade-intolerant tree seedlings. Shade intolerance may result from a resource allocation strategy characterized by rapid growth and high metabolic costs, which may make shade-intolerant species particularly sensitive to nutrient limitation and pathogen pressure. In this study, we evaluated the degree to which nitrogen availability and fungal pathogen pressure interact to influence plant performance across different light environments. To test this, we manipulated nitrogen availability (high, low) and access by foliar fungal pathogens (sprayed with fungicide, unsprayed) to seedlings of the shade-intolerant tree, Liquidambar styraciflua, growing at low and high light availability, from forest understory to adjacent old field. Foliar fungal damage varied with light and nitrogen availability; in low light, increasing nitrogen availability tripled foliar damage, suggesting that increased nutrient availability in low light makes plants more susceptible to disease. Despite higher foliar damage under low light, spraying fungicide to exclude pathogens promoted 14% greater plant height only under high light conditions. Thus, although nitrogen availability and pathogen pressure each influenced aspects of plant performance, these effects were context dependent and overwhelmed by light limitation. This suggests that failure of shade-intolerant species to invade closed-canopy forest can be explained by light limitation alone.

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van Esse, H. Peter, Emilie F. Fradin, Philip J. de Groot, Pierre J. G. M. de Wit et Bart P. H. J. Thomma. « Tomato Transcriptional Responses to a Foliar and a Vascular Fungal Pathogen Are Distinct ». Molecular Plant-Microbe Interactions® 22, n^o 3 (mars 2009) : 245–58. http://dx.doi.org/10.1094/mpmi-22-3-0245.

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Plant activation of host defense against pathogenic microbes requires significant host transcriptional reprogramming. In this study, we compared transcriptional changes in tomato during compatible and incompatible interactions with the foliar fungal pathogen Cladosporium fulvum and the vascular fungal pathogen Verticillium dahliae. Although both pathogens colonize different host tissues, they display distinct commonalities in their infection strategy; both pathogens penetrate natural openings and grow strictly extracellular. Furthermore, resistance against both pathogens is conveyed by the same class of resistance proteins, the receptor-like proteins. For each individual pathogen, the expression profile of the compatible and incompatible interaction largely overlaps. However, when comparing between the two pathogens, the C. fulvum-induced transcriptional changes show little overlap with those induced by V. dahliae. Moreover, within the subset of genes that are regulated by both pathogens, many genes show inverse regulation. With pathway reconstruction, networks of tomato genes implicated in photorespiration, hypoxia, and glycoxylate metabolism were identified that are repressed upon infection with C. fulvum and induced by V. dahliae. Similarly, auxin signaling is differentially affected by the two pathogens. Thus, differentially regulated pathways were identified with novel strategies that allowed the use of state-of-the-art tools, even though tomato is not a genetic model organism.

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Akanmu, Akinlolu Olalekan, Timothy Oladiran Ajiboye, Masego Seleke, Sabelo D. Mhlanga, Damian C. Onwudiwe et Olubukola Oluranti Babalola. « The Potency of Graphitic Carbon Nitride (gC3N4) and Bismuth Sulphide Nanoparticles (Bi2S3) in the Management of Foliar Fungal Pathogens of Maize ». Applied Sciences 13, n^o 6 (15 mars 2023) : 3731. http://dx.doi.org/10.3390/app13063731.

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Maize (Zea mays L.) is the most significant grain crop in South Africa. Despite its importance, the cereal is ravaged by several foliar fungal pathogens, which reduce maize quality and quantity at harvest. Hence, this study investigates the fungi associated with foliar diseases of maize in Molelwane, North-West Province, South Africa. The fungi were isolated, characterized and subjected to in vitro nanoparticle control. Samples of diseased maize leaves were aseptically collected from two maize-growing farms. Fungi associated with the samples were isolated and characterized using standard procedures. Bi2S3 (metal-containing) and gC3N4 (non-metallic carbon-based) nanoparticles were synthesized and used to challenge the pathogens using standard procedures. Foliar fungal pathogens isolated from the diseased maize leaves in this study were characterized as Bipolaris zeicola, Phoma herbarum, Epicoccum nigrum, Alternaria alternata and Fusarium brachygibbosum. Phoma herbarium > A. alternata > B. zeicola > F. brachygibbosum > E. nigrum was the order of percentage fungal inhibition by the nanoparticles. Bi2S3 was more effective against the pathogens at lower concentrations and gC3N4 at higher concentration levels. The two nanoparticle types evaluated in vitro shows potential for managing the foliar fungal pathogens, and this needs to be further validated in field studies.

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Barbetti, M. J., et M. P. You. « Opportunities and challenges for improved management of foliar pathogens in annual clover pastures across southern Australia ». Crop and Pasture Science 65, n^o 12 (2014) : 1249. http://dx.doi.org/10.1071/cp14117.

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Foliar pathogens result in significant losses in herbage and seed yields and regeneration capacity in annual clover pastures, the last leading to their rapid deterioration and lack of persistence. The most important pathogens include Kabatiella caulivora (clover scorch), Cercospora zebrina (cercospora), Uromyces trifolii-repentis (rust), Erysiphe trifoliorum (powdery mildew), and Leptosphaerulina trifolii (pepper spot). Several other foliar pathogens on annual clovers, in particular Phoma medicaginis (black stem and leaf spot), one or more Stemphylium spp. (stemphylium leaf spot), Pseudopeziza trifolii (common leaf spot), Stagonospora spp. (stagonospora leaf spot), Colletotrichum trifolii (anthracnose) and Sclerotinia trifoliorum (sclerotinia), occur widely and together contribute to reduce productivity in some localities. Severe attack by the most important pathogens (e.g. K. caulivora, U. trifolii-repentis, E. trifoliorum) not only greatly reduces winter–spring pasture production but frequently also coincides with the critical feed shortage across autumn–winter, leading to significantly decreased autumn–winter biomass production in regenerating stands. Approaches to disease control include a range of management strategies. Wider utilisation of cultural and fungicidal control strategies offers producers greater management flexibility, particularly in conjunction with deployment of cultivars with useful resistance. Host resistance offers the greatest potential for delivering the most cost-effective and long-term control. Many of these foliar pathogens co-occur, magnifying losses; this highlights the need for individual host genotypes with resistance to multiple pathogens and unique geographic locations such as Sardinia offer enormous scope to select such clovers. Future research opportunities and critical priorities to improve management of foliar pathogens in annual clover pastures across southern Australia include the need to: (i) define pathogen strain–race structures, particularly for K. caulivora and U. trifolii-repentis, and determine associated host resistances against specific strains–races to allow strategic deployment of host resistances; (ii) define relative resistances to major fungal foliar pathogens of all parental and near-release breeding genotypes and all commercial cultivars across important annual clover species; (iii) identify new sources of host resistance, particularly genotypes with cross-resistance to multiple pathogens, for breeders to utilise; (iv) identify and demonstrate the benefits to farmers of effective cultural (e.g. grazing, removal of infested residues) and fungicidal control options that allow greater management flexibility to reduce the impact of fungal foliar diseases; and (v) determine current incidences and impacts (losses and economic importance) of major fungal foliar diseases in the different agro-climatic regions across southern Australia. Failure to address these critical issues leaves livestock industries carrying the risks from release of new varieties of unknown susceptibilities to one or more of the major foliar diseases, and the risks from continued use of older varieties exposed to new pathogen races; with few if any flexible management options during periods of critical feed shortage; and without the basic information on current disease impacts that is needed to make sensible management and funding decisions.

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Dawadi, Sujan, Fulya Baysal-Gurel, Karla M. Addesso, Prabha Liyanapathiranage et Terri Simmons. « Fire Ant Venom Alkaloids : Possible Control Measure for Soilborne and Foliar Plant Pathogens ». Pathogens 10, n^o 6 (27 mai 2021) : 659. http://dx.doi.org/10.3390/pathogens10060659.

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The purpose of this study was to evaluate fire ant venom alkaloids and an alarm pheromone analog against several plant pathogens, including Botrytis cinerea, Fusarium oxysporum, Phytophthora nicotianae, P. cryptogea, Pseudomonas syringae, Phytopythium citrinum, Rhizoctonia solani, Sclerotonia rolfsii, Xanthomonas axonopodis, and X. campestris. All pathogens were tested against red imported fire ant venom alkaloid extract and alarm pheromone compound for growth inhibition in in vitro assay. The venom alkaloid extract inhibited fungal and oomycete pathogens. Neither of the treatments were effective against bacterial pathogens. Three soilborne pathogens, P. nicotianae, R. solani, F. oxysporum, and one foliar pathogen, B. cinerea were selected for further in-vivo assays on impatiens (Impatiens walleriana ‘Super Elfin XP violet’). Total plant and root weight were higher in venom alkaloid treated plants compared to an inoculated control. The venom alkaloid treatment reduced damping-off, root rot severity, and pathogen recovery in soilborne pathogen inoculated plants. Similarly, venom alkaloid reduced Botrytis blight. However, higher venom rates caused foliar phytotoxicity on plants. Therefore, additional work is needed to evaluate rates of venom alkaloids or formulations to eliminate negative impacts on plants. Overall, these results suggest that red imported fire ant venom alkaloids may provide a basis for new products to control soilborne and foliar plant pathogens.

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Tomoshevich, M. A., D. Belomesyatseva, E. V. Banaev, I. G. Vorob’eva et T. Shabashova. « Comparative Analysis of Foliar Diseases of Some Native and Non-Native Tree Species in Belarus and Siberia ». Contemporary Problems of Ecology 16, n^o 2 (avril 2023) : 217–29. http://dx.doi.org/10.1134/s1995425523020166.

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Abstract Urban green spaces are known to be subjected to additional anthropogenic stress. Using native plants in monoculture, i.e., planting trees of the same species, may favour disease outbreaks and plant death. Non-native plants to be used in large cities for creating sustainable plantations are being searched for worldwide. Meanwhile, it is necessary to control plant pathogens in the variable conditions of the region and natural habitat. In Siberian cities, non-native European trees are used, and non-native Siberian plants are introduced in Belarus. This article reports long-term observations of foliar fungal pathogens attacking 21 woody plants (19 European, 2 Siberian) in Siberian and Belarusian cities. In both regions, 48 leaf fungal pathogens were detected, with powdery mildew fungi predominating in Belarus and leaf spotting fungi prevailing in Siberia. In both research regions, the greatest number of fungal species was found on Syringa vulgaris L. In Siberia, many pathogens were found on the non-native European plant Berberis vulgaris (9 species) and native plant Caragana arborescens Lam. (8 species). We have not detected the pathogens on European plants: Acer campestre L., Acer platanoides L., Euonymus europaeus L., Lonicera caprifolium L. in urban green areas in Siberia, while we have identified one to four foliar fungal pathogens on these plants in Belarus. To sum up: more pathogens were found on native plants in Siberia and Belarus; some leaf pathogen species (Sawadaea tulasnei (Fuckel) Homma, Erysiphe alphitoides (Griffon & Maubl.) U. Braun & S. Takam., Cladosporium syringae (Oudem.) Montem., Erysiphe syringae Schwein., Erysiphe palczewskii (Jacz.) U. Braun & S. Takam.) followed their host plants (Acer tataricum L., Syringa vulgaris L., Caragana arborescens Lam.) when introduced into new areas; and some local pathogens were also observed to spread to the non-native plants of closely related species.

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Magarey, R. D., T. B. Sutton et C. L. Thayer. « A Simple Generic Infection Model for Foliar Fungal Plant Pathogens ». Phytopathology® 95, n^o 1 (janvier 2005) : 92–100. http://dx.doi.org/10.1094/phyto-95-0092.

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In this study, a simple generic infection model was developed for predicting infection periods by fungal foliar pathogens. The model is designed primarily for use in forecasting pathogens that do not have extensive epidemiological data. Most existing infection models require a background epidemiological data set, usually including laboratory estimates of infection at multiple temperature and wetness combinations. The model developed in this study can use inputs based on subjective estimates of the cardinal temperatures and the wetness duration requirement. These inputs are available for many pathogens or may be estimated from related pathogens. The model uses a temperature response function which is scaled to the minimum and optimum values of the surface wetness duration requirement. The minimum wetness duration requirement (Wmin) is the number of hours required to produce 20% disease incidence or 5% disease severity on inoculated plant parts at a given temperature. The model was validated with published data from 53 controlled laboratory studies, each with at least four combinations of temperature and wetness. Validation yielded an average correlation coefficient of 0.83 and a root mean square error of 4.9 h, but there was uncertainty about the value of the input parameters for some pathogens. The value of Wmin varied from 1 to 48 h and was relatively uniform for species in the genera Cercospora, Alternaria, and Puccinia but less so for species of Phytophthora, Venturia, and Colletotrichum. Operationally, infection models may use hourly or daily weather inputs. In the case of the former, information also is required to estimate the critical dry-period interruption value, defined as the duration of a dry period at relative humidities <95% that will result in a 50% reduction in disease compared with a continuous wetness period. Pathogens were classified into three groups based on their critical dry-period interruption value. The infection model is being used to create risk maps of exotic pests for the U.S. Department of Agriculture's Animal Plant Health and Inspection Service.

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Meller Harel, Yael, Yigal Elad, Dalia Rav-David, Menachem Borenstein, Ran Shulchani, Beni Lew et Ellen R. Graber. « Biochar mediates systemic response of strawberry to foliar fungal pathogens ». Plant and Soil 357, n^o 1-2 (25 février 2012) : 245–57. http://dx.doi.org/10.1007/s11104-012-1129-3.

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Makowski, D., R. Bancal et A. Vicent. « Estimation of Leaf Wetness Duration Requirements of Foliar Fungal Pathogens with Uncertain Data—An Application to Mycosphaerella nawae ». Phytopathology® 101, n^o 11 (novembre 2011) : 1346–54. http://dx.doi.org/10.1094/phyto-01-11-0024.

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Wetness of the host surface is a critical environmental factor for the development of foliar fungal diseases, but it is difficult to estimate the wetness durations required by pathogens for infection when only few experimental data are available. In this paper, we propose a method to estimate wetness duration requirements of foliar fungal pathogens when precise experimental data are not available. The proposed method is based on approximate Bayesian computation. It only requires lower and upper bounds of wetness duration requirements for one or fewer temperatures. We describe the method, show how to apply it to an infection model, and then present a case study on Mycosphaerella nawae, the causal agent of circular leaf spot of persimmon. In this example, the parameters of a simple infection model were estimated using experimental data found in the literature for the pathogen, and the model was applied to assess the risk in a Spanish area recently affected by the disease. The results showed that the probability of successful infection was higher than 0.5 for 32% of the on-site wetness durations recorded in the affected area. Results obtained with simulated data showed that our method was able to improve the estimation of wetness duration requirement. Given the flexibility of the proposed method, we expect it to become adopted for assessing the risk of introduction of exotic fungal plant pathogens.

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Díaz-Cruz, Gustavo A., et Bryan J. Cassone. « Amplicon Sequencing Reveals Extensive Coinfections of Foliar Pathogens in Soybean ». Plant Disease 105, n^o 1 (janvier 2021) : 127–33. http://dx.doi.org/10.1094/pdis-06-20-1165-re.

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Soybean (Glycine max) is one of the most economically important crops grown in North America and in other regions worldwide. However, the plant is susceptible to a variety of foliar pathogenic microorganisms, some of which are a significant threat to production. Several molecular and serological approaches are currently available to diagnose plant pathogens, but all have limitations including their capability to accurately detect coinfections of individual plants. We therefore used 16S and internal transcribed spacer amplicon sequencing to identify the suite of bacterial and fungal organisms infecting 96 soybean leaf samples collected throughout southern Manitoba, Canada, at two growth stages (V2/3 and R6). We were able to confirm the presence of pathogens previously known to our sampling regions, such as Septoria glycines, Alternaria alternata, and Pseudomonas spp. Importantly, we found that most of plants were infected by more than one putative pathogen, with 64% of V2/3 and 26% of R6 plants infected by three or more pathogens. Amplicon sequencing also indicated the presence of residual pathogens that infect crops other than soybean, as well as nonfoliar pathogens and nonpathogenic microorganisms. We discuss some of the benefits and drawbacks of using amplicon sequencing to detect foliar pathogens of soybean.

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Peterson, P. D., et C. L. Campbell. « Prevalence and Ecological Association of Foliar Pathogens of Cucumber in North Carolina, 1996-1998 ». Plant Disease 86, n^o 10 (octobre 2002) : 1094–100. http://dx.doi.org/10.1094/pdis.2002.86.10.1094.

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During the fall growing seasons of 1996-98, 5,400 leaves exhibiting leaf spots were collected from cucumber (Cucumis sativus L.) fields and microscopically examined to identify the organisms associated with these symptoms. Five fungal pathogens were associated with leaf lesions: Alternaria cucumerina, Colletotrichum orbiculare, Corynespora cassiicola, Didymella bryoniae, and Pseudoperonospora cubensis; D. bryoniae and C. orbiculare occurred most frequently. When pathogens were paired on five or more leaves, associations between pathogen pairs were tested for independence via a 2-by-2 contingency table χ2 analysis. In all, 66 two-way pathogen associations were tested. Of these, 39 associations were negative (occurred together less often than expected at random), 1 was positive (occurred together more often than expected at random), and, in 16 cases, the pathogens were not associated. An association between C. orbiculare and D. bryoniae occurred 24 times and, each time, the relationship was negative. This result, combined with different environmental requirements for infection, suggests that these pathogens either occupy different niches in the plant canopy or are antagonistic. No relationship between the cultivars grown or the fungicides applied and the pathogens isolated from specific field sites was found. Information on the dominant pathogens responsible for leaf spot epidemics in North Carolina's cucumber fields will be useful to target breeding and disease control strategies.

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Jerushalmi, Shachar, Marcel Maymon, Aviv Dombrovsky et Stanley Freeman. « Fungal Pathogens Affecting the Production and Quality of Medical Cannabis in Israel ». Plants 9, n^o 7 (13 juillet 2020) : 882. http://dx.doi.org/10.3390/plants9070882.

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The use of and research on medical cannabis (MC) is becoming more common, yet there are still many challenges regarding plant diseases of this crop. For example, there is a lack of formal and professional knowledge regarding fungi that infect MC plants, and practical and effective methods for managing the casual agents of disease are limited. The purpose of this study was to identify foliar, stem, and soilborne pathogens affecting MC under commercial cultivation in Israel. The predominant major foliage pathogens were identified as Alternaria alternata and Botrytis cinerea, while the common stem and soilborne pathogens were identified as Fusarium oxysporum and F. solani. Other important fungi that were isolated from foliage were those producing various mycotoxins that can directly harm patients, such as Aspergillus spp. and Penicillium spp. The sampling and characterization of potential pathogenic fungi were conducted from infected MC plant parts that exhibited various disease symptoms. Koch postulates were conducted by inoculating healthy MC tissues and intact plants with fungi isolated from infected commercially cultivated symptomatic plants. In this study, we report on the major and most common plant pathogens of MC found in Israel, and determine the seasonal outbreak of each fungus.

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Ch, Yamuna, Bhattiprolu SL, Prasanna Kumari V et Chiranjeevi Ch. « In vitro evaluation of fungicides against fungal foliar pathogens of cotton ». International Journal of Chemical Studies 8, n^o 2 (1 mars 2020) : 2829–35. http://dx.doi.org/10.22271/chemi.2020.v8.i2aq.9178.

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Friesen, Timothy L., et Justin D. Faris. « Characterization of Effector–Target Interactions in Necrotrophic Pathosystems Reveals Trends and Variation in Host Manipulation ». Annual Review of Phytopathology 59, n^o 1 (25 août 2021) : 77–98. http://dx.doi.org/10.1146/annurev-phyto-120320-012807.

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Great strides have been made in defining the details of the plant defense response involving biotrophic fungal and bacterial pathogens. The groundwork for the current model was laid by H.H. Flor and others who defined the gene-for-gene hypothesis, which is now known to involve effector-triggered immunity (ETI). PAMP-triggered immunity (PTI) is also a highly effective response to most pathogens because of the recognition of common pathogen molecules by pattern recognition receptors. In this article, we consider the three pathogens that make up the foliar disease complex of wheat, Zymoseptoria tritici, Pyrenophora tritici-repentis, and Parastagonospora nodorum, to review the means by which necrotrophic pathogens circumvent, or outright hijack, the ETI and PTI pathways to cause disease.

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Abbasi, P. A., et G. Lazarovits. « Effect of acidic electrolyzed water on the viability of bacterial and fungal plant pathogens and on bacterial spot disease of tomato ». Canadian Journal of Microbiology 52, n^o 10 (1 octobre 2006) : 915–23. http://dx.doi.org/10.1139/w06-048.

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Acidic electrolyzed water (AEW), known to have germicidal activity, was obtained after electrolysis of 0.045% aqueous solution of sodium chloride. Freshly prepared AEW (pH 2.3–2.6, oxidation–reduction potential 1007–1025 mV, and free active chlorine concentration 27–35 ppm) was tested in vitro and (or) on tomato foliage and seed surfaces for its effects on the viability of plant pathogen propagules that could be potential seed contaminants. Foliar sprays of AEW were tested against bacterial spot disease of tomato under greenhouse and field conditions. The viability of propagules of Xanthomonas campestris pv. vesicatoria (bacterial spot pathogen), Streptomyces scabies (potato scab pathogen), and Fusarium oxysporum f.sp. lycopersici (root rot pathogen) was significantly reduced 4–8 log units within 2 min of exposure to AEW. Immersion of tomato seed from infected fruit in AEW for 1 and 3 min significantly reduced the populations of X. campestris pv. vesicatoria from the surface of the seed without affecting seed germination. Foliar sprays of AEW reduced X. campestris pv. vesicatoria populations and leaf spot severity on tomato foliage in the greenhouse. In the field, multiple sprays of AEW consistently reduced bacterial spot severity on tomato foliage. Disease incidence and severity was also reduced on fruit, but only in 2003. Fruit yield was either enhanced or not affected by the AEW sprays. These results indicate a potential use of AEW as a seed surface disinfectant or contact bactericide.Key words: electrolyzed oxidizing water, seed disinfectant, foliar sprays, bacterial spot control.

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Pablo-Rodríguez, José Luis, Ángel E. Bravo-Monzón, Cristina Montiel-González, Julieta Benítez-Malvido, Sandra Álvarez-Betancourt, Oriana Ramírez-Sánchez, Ken Oyama, María Leticia Arena-Ortiz, Mariana Yólotl Alvarez-Añorve et Luis Daniel Avila-Cabadilla. « Linking Anthropogenic Landscape Perturbation to Herbivory and Pathogen Leaf Damage in Tropical Tree Communities ». Plants 12, n^o 22 (13 novembre 2023) : 3839. http://dx.doi.org/10.3390/plants12223839.

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Anthropogenic disturbance of tropical humid forests leads to habitat loss, biodiversity decline, landscape fragmentation, altered nutrient cycling and carbon sequestration, soil erosion, pest/pathogen outbreaks, among others. Nevertheless, the impact of these alterations in multitrophic interactions, including host–pathogen and vector–pathogen dynamics, is still not well understood in wild plants. This study aimed to provide insights into the main drivers for the incidence of herbivory and plant pathogen damage, specifically, into how vegetation traits at the local and landscape scale modulate such interactions. For this purpose, in the tropical forest of Calakmul (Campeche, Mexico), we characterised the foliar damage caused by herbivores and pathogens in woody vegetation of 13 sampling sites representing a gradient of forest disturbance and fragmentation in an anthropogenic landscape from well preserved to highly disturbed and fragmented areas. We also evaluated how the incidence of such damage was modulated by the vegetation and landscape attributes. We found that the incidence of damage caused by larger, mobile, generalist herbivores, was more sensitive to changes in landscape configuration, while the incidence of damage caused by small and specialised herbivores with low dispersal capacity was more influenced by vegetation and landscape composition. In relation to pathogen symptoms, the herbivore-induced foliar damage seems to be the main factor related to their incidence, indicating the enormous importance of herbivorous insects in the modulation of disease dynamics across tropical vegetation, as they could be acting as vectors and/or facilitating the entry of pathogens by breaking the foliar tissue and the plant defensive barriers. The incidence of pathogen damage also responded to vegetation structure and landscape configuration; the incidence of anthracnose, black spot, and chlorosis, for example, were favoured in sites surrounded by smaller patches and a higher edge density, as well as those with a greater aggregation of semi-evergreen forest patches. Fungal pathogens were shown to be an important cause of foliar damage for many woody species. Our results indicate that an increasing transformation and fragmentation of the tropical forest of southern Mexico could reduce the degree of specialisation in plant–herbivore interactions and enhance the proliferation of generalist herbivores (chewers and scrapers) and of mobile leaf suckers, and consequently, the proliferation of some symptoms associated with fungal pathogens such as fungus black spots and anthracnose. The symptoms associated with viral and bacterial diseases and to nutrient deficiency, such as chlorosis, could also increase in the vegetation in fragmented landscapes with important consequences in the health and productivity of wild and cultivated plant species. This is a pioneering study evaluating the effect of disturbances on multitrophic interactions, offering key insights on the main drivers of the changes in herbivory interactions and incidence of plant pathogens in tropical forests.

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Nasir, Muhammad Nasir. « Management Of Aspergillus Leaf Spot Diseases on Terminalia Catappa In Sokoto, Nigeria ». Pacific International Journal 4, n^o 1 (30 juin 2021) : 07–12. http://dx.doi.org/10.55014/pij.v4i1.26.

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Research on the diseased leaves of Terminalia catappa (tropical almond) was conducted in Usmanu Danfodiyo University Permanent site, Wammako local government, Sokoto. The locations where the diseased leaves were collected, purposively selected because of the abundance of the tree species in those locations. The objective was to identify fungal foliar diseases associated with Terminalia catappa and then develop control measures of the pathogen. Diseased leaves were collected and taken to the department of biological sciences, Mycology laboratory, Botany unit, Usmanu Danfodiyo University for identification. Aspergillus niger, Aspergillus ustus and, Aspergillus flavus were the fungal pathogens identified and suspected to be the cause of the foliar diseases on the tree species. Suncozeb, a broad-spectrum fungicide was obtained for the management of these diseases. The chemical was applied at different concentration rates (50%, 100% and, 150%) and the zones of inhibitions were observed and measured. It was observed that the higher the concentration the higher the zones of inhibition; this was the case for all the organisms identified. Past research showed that high temperature makes this species prone to soil-borne pathogens and this is the case with the study area of this research. As part of the recommendation, since it was observed that 150% of Suncozeb clearly inhibited the growth of the pathogen to a certain level, a higher concentration of this same chemical will increase the inhibition zone and possibly bring a complete stoppage of the pathogen spread.

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Nganga, Everlyne M., Martina Kyallo, Philemon Orwa, Felix Rotich, Emily Gichuhi, John M. Kimani, David Mwongera et al. « Foliar Diseases and the Associated Fungi in Rice Cultivated in Kenya ». Plants 11, n^o 9 (7 mai 2022) : 1264. http://dx.doi.org/10.3390/plants11091264.

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We conducted a survey to assess the occurrence and severity of rice blast and brown spot diseases on popular cultivars grown in the Busia, Kirinyaga, and Kisumu counties of Kenya in 2019. Working with agricultural extension workers within rice production areas, we interviewed farmers (n = 89) regarding their preferred cultivars and their awareness of blast disease, as this was the major focus of our research. We scored the symptoms of blast and brown spot and assessed the lodging, plant height, and maturity of the crops (days after planting). Furthermore, we collected leaf and neck tissues for the assessment of the prevailing fungal populations. We used specific DNA primers to screen for the prevalence of the causal pathogens of blast, Magnaporthe oryzae, and brown spot, Cochliobolus miyabeanus, on asymptomatic and symptomatic leaf samples. We also conducted fungal isolations and PCR-sequencing to identify the fungal species in these tissues. Busia and Kisumu had a higher diversity of cultivars compared to Kirinyaga. The aromatic Pishori (NIBAM 11) was preferred and widely grown for commercial purposes in Kirinyaga, where 86% of Kenyan rice is produced. NIBAM108 (IR2793-80-1) and BW196 (NIBAM 109) were moderately resistant to blast, while NIBAM110 (ITA310) and Vietnam were susceptible. All the cultivars were susceptible to brown spot except for KEH10005 (Arize Tej Gold), a commercial hybrid cultivar. We also identified diverse pathogenic and non-pathogenic fungi, with a high incidence of Nigrospora oryzae, in the rice fields of Kirinyaga. There was a marginal correlation between disease severity/incidence and the occurrence of causal pathogens. This study provides evidence of the need to strengthen pathogen surveillance through retraining agricultural extension agents and to breed for blast and brown spot resistance in popular rice cultivars in Kenya.

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Vagelas, Ioannis, Chris Cavalaris, Lefkothea Karapetsi, Charalambos Koukidis, Dimitris Servis et Panagiotis Madesis. « Protective Effects of Systiva® Seed Treatment Fungicide for the Control of Winter Wheat Foliar Diseases Caused at Early Stages Due to Climate Change ». Agronomy 12, n^o 9 (24 août 2022) : 2000. http://dx.doi.org/10.3390/agronomy12092000.

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Foliar fungal diseases are a serious threat to winter wheat production and climate change appears to favor pathogens associated with leaf blotch and tan spot symptoms in the Mediterranean area. The present work aimed to highlight these risks and propose appropriate disease management strategies by evaluating the seed treatment with the Systiva® (BASF) fungicide as a means to protect the crop against foliar fungal infections during the early growing stages. Towards that aim, plant tissue symptoms affected by the pathogens Pyrenophora tritici-repentis and Septoria spp. were systematically recorded in a study field in the region of Larissa, central Greece for three years (2016–2018), and the findings were associated with the monthly weather anomalies. Consequently, for the growing period of 2021–2022, a field experiment was established in the same disease prone field, comparing different doses of the seed treatment with Systiva® fungicide against leaf blotch and tan spot diseases. The evaluation was made by visual disease assessments, remote sensing with an unmanned aerial vehicle (UAV) and metagenomics analysis. Parallel measurements on straw residues were also made to characterize the plant residues perithecia (pseudothecia). Visual leaf disease assessments and UAV remote sensing data showed that Systiva® treatments at doses of 125 cc and 150 cc per 100 kg of wheat seed can reduce the percentage of infected wheat plants caused by foliar fungal pathogens at wheat growth stages GS23-25 and GS30-31. Moreover, the metagenomics analyses performed on the microbial communities revealed that Systiva® can decrease the degree of infection by P. tritici-repentis and Z. tritici but do not provide sufficient protection against P. nodorum. Foliar diseases were influenced by the soil surface area covered with straw residue with a high proportion of natural inoculum (pseudothecia/ascospores).

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Jayaraj, J., M. Rahman, A. Wan et Z. K. Punja. « Enhanced resistance to foliar fungal pathogens in carrot by application of elicitors ». Annals of Applied Biology 155, n^o 1 (août 2009) : 71–80. http://dx.doi.org/10.1111/j.1744-7348.2009.00321.x.

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Percival, Glynn, et Sean Graham. « Calcium and Silicon Fertiliser Influence on Fungicide Efficacy Against Guignardia Leaf Blotch and Apple Scab Management ». Arboriculture & ; Urban Forestry 47, n^o 4 (1 juillet 2021) : 170–81. http://dx.doi.org/10.48044/jauf.2021.016.

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Management of fungal diseases within urban landscapes relies heavily on repeat fungicide sprays. Environmental concerns have led to a need to eliminate or reduce fungicide use. Foliar sprays of calcium- (Ca) and silicon- (Si) based fertilisers have been shown to reduce symptom severity of several fungal pathogens. The aim of our research was to evaluate the influence of Ca chloride, Ca metasolate, tetra ethyl silicate, and potassium silicate fertilisers, applied independently and in combination with a synthetic fungicide (penconazole) at full and half strength, on apple scab (Venturia inaequalis) and Guignardia leaf blotch (Guignardia aesculi) symptom severity, as well as leaf chlorophyll content, fruit yield, and crown volume. Trials used container-grown Aesculus hippocastanum and field-grown Malus domestica cv. ‘Golden Delicious’. Applications of Ca, Si, and penconazole sprays alone significantly reduced scab and leaf blotch severity compared to water-sprayed controls; however, a significant difference between the type of Ca and Si fertilisers was recorded. A combined mix of a Ca or Si fertiliser with a full or half dose of penconazole was more effective at reducing symptom severity of both foliar pathogens than a full or half dose of penconazole alone. Data analysed with Limpel’s formula indicated positive synergistic effects between Ca and Si and penconazole in some, but not all, cases. The integration of Ca and Si foliar sprays as an alternative to, or additive with, penconazole for scab and leaf blotch management appears feasible based on results of our studies and may have applicability against other fungal pathogens.

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You, Ming Pei, Jay Ram Lamichhane, Jean-Noël Aubertot et Martin J. Barbetti. « Understanding Why Effective Fungicides Against Individual Soilborne Pathogens Are Ineffective with Soilborne Pathogen Complexes ». Plant Disease 104, n^o 3 (mars 2020) : 904–20. http://dx.doi.org/10.1094/pdis-06-19-1252-re.

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Annual forage legumes across southern Australia continue to be devastated by soilborne diseases. Nine fungicide seed treatments (thiram, metalaxyl, iprodione, phosphonic acid, propamocarb, fluquinconazole, difenoconazole + metalaxyl, ipconazole + metalaxyl, sedaxane + difenoconazole + metalaxyl) and four foliar fungicide treatments (phosphonic acid, metalaxyl, propamocarb, iprodione) were tested on four subterranean clover cultivars against individual oomycete soilborne pathogens Pythium irregulare, Aphanomyces trifolii, and Phytophthora clandestina and the fungal pathogen Rhizoctonia solani. Best treatments were then further tested across southern Australia in 2 years of field experiments. Under controlled conditions, seed treatment with thiram was best against damping-off caused by P. irregulare across the four cultivars (Woogenellup, Riverina, Seaton Park, Meteora), while metalaxyl was the most effective for maximizing root and shoot weights. Against A. trifolii, metalaxyl, iprodione, difenoconazole + metalaxyl, ipconazole + metalaxyl, and sedaxane + difenoconazole + metalaxyl, all reduced damping-off; sedaxane + difenoconazole + metalaxyl, fluquinconazole, and ipconazole + metalaxyl all reduced lateral root disease across two or more cultivars; while iprodione, thiram, and sedaxane + difenoconazole + metalaxyl increased shoot dry weight. Against P. clandestina, metalaxyl was the most effective in reducing tap and lateral root rot followed by ipconazole + metalaxyl or phosphonic acid for tap and lateral rot, respectively. Against R. solani, there were no effects of fungicides. For P. irregulare and P. clandestina, there were strong seed fungicide × cultivar interactions (P < 0.001). Under controlled conditions for foliar fungicide spray treatments, phosphonic acid was best at preventing productivity losses from A. trifolii, but was ineffective against P. clandestina, P. irregulare, or R. solani. Overall, controlled environment studies highlighted strong potential for utilizing seed treatments against individual pathogens to ensure seedling emergence and early survival, with seed and foliar sprays enhancing productivity by reducing seedling damping-off and root disease from individual pathogens. However, in field experiments over 2 years across southern Australia against naturally occurring soilborne pathogen complexes involving these same pathogens, only rarely did fungicide seed treatments or foliar sprays tested show any benefit. It is evident that currently available fungicide seed and/or foliar spray treatment options do not offer effective field mitigation of damping-off and root disease on annual forage legumes that underpin livestock production across southern Australia. The main reason for this failure relates to the unpredictable and ever-changing soilborne pathogen complexes involved, highlighting a need to now refocus away from fungicide options, particularly toward developing and deploying new host tolerances, but also in deploying appropriate cultural control options.

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Mondal, S. N., Alka Bhatia, Turksen Shilts et L. W. Timmer. « Baseline Sensitivities of Fungal Pathogens of Fruit and Foliage of Citrus to Azoxystrobin, Pyraclostrobin, and Fenbuconazole ». Plant Disease 89, n^o 11 (novembre 2005) : 1186–94. http://dx.doi.org/10.1094/pd-89-1186.

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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.

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Justesen, Annemarie Fejer, Beatrice Corsi, Andrea Ficke, Lorenz Hartl, Sarah Holdgate, Lise Nistrup Jørgensen, Morten Lillemo et al. « Hidden in plain sight : a molecular field survey of three wheat leaf blotch fungal diseases in North-Western Europe shows co-infection is widespread ». European Journal of Plant Pathology 160, n^o 4 (25 mai 2021) : 949–62. http://dx.doi.org/10.1007/s10658-021-02298-5.

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AbstractWheat (Triticum aestivum L.) yields are commonly affected by foliar infection by fungal pathogens. Of these, three wheat leaf blotch fungal diseases, septoria nodorum blotch (SNB), tan spot (TS) and septoria tritici blotch (STB), caused by Parastagonospora nodorum (Pn), Pyrenophora tritici-repentis (Ptr) and Zymoseptoria tritici (Zt), respectively, induce major yield losses. Infection results in necrotic areas on the leaf, and it is often difficult to determine the underlying causative pathogen from visible symptoms alone, especially in mixed infections. Here, a regional survey of 330 wheat samples collected across three seasons (years 2015–2017) from four north-west European countries was undertaken. Using quantitative polymerase chain reaction (qPCR) assays specific for each pathogen, as well as disease assessment of leaf materials, distinct regional differences were identified. Two-thirds (65%) of all samples harbored at least two of the three pathogens. Norway had high SNB abundance, but also showed mixed infections of SNB, TS and STB. In Germany, TS was prevalent, with STB also common. Danish samples commonly possessed all three pathogens, with STB prevalent, followed by TS and SNB. The UK had a major prevalence of STB with minimal occurrence of TS and SNB. Across all samples, qPCR identified Zt, Pn and Ptr in 90%, 54% and 57% of samples, respectively. For each pathogen, average disease levels via visual assessment showed modest positive correlation with fungal DNA concentrations (R2 = 0.13–0.32). Overall, our study highlights that the occurrence of mixed infection is common and widespread, with important implications for wheat disease management and breeding strategies.

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Saadani, Mariem, Lydia Hönig, Steffen Bien, Michael Koehler, Gemma Rutten, Tesfaye Wubet, Uwe Braun et Helge Bruelheide. « Local Tree Diversity Suppresses Foliar Fungal Infestation and Decreases Morphological but Not Molecular Richness in a Young Subtropical Forest ». Journal of Fungi 7, n^o 3 (27 février 2021) : 173. http://dx.doi.org/10.3390/jof7030173.

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Leaf fungal pathogens alter their host species’ performance and, thus, changes in fungal species composition can translate into effects at the tree community scale. Conversely, the functional diversity of tree species in a host tree’s local neighbourhood can affect the host’s foliar fungal infestation. Therefore, understanding the factors that affect fungal infestations is important to advance our understanding of biodiversity-ecosystem functioning (BEF) relationships. Here we make use of the largest BEF tree experiment worldwide, the BEF-China experiment, where we selected tree host species with different neighbour species. Identifying fungal taxa by microscopy and by high-throughput DNA sequencing techniques based on the internal transcribed spacer (ITS) rDNA region, we analysed the fungal richness and infestation rates of our target trees as a function of local species richness. Based on the visual microscopic assessment, we found that a higher tree diversity reduced fungal richness and host-specific fungal infestation in the host’s local neighbourhood, while molecular fungal richness was unaffected. This diversity effect was mainly explained by the decrease in host proportion. Thus, the dilution of host species in the local neighbourhood was the primary mechanism in reducing the fungal disease severity. Overall, our study suggests that diverse forests will suffer less from foliar fungal diseases compared to those with lower diversity.

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Groben, Glen, Bruce B. Clarke, James Murphy, Paul Koch, Jo Anne Crouch, Sangkook Lee et Ning Zhang. « Real-Time PCR Detection of Clarireedia spp., the Causal Agents of Dollar Spot in Turfgrasses ». Plant Disease 104, n^o 12 (décembre 2020) : 3118–23. http://dx.doi.org/10.1094/pdis-04-20-0726-re.

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Dollar spot is one of the most economically important diseases of turfgrasses. Recent taxonomic revisions have placed the dollar spot fungal pathogens in the new genus Clarireedia, with five species described. The main goal of this study was to develop a quantitative real-time PCR (qPCR) molecular detection assay based on the internal transcribed spacer (ITS) of the ribosomal RNA genes to quantify the abundance of Clarireedia spp. from environmental (field) samples. The qPCR assay was able to detect isolates of the four tested Clarireedia spp. but did not cross react with nontarget fungi, including closely related taxa, other turfgrass pathogens, or other fungal species commonly isolated from turfgrass. The assay is capable of detecting as little as 38.0 fg (3.8 × 10−14 g) of Clarireedia genomic DNA in 3 h. The qPCR assay detected Clarireedia spp. in both symptomatic and asymptomatic creeping bentgrass (Agrostis stolonifera) foliar tissue. Clarireedia spp. were rarely detected in the thatch or soil, indicating that these pathogens are not widely distributed in these areas of the environment. The fact that the pathogen was detected in asymptomatic tissue suggests that creeping bentgrass may be able to tolerate a certain quantity of the pathogens in leaves before disease symptoms appear; however, further research is needed to validate this hypothesis.

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Agan, Ahto, Halvor Solheim, Kalev Adamson, Ari Mikko Hietala, Leho Tedersoo et Rein Drenkhan. « Seasonal Dynamics of Fungi Associated with Healthy and Diseased Pinus sylvestris Needles in Northern Europe ». Microorganisms 9, n^o 8 (17 août 2021) : 1757. http://dx.doi.org/10.3390/microorganisms9081757.

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The relationship between the ecological success of needle pathogens of forest trees and species richness of co-inhabiting endophytic fungi is poorly understood. One of the most dangerous foliar pathogens of pine is Dothistroma septosporum, which is a widely spread threat to northern European forests. We sampled two Pinus sylvestris sites in Estonia and two in Norway in order to analyse the relations between the abundance of D. septosporum and overall fungal richness, specific fungal species composition, time of season, needle age and position in the canopy. In both countries, the overall species richness of fungi was highest in autumn, showing a trend of increase with needle age. The overall species richness in the second-year needles in Estonia and third-year needles in Norway was similar, suggesting that a critical colonization threshold for needle shed in P. sylvestris is breached earlier in Estonia than in Norway. The fungal species richness in P. sylvestris needles was largely affected by Lophodermium conigenum. Especially in older needles, the relative abundance of L. conigenum was significantly higher in spring compared to summer or autumn. The timing of recruitment and colonization mechanisms of different foliage endophytes are shortly discussed.

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Lanzotti, Virginia, Attilio Anzano, Laura Grauso, Maurizio Zotti, Adriana Sacco, Mauro Senatore, Mauro Moreno et al. « NMR Metabolomics and Chemometrics of Lettuce, Lactuca sativa L., under Different Foliar Organic Fertilization Treatments ». Plants 11, n^o 16 (20 août 2022) : 2164. http://dx.doi.org/10.3390/plants11162164.

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Lettuce plants were grown in a greenhouse affected by the fungal pathogen Fusarium oxysporum to test the effects on plant metabolomics by different organic treatments. Three foliar application treatments were applied: a commercial compost tea made of aerobically fermented plant organic matter, a pure lyophilized microalga Artrospira platensis, commonly named spirulina, and the same microalga previously exposed during its culture to a natural uptake from medium enriched with F. oxysporum fragmented DNA (NAT). The experiment is the first attempt to observe in field conditions, the use and effects of a natural microbial library as a carrier of pathogenic fungal DNA for disease control. Untargeted NMR metabolomics and chemometrics showed that foliar organic application significantly reduced fumaric and formic acids, aromatic amino acids, and nucleosides, while increasing ethanolamine. A strong decrease in phenolic acids and an increase in citric acid and glutamine were specifically observed in the NAT treatment. It is noteworthy that the exposure of a known biostimulant microalga to fungal DNA in its culture medium was sufficient to induce detectable changes in the metabolomic profiles of the fertilized plants. These findings deserve further investigation to assess the potential relevance of the presented approach in the field of crop biostimulation and biocontrol of plant pathogens.

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Tomoshevich, M. A. « Interrelations between Alien and Native Foliar Fungal Pathogens and Woody Plants in Siberia ». Contemporary Problems of Ecology 12, n^o 6 (novembre 2019) : 642–57. http://dx.doi.org/10.1134/s1995425519060143.

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Koné, Souleymane B., Antoine Dionne, Russell J. Tweddell, Hani Antoun et Tyler J. Avis. « Suppressive effect of non-aerated compost teas on foliar fungal pathogens of tomato ». Biological Control 52, n^o 2 (février 2010) : 167–73. http://dx.doi.org/10.1016/j.biocontrol.2009.10.018.

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Hantsch, Lydia, Uwe Braun, Josephine Haase, Oliver Purschke, Michael Scherer-Lorenzen et Helge Bruelheide. « No plant functional diversity effects on foliar fungal pathogens in experimental tree communities ». Fungal Diversity 66, n^o 1 (10 janvier 2014) : 139–51. http://dx.doi.org/10.1007/s13225-013-0273-2.

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Harms, Nathan, Judy Shearer, James T. Cronin et John F. Gaskin. « Geographic and genetic variation in susceptibility of Butomus umbellatus to foliar fungal pathogens ». Biological Invasions 22, n^o 2 (16 octobre 2019) : 535–48. http://dx.doi.org/10.1007/s10530-019-02109-3.

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Liu, Xiang, Mu Liu et Yao Xiao. « The effect of foliar fungal pathogens on plant species coexistence : Progress and challenges ». Biodiversity Science 31, n^o 2 (2023) : 22525. http://dx.doi.org/10.17520/biods.2022525.

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BESSADAT, Nabahat, Bruno HAMON, Nelly BATAILLÉ-SIMONEAU, Nisserine HAMINI-KADAR, Mabrouk KIHAL et Philippe SIMONEAU. « Identification and characterization of fungi associated with leaf spot/blight and melting-out of turfgrass in Algeria ». Phytopathologia Mediterranea 62, n^o 1 (8 mai 2023) : 73–93. http://dx.doi.org/10.36253/phyto-14169.

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Symptoms of foliar blight were observed on turfgrass in Oran (Algeria), including yellow chlorotic patches on leaves during the 2020 summer (temperatures between 35 and 40°C). Symptoms extended downward from leaf tips and entire leaves became blighted, leading to irregular discoloured areas that later turned brown. Isolations from infected plants included 214 isolates identified as Curvularia or Bipolaris, based on morphological traits. Other isolates included Fusarium, Myrothecium and Acremonium spp. Three molecular loci, ITS rDNA, gpd and tef1, were amplified and sequenced. Morphological and multi-locus phylogenetic analyses revealed four fungal species viz. B. sorokiniana, C. spicifera, C. verruculosa, C. geniculata, and two additional Curvularia lineages, some of these fungi are reported are first records for Algeria. Koch’s postulates were confirmed by inoculating potted turfgrass with spore suspensions of 16 isolates and re-isolating of the inoculated pathogens from symptomatic tissues. Bipolaris sorokiniana was the most virulent pathogen causing numerous foliar necrotic lesions similar to those observed in the field. Other isolates infected basal leaves only, and caused less severe symptoms. The results show that Curvularia species may be secondary pathogens infecting stressed plants, and that simultaneous occurrence of high temperatures and poor water quality have influenced disease progression. Correct identification of these pathogens is important for applying appropriate and timely disease management.

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Rennberger, Gabriel, Patrick Gerard et Anthony P. Keinath. « Factors Influencing the Occurrence of Foliar Pathogens in Commercial Watermelon Fields in South Carolina Based on Stratified Cluster Sampling ». Plant Disease 103, n^o 3 (mars 2019) : 484–94. http://dx.doi.org/10.1094/pdis-07-18-1188-re.

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The influence of environmental and management factors on the occurrence of foliar pathogens of watermelon was analyzed using survey-sampling data collected from commercial farms in South Carolina in spring 2015 and spring and fall 2016. A stratified two-stage cluster sampling design was used to sample symptomatic watermelon leaves from 56 fields of 27 growers in seven counties representing the main watermelon-producing areas in the state. In the sampling design, counties corresponded to strata, growers to first-stage clusters, and fields to second-stage clusters. Pathogens were identified on 100 leaves collected per field based on reproductive structures that formed on the leaves. Information about previous crops, fruit type, field size, transplanting date, first harvest date, and fungicides applied within 7 days and within 7 to 14 days prior to sampling was obtained from growers. Field alignment was determined with a compass. Survey-specific logistic regression procedures were used to analyze the effect of these factors on the probabilities of pathogen occurrence. Five fungal pathogens, Stagonosporopsis spp., Podosphaera xanthii, Cercospora citrullina, Colletotrichum orbiculare, and Myrothecium sensu lato (s.l.), and the oomycete Pseudoperonospora cubensis were included in the analyses. Among the factors we analyzed, there was a consistent increased probability of occurrence of Stagonosporopsis spp. in fields with a previous cucurbit crop, increasing probabilities of pathogen occurrence with increasing plant age, a lower probability of occurrence of some pathogens on triploid cultivars compared with diploid cultivars, and a decrease in probability of pathogen occurrence in fields aligned toward southwest or west. Application of fungicides significantly reduced the probability of observing C. citrullina, P. cubensis, and Stagonosporopsis spp. in 2015 and P. xanthii in spring 2016. This study emphasizes the importance of crop rotation and fungicide applications to manage foliar diseases of watermelon, particularly gummy stem blight, powdery mildew, and downy mildew. Crop age, cultivar type, and field alignment also were found to significantly influence the probability of pathogen occurrence. To the best of our knowledge, this is the first study examining the influence of various factors on foliar pathogens of watermelon with data collected from commercial fields.

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Rennberger, Gabriel, Patrick Gerard et Anthony P. Keinath. « Occurrence of Foliar Pathogens of Watermelon on Commercial Farms in South Carolina Estimated with Stratified Cluster Sampling ». Plant Disease 102, n^o 11 (novembre 2018) : 2285–95. http://dx.doi.org/10.1094/pdis-03-18-0468-re.

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A survey of foliar pathogens of watermelon based on two-stage cluster sampling was conducted on commercial farms in South Carolina in spring 2015, spring and fall 2016, and fall 2017. In total, 60 fields from 27 different growers in seven counties representing the main watermelon-producing areas in the state were sampled, using a stratified two-stage cluster sampling approach. In the sampling design, counties corresponded to strata, growers to first-stage clusters, and fields to second-stage clusters. In each field, 100 symptomatic leaves were collected at five equidistant sampling points along four transects encompassing a square shape of 2,500 m2. After collection, pathogens were identified based on reproductive structures formed on leaves during >12 h incubation. Estimates were obtained for the statewide probability of pathogen occurrence and associations between pathogen pairs. Six fungal pathogens, Stagonosporopsis spp., Podosphaera xanthii, Cercospora citrullina, Colletotrichum orbiculare, Myrothecium sensu lato (s.l.), and Corynespora cassiicola; the oomycete Pseudoperonospora cubensis; and three viral pathogens were identified on the examined leaves. With the exception of fall 2017, Stagonosporopsis spp. was the most prevalent pathogen in every season, followed by P. xanthii. The highest occurrence of P. cubensis was in spring 2015; it did not occur in 2016. The highest occurrence of C. orbiculare was in spring 2016; it did not occur in spring 2015. Myrothecium s.l. was the most common pathogen in fall 2017 and the second most common pathogen occurring by itself in fall 2016. The third most common pathogen in fall 2017, Corynespora cassiicola, was not observed in any other season. Eight of the 80 isolates of Stagonosporopsis spp. collected were identified as S. caricae, the rest as S. citrulli. All isolates of S. caricae were found in spring 2015 and originated from two fields in different counties. A total of three positive and five negative associations were found between pathogen pairs co-occurring on the same leaf. A positive association between Stagonosporopsis spp. and C. citrullina was the only significant association between pathogens found in two seasons, spring 2015 and spring 2016. Based on estimates of probability of pathogen occurrence across seasons, Stagonosporopsis spp. and P. xanthii are the most common pathogens on watermelons in South Carolina. This is the first report of C. cassiicola, S. caricae, and Myrothecium s.l. on watermelon in South Carolina.

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Xing, Lijuan, et Andreas Westphal. « Interaction of Fusarium solani f. sp. glycines and Heterodera glycines in Sudden Death Syndrome of Soybean ». Phytopathology® 96, n^o 7 (juillet 2006) : 763–70. http://dx.doi.org/10.1094/phyto-96-0763.

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Sudden death syndrome (SDS) of soybean is caused by the soilborne Fusarium solani f. sp. glycines (synonym F. virguliforme). In a sequential approach, two multifactor factorial-design microplot experiments were conducted to investigate the effects of fungal infestation levels and soil moisture on both root necrosis and foliar SDS severity, and the interaction between F. solani f. sp. glycines and Heterodera glycines in fumigated versus nonfumigated soil. In 2003, soybean cv. Spencer was grown in nonfumigated or methyl bromide-fumigated soil and infested with increasing levels of F. solani f. sp. glycines, either under rainfall or irrigated after growth stage V6/R1. In 2004, interactions between F. solani f. sp. glycines and H. glycines were explored in a factorial inoculation design in fumigated or nonfumigated soil, planted to Williams 82 or Cyst-X20-18. In both years, higher levels of foliar SDS severity and root necrosis were found in F. solani f. sp. glycines-infested soils with H. glycines than in soils without the nematode on the soybean cultivars susceptible to both pathogens. Both natural infestations of H. glycines in 2003 and artificially amended populations of H. glycines in 2004 contributed to higher foliar SDS severity. More severe foliar SDS symptoms always were associated with more root necrosis, but elevated levels of root necrosis did not predict severe leaf symptoms. In contrast to the critical role of H. glycines, increasing fungal infestation levels had no significant effects on increasing either foliar SDS symptoms or root necrosis. Effects of moisture regime and fungal infestation levels also were examined in factorial greenhouse and growth chamber experiments. High soil moisture resulted in higher levels of SDS root necrosis. In the greenhouse, root necrosis increased at a higher rate in low soil moisture than the rate in high soil moisture. The two pathogens acted as a complex and the disease development was strongly dependent on high soil moisture.

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Das, Debarati, Papan Chowhan, Parimal Mandal et Arka Pratim Chakraborty. « Studies on variability in mode of infection by the isolates of leaf pathogens isolated from diseased leaves of Musa paradisiaca from Uttar Dinajpur District ». F1000Research 13 (23 avril 2024) : 370. http://dx.doi.org/10.12688/f1000research.136445.1.

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Banana is (Musa sp) one of the most exoteric and materialistic fruit crop of many tropical and subtropical areas in India. Banana leaf diseases, caused by several fungal pathogens are one of the major diseases. Among the fungi causing banana leaf diseases, Curvularia sp/C. lunata is one of the main causal organisms causing leaf spot disease in banana plant. Two fungal isolates- MUSLF-2, MUSLF-3 and one fungal isolate- MUSLF-1 were isolated from the infected leaf from Ramganj and Gotgaon locations. Based on light microscopic and scanning electron microscopic studies, MUSLF-2 and MUSLF-3 were identified as Curvularia sp. After Koch’s postulate, three fungal isolates- MUSLF-2, MUSLF-3 [Curvularia sp] and MUSLF-1 were applied in banana field along with foliar spray of spore suspensions. The symptoms were similar to those observed in the in vitro detached leaf inoculation technique. The present research work depicts about the severity of leaf spot diseases of Musa paradisiaca and the nature of mode of infections exhibited by the fungal pathogens.

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Gagliardi, Stephanie, Jacques Avelino, Adam R. Martin, Marc Cadotte, Elias de Melo Virginio Filho et Marney E. Isaac. « Leaf functional traits and pathogens : Linking coffee leaf rust with intraspecific trait variation in diversified agroecosystems ». PLOS ONE 18, n^o 4 (13 avril 2023) : e0284203. http://dx.doi.org/10.1371/journal.pone.0284203.

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Research has demonstrated that intraspecific functional trait variation underpins plant responses to environmental variability. However, few studies have evaluated how trait variation shifts in response to plant pathogens, even though pathogens are a major driver of plant demography and diversity, and despite evidence of plants expressing distinct strategies in response to pathogen pressures. Understanding trait-pathogen relationships can provide a more realistic understanding of global patterns of functional trait variation. We examined leaf intraspecific trait variability (ITV) in response to foliar disease severity, using Coffea arabica cv. Caturra as a model species. We quantified coffee leaf rust (CLR) severity—a fungal disease prominent in coffee systems—and measured key coffee leaf functional traits under contrasting, but widespread, management conditions in an agroforestry system. We found that coffee plants express significant ITV, which is largely related to shade tree treatment and leaf position within coffee canopy strata. Yet within a single plant canopy stratum, CLR severity increased with increasing resource conserving trait values. However, coffee leaves with visible signs of disease expressed overall greater resource acquiring trait values, as compared to plants without visible signs of disease. We provide among the first evidence that leaf traits are correlated with foliar disease severity in coffee, and that functional trait relationships and syndromes shift in response to increased disease prevalence in this plant-pathogen system. In doing so, we address a vital gap in our understanding of global patterns of functional trait variation and highlight the need to further explore the potential role of pathogens within established global trait relationships and spectra.

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Won, Sang-Jae, Jun-Hyeok Kwon, Dong-Hyun Kim et Young-Sang Ahn. « The Effect of Bacillus licheniformis MH48 on Control of Foliar Fungal Diseases and Growth Promotion of Camellia oleifera Seedlings in the Coastal Reclaimed Land of Korea ». Pathogens 8, n^o 1 (9 janvier 2019) : 6. http://dx.doi.org/10.3390/pathogens8010006.

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This study investigated the control of foliar fungal diseases and growth promotion of Camellia oleifera seedlings in coastal reclaimed land through the use of Bacillus licheniformis MH48. B. licheniformis MH48 can produce lytic enzymes chitinase and β-1,3-glucanase that can inhibit foliar pathogens by 37.4 to 50.5%. Nevertheless, foliar diseases appeared in the seedlings with bacterial inoculation, and their survival rate decreased because they were unable to withstand salt stress. However, B. licheniformis MH48 significantly increased the total nitrogen and phosphorus contents in the soils through fixing atmospheric nitrogen and solubilizing phosphorus. The growth of seedlings with bacterial inoculation increased, particularly in root dry weight, by 7.42 g plant−1, which was 1.7-fold greater than that of the control. B. licheniformis MH48 produces the phytohormone auxin, which potentially stimulates seedling root growth. C. oleifera seedlings significantly increased in total nitrogen content to 317.57 mg plant−1 and total phosphorus content to 46.86 mg plant−1. Our results revealed the effectiveness of B. licheniformis MH48 not only in the control of foliar fungal diseases but also in the growth promotion of C. oleifera seedlings in coastal lands.

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Mosen, Ashleigh M., Yanan Guo, Berit Hassing, Carl H. Mesarich et Rosie E. Bradshaw. « An RNA interference (RNAi) target with potential to control Dothistroma needle blight ». New Zealand Plant Protection 76 (4 octobre 2023) : 35–53. http://dx.doi.org/10.30843/nzpp.2023.76.11770.

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Spray-induced gene silencing (SIGS) involves exogenous spray applications of double-stranded RNA (dsRNA) molecules targeting specific genes, such as those essential to pathogens. This technique has shown great potential for controlling fungal pathogens of horticultural and agricultural plants, but few studies have evaluated its application to forest pathogens. Here we report the first demonstration of exogenous application of dsRNA molecules targeting a gene required for virulence in the foliar pine pathogen Dothistroma septosporum, the causal agent of Dothistroma needle blight (DNB). Constructs expressing sense and antisense dsRNAs were generated targeting a 509 bp fragment of the dothistromin toxin regulatory gene (DsAflR) in D. septosporum. DsAflR is required for the production of dothistromin, a phytotoxin essential for full pathogen virulence. We found that exogenous dsRNA is taken up and the RNA silencing mechanism is functional in D. septosporum through a series of in vitro and in planta trials, such as monitoring the uptake of fluorescently labelled DsAflR-dsRNA into the cell by confocal microscopy and quantifying the extent of gene silencing by quantitative Polymerase Chain Reaction (qPCR). In vitro applications of DsAflR-dsRNA to D. septosporum reduced the accumulation of DsAflR mRNA compared to controls and, in some cases, were found to be statistically significant, despite a high level of variability in the results. Our study also demonstrated a reduction in DNB symptoms on infected pine needles sprayed with DsAflR-dsRNA, which was further supported by a significant reduction in fungal biomass. This preliminary study highlights the potential for SIGS as a future management scheme for controlling the forest pathogen D. septosporum, as well as other forest pathogens.

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Nichols, P. G. H., R. A. C. Jones, T. J. Ridsdill-Smith et M. J. Barbetti. « Genetic improvement of subterranean clover (Trifolium subterraneum L.). 2. Breeding for disease and pest resistance ». Crop and Pasture Science 65, n^o 11 (2014) : 1207. http://dx.doi.org/10.1071/cp14031.

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Subterranean clover (Trifolium subterraneum L.) is the most widely sown pasture legume in southern Australia and resistance to important diseases and pests has been a major plant-breeding objective. Kabatiella caulivora, the cause of clover scorch, is the most important foliar fungal pathogen, and several cultivars have been developed with resistance to both known races. Screening of advanced breeding lines has been conducted to prevent release of cultivars with high susceptibility to other important fungal foliar disease pathogens, including rust (Uromyces trifolii-repentis), powdery mildew (Oidium sp.), cercospora (Cercospora zebrina) and common leaf spot (Pseudopeziza trifolii). Several oomycete and fungal species cause root rots of subterranean clover, including Phytophthora clandestina, Pythium irregulare, Aphanomyces trifolii, Fusarium avenaceum and Rhizoctonia solani. Most breeding efforts have been devoted to resistance to P. clandestina, but the existence of different races has confounded selection. The most economically important virus diseases in subterranean clover pastures are Subterranean clover mottle virus and Bean yellow mosaic virus, while Subterranean clover stunt virus, Subterranean clover red leaf virus (local synonym for Soybean dwarf virus), Cucumber mosaic virus, Alfalfa mosaic virus, Clover yellow vein virus, Beet western yellows virus and Bean leaf roll virus also cause losses. Genotypic differences for resistance have been found to several of these fungal, oomycete and viral pathogens, highlighting the potential to develop cultivars with improved resistance. The most important pests of subterranean clover are redlegged earth mite (RLEM) (Halotydeus destructor), blue oat mite (Penthaleus major), blue-green aphid (Acyrthosiphon kondoi) and lucerne flea (Sminthurus viridis). New cultivars have been bred with increased RLEM cotyledon resistance, but limited selection has been conducted for resistance to other pests. Screening for disease and pest resistance has largely ceased, but recent molecular biology advances in subterranean clover provide a new platform for development of future cultivars with multiple resistances to important diseases and pests. However, this can only be realised if skills in pasture plant pathology, entomology, pre-breeding and plant breeding are maintained and adequately resourced. In particular, supporting phenotypic disease and pest resistance studies and understanding their significance is critical to enable molecular technology investments achieve practical outcomes and deliver subterranean clover cultivars with sufficient pathogen and pest resistance to ensure productive pastures across southern Australia.

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Brunner, Kurt, Susanne Zeilinger, Rosalia Ciliento, Sheridian L. Woo, Matteo Lorito, Christian P. Kubicek et Robert L. Mach. « Improvement of the Fungal Biocontrol Agent Trichoderma atroviride To Enhance both Antagonism and Induction of Plant Systemic Disease Resistance ». Applied and Environmental Microbiology 71, n^o 7 (juillet 2005) : 3959–65. http://dx.doi.org/10.1128/aem.71.7.3959-3965.2005.

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ABSTRACT Biocontrol agents generally do not perform well enough under field conditions to compete with chemical fungicides. We determined whether transgenic strain SJ3-4 of Trichoderma atroviride, which expresses the Aspergillus niger glucose oxidase-encoding gene, goxA, under a homologous chitinase (nag1) promoter had increased capabilities as a fungal biocontrol agent. The transgenic strain differed only slightly from the wild-type in sporulation or the growth rate. goxA expression occurred immediately after contact with the plant pathogen, and the glucose oxidase formed was secreted. SJ3-4 had significantly less N-acetylglucosaminidase and endochitinase activities than its nontransformed parent. Glucose oxidase-containing culture filtrates exhibited threefold-greater inhibition of germination of spores of Botrytis cinerea. The transgenic strain also more quickly overgrew and lysed the plant pathogens Rhizoctonia solani and Pythium ultimum. In planta, SJ3-4 had no detectable improved effect against low inoculum levels of these pathogens. Beans planted in heavily infested soil and treated with conidia of the transgenic Trichoderma strain germinated, but beans treated with wild-type spores did not germinate. SJ3-4 also was more effective in inducing systemic resistance in plants. Beans with SJ3-4 root protection were highly resistant to leaf lesions caused by the foliar pathogen B. cinerea. This work demonstrates that heterologous genes driven by pathogen-inducible promoters can increase the biocontrol and systemic resistance-inducing properties of fungal biocontrol agents, such as Trichoderma spp., and that these microbes can be used as vectors to provide plants with useful molecules (e.g., glucose oxidase) that can increase their resistance to pathogens.

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Hoang, Bao Tram L., Stephen J. Fletcher, Christopher A. Brosnan, Amol B. Ghodke, Narelle Manzie et Neena Mitter. « RNAi as a Foliar Spray : Efficiency and Challenges to Field Applications ». International Journal of Molecular Sciences 23, n^o 12 (14 juin 2022) : 6639. http://dx.doi.org/10.3390/ijms23126639.

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RNA interference (RNAi) is a powerful tool that is being increasingly utilized for crop protection against viruses, fungal pathogens, and insect pests. The non-transgenic approach of spray-induced gene silencing (SIGS), which relies on spray application of double-stranded RNA (dsRNA) to induce RNAi, has come to prominence due to its safety and environmental benefits in addition to its wide host range and high target specificity. However, along with promising results in recent studies, several factors limiting SIGS RNAi efficiency have been recognized in insects and plants. While sprayed dsRNA on the plant surface can produce a robust RNAi response in some chewing insects, plant uptake and systemic movement of dsRNA is required for delivery to many other target organisms. For example, pests such as sucking insects require the presence of dsRNA in vascular tissues, while many fungal pathogens are predominately located in internal plant tissues. Investigating the mechanisms by which sprayed dsRNA enters and moves through plant tissues and understanding the barriers that may hinder this process are essential for developing efficient ways to deliver dsRNA into plant systems. In this review, we assess current knowledge of the plant foliar and cellular uptake of dsRNA molecules. We will also identify major barriers to uptake, including leaf morphological features as well as environmental factors, and address methods to overcome these barriers.

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Andreadelli, Aggeliki, Spyros Petrakis, Antiopi Tsoureki, George Tsiolas, Sofia Michailidou, Penelope Baltzopoulou, Robert van Merkestein et al. « Effects of Magnesium Oxide and Magnesium Hydroxide Microparticle Foliar Treatment on Tomato PR Gene Expression and Leaf Microbiome ». Microorganisms 9, n^o 6 (4 juin 2021) : 1217. http://dx.doi.org/10.3390/microorganisms9061217.

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Recently, metal oxides and magnesium hydroxide nanoparticles (NPs) with high surface-to-volume ratios were shown to possess antibacterial properties with applications in biomedicine and agriculture. To assess recent observations from field trials on tomatoes showing resistance to pathogen attacks, porous micron-scale particles composed of nano-grains of MgO were hydrated and sprayed on the leaves of healthy tomato (Solanum lycopersicum) plants in a 20-day program. The results showed that the spray induced (a) a modest and selective stress gene response that was consistent with the absence of phytotoxicity and the production of salicylic acid as a signalling response to pathogens; (b) a shift of the phylloplane microbiota from near 100% dominance by Gram (−) bacteria, leaving extremophiles and cyanobacteria to cover the void; and (c) a response of the fungal leaf phylloplane that showed that the leaf epiphytome was unchanged but the fungal load was reduced by about 70%. The direct microbiome changes together with the low level priming of the plant’s immune system may explain the previously observed resistance to pathogen assaults in field tomato plants sprayed with the same hydrated porous micron-scale particles.

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Newell, L., I. E. Widders et R. Hammerschrmidt. « ACQUIRED DISEASE RESISTANCE TO ANGULAR LEAF SPOT (PSEUDOMONAS SYRINGAE CV. LACHRYMANS) IN CUCUMBER ». HortScience 28, n^o 5 (mai 1993) : 590c—590. http://dx.doi.org/10.21273/hortsci.28.5.590c.

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Resistance to fungal and bacterial pathogens can be induced in cucurbit crops by limited inoculation of young plants with necrosis inducing pathogens or by treatment with certain salt solutions. In greenhouse experiments with pickling cucumber (cv. Flurry), foliar applications of 2,6-dichloroisonicotinic acid (CGA-41396; Ciba Geigy) to seedlings enhanced both acid peroxidase activity and reduced the number of lesions per leaf in a dose dependent manner following a challenge inoculation. Maximum response was obtained with 20-30 mg a.i./L CGA 41396 treatment. Soil drenches were equally effective in inducing resistance. Under field conditions, multiple foliar applications of 35 mg a.i./L of CGA 41396 prior to flowering reduced the incidence of angular leaf spot lesions by >70% on leaves at harvest. Pickling cucumber fruit yields were significantly lower in controls than in CGA treatments due to disease pressure.

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Zahn, Geoffrey, et Anthony S. Amend. « Foliar microbiome transplants confer disease resistance in a critically-endangered plant ». PeerJ 5 (10 novembre 2017) : e4020. http://dx.doi.org/10.7717/peerj.4020.

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There has been very little effort to incorporate foliar microbiomes into plant conservation efforts even though foliar endophytes are critically important to the fitness and function of hosts. Many critically endangered plants that have been extirpated from the wild are dependent on regular fungicidal applications in greenhouses that cannot be maintained for remote out-planted populations, which quickly perish. These fungicides negatively impact potentially beneficial fungal symbionts, which may reduce plant defenses to pathogens once fungicide treatments are stopped. Using the host/parasite system of Phyllostegia kaalaensis and Neoerysiphe galeopsidis, we conducted experiments to test total foliar microbiome transplants from healthy wild relatives onto fungicide-dependent endangered plants in an attempt to mitigate disease and reduce dependency on fungicides. Plants were treated with total microbiome transplants or cultured subsets of this community and monitored for disease severity. High-throughput DNA screening of fungal ITS1 rDNA was used to track the leaf-associated fungal communities and evaluate the effectiveness of transplantation methods. Individuals receiving traditionally isolated fungal treatments showed no improvement, but those receiving applications of a simple leaf slurry containing an uncultured fungal community showed significant disease reduction, to which we partially attribute an increase in the mycoparasitic Pseudozyma aphidis. These results were replicated in two independent experimental rounds. Treated plants have since been moved to a native habitat and, as of this writing, remain disease-free. Our results demonstrate the effectiveness of a simple low-tech method for transferring beneficial microbes from healthy wild plants to greenhouse-raised plants with reduced symbiotic microbiota. This technique was effective at reducing disease, and in conferring increased survival to an out-planted population of critically endangered plants. It was not effective in a closely related plant. Plant conservation efforts should strive to include foliar microbes as part of comprehensive management plans.

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