`Researchers Find Another Disease Afflicting Olive Groves in Puglia - Olive Oil Times


Researchers Find Another Disease Afflicting Olive Groves in Puglia

By Paolo DeAndreis
Feb. 28, 2022 14:03 UTC

New research has con­firmed that another dis­ease is spread­ing among olive trees in Puglia, along with the olive quick decline syn­drome (OQDS) caused by Xylella fas­tidiosa pauca.

Scientists said the iso­la­tion of Neofusicoccum mediter­ra­neum, a fun­gus that spreads quickly and dam­ages the olive tree, is mean­ing­ful. The fun­gus might also attack trees already infected by Xylella fas­tidiosa.

We are now in the first phase of the study, and a full light has still to be shed on this phy­tosan­i­tary prob­lem. Then, on the basis of the acquired knowl­edge, it will be estab­lished how to man­age the dis­ease.- Massimo Pilotti, researcher, CREA-DC

According to the Neofusicoccum mediter­ra­neum Is Involved in a Twig and Branch Dieback of Olive Trees Observed in Salento” study pub­lished in Pathogens, researchers have devel­oped new insights on how to cur­tail the dry­ing dis­ease bet­ter. Still, many ques­tions remain to be answered.

Massimo Pilotti, the cor­re­spond­ing author of the study, from the Research Center for Plant Protection and Certification (CREA-DC) in Rome, said the inves­ti­ga­tion was prompted by the fact that a wilt­ing phe­nom­e­non, char­ac­ter­ized by pre­vi­ously unseen symp­to­ma­to­log­i­cal fea­tures, was emerg­ing in the olive groves since 2019.”

See Also:Research News

He empha­sized how find­ing a new wilt­ing syn­drome in Puglia adds fur­ther com­plex­ity to the phy­tosan­i­tary sta­tus of olive grow­ing in this region.”

Several con­cerns are raised,” Pilotti added. What is the impact of Branch and Twig Dieback (BTD) on olive-grow­ing in Puglia? How many provinces are really affected? Is BTD actively spread­ing? Are BTD and OQDS over­lap­ping in the same olive groves? And can they be con­fused with each other?”

To date, nearly all these ques­tions remain unan­swered, but we are con­duct­ing in-depth inves­ti­ga­tions to shed full light on the mat­ter,” he con­tin­ued.

Pilotti noted how the emo­tional impact of OQDS on olive grow­ing in Puglia, as well as the his­tor­i­cal knowl­edge of ver­ti­cil­lium wilt, another well-known wilt­ing dis­ease of the olive tree, can make BTD go unno­ticed. Thus, it is nec­es­sary to reveal the nature of the dis­ease.”

The researcher con­firmed that cor­rectly dis­tin­guish­ing BTD and OQDS onset might be chal­leng­ing.

Symptoms of BTD are sim­i­lar to OQDS at first glance or if wilt­ing occurred for a long time,” Pilotti said. Really, when symp­toms are appear­ing, BTD and OQDS are dis­tin­guish­able by BTD’s typ­i­cal red-bronze necrotic patches appear­ing on the leaf blades fol­lowed by the leaves curl­ing down­ward.”

Certainly, a cor­rect and defin­i­tive diag­no­sis is only based on pathogen iso­la­tion or mol­e­c­u­lar pathogen detec­tion,” he added.

The role of Neofusicoccum mediter­ra­neum in BTD remains to be assessed.

Let’s not make the basic mis­take of con­sid­er­ing Neofusicoccum mediter­ra­neum as the only agent of BTD,” Pilotti said. This still has to be fully demon­strated, though the fun­gus reacted highly aggres­sively in our path­o­genic­ity tests.“

The researchers added how the fun­gus was found in the first sur­vey, and cer­tainly its pres­ence is a rel­e­vant find­ing as it is well known in other coun­tries (Spain, the United States) as the main agent of BTD.”


However, in those coun­tries, addi­tional fun­gal species have been found asso­ci­ated with BTD and were shown to con­tribute to dis­ease devel­op­ment,” Pilotti said. Thus, we will have to exam­ine a large num­ber of sam­ples from the dif­fer­ent areas where BTD emerged to defin­i­tively clear the eti­ol­ogy of the dis­ease and the asso­ci­ated myco­biota.” All the fungi present in a spe­cific habi­tat con­sti­tute the myco­biota.

The researchers also noted how Neofusicoccum mediter­ra­neum had been reported in Apulian olive groves by other researchers 13 years ago. However, the researchers only found the fun­gus on fruits and only with a min­i­mal fre­quency.

Pilotti hypoth­e­sized that the fun­gus changed its rela­tion­ship with the host due to the nat­ural selec­tion of new path­o­genic strains or sim­ply changed its aggres­sive­ness as a con­se­quence of changes in the eco­log­i­cal niche of the olive groves.”


The CREA-DC researcher also explained how the fun­gus and other Botryospaeriaceae fungi can infect and dam­age many peren­nial agri­cul­tural and nat­u­rally-occur­ring species in which a latent phase alter­nates with full vir­u­lence accord­ing to the degree of stress suf­fered by the host.

Important crop species sus­cep­ti­ble to Botryospaeriaceae fungi species are: grapevine, almond, pis­ta­chio, wal­nut and cit­rus,” Pilotti said.

See Also:New Projects in Puglia Emphasize Early Detection Against Xylella

Scientists also explained how the BTD devel­ops in the region still has to be assessed.

In gen­eral, Botryospaeriaceae fungi species infect the host plant by enter­ing through the wounds caused by prun­ing tools and canopy-con­tact mechan­i­cal har­vester tools, which also facil­i­tate inocu­lum spread within and between the orchards,” Pilotti said.

Occurrence of frost and hail­storms is another pos­si­ble wound-linked infec­tion mech­a­nism,” he added. In addi­tion, in the pres­ence of wounds, rain or any splash­ing water plays a role in spread­ing the fun­gal inocu­lum and facil­i­tat­ing the reach of the entry points.”

Given the ongo­ing progress in the inves­ti­ga­tions, the researchers noted how cru­cial it is to be aware of the pres­ence of this dis­ease in order not to con­fuse it with OQDS or ver­ti­cil­lium wilt.”

We recorded super-infec­tions with the agents of both OQDS and BTD,” Pilotti said. Thus, won­der­ing whether the pres­ence of dis­ease con­di­tions the progress and the sever­ity of the other is fair.”

The researchers believe that it is very rel­e­vant to dis­crim­i­nate between the fun­gus and the Xylella fas­tidiosa infec­tions.

For exam­ple, in the eval­u­a­tion tests of the effec­tive­ness of OQDS con­trol strate­gies, it should be ensured that the treated plants are not also affected by BTD,” Pilotti said. If wilt­ing phe­nom­ena erro­neously attrib­uted to Xylella fas­tidiosa con­tinue to occur on trees treated to restrict OQDS, this can gen­er­ate a mis­in­ter­pre­ta­tion of the real effi­cacy of the con­trol inter­ven­tions.”

Moreover, we can­not expect that a con­trol strat­egy effec­tive against one dis­ease is so even against the other,” he added.

Among the urgent goals of the cur­rent research is to define poten­tial con­tain­ment mea­sures for the fun­gus, as it might be pos­si­ble that it is spread­ing and it could reach other areas.

We are now in the first phase of the study, and a full light has still to be shed on this phy­tosan­i­tary prob­lem,” Pilotti said. Then, on the basis of the acquired knowl­edge, it will be estab­lished how to man­age the dis­ease.”

Importantly, to date, we observed that the olive groves not recently pruned are not affected by the symp­to­ma­tol­ogy,” he con­tin­ued. This seems to be rel­e­vant for under­stand­ing the dif­fu­sion modal­i­ties of the dis­ease and con­se­quently, if con­firmed, estab­lish effec­tive con­tain­ment mea­sures.”

The researchers next hope to expand sam­pling in all affected areas, iden­tify the asso­ci­ated fungi, assess their path­o­genic­ity and iden­tify epi­demi­o­log­i­cal fac­tors facil­i­tat­ing the spread of the dis­ease.


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