New Biopesticides Prove Effective at Mitigating Symptoms of Xylella

Summary

The Biovexo project has devel­oped three new com­pounds to tar­get the Xylella fas­tidiosa bac­terium, which could help com­bat the epi­demic, although they can­not cure infected plants. Extensive field tri­als have been con­ducted on olive trees in infected areas to eval­u­ate the effi­cacy and sus­tain­abil­ity of the prod­ucts, with hopes of mak­ing them avail­able on the mar­ket pend­ing reg­u­la­tory com­pli­ance checks and indus­try inter­est.

Three new com­pounds tar­get­ing the Xylella fas­tidiosa bac­terium, devel­oped within the European Union-funded Biovexo project, may soon be avail­able for pur­chase.

Once avail­able, the prod­ucts fine-tuned by the Biovexo con­sor­tium would rep­re­sent a cru­cial step towards cur­tail­ing the Xylella fas­tidiosa epi­demic.

“Those new biopes­ti­cides can not cure the plants that have been infected, as they can­not elim­i­nate the bac­terium from an infected olive tree,” Stéphane Compant, Biovexo’s sci­en­tific coor­di­na­tor and a senior sci­en­tist at the Austrian Institute of Technology, told Olive Oil Times. ​“Still, some slow down Xylella fastidiosa’s symp­toms or reduce insect vec­tor pop­u­la­tions.”

“Their appli­ca­tion in the field showed that they can relieve the pres­sure of the bac­te­ria while also sup­port­ing the green­ing of infected olive trees,” he added.

Since 2020, the consortium’s researchers and part­ners have tested sev­eral dif­fer­ent solu­tions aimed at cur­ing olive trees from the bac­te­ria or enhanc­ing their chance of sur­viv­ing the infec­tion and return­ing to pro­duc­tion.

A cru­cial part of Biovexo’s work has been turn­ing promis­ing lab dis­cov­er­ies into prac­ti­cal tools for farm­ers. 

The focus was on for­mu­lat­ing sub­stances for biopes­ti­cides tar­get­ing both bac­te­ria and insects, and scal­ing them up from lab­o­ra­tory exper­i­ments to indus­trial pro­duc­tion, enabling large-scale field tri­als.

“We have done field tri­als in Puglia, Mallorca, and also in Alicante. We began with sev­eral biopes­ti­cides and now, while the project reaches its final stage, we focus on three of them,” Compant said.

The exten­sive field tests allowed researchers to eval­u­ate the effi­cacy of the prod­ucts, as well as their sus­tain­abil­ity, upscal­ing pro­duc­tion oppor­tu­ni­ties, and cor­rect for­mu­la­tion.

“This is a unique project, the only one to test a large num­ber of plants over the years,” said Pasquale Saldarelli, the coor­di­na­tor for Biovexo’s field tri­als.

“We did not only work in the green­house. Biovexo grew its own olive trees in the infected area, to have nat­u­rally infected trees to ana­lyze and fol­low,” he said.

Existing almond and olive groves were also included in the project to test the prod­ucts for their pos­si­ble pre­ven­tive and cura­tive effects.

The field tests on olives were con­ducted on vari­eties known to be sus­cep­ti­ble to Xylella fas­tidiosa, in col­lab­o­ra­tion with Enza Dongiovanni of the Basile Caramia agri­cul­tural research, train­ing, and exper­i­men­ta­tion cen­ter in Locorotondo, Bari.

“We chose the Cellina di Nardò cul­ti­var for the grove not far from Brindisi, in the infected area where the bac­terium is now endemic,” Saldarelli said. ​“We also expanded the tests in mature olive groves to ana­lyze the impact in dif­fer­ent con­di­tions.”

“Close to Brindisi, we fol­lowed 30-year-old orchards includ­ing Cellina di Nardò and Cima di Melfi cul­ti­vars,” he added, hint­ing at the impor­tance of exam­in­ing all the steps of the infection’s pro­gres­sion and whether con­trol­ling it is fea­si­ble.

“In the field, we have not only data of visual assess­ment of symp­toms, but also data of the micro­biome of the treated plants and data about their phys­i­o­log­i­cal con­di­tion,” Saldarelli explained.

Every six months, the con­di­tions of all groves have been assessed for the bac­terium and its symp­toms. 

Moreover, an inte­grated pest man­age­ment approach, con­sist­ing of the use of biopes­ti­cides against both the bac­terium and the insect, is ongo­ing in fur­ther tri­als.

“What we saw were the dif­fer­ent modes of action of our biopes­ti­cides. Some tar­get­ing the insect vec­tor, some being effec­tive or inef­fec­tive in reduc­ing the symp­toms in plants,” Compant said.

“As for the Xylella fas­tidiosa infec­tion per se, we noticed that it is not directly affected by the com­pounds. The cor­rect approach is broader, though, as it aims to reduce and cur­tail the dis­ease,” he added.

This broad approach reflects the many part­ner­ships Biovexo has acti­vated with lead­ing research insti­tutes and indus­try play­ers across Europe.

The biopes­ti­cides, based on microor­gan­isms and plant extracts, were designed to be sus­tain­able and envi­ron­men­tally friendly prod­ucts.

Researchers con­ducted life-cycle assess­ments of the selected biopes­ti­cides to mea­sure their envi­ron­men­tal foot­print, along­side exten­sive tox­i­c­ity test­ing to ensure safety for crops, ecosys­tems, and ben­e­fi­cial insects, such as bees.

Biovexo devel­oped bio-process con­trol para­me­ters to ensure con­sis­tency and qual­ity, while also look­ing at the best ways to max­i­mize effi­cacy.

Economic via­bil­ity was also eval­u­ated to con­firm that the solu­tions can be real­is­ti­cally adopted in the agri­cul­tural sec­tor.

The com­pany warned that, for those prod­ucts to be made ready for the mar­ket and reach the farm­ers, some addi­tional time will be needed.

Each prod­uct will undergo manda­tory reg­u­la­tory com­pli­ance checks. According to the con­sor­tium, the broad test­ing and analy­sis will enable the indus­try to scale up the prod­ucts and pre­pare them for mar­ket entry.

“A lot of resources and money need to be put into these solu­tions before they can be made avail­able,” Compant said. ​“Most of all, it will take the direct inter­est of the spe­cial­ized indus­try.” 

Looking ahead, researchers hope to main­tain at least one exper­i­men­tal field after the project’s con­clu­sion.

On November 13, 2025, Biovexo will host its final con­fer­ence in Locorotondo, Puglia, the south­ern Italian region where the Xylella fas­tidiosa cri­sis in Europe orig­i­nated.

The full-day event will bring together researchers, farm­ers, pol­i­cy­mak­ers, and indus­try lead­ers to show­case the project’s mile­stones and future out­look.

Under the theme ​“Biocontrol of Xylella and its vec­tor in olive trees for inte­grated pest man­age­ment,” ses­sions will high­light field appli­ca­tions, safety data and strate­gies for scal­ing up biopes­ti­cides.

“The con­fer­ence marks a deci­sive moment for trans­lat­ing five years of research into prac­ti­cal, sus­tain­able solu­tions,” Compant con­cluded.