Xf-Rovim. A Field Robot to Detect Olive Trees Infected by Xylella Fastidiosa Using Proximal Sensing

The use of remote sensing to map the distribution of plant diseases has evolved considerably over the last three decades and can be performed at different scales, depending on the area to be monitored, as well as the spatial and spectral resolution required. This work describes the development of a small low-cost field robot (Remotely Operated Vehicle for Infection Monitoring in orchards, XF-ROVIM), which is intended to be a flexible solution for early detection of Xylella fastidiosa (X. fastidiosa) in olive groves at plant to leaf level. The robot is remotely driven and fitted with different sensing equipment to capture thermal, spectral and structural information about the plants. Taking into account the height of the olive trees inspected, the design includes a platform that can raise the cameras to adapt the height of the sensors to a maximum of 200 cm. The robot was tested in an olive grove (4 ha) potentially infected by X. fastidiosa in the region of Apulia, southern Italy. The tests were focused on investigating the reliability of the mechanical and electronic solutions developed as well as the capability of the sensors to obtain accurate data. The four sides of all trees in the crop were inspected by travelling along the rows in both directions, showing that it could be easily adaptable to other crops. XF-ROVIM was capable of inspecting the whole field continuously, capturing geolocated spectral information and the structure of the trees for later comparison with the in situ observations.

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Increase in ring width, vessel number and δ18O in olive trees infected with Xylella fastidiosa

Tree Physiology ◽

10.1093/treephys/tpaa095 ◽

2020 ◽

Vol 40 (11) ◽

pp. 1583-1594

Author(s):

Erika Sabella ◽

Samuele Moretti ◽

Holger Gärtner ◽

Andrea Luvisi ◽

Luigi De Bellis ◽

...

Keyword(s):

Xylella Fastidiosa ◽

Ring Width ◽

Plant Diseases ◽

Susceptible Cultivar ◽

Water Conductivity ◽

Leaf Transpiration ◽

Leaf Level ◽

Olive Quick Decline Syndrome ◽

Olive Trees ◽

Tree Stem

Abstract Xylella fastidiosa (Xf) Wells, Raju et al., 1986 is a bacterium that causes plant diseases in the Americas. In Europe, it was first detected on the Salento Peninsula (Italy), where it was found to be associated with the olive quick decline syndrome. Here, we present the results of the first tree-ring study of infected and uninfected olive trees (Olea europaea L.) of two different cultivars, one resistant and one susceptible, to establish the effects induced by the spread of the pathogen inside the tree. Changes in wood anatomical characteristics, such as an increase in the number of vessels and in ring width, were observed in the infected plants of both the cultivars Cellina di Nardò (susceptible to Xf infection) and Leccino (resistant to Xf infection). Thus, whether infection affects the mortality of the tree or not, the tree shows a reaction to it. The presence of occlusions was detected in the wood of both 4-year-old branches and the tree stem core. As expected, the percentage of occluded vessels in the Xf-susceptible cultivar Cellina di Nardò was significantly higher than in the Xf-resistant cultivar Leccino. The δ 18O of the 4-year-old branches was significantly higher in infected trees of both cultivars than in noninfected trees, while no variations in δ 13C were observed. This suggests a reduction in leaf transpiration rates during infection and seems to be related to the occlusions observed in rings of the 4-year-old branches. Such occlusions can determine effects at leaf level that could influence stomatal activity. On the other hand, the significant increase in the number of vessels in infected trees could be related to the tree’s attempt to enhance water conductivity in response to the pathogen-induced vessel occlusions.

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Semi-Automatic Method for Early Detection of Xylella fastidiosa in Olive Trees Using UAV Multispectral Imagery and Geostatistical-Discriminant Analysis

Remote Sensing ◽

10.3390/rs13010014 ◽

2020 ◽

Vol 13 (1) ◽

pp. 14

Author(s):

Annamaria Castrignanò ◽

Antonella Belmonte ◽

Ilaria Antelmi ◽

Ruggiero Quarto ◽

Francesco Quarto ◽

...

Keyword(s):

Discriminant Analysis ◽

Early Detection ◽

Plant Pathogens ◽

Early Stage ◽

Xylella Fastidiosa ◽

Mediterranean Countries ◽

Parametric Classification ◽

Aerial Vehicle ◽

Olive Groves ◽

Olive Trees

Xylella fastidiosa subsp. pauca (Xfp) is one of the most dangerous plant pathogens in the world. Identified in 2013 in olive trees in south–eastern Italy, it is spreading to the Mediterranean countries. The bacterium is transmitted by insects that feed on sap, and causes rapid wilting in olive trees. The paper explores the use of Unmanned Aerial Vehicle (UAV) in combination with a multispectral radiometer for early detection of infection. The study was carried out in three olive groves in the Apulia region (Italy) and involved four drone flights from 2017 to 2019. To classify Xfp severity level in olive trees at an early stage, a combined method of geostatistics and discriminant analysis was implemented. The results of cross-validation for the non-parametric classification method were of overall accuracy = 0.69, mean error rate = 0.31, and for the early detection class of accuracy 0.77 and misclassification probability 0.23. The results are promising and encourage the application of UAV technology for the early detection of Xfp infection.

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Further In Vitro Assessment and Mid-Term Evaluation of Control Strategy of Xylella fastidiosa subsp. pauca in Olive Groves of Salento (Apulia, Italy)

Pathogens ◽

10.3390/pathogens10010085 ◽

2021 ◽

Vol 10 (1) ◽

pp. 85

Author(s):

Giuseppe Tatulli ◽

Vanessa Modesti ◽

Nicoletta Pucci ◽

Valeria Scala ◽

Alessia L’Aurora ◽

...

Keyword(s):

Control Strategy ◽

Xylella Fastidiosa ◽

In Planta ◽

Bacterial Concentration ◽

Infected Area ◽

Olive Groves ◽

Term Evaluation ◽

In Vitro Assessment ◽

Olive Trees

During recent years; Xylella fastidiosa subsp. pauca (Xfp) has spread in Salento causing relevant damage to the olive groves. Measures to contain the spreading of the pathogen include the monitoring of the areas bordering the so-called “infected” zone and the tree eradication in case of positive detection. In order to provide a control strategy aimed to maintain the tree productivity in the infected areas, we further evaluated the in vitro and in planta mid-term effectiveness of a zinc-copper-citric acid biocomplex. The compound showed an in vitro bactericidal activity and inhibited the biofilm formation in representative strains of X. fastidiosa subspecies, including Xfp isolated in Apulia from olive trees. The field mid-term evaluation of the control strategy assessed by quantitative real-time PCR in 41 trees of two olive groves of the “infected” area revealed a low concentration of Xfp over the seasons upon the regular spraying of the biocomplex over 3 or 4 consecutive years. In particular, the bacterial concentration lowered in July and October with respect to March, after six consecutive treatments. The trend was not affected by the cultivar and it was similar either in the Xfp-sensitive cultivars Ogliarola salentina and Cellina di Nardò or in the Xfp-resistant Leccino. Moreover, the scoring of the number of wilted twigs over the seasons confirmed the trend. The efficacy of the treatment in the management of olive groves subjected to a high pathogen pressure is highlighted by the yielded a good oil production

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Influence of weed cover on leaf-level CO2 and H2O fluxes in an olive grove

10.5194/egusphere-egu2020-5181 ◽

2020 ◽

Author(s):

Sergio Aranda-Barranco ◽

Andrew S Kowalski ◽

Penélope Serrano-Ortiz ◽

Enrique P Sánchez-Cañete

Keyword(s):

Random Trees ◽

The Other ◽

Organic Carbon Content ◽

Olive Grove ◽

Weed Cover ◽

Leaf Level ◽

Olive Groves ◽

Ecosystem Level ◽

Olive Trees

The management of olive groves has a direct impact on the environment in the Mediterranean region since it is one of the most representative crops in this area. In order to prevent erosion and improve the physical-chemical conditions of the soil in these crops, the maintenance of weed cover in the alleys is an increasingly common practice. It increases the organic carbon content in the soil, improves biodiversity indices and enhances various ecosystem services such as pollination and infiltration. Now, the role of vegetation cover in olive groves on biogeochemical cycles is being studied. Although previous studies have quantified the combined effect of weed cover and olive trees on carbon and water at ecosystem level, the role of this conservation practice at the leaf level has not yet been explored.The aim of this study is to quantify the effect of weed cover on the net CO2 assimilation (An) and transpiration (T) rates in an irrigated olive grove. To do this, two plots of olive trees with irrigation (Olea europea L. "Arbequina") in southeast Spain were sampled. In the weed-cover one (WC), spontaneous vegetation is maintained until it is mechanically mowed and left in place. In the weed-free (WF) a glyphosate-based herbicide is applied. The data were taken with a portable gas analyzer (LI-6800, Li-Cor) controlling the following environmental variables on olive leaves: atmospheric CO2, relative humidity, photosynthetic active radiation and temperature. One campaign per month was carried out (from January-2018 to January-2019) where 10 random trees were analysed in each treatment. In addition, an eddy covariance tower provided CO2 and H2O fluxes at ecosystem level and they were compared with the fluxes obtained from leaf-level campaigns.The results shown significant differences for T only in the period after mowing with Twc= 2.0 &#177; 0.7 mmol H2O m-2s-1 vs Twf = 2.5 &#177; 1.0 mmol H2O m-2s-1. However, in this period ET is equal in both treatments, which suggests that the alleys with mowed weed has more ET than bare soil in the other treatment. On the other hand, there are significant differences for Anet only in the period before mowing with Anet-wc = 5.5 &#177; 3.1 &#956;mol CO2 m-2s-1 vs Anet-wf = 8.0 &#177; 3.6 &#956;mol CO2 m-2s-1. When the weeds are mowed, Anet is matched in both treatments. However, higher values of NEEwc than NEEwf &#160;are observed in the period before mowing. This suggest that the weed-cover olive groves at ecosystem level take up more carbon when the weed-cover is established although the leaves of olive trees are capturing less CO2.

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Progress towards Sustainable Control of Xylella fastidiosa subsp. pauca in Olive Groves of Salento (Apulia, Italy)

Pathogens ◽

10.3390/pathogens10060668 ◽

2021 ◽

Vol 10 (6) ◽

pp. 668

Author(s):

Marco Scortichini ◽

Stefania Loreti ◽

Nicoletta Pucci ◽

Valeria Scala ◽

Giuseppe Tatulli ◽

...

Keyword(s):

Control Strategy ◽

Laser Scanning ◽

Vascular System ◽

Xylella Fastidiosa ◽

Low Cost ◽

Interdisciplinary Studies ◽

Laser Scanning Microscopy ◽

Confocal Laser ◽

Olive Groves

Xylella fastidiosa subsp. pauca is the causal agent of “olive quick decline syndrome” in Salento (Apulia, Italy). On April 2015, we started interdisciplinary studies to provide a sustainable control strategy for this pathogen that threatens the multi-millennial olive agroecosystem of Salento. Confocal laser scanning microscopy and fluorescence quantification showed that a zinc-copper-citric acid biocomplex—Dentamet®—reached the olive xylem tissue either after the spraying of the canopy or injection into the trunk, demonstrating its effective systemicity. The biocomplex showed in vitro bactericidal activity towards all X. fastidiosa subspecies. A mid-term evaluation of the control strategy performed in some olive groves of Salento indicated that this biocomplex significantly reduced both the symptoms and X. f. subsp. pauca cell concentration within the leaves of the local cultivars Ogliarola salentina and Cellina di Nardò. The treated trees started again to yield. A 1H-NMR metabolomic approach revealed, upon the treatments, a consistent increase in malic acid and γ-aminobutyrate for Ogliarola salentina and Cellina di Nardò trees, respectively. A novel endotherapy technique allowed injection of Dentamet® at low pressure directly into the vascular system of the tree and is currently under study for the promotion of resprouting in severely attacked trees. There are currently more than 700 ha of olive groves in Salento where this strategy is being applied to control X. f. subsp. pauca. These results collectively demonstrate an efficient, simple, low-cost, and environmentally sustainable strategy to control this pathogen in Salento.

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How Ecosystem Services Can Strengthen the Regeneration Policies for Monumental Olive Groves Destroyed by Xylella fastidiosa Bacterium in a Peri-Urban Area

Sustainability ◽

10.3390/su13168778 ◽

2021 ◽

Vol 13 (16) ◽

pp. 8778

Author(s):

Teodoro Semeraro ◽

Elisa Gatto ◽

Riccardo Buccolieri ◽

Valentina Catanzaro ◽

Luigi De Bellis ◽

...

Keyword(s):

Land Use ◽

Ecosystem Services ◽

Land Cover ◽

Cultural Heritage ◽

Urban Area ◽

Urban Areas ◽

Xylella Fastidiosa ◽

Trade Offs ◽

Olive Groves ◽

Olive Trees

The Apulian Region (Italy) is a socio-ecological system shaped by the millennial co-evolution between human actions and ecological processes. It is characterized by monumental olive groves protected from Regional Law 14/2007 for the cultural value of the landscape, currently threatened by the spread of a devastating phytopathogen, the bacteria Xylella fastidiosa. The aim of this paper is to apply landscape resilience analysis focusing on ecosystem services to understand the potential effects and trade-offs of regeneration policies in a peri-urban area characterized by monumental olive groves land cover. The study involved land-cover and land-use analysis, supported by a survey on the inhabitants and an ecosystem services analysis. The results showed a mismatch between the agroecosystem and the social and economic use linked to leisure or hospitality. The study area was defined as a peri-urban landscape characterized by tourist use. From the interviews of the users, the cultural heritage of olive groves seems linked to the presence of olive trees like a status quo of the landscape and olive oil productions. The culture aspect could thus be preserved by changing the type of olive trees. In addition, the analysis showed that the microclimate could be preserved and enhanced in terms of air temperature and thermal comfort, by replacing the olive trees with varieties resistant to Xylella, such as cv. Leccino. Therefore, regeneration policies that promote replacing dead olive groves with new olive trees could be efficient to stimulate social components of the landscape and improve the resilience of ecosystem services in peri-urban areas in the interest of the cultural heritage of the users and benefits that they provide. An ecosystem services analysis at a local scale could be a strategy for an integrated regenerate approach between land-use and land-cover with social, ecological, and economic evolutions vision orientated to a sustainable and desirable future.

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Distribution and Relative Abundance of Insect Vectors of Xylella fastidiosa in Olive Groves of the Iberian Peninsula

Insects ◽

10.3390/insects9040175 ◽

2018 ◽

Vol 9 (4) ◽

pp. 175 ◽

Cited By ~ 28

Author(s):

Marina Morente ◽

Daniele Cornara ◽

María Plaza ◽

José Durán ◽

Carmen Capiscol ◽

...

Keyword(s):

Sampling Method ◽

Sampling Methods ◽

Xylella Fastidiosa ◽

Ground Cover ◽

Ground Vegetation ◽

Insect Vectors ◽

Central Spain ◽

Tree Canopies ◽

Olive Groves ◽

Olive Trees

The phytosanitary emergency caused by the spread of Xylella fastidiosa in the Mediterranean has raised demands for a better understanding of the ecology of its presumed and candidate insect vectors. Here, we present the results of a two-year survey carried out in olive groves across southern, eastern and Central Spain and northeastern Portugal. Several sampling methods were tested and compared to select the most appropriate to estimate population levels of potential vectors of X. fastidiosa. The spittlebugs Philaenus spumarius and Neophilaenus campestris (Hemiptera: Aphrophoridae) were the main species associated with olive groves. Both species were widely present on herbaceous ground vegetation within the olive groves; P. spumarius mainly associated with Asteraceae and N. campestris with Poaceae. Due to the patchy distribution of spittlebugs within the olive groves, sweep nets were the most effective and least time-consuming sampling method for the estimation of population size both in the ground cover and tree canopies. Trends in population density showed that spittlebugs can be abundant on ground vegetation but very rare on olive canopies. Spittlebugs disperse in late spring to non-cultivated hosts that act as natural reservoirs. In late fall, adults return to the olive groves for oviposition. However, olive trees may act as transient hosts for spittlebugs and high population densities of these insect vectors should be avoided in areas where X. fastidiosa is present.

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Canopy Index Evaluation for Precision Management in an Intensive Olive Orchard

Sustainability ◽

10.3390/su13158266 ◽

2021 ◽

Vol 13 (15) ◽

pp. 8266

Author(s):

Alberto Assirelli ◽

Elio Romano ◽

Carlo Bisaglia ◽

Enrico Maria Lodolini ◽

Davide Neri ◽

...

Keyword(s):

Precision Agriculture ◽

Ambient Air ◽

Plant Diseases ◽

Precision Management ◽

Practical Support ◽

Index Evaluation ◽

Leaf Level ◽

Olive Groves ◽

Cultivation Techniques ◽

Monitoring Information

The evaluation of the canopy in orchard cultivation is a key aspect for the main cultivation techniques, such as pruning, thinning, harvesting, production and improved fruit quality. The possibility of having a periodic screening of the state of development of the vegetation can be of practical support to growers. Research on the application of precision agriculture has provided tools for reading and interpreting crops, and the resulting information is potentially useful. Many of the systems under study provide after monitoring information processing systems that reduce the timeliness of intervention. Especially in intensive systems such as olive groves, knowing the precise intervention points is often essential. In the present work, a multi-parameter instrument was used for field monitoring on the agricultural tractor to analyse the canopy. The system allows measuring various indicators such as height and density of the canopy and the temperature and humidity of the ambient air and at the leaf level. The first evaluation of the data made it possible to identify areas with greater vegetative concentration and greater or lesser development. The system made it possible to identify with good approximation the homogeneous areas, based on the Canopy Index (CI) evaluation to be subjected to subsequent and specific management efforts, dividing them into low, ordinary, and high vegetative growth. The results highlight the possibility of directly combining operators able to intervene with the same passage, selecting based on differences in growth, typical varietal specificities, and areas of deficient development or that are affected by plant diseases, confirming the objective of defining the areas of the orchard that require different management and workload techniques.

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The Multi-Millennial Olive Agroecosystem of Salento (Apulia, Italy) Threatened by Xylella Fastidiosa Subsp. Pauca: A Working Possibility of Restoration

Sustainability ◽

10.3390/su12176700 ◽

2020 ◽

Vol 12 (17) ◽

pp. 6700

Author(s):

Marco Scortichini

Keyword(s):

Cell Concentration ◽

Control Strategies ◽

Xylella Fastidiosa ◽

First Record ◽

Interdisciplinary Studies ◽

Insect Vector ◽

Infected Area ◽

Olive Groves ◽

Olive Trees ◽

Spray Treatment

In Salento, the olive agro-ecosystem has lasted more than 4000 years, and represents an invaluable local heritage for landscape, trade, and social traditions. The quarantine bacterium Xylella fastidiosa subsp. pauca was introduced in the area from abroad and has been widely threatening olive groves in the area. The successful eradication of quarantine phytopathogens requires a prompt identification of the causative agent at the new site, a restricted infected area, a highly effective local organization for crop uprooting and biological features of the micro-organism that would guarantee its complete elimination. However, at the time of the first record, these criteria were not met. Interdisciplinary studies showed that a zinc-copper-citric acid biocomplex allowed a consistent reduction of field symptoms and pathogen cell concentration within infected olive trees. In this perspective article, it is briefly described the implementation of control strategies in some olive farms of Salento. The protocol includes spray treatment with the biocomplex during spring and summer, regular pruning of the trees and mowing of soil between February and April to reduce the juvenile of the insect vector(s). Thus far, more than 500 ha have begun to follow this eco-friendly strategy within the “infected” and “containment” areas of Salento.

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