[{"command":"openDialog","selector":"#drupal-modal","settings":null,"data":"\u003Cdiv id=\u0022republish_modal_form\u0022\u003E\u003Cform class=\u0022modal-form-example-modal-form ecl-form\u0022 data-drupal-selector=\u0022modal-form-example-modal-form\u0022 action=\u0022\/en\/article\/modal\/7211\u0022 method=\u0022post\u0022 id=\u0022modal-form-example-modal-form\u0022 accept-charset=\u0022UTF-8\u0022\u003E\u003Cp\u003EHorizon articles can be republished for free under the Creative Commons Attribution 4.0 International (CC BY 4.0) licence.\u003C\/p\u003E\n \u003Cp\u003EYou must give appropriate credit. We ask you to do this by:\u003Cbr \/\u003E\n 1) Using the original journalist\u0027s byline\u003Cbr \/\u003E\n 2) Linking back to our original story\u003Cbr \/\u003E\n 3) Using the following text in the footer: This article was originally published in \u003Ca href=\u0027#\u0027\u003EHorizon, the EU Research and Innovation magazine\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003ESee our full republication guidelines \u003Ca href=\u0027\/horizon-magazine\/republish-our-stories\u0027\u003Ehere\u003C\/a\u003E\u003C\/p\u003E\n \u003Cp\u003EHTML for this article, including the attribution and page view counter, is below:\u003C\/p\u003E\u003Cdiv class=\u0022js-form-item form-item js-form-type-textarea form-item-body-content js-form-item-body-content ecl-form-group ecl-form-group--text-area form-no-label ecl-u-mv-m\u0022\u003E\n \n\u003Cdiv\u003E\n \u003Ctextarea data-drupal-selector=\u0022edit-body-content\u0022 aria-describedby=\u0022edit-body-content--description\u0022 id=\u0022edit-body-content\u0022 name=\u0022body_content\u0022 rows=\u00225\u0022 cols=\u002260\u0022 class=\u0022form-textarea ecl-text-area\u0022\u003E\u003Ch2\u003EThe fight to save Europe\u2019s olive trees from disease\u003C\/h2\u003E\u003Cp\u003EIn the late summer harvest of 2013, olive farmers in the Puglia region of southern Italy noticed that the leaves on several of their trees were turning brown and their shoots withering. The problem spread from one orchard to another, as more olive farmers found their trees were drying out and beginning to die.\u003C\/p\u003E\u003Cp\u003EGenetic testing confirmed them to be infected with \u003Cem\u003EXyella fastidiosa,\u003C\/em\u003E a bacteria originally found in America. Soon outbreaks appeared throughout the Mediterranean, even briefly as far north as Germany in 2016.\u003C\/p\u003E\u003Cp\u003EThe bacteria is mainly spread by sap-sucking insects known as spittlebugs and sharpshooters. As the insects feed, the bacteria is able to infect the vessels that transport water and nutrients around the plant, known as the xylem. As the bacteria destroy the xylem, it slowly chokes the plant.\u003C\/p\u003E\u003Cp\u003E\u2018We are dealing with a very severe situation in southern Italy,\u2019 said Dr Maria Saponari, based at the Institute for Sustainable Plant Protection in Bari, Italy. Europe\u2019s researchers were caught off-guard by the epidemic, she explained. \u2018When the bacterium was discovered here, there wasn\u2019t any research centre in Europe working specifically on this pathogen. We were starting from zero.\u2019\u003C\/p\u003E\u003Cp\u003EThe disease can infect a wide range of plants, including shrubs like the myrtle-leaf milkwort and rosemary, oak trees, and important crops like lavender. Food crops including cherry trees, plum trees and olive trees are among the \u003Ca href=\u0022https:\/\/ec.europa.eu\/food\/plant\/plant_health_biosecurity\/legislation\/emergency_measures\/xylella-fastidiosa_en\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003Especies considered to be at high risk\u003C\/a\u003E.\u003C\/p\u003E\u003Cp\u003EIn particular, the outbreak has amplified problems in Italy\u2019s strained olive oil sector. In 2018, the country reported a \u003Ca href=\u0022http:\/\/www.ismeamercati.it\/flex\/cm\/pages\/ServeBLOB.php\/L\/IT\/IDPagina\/9224\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003E57% drop in its olive harvest\u003C\/a\u003E compared to 2017 \u2013 a 25-year low. Researchers blamed a frosty spring followed by a summer drought, which weakened the olive trees and left them even more susceptible to infection.\u003C\/p\u003E\u003Cp\u003EThe intense summer weather in southern Italy may also have made it easier for the disease to spread among olive trees as insects carrying the bacteria sought out food in the dry conditions. \u2018Here in summer, olives are the only green plants that we see,\u2019 said Dr Saponari. \u2018Olive canopies, for them, (are) like a refuge to survive.\u2019\u003C\/p\u003E\u003Cp\u003EWhile the disease has been found in a number of EU countries, it appears \u2018the strains that have been imported in Corsica or in Spain are much less aggressive than the strain spreading in Puglia\u2019, added Dr Saponari.\u003C\/p\u003E\u003Cp\u003EIn response, Dr Saponari is leading one of several Europe-wide projects seeking ways to curb this new threat to Europe\u2019s olive crops, and monitor its spread. Her \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/727987\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EXF-actors project\u003C\/a\u003E is examining olive trees\u2019 genetics to see if some of the plants have natural resistance to \u003Cem\u003EXyella fastidiosa\u003C\/em\u003E that can then be used to breed crops that are more resilient against the disease.\u003C\/p\u003E\u003Cp\u003E\u003Cblockquote class=\u0022tw-text-center tw-text-blue tw-font-bold tw-text-2xl lg:tw-w-1\/2 tw-border-2 tw-border-blue tw-p-12 tw-my-8 lg:tw-m-12 lg:tw--ml-16 tw-float-left\u0022\u003E\n \u003Cspan class=\u0022tw-text-5xl tw-rotate-180\u0022\u003E\u201c\u003C\/span\u003E\n \u003Cp class=\u0022tw-font-serif tw-italic\u0022\u003E\u2018We are dealing with a very severe situation in southern Italy.\u2019\u003C\/p\u003E\n \u003Cfooter\u003E\n \u003Ccite class=\u0022tw-not-italic tw-font-normal tw-text-sm tw-text-black\u0022\u003EDr Maria Saponari, Institute for Sustainable Plant Protection, Italy \u003C\/cite\u003E\n \u003C\/footer\u003E\n\u003C\/blockquote\u003E\n\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EBorder plants\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EResearchers on the project are also conducting field experiments to look at natural strategies to combat the disease, such as using kaolin clay as an insect repellent. Others are experimenting with \u2018border plants\u2019 that can be grown around olive groves and other important crops to draw the bacteria-carrying insects away from the crops, and \u2018sentinel plants\u2019 such as the myrtle-leaf milkwort which show symptoms of bacterial infection sooner, allowing action to be taken quickly to contain an infection.\u003C\/p\u003E\u003Cp\u003EIt is also hoped it may be possible to contain the disease by chopping down infected plants, using more insecticide, or planting crops that are less susceptible to the bacterial strain.\u003C\/p\u003E\u003Cp\u003EThe project team\u2019s priority lies in assisting the early detection and containment of the disease. Field inspections and new imaging technology developed by the XF-actors project can already predict how the bacteria may spread, and how to contain it. For example, a combination of thermal images, fieldwork, and spectroscopy can now detect infection in plants and trees before any symptoms appear.\u003C\/p\u003E\u003Cp\u003EAll this information can then be put together to give the authorities a better idea of in which areas the disease is more likely to spread, and so where to send their inspectors next.\u0026nbsp;\u0026nbsp; \u0026nbsp;\u003C\/p\u003E\u003Cp\u003ETo date, monitoring and predicting outbreaks has proven difficult. Even tracking the disease-carrying insect vectors involves hours of sweeping trees and shrubs with entomological nets, and scientists still have to unravel exactly how the bacteria passes from the insects to the plants.\u003C\/p\u003E\u003Cp\u003E\u2018(Nets are) the best way to catch them,\u2019 said Professor Alberto Fereres, an entomologist based at Spain\u2019s Institute of Agricultural Sciences in Madrid. \u2018They are not very much attracted to sticky-colour traps. They communicate by sound \u2013 they don\u2019t use colours as visual cues to find their host plants.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cfigure role=\u0022group\u0022 class=\u0022@alignleft@\u0022\u003E\n\u003Cimg alt=\u0022Spittlebugs are among the insects that carry the Xyella fastidiosa bacteria and infect plants as they feed. Image credit - Pavel Kirillov\/Wikimedia commons, licenced under CC BY-SA 2.0\u0022 height=\u0022850\u0022 src=\u0022\/research-and-innovation\/sites\/default\/files\/hm\/IMCEUpload\/spittlebug_prosapia_bicincta.jpg\u0022 title=\u0022Spittlebugs are among the insects that carry the Xyella fastidiosa bacteria and infect plants as they feed. Image credit - Pavel Kirillov\/Wikimedia commons, licenced under CC BY-SA 2.0\u0022 width=\u00221280\u0022\u003E\n\u003Cfigcaption class=\u0022tw-italic tw-mb-4\u0022\u003ESpittlebugs are among the insects that carry the Xyella fastidiosa bacteria and infect plants as they feed. Image credit - Pavel Kirillov\/Wikimedia commons, licenced under CC BY-SA 2.0\u003C\/figcaption\u003E\n\u003C\/figure\u003E\n\u003C\/p\u003E\u003Cp\u003EProf. Fereres works on the XF-actors project while also leading another project aimed at tackling pest-spread pathogens in Europe, called \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/635646\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EPOnTE\u003C\/a\u003E. Prof. Fereres and his team are hoping to understand how insects transmit bacterial diseases like \u003Cem\u003EXyella fastidiosa.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003ETheir research is providing some early clues for strategies to stem the transmission of the disease. One involves introducing other non-harmful bacteria into the insects that make it harder for \u003Cem\u003EXyella \u003C\/em\u003E\u003Cem\u003Efastidiosa\u003C\/em\u003E to spread.\u003C\/p\u003E\u003Cp\u003E\u2018These can do two things \u2013 they can try to suppress the replication of the (\u003Cem\u003EXyella\u003C\/em\u003E) bacteria, (and) they can also compete with the bacteria in the vector for binding sites,\u2019 explained Prof. Fereres.\u003C\/p\u003E\u003Cp\u003E\u2018(This) binding site is the precise place where the virus or bacteria binds inside the insects mouthparts,\u2019 said Prof. Fereres.\u003C\/p\u003E\u003Cp\u003EHis team is also experimenting with antimicrobial peptides \u2013 short bits of protein \u2013 and chemicals that can interfere with the bacteria\u2019s ability to remain inside insects\u2019 bodies.\u003C\/p\u003E\u003Cp\u003EThe project is trying to prove which insects can pick up the bacteria from a plant and which are able to successfully transfer it to other plants as they feed.\u003C\/p\u003E\u003Cp\u003EThe team are conducting laboratory experiments that place infected insects on plants in controlled environments so they can pinpoint what exactly needs to happen for insects to transmit the bacteria to other plants \u2013 do they need to bite into the xylem specifically or just into other parts of the plant, for example.\u003C\/p\u003E\u003Cp\u003EThe bacteria could also affect each plant species differently.\u003C\/p\u003E\u003Cp\u003E\u2018We don\u2019t know the genetic determinants which lead to the infection of some plant species and not other ones\u2026 that are genetically close,\u2019 says Dr Anne Sicard of the Institut National de la Recherche Agronomique (INRAE) in Montpellier, France.\u003C\/p\u003E\u003Cp\u003EDr Sicard leads the \u003Ca href=\u0022https:\/\/cordis.europa.eu\/project\/id\/707013\u0022 target=\u0022_blank\u0022 rel=\u0022noopener noreferrer\u0022\u003EXYL-EID project\u003C\/a\u003E, a joint effort between INRAE, the University of California Berkeley, US, and Italy\u2019s National Research Council, which is analysing the bacteria\u2019s DNA to find out why such differences occur.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EOutbreak origins\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EThe project is searching for genes involved in helping the bacteria adapt to new environments, and in particular what happened in the outbreak in Puglia. They have analysed 74 bacteria samples collected from infected olive trees from across the affected area by sequencing each of their genomes.\u003C\/p\u003E\u003Cp\u003EThis work is already offering some promising insights into the origin of the outbreak. All samples are genetically very similar to one another, confirming that the outbreak in Puglia is the result of the introduction and subsequent establishment of a single strain of \u003Cem\u003EXyella\u003C\/em\u003E\u003Cem\u003E fastidiosa\u003C\/em\u003E. They also had a genetic similarity to a strain of the bacteria found in coffee plants in Costa Rica.\u003C\/p\u003E\u003Cp\u003EBut while this research may ultimately provide new ways of fighting the disease, it is unlikely to eradicate it, added Prof. Fereres.\u003C\/p\u003E\u003Cp\u003E\u2018We will have to learn how to live with \u003Cem\u003EXyella\u003C\/em\u003E, but we will have to also develop ways to contain the disease as much as possible and to avoid situations as in the south of Italy.\u2019\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThe research in this article was funded by the EU. 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