Strategy to Contain Xylella Fastidiosa Organically Shows Promise

Researchers used organic substances to stimulate the plant's development of phytoalexins, which are barriers used in its internal war against the pathogen.

Aug. 25, 2016
By Ylenia Granitto

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Researchers of the University of Foggia in col­lab­o­ra­tion with Copagri, the con­fed­er­a­tion of agri­cul­ture man­u­fac­tur­ers, started a trial in 2015 on olive trees affected by Rapid Complex Desiccation, or so-called CoDiRO, the epi­demic caused by the Xylella fas­tidiosa bac­terium, to eval­u­ate the abil­ity to con­tain its symp­toms with organic prod­ucts with dif­fer­ent activ­i­ties like fer­til­iz­ers, agro­chem­i­cals and resis­tance induc­ers com­bined with good agri­cul­tural prac­tices.

At this point we have to learn to live with the dis­ease.- Francesco Lops, University of Foggia

The results, which will have to be con­firmed through addi­tional tests, high­light the abil­ity of plants to react to path­o­genic attack that, based on the first sur­vey, did not cause an impair­ment of pro­duc­tion.

We met Francesco Lops, pro­fes­sor of plant pathol­ogy at the University of Foggia and sci­en­tific coor­di­na­tors of the sur­vey to bet­ter under­stand the research.
See Also: Articles on Xylella Fastidiosa
The direc­tion of Copagri con­tacted us to pro­vide answers about the con­di­tion of olive trees affected by rapid des­ic­ca­tion,” he explained to Olive Oil Times. With the pro­fes­sor of plant pathol­ogy at the University of Foggia, Antonia Carlucci, and the direc­tor of Copagri, Fabio Ingrosso, Lops coor­di­nated the launch of research activ­ity con­ducted last year in dif­fer­ent olive groves in the area of Matino, in the province of Lecce.

At this point we have to learn to live with the dis­ease,” said Lops. Especially in the infected area, the main need and pur­pose of the study is to find a rem­edy to pre­vent fur­ther progress.”

Lops said that the bac­terium is enrolled in the list of quar­an­tined pathogens and in these cases we should pro­ceed with erad­i­ca­tion to ward off the pathogen from the ter­ri­tory. This can be applied in areas free’ from the bac­terium, but in infected areas, the con­cept of quar­an­tine is under­mined since the pathogen has become set­tled. It is now appar­ent that the bac­terium is exis­tent through­out the Mediterranean basin.

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Since the bac­terium lives in the xylem ves­sels, it is dif­fi­cult to reach it, and to find prod­ucts that have a direct effect on it is almost impos­si­ble, both for the dif­fi­culty to arrive at the ves­sels, and because there are not many antibac­te­r­ial sub­stances,” the pro­fes­sor explained.

As in every host-pathogen rela­tion­ship, there is always an action of mutual con­flict. The spirit of the study con­sists of facil­i­tat­ing the response of the host plant and stim­u­lat­ing a reac­tion of effec­tive block and con­tain­ment.”

For this pur­pose, the researchers used var­i­ous organic sub­stances and made a com­par­i­son, in order to stim­u­late the plant and develop phy­toalex­ins, which are bar­ri­ers that the plant uses as a strat­egy in its inter­nal war against the pathogen. Our goal is to strengthen this atti­tude of the olive tree with organic sub­stances, in accor­dance with Directive 2009/128/EC on sus­tain­able use and man­age­ment of pes­ti­cides,” Lops pointed out.

The results obtained from the tests both in the field and in vitro demon­strated the abil­ity of olive plants to react to path­o­genic attack, when actions of ordi­nary agro­nomic (plow­ing, milling, prun­ing) and phy­toiatric man­age­ment are imple­mented. Moreover, it seems that the best results were reg­is­tered in the tests where two or more prod­ucts, with dif­fer­ent char­ac­ter­is­tics, have been com­bined.

This means that strate­gic actions that meet all the needs of the plant, from nutri­tional to pro­tec­tive and defen­sive, are desir­able in this case. Therefore, after just 5 months of exper­i­men­ta­tion, the researchers con­sider it appro­pri­ate not to empha­size the results since the analy­ses on the assess­ment the bac­terium Xylella fas­tidiosa were always pos­i­tive in all sam­ples and this means that it is present in the tis­sues of the treated plants.

Nevertheless, after the last sur­vey car­ried out in November 2015, olive trees had not shown any symp­toms. These pre­lim­i­nary and par­tial results of exper­i­men­tal activ­i­ties car­ried out for one year need to be con­firmed and val­i­dated by sub­se­quent exper­i­ments that will be repeated over the com­ing months.


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