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18 pages, 5357 KiB

Open AccessArticle

Assessment of Peacock Spot Disease (Fusicladium oleagineum) in Olive Orchards Through Agronomic Approaches and UAV-Based Multispectral Imaging

by Hajar Hamzaoui, Ilyass Maafa, Hasnae Choukri, Ahmed El Bakkali, Salma El Iraqui El Houssaini, Rachid Razouk, Aziz Aziz, Said Louahlia and Khaoula Habbadi

Horticulturae 2025, 11(1), 46; https://doi.org/10.3390/horticulturae11010046 - 6 Jan 2025

Cited by 1 | Viewed by 1317

Abstract

Olive leaf spot (OLS), caused by Fusicladium oleagineum, is a significant disease affecting olive orchards, leading to reduced yields and compromising olive tree health. Early and accurate detection of this disease is critical for effective management. This study presents a comprehensive assessment of OLS disease progression in olive orchards by integrating agronomic measurements and multispectral imaging techniques. Key disease parameters—incidence, severity, diseased leaf area, and disease index—were systematically monitored from March to October, revealing peak values of 45% incidence in April and 35% severity in May. Multispectral drone imagery, using sensors for NIR, Red, Green, and Red Edge spectral bands, enabled the calculation of vegetation indices. Indices incorporating Red Edge and near-infrared bands, such as Red Edge and SR705-750, exhibited the strongest correlations with disease severity (correlation coefficients of 0.72 and 0.68, respectively). This combined approach highlights the potential of remote sensing for early disease detection and supports precision agriculture practices by facilitating targeted interventions and optimized orchard management. The findings underscore the effectiveness of integrating a traditional agronomic assessment with advanced spectral analysis to improve OLS disease surveillance and promote sustainable olive cultivation. Full article

(This article belongs to the Section Fruit Production Systems)

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12 pages, 805 KiB

Open AccessEditor’s ChoiceArticle

Deficit Irrigation Regime Improves Phytosanitary Status of Cultivar Arbosana Grown in a Super High-Density Olive Orchard

by Francesco Nicolì, Marco Anaclerio, Francesco Maldera, Franco Nigro and Salvatore Camposeo

Agronomy 2024, 14(10), 2380; https://doi.org/10.3390/agronomy14102380 - 15 Oct 2024

Cited by 2 | Viewed by 1091

Abstract

Super high-density (SHD) planting systems are very efficient in terms of production and water use. In these orchards, water-saving irrigation strategies are used precisely to keep the best sustainability compared to traditional orchards. With agro-climatic and eco-physiological parameter monitoring, the SHD planting system has become even more efficient. SHD orchards, however, could also be more so affected by other pests and diseases than traditional systems, but field responses are still unknown when olive trees are grown in SHD groves. The goal of this two-year field research was to investigate the seasonal changes of the phytosanitary status of ‘Arbosana’ grown in an SHD orchard under both regulated deficit (RDI) and full irrigation regimes (FI). This study investigated the influence of the two different irrigation regimes on the infections of three olive tree key diseases: cercosporiosis (Pseudocercospora cladosporioides), cycloconium (Fusicladium oleagineum), and olive knot (Pseudomonas savastanoi pv. savastanoi). RDI significantly reduced the severity of cercosporiosis in 2020 compared to FI but not in 2021. Cycloconium was observed only as a latent infection during the two studied years and olive knot was not influenced by irrigation but only by weather conditions. These findings suggest that irrigation management can play a key role in controlling cercosporiosis effectively in SHD olive orchards, but also that weather conditions have an even higher impact on the tree key diseases. Full article

(This article belongs to the Section Pest and Disease Management)

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12 pages, 2676 KiB

Open AccessArticle

Differential Response of Olive Cultivars to Leaf Spot Disease (Fusicladium oleagineum) under Climate Warming Conditions in Morocco

by Khaoula Habbadi, Ilyass Maafa, Abdellatif Benbouazza, Faiçal Aoujil, Hasnae Choukri, Salma El Iraqui El Houssaini and Ahmed El Bakkali

Horticulturae 2023, 9(5), 589; https://doi.org/10.3390/horticulturae9050589 - 16 May 2023

Cited by 5 | Viewed by 3603

Abstract

Olive leaf spot (OLS), also called olive scab and peacock eye, caused by Fusicladium oleagineum, is a major disease that causes significant damage to olive trees. However, we still lack information about how cultivar and environmental factors influence disease development. In this study, evaluation of the incidence and severity on twenty olive cultivars (Olea europaea L.), maintained in an ex situ collection in Morocco, was carried out monthly during the period from March to July 2021. Biochemical parameters were also evaluated for each cultivar including leaf chlorophyll, polyphenols and flavonoid contents. Results revealed that the OLS incidence was highly correlated with severity (r = 0.94) and found to be related to climatic conditions and cultivars. The studied cultivars were classified into four major groups, i.e., susceptible, moderately susceptible, moderately resistant and resistant. Finally, our investigations revealed a partial relationship between resistance to the OLS disease and phenolic and flavonoid leaf contents, supporting the assumption of the potential involvement of such components in cultivar resistance to the disease. Overall, our work highlights the importance of characterizing olive cultivar resistance to OLS in driving the choice of the best varieties for an effective control of the disease in specific warming regions such as Morocco. Full article

(This article belongs to the Section Biotic and Abiotic Stress)

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16 pages, 3068 KiB

Open AccessArticle

Fungal Phytopathogenic Spore First Assessment in an Olive Orchard of Northwestern Spain

by Alejandro Garrido, María Fernández-González, Jose A. Cortiñas Rodríguez, Lucía Carrera, Estefanía González-Fernández, Michel Almaguer-Chávez and Fco. Javier Rodríguez-Rajo

Agronomy 2022, 12(2), 246; https://doi.org/10.3390/agronomy12020246 - 19 Jan 2022

Cited by 4 | Viewed by 2847

Abstract

The most common fungal diseases of Olea europaea are olive leaf spot (Fusicladium oleagineum), anthracnose (Colletotrichum spp.) and cercospora leaf spot (Pseudocercospora cladosporioides). To know the fungal load during the vegetative olive cycle, an aerobiological and phenological study was conducted in an olive grove in North-West Spain. For the aerobiological study, the Spanish Aerobiological Network protocol was followed using a Hirst-type spore trap. The goal of the study was to assess the spore concentrations in the atmosphere of the olive grove and their relationship with the meteorological parameters by applying statistical procedures, including a Cluster analysis, Spearman’s correlation test and PCA analysis. The most abundant spores belong to Fusicladium, registering the double of values than Colletotrichum and Pseudocercospora. The hours with the highest spores’ presence were from 11:00 to 12:00 for Fusicladium and Colletotrichum, and from 17:00 to 18:00 for Pseudocercospora. The Spearman’s and PCA test showed a positive association between temperature and relative humidity with the spores’ concentrations. The combination of meteorological, phenological and aerobiological parameters is a useful tool to understand the ecological behavior of the considered phytopathogenic fungal spores in order to develop futures strategies for the integrated management of fungal olive diseases in areas at the limit of this tree distribution. Full article

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19 pages, 4829 KiB

Open AccessArticle

Synthesis and Characterization of Novel Copper Nanoparticles for the Control of Leaf Spot and Anthracnose Diseases of Olive

by Panagiota Ntasiou, Alexandra Kaldeli Kerou, Theodora Karamanidou, Afrodite Vlachou, George T. Tziros, Alexander Tsouknidas and George S. Karaoglanidis

Nanomaterials 2021, 11(7), 1667; https://doi.org/10.3390/nano11071667 - 24 Jun 2021

Cited by 23 | Viewed by 4492

Abstract

Olive crop is frequently treated with copper fungicides to combat foliar and fruit diseases such as olive leaf spot caused by Fusicladium oleagineum and anthracnose caused by Colletotrichum spp. The replacement of copper-based products with more eco-friendly alternatives is a priority. Metal nanoparticles synthesized in several ways have recently revolutionized crop protection with applications against important crop pathogens. In this study, we present the development of four copper-based nanoparticles (CuNP Type 1 to 4) synthesized with a wet chemistry approach. The CuNPs were characterized using Transmission Electron Microscopy, Dynamic Light Scattering, Laser Doppler Electrophoresis, and Attenuated Total Reflection measurements. In addition, the activity of the four CuNP types was tested in vitro and in planta against F. oleagineum and Colletotrichum spp. In vitro sensitivity measurements showed that for both pathogens, mycelial growth was the most susceptible developmental stage to the tested compounds. Against both pathogens, CuNP Type 1 and Type 2 were found to be more active in reducing mycelial growth compared to the reference commercial compounds of copper oxide and copper hydroxide. In planta experiments showed that CuNP Type 3 and CuNP Type 4 exhibited a strong protectant activity against both F. oleagineum and Colletotrichum acutatum with control efficacy values significantly higher than those achieved by the applications of either reference product. Full article

(This article belongs to the Special Issue Bionanotechnology)

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13 pages, 1091 KiB

Open AccessArticle

Laminarin Induces Defense Responses and Efficiently Controls Olive Leaf Spot Disease in Olive

by George T. Tziros, Anastasios Samaras and George S. Karaoglanidis

Molecules 2021, 26(4), 1043; https://doi.org/10.3390/molecules26041043 - 17 Feb 2021

Cited by 15 | Viewed by 5144

Abstract

Olive leaf spot (OLS) caused by Fusicladiumoleagineum is mainly controlled using copper fungicides. However, the replacement of copper-based products with eco-friendly alternatives is a priority. The use of plant resistance-inducers (PRIs) or biological control agents (BCAs) could contribute in this direction. In this study we investigated the potential use of three PRIs (laminarin, acibenzolar-S-methyl, harpin) and a BCA (Bacillus amyloliquefaciens FZB24) for the management of OLS. The tested products provided control efficacy higher than 68%. In most cases, dual applications provided higher (p < 0.05) control efficacies compared to that achieved by single applications. The highest control efficacy of 100% was achieved by laminarin. Expression analysis of the selected genes by RT-qPCR revealed different kinetics of induction. In laminarin-treated plants, for most of the tested genes a higher induction rate (p < 0.05) was observed at 3 days post application. Pal, Lox, Cuao and Mpol were the genes with the higher inductions in laminarin-treated and artificially inoculated plants. The results of this study are expected to contribute towards a better understanding of PRIs in olive culture and the optimization of OLS control, while they provide evidence for potential contributions in the reduction of copper accumulation in the environment. Full article

(This article belongs to the Special Issue Characterization of Olive Products from Greece)

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18 pages, 2125 KiB

Open AccessArticle

The Application of Trichoderma Strains or Metabolites Alters the Olive Leaf Metabolome and the Expression of Defense-Related Genes

by Roberta Marra, Mariangela Coppola, Angela Pironti, Filomena Grasso, Nadia Lombardi, Giada d’Errico, Andrea Sicari, Sergio Bolletti Censi, Sheridan L. Woo, Rosa Rao and Francesco Vinale

J. Fungi 2020, 6(4), 369; https://doi.org/10.3390/jof6040369 - 16 Dec 2020

Cited by 21 | Viewed by 4188

Abstract

Biocontrol fungal strains of the genus Trichoderma can antagonize numerous plant pathogens and promote plant growth using different mechanisms of action, including the production of secondary metabolites (SMs). In this work we analyzed the effects of repeated applications of selected Trichoderma strains or SMs on young olive trees on the stimulation of plant growth and on the development of olive leaf spot disease caused by Fusicladium oleagineum. In addition, metabolomic analyses and gene expression profiles of olive leaves were carried out by LC–MS Q-TOF and real-time RT-PCR, respectively. A total of 104 phenolic compounds were detected from olive leave extracts and 20 were putatively identified. Targeted and untargeted approaches revealed significant differences in both the number and type of phenolic compounds accumulated in olive leaves after Trichoderma applications, as compared to water-treated plants. Different secoiridoids were less abundant in treated plants than in controls, while the accumulation of flavonoids (including luteolin and apigenin derivatives) increased following the application of specific Trichoderma strain. The induction of defense-related genes, and of genes involved in the synthesis of the secoiridoid oleuropein, was also analyzed and revealed a significant variation of gene expression according to the strain or metabolite applied. Full article

(This article belongs to the Special Issue Mycorrhizal Fungi and Plants)

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