Strategy to Contain Xylella Fastidiosa Organically Shows Promise

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.

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.

“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.