Xylella fastidiosa in Olive: A Review of Control Attempts and Current Management

Since 2013, Xylella fastidiosa Wells et al. has been reported to infect several hosts and to be present in different areas of Europe. The main damage has been inflicted on the olive orchards of southern Apulia (Italy), where a severe disease associated with X. fastidiosa subspecies pauca strain De Donno has led to the death of millions of trees. This dramatic and continuously evolving situation has led to European and national (Italian and Spanish) measures being implemented to reduce the spread of the pathogen and the associated olive quick decline syndrome (OQDS). Research has been also carried out to find solutions to better and directly fight the bacterium and its main insect vector, Philaenus spumarius L. In the course of this frantic effort, several treatments based on chemical or biological substances have been tested, in addition to plant breeding techniques and integrated pest management approaches. This review aims to summarize the attempts made so far and describe the prospects for better management of this serious threat, which poses alarming questions for the future of olive cultivation in the Mediterranean basin and beyond.

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The origin and spread of olive cultivation in the Mediterranean Basin: The fossil pollen evidence

The Holocene ◽

10.1177/0959683619826654 ◽

2019 ◽

Vol 29 (5) ◽

pp. 902-922 ◽

Cited By ~ 15

Author(s):

Dafna Langgut ◽

Rachid Cheddadi ◽

Josѐ Sebastián Carrión ◽

Mark Cavanagh ◽

Daniele Colombaroli ◽

...

Keyword(s):

Mediterranean Basin ◽

Large Scale ◽

Fossil Pollen ◽

Southern Levant ◽

Secondary Products ◽

Early Management ◽

Olive Cultivation ◽

The Mediterranean ◽

The Mediterranean Basin ◽

Pollen Records

Olive ( Olea europaea L.) was one of the most important fruit trees in the ancient Mediterranean region and a founder species of horticulture in the Mediterranean Basin. Different views have been expressed regarding the geographical origins and timing of olive cultivation. Since genetic studies and macro-botanical remains point in different directions, we turn to another proxy – the palynological evidence. This study uses pollen records to shed new light on the history of olive cultivation and large-scale olive management. We employ a fossil pollen dataset composed of high-resolution pollen records obtained across the Mediterranean Basin covering most of the Holocene. Human activity is indicated when Olea pollen percentages rise fairly suddenly, are not accompanied by an increase of other Mediterranean sclerophyllous trees, and when the rise occurs in combination with consistent archaeological and archaeobotanical evidence. Based on these criteria, our results show that the southern Levant served as the locus of primary olive cultivation as early as ~6500 years BP (yBP), and that a later, early/mid 6th millennium BP cultivation process occurred in the Aegean (Crete) – whether as an independent large-scale management event or as a result of knowledge and/or seedling transfer from the southern Levant. Thus, the early management of olive trees corresponds to the establishment of the Mediterranean village economy and the completion of the ‘secondary products revolution’, rather than urbanization or state formation. From these two areas of origin, the southern Levant and the Aegean olive cultivation spread across the Mediterranean, with the beginning of olive horticulture in the northern Levant dated to ~4800 yBP. In Anatolia, large-scale olive horticulture was palynologically recorded by ~3200 yBP, in mainland Italy at ~3400 yBP, and in the Iberian Peninsula at mid/late 3rd millennium BP.

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Shedding light on the effects of climate change on the potential distribution of Xylella fastidiosa in the Mediterranean basin

Biological Invasions ◽

10.1007/s10530-016-1118-1 ◽

2016 ◽

Vol 18 (6) ◽

pp. 1759-1768 ◽

Cited By ~ 53

Author(s):

Luciano Bosso ◽

Mirko Di Febbraro ◽

Gennaro Cristinzio ◽

Astolfo Zoina ◽

Danilo Russo

Keyword(s):

Climate Change ◽

Mediterranean Basin ◽

Potential Distribution ◽

Xylella Fastidiosa ◽

The Mediterranean ◽

The Mediterranean Basin

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Aphrophoridae Role in Xylella fastidiosa subsp. pauca ST53 Invasion in Southern Italy

Pathogens ◽

10.3390/pathogens10081035 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1035

Author(s):

Ugo Picciotti ◽

Nada Lahbib ◽

Valdete Sefa ◽

Francesco Porcelli ◽

Francesca Garganese

Keyword(s):

Pest Management ◽

Plant Pathogen ◽

Southern Italy ◽

Xylella Fastidiosa ◽

Xylem Sap ◽

Disease Spread ◽

Insect Vector ◽

Transmission Control ◽

Olive Quick Decline Syndrome ◽

Olive Trees

The Philaenus spumarius L. (Hemiptera Aphrophoridae) is a xylem-sap feeder vector that acquires Xylella fastidiosa subsp. pauca ST53 during feeding on infected plants. The bacterium is the plant pathogen responsible for olive quick decline syndrome that has decimated olive trees in Southern Italy. Damage originates mainly from the insect vector attitude that multiplies the pathogen potentialities propagating Xf in time and space. The principal action to manage insect-borne pathogens and to contain the disease spread consists in vector and transmission control. The analysis of an innovative and sustainable integrated pest management quantitative strategy that targets the vector and the infection by combining chemical and physical control means demonstrates that it is possible to stop the Xylella invasion. This review updates the available topics addressing vectors’ identification, bionomics, infection management, and induced disease by Xylella invasion to discuss major available tools to mitigate the damage consequent to the disease.

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BURSAPHELENCHUS SPECIES (NEMATODA: APHELENCHIDA) ASSOCIATED WITH AN OLIVE TREE IN CENTRAL ITALY

Redia ◽

10.19263/redia-103.20.19 ◽

2020 ◽

Vol 103 ◽

pp. 121-127

Author(s):

GIULIA TORRINI ◽

AGOSTINO STRANGI ◽

STEFANIA SIMONCINI ◽

ILARIA CUTINO ◽

GIUSEPPE MAZZA ◽

...

Keyword(s):

Mediterranean Basin ◽

Central Italy ◽

Olive Tree ◽

Dead Tree ◽

Phytoparasitic Nematodes ◽

Olive Cultivation ◽

Cultural Interest ◽

Olive Trees ◽

The Mediterranean Basin

Olive cultivation is of great economic, ecological, and cultural interest in Italy, as well as in the rest of the Mediterranean basin. Among the pests of olive trees, several groups of insects, mites, and nematodes have been reported. Phytoparasitic nematodes especially of the genera Meloidogyne, Pratylenchus, Helicotylenchus, Xiphinema, Tylenchulus, Rotylenchulus, and Heterodera have usually been extracted from roots and soil around trees. On the other hand, no information is available concerning nematodes directly associated with the wood. At the end of September 2018, in a high-density cultivated olive grove in Tuscany (central Italy), several olive trees with decline symptoms were observed. Three Bursaphelenchus species, B. fungivorus, B. minutus, and B. sexdentati were extracted from the wood of one dead tree. Even though these species had already been reported in Italy, these findings were the first ones recorded in olive wood. Moreover, another undescribed Bursaphelenchusspecies was found associated with the bark beetle Hylesinus fraxini collected from olive trunks and branches. Further research is needed to investigate the role of insects and Bursaphelenchus spp. in the decline processes of olive trees.

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Transmission of Xylella fastidiosa Subspecies Pauca Sequence Type 53 by Different Insect Species

Insects ◽

10.3390/insects10100324 ◽

2019 ◽

Vol 10 (10) ◽

pp. 324 ◽

Cited By ~ 17

Author(s):

Vincenzo Cavalieri ◽

Giuseppe Altamura ◽

Giulio Fumarola ◽

Michele di Carolo ◽

Maria Saponari ◽

...

Keyword(s):

Xylella Fastidiosa ◽

Severe Disease ◽

Xylem Sap ◽

Seasonal Abundance ◽

Philaenus Spumarius ◽

Olive Groves ◽

Sap Feeding ◽

Olive Quick Decline Syndrome ◽

Exotic Pathogen

Diseases associated with Xylella fastidiosa have been described mostly in North and South America. However, during the last five years, widespread X. fastidiosa infections have been reported in a constrained area of the Apulia region (southern Italy), in olives trees suffering a severe disease, denoted as Olive Quick Decline Syndrome (OQDS). Because many xylem sap-feeding insects can function as vectors for the transmission of this exotic pathogen in EU, several research programs are ongoing to assess the role of candidate vectors in the spread of the infections. Initial investigations identified Philaenus spumarius (L.) as the predominant vector species in the olive orchards affected by the OQDS. Additional experiments have been carried out during 2016 and 2017 to assess the role of other species. More specifically, adults of the spittlebugs Philaenus italosignus Drosopolous and Remane, Neophilaenus campestris (Fallen) and of the planthopper Latilica tunetana (Matsumura) (Issidae) have been tested in transmission experiments to assess their ability to acquire the bacterium from infected olives and to infect different susceptible hosts (olives, almond, myrtle –leaf milkwort, periwinkle). Acquisition rates determined by testing individual insects in quantitative PCR assays, ranging from 5.6% in N. campestris to 22.2% in P. italosignus, whereas no acquisition was recorded for L. tunetana. Successful transmissions were detected in the recipient plants exposed to P. italosignus and N. campestris, whereas no trasmissions occurred with L. tunetana. The known vector Philaenus spumarius has been included in all the experiments for validation. The systematic surveys conducted in 2016 and 2017 provided further evidence on the population dynamics and seasonal abundance of the spittlebug populations in the olive groves.

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Candidatus phytoplasma phoenicium.

10.1079/cpc.118193.20210204886 ◽

2021 ◽

Author(s):

Fabio Quaglino

Keyword(s):

Mediterranean Basin ◽

Severe Disease ◽

Fruit Production ◽

Plant Diseases ◽

Insect Vectors ◽

Aetiological Agent ◽

Mountainous Areas ◽

Rapid Spread ◽

Almond Trees ◽

The Mediterranean Basin

Abstract Phytoplasmas are wall-less parasitic bacteria living exclusively in plant phloem as consequence of transmission by sap-sucking insect vectors (Lee et al., 2000); they have been associated with several hundred plant diseases. 'Candidatus Phytoplasma phoenicium' (CaPphoe), subgroup 16SrIX-B, is the aetiological agent of almond witches'-broom (AlmWB), a severe disease affecting almond, peach and nectarine trees in Lebanon and Iran. The first epidemics of AlmWB occurred in almond trees in Lebanon in the early 1990s and in Iran in 1995. In Lebanon, the disease rapidly spread from coastal to high mountainous areas, killing almost 150,000 trees over a period of 15 years. CaPphoe was first added to the EPPO Alert List in 2001 and removed from the list in 2006. The more recent rapid spread of CaPphoe in peach and nectarine orchards and in other plant hosts, along with the identification of efficient insect vectors, increased the alarm about the risk it poses for stone fruit production in the Middle East and in all the countries of the Mediterranean basin. Thus it was re-inserted in the EPPO Alert List in 2015.

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Predisposing Factors for “Olive Quick Decline Syndrome” in Salento (Apulia, Italy)

Agronomy ◽

10.3390/agronomy10091445 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1445 ◽

Cited By ~ 1

Author(s):

Marco Scortichini

Keyword(s):

Southern Italy ◽

Xylella Fastidiosa ◽

Severe Disease ◽

Pathogenic Fungi ◽

Predisposing Factors ◽

Local Cultivar ◽

Fragile Environment ◽

The Common ◽

Olive Quick Decline Syndrome ◽

Cultivar Susceptibility

Recently, a new severe disease has been reported in the Salento area (Apulia region, southern Italy) in the multimillennial olive agro-ecosystem, given the common name “olive quick decline syndrome” (OQDS). Together with Xylella fastidiosa subsp. pauca, some pathogenic fungi such as Phaeoacremonium spp. have been found associated with the disease. The main predisposing factors to the disease seem to be local cultivar susceptibility, depletion of some micronutrients in the soil that could be related to some agronomical practices favoring the depletion of soil fertility, an incorrect pruning cycle, climatic changes that result in increased soil waterlogging, and frost and drought events. The possible synergistic action of microorganisms other than X. f. subsp. pauca cannot be excluded. The features characterizing the areas where OQDS first appeared and subsequently spread, described and discussed here, would point to a rather fragile environment where one or more adverse climatic and/or edaphic factors could have acted together. The intrinsic peculiarities and management of the Salento olive agro-ecosystem could also have played a fundamental role in enhancing the virulence of X. f. subsp. pauca once introduced from abroad.

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Identification of Arthrinium marii as Causal Agent of Olive Tree Dieback in Apulia (Southern Italy)

Plant Disease ◽

10.1094/pdis-03-19-0569-re ◽

2020 ◽

Vol 104 (3) ◽

pp. 694-701

Author(s):

Donato Gerin ◽

Franco Nigro ◽

Francesco Faretra ◽

Stefania Pollastro

Keyword(s):

Mediterranean Basin ◽

Southern Italy ◽

Olive Tree ◽

Agricultural Communities ◽

Tree Dieback ◽

Olive Cultivation ◽

Olive Trees ◽

Genomic Regions ◽

The Mediterranean Basin ◽

Fungal Genus

Olive (Olea europaea L. var. sativa) is one of the most economically important tree crops grown in the Mediterranean basin. Arthrinium Kunze ex Fr. (teleomorph: Apiospora Sacc.) is a widespread fungal genus, and Arthrinium marii Larrondo & Calvo is a ubiquitous species, found in algae, soil, plants, and agricultural communities. A. marii was isolated from olive trees showing dieback from orchards located in Andria and in Fasano, Brindisi (Apulia, southern Italy) and identified based on morphological features and molecular analysis of four genomic regions (ITS, TUB2, TEF1, and LSU). Two-year-old olive plants artificially inoculated with three representative A. marii isolates showed complete dieback within 6 months, and the fungus was reisolated, satisfying Koch’s postulates. This is the first report of A. marii causing dieback on olive trees that could represent an important threat for olive cultivation.

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