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Study Reveals Potential Economic Impact of Xylella on Spain, Italy, Greece

The disease could cost billions, as almost all producing areas of the three countries are susceptible to the bacterium due to the prevailing climatic conditions.

Apr. 20, 2020
By Costas Vasilopoulos

Researchers from var­i­ous uni­ver­si­ties devel­oped an eco­nomic model to val­i­date the long-term impact of Xylella fas­tidiosa (Xf) on the olive oil indus­tries of Spain, Italy and Greece. They found that the poten­tial cost could be mea­sured in bil­lions of euros if the spread of the dis­ease is not mit­i­gated effec­tively.

Olive quick decline syn­drome could cost bil­lions of euros over the next 50 years in Greece, Italy and Spain.- Kevin Schnei­der, lead author.

The pos­si­ble loss for Italy was esti­mated at €5 bil­lion ($5.42 bil­lion) over the course of 50 years, while Spain and Greece were likely to suf­fer losses of 17 bil­lion euros ($18.44 bil­lion) and 2 bil­lion euros ($2.17 bil­lion) respec­tively over the same time period.

Xf is one of the most dan­ger­ous plant-path­o­genic bac­te­ria world­wide, the researchers noted. It causes quick decline syn­drome on olive trees and many other plant species. In the Euro­pean Union alone, over 84 host plants for the pathogen have been iden­ti­fied so far.

See more: Spain Deploys New Tech­nol­ogy to Com­bat Olive Tree Pathogens

Olive quick decline syn­drome could cost bil­lions of euros over the next 50 years in Greece, Italy and Spain,” lead study author Kevin Schnei­der, of the Wagenin­gen Uni­ver­sity in the Nether­lands, told Olive Oil Times. Even under slow dis­ease spread and the abil­ity to replant with resis­tant cul­ti­vars, pro­jec­tions of future eco­nomic impact in affected coun­tries run in the bil­lions of euro.”

For the sake of the research, a bio-eco­nomic model was con­structed for the strain of the bac­terium detected in Apu­lia. The model com­bined data from cli­matic-suit­abil­ity mod­el­ing, sim­u­la­tions of the dis­ease spread based on radial range expan­sion, and an algo­rith­mic method to com­pute the eco­nomic impact on olive grow­ers.

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An assess­ment period of 50 years was selected due to the slow rate of devel­op­ment of olive trees, and dif­fer­ent intro­duc­tion points and dis­per­sal rates of the pathogen were fed to the model to sim­u­late the future spread of the dis­ease. The spread of the dis­ease was cal­cu­lated at 5 kilo­me­ters (3.1 miles) per year on aver­age, likely to be reduced to 1 kilo­me­ter (.62 miles) per year with the appli­ca­tion of proper con­trol mea­sures. Dif­fer­ent sim­u­lat­ing sce­nar­ios accounted for vari­a­tions in the dis­per­sal rate.

Results showed that almost all pro­duc­ing ter­ri­to­ries are sus­cep­ti­ble to infec­tion from Xf, with the affected area vary­ing between 85 and 99 per­cent of the olive groves of each coun­try. Fur­ther­more, an esca­la­tion of the dis­ease match­ing the sim­u­la­tions would cause great eco­nomic dam­age to olive grow­ers and pro­duc­ers. Replac­ing the affected olive trees with Xf-resis­tant cul­ti­vars would limit the dam­age con­sid­er­ably.

The find­ings sug­gest that most Euro­pean pro­duc­tion sites fall into the cli­mat­i­cally suit­able ter­ri­tory for estab­lish­ment and dis­per­sal of the dis­ease,” Schnei­der explained. In Italy, ces­sa­tion of pro­duc­tion after orchard die-off results in an eco­nomic impact of up to €5.2 bil­lion ($5.7 bil­lion) if the pathogen spreads beyond the cur­rent extent. Replant­ing orchards with resis­tant vari­eties can lower the impact to €1.6 bil­lion ($1.7 bil­lion). Reduc­ing the annual rate of spread could save up to €1.3 bil­lion ($1.4 bil­lion). Intro­duc­tions into Greece and Spain could result in an impact between €2 bil­lion and €17 bil­lion ($2.2 bil­lion and $18.4 bil­lion), respec­tively.”

The three coun­tries were the most suit­able for the research scope as together, they account for almost 95 per­cent of Euro­pean olive oil pro­duc­tion. South­ern Italy is severely hit by Xf with almost 17 per­cent of its olive pro­duc­ing ter­ri­to­ries cur­rently infected. Spain also suf­fers from the pathogen spo­rad­i­cally present on the main­land and in some islands, whereas Greece remains unaf­fected.

Schnei­der also spec­i­fied that, due to its mor­phol­ogy, Greece exhibits an advan­tage over Italy and Spain in the case the pathogen man­i­fests itself on a sin­gle entry point.

We did find that impacts in Greece were lower than com­pared to Italy or Spain,” he said. While this was influ­enced by a few fac­tors, one key dif­fer­ence was the sea as a nat­ural bar­rier for the spread between the areas of pro­duc­tion. Albeit, that this is based on the assump­tion that we only con­sider one intro­duc­tion of the pathogen and not mul­ti­ple intro­duc­tions.”

A cure for Xf has yet to be dis­cov­ered, Schnei­der added, empha­siz­ing that plant­ing of resis­tant cul­ti­vars, along with con­trol mea­sures, appeared to be effec­tive in con­trol­ling the spread of the bac­terium.

Cur­rently, there is no prac­ti­cal cure under field con­di­tions,” he said. While impor­tant research on vec­tor con­trol is ongo­ing, adap­ta­tion through resis­tant trees seems the most promis­ing long-term strat­egy. The find­ings stress the neces­sity to strengthen the ongo­ing research on cul­ti­var resis­tance traits and appli­ca­tion of phy­tosan­i­tary mea­sures includ­ing vec­tor con­trol and inocu­lum sup­pres­sion by remov­ing host plants.”

Fur­ther­more, many olive trees sur­round­ing pock­ets of infected trees can be asymp­to­matic, infected with the pathogen but exhibit­ing no symp­toms of the dis­ease. The study rec­om­mended that a cor­don san­i­taire should be cre­ated in the perime­ter of those pock­ets by remov­ing the symp­tom­less trees. The study stressed that the asymp­to­matic, but infec­tious, olive trees pose a sig­nif­i­cant hin­drance to a pos­si­ble erad­i­ca­tion of the dis­ease.

Unpop­u­lar prac­tices like felling seem­ingly healthy olive trees can, how­ever, result in great soci­etal unrest in the affected region,” the researchers warned.

Schnei­der also acknowl­edged the strictly sci­en­tific approach of the study, leav­ing aside the cul­tural side of the olive tree groves of Europe.

The study did not account for the cul­tural her­itage value of the Euro­pean olive trees, many of which are hun­dreds of years old,” he said.

Schnei­der urged olive grow­ers to seek offi­cial advice and apply the proper mea­sures in coop­er­a­tion with the author­i­ties.

Farm­ers need to stay vig­i­lant and adhere to the imposed mit­i­ga­tion mea­sures. Gov­ern­ment inter­ven­tions are war­ranted with regard to eco­nomic con­sid­er­a­tions, and gov­ern­ment sup­port for adap­ta­tion strate­gies, such as [devel­op­ing and prop­a­gat­ing] resis­tant vari­eties, is impor­tant,” he said



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