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Greek Olive Growers Face Sharp Declines as Pests Ravage Harvest

Late rains, pest infestations and labor shortages are converging to make this one of Greece’s most difficult olive oil seasons in decades.
Healthy Koroneiki olives and olives infected by the gloeosporium (brown olives) being processed at a mill in the Peloponnese (Photo: Costas Vasilopoulos)
By Costas Vasilopoulos
Jan. 7, 2026 15:14 UTC
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The olive har­vest in Greece is fac­ing a cri­sis due to below-aver­age yields caused by late-autumn rains and humid­ity, lead­ing to sig­nif­i­cant dam­age to olive fruit and a poten­tial 30 – 35% decrease in pro­duc­tion com­pared to the pre­vi­ous year. Proliferation of pests like the fruit fly and gloeospo­rium has caused wide­spread dam­age in some regions, with some farm­ers resort­ing to joint milling prac­tices to address labor short­ages and pro­cess­ing chal­lenges.

The year’s olive har­vest is unfold­ing as a cri­sis in Greece, as ini­tial pro­jec­tions for a below-aver­age olive oil yield increas­ingly become real­ity.

We are likely expe­ri­enc­ing the worst olive oil sea­son in 30 years.- Yiannis Iliadis, Messenia olive oil millers’ asso­ci­a­tion

The impact is most severe in the country’s south­west, where late-autumn rains and ele­vated humid­ity have fueled pest out­breaks that have sig­nif­i­cantly dam­aged olive fruit.

We are likely expe­ri­enc­ing the worst olive oil sea­son in 30 years,” said Yiannis Iliadis, a mill owner from the vil­lage of Andania and head of the olive oil millers’ asso­ci­a­tion of Messenia in the Peloponnese.

The fruit fly and gloeospo­rium have taken a heavy toll on the season’s fresh olive oils,” Iliadis added. The olives have already started to rot, and pro­duc­ers are rush­ing to extract what­ever quan­tity of olive oil they can.”

Messenian olive farm­ers and pro­duc­ers said state-run crop-dust­ing oper­a­tions to con­trol the olive fruit fly were car­ried out too late this year, allow­ing the pest pop­u­la­tion to mul­ti­ply dur­ing the sum­mer and inflict wide­spread dam­age.

Koroneiki olives and olives infected by the gloeosporium (brown olives) being processed at a mill in the Peloponnese (Photo: Costas Vasilopoulos)

The agri­cul­tural asso­ci­a­tion of Chandrinos in cen­tral Messenia has also filed a law­suit against those respon­si­ble, argu­ing that delayed pest-con­trol mea­sures exac­er­bated the cri­sis and caused sig­nif­i­cant finan­cial losses.

In nearby Strefi and Aristomenis, millers reported acid­ity lev­els in some freshly pro­duced olive oils rang­ing from 1 to 2, and even higher.

We have even seen olive oils with acid­ity above two degrees this sea­son due to pest dam­age,” local millers said. We need colder win­ters, which unfor­tu­nately are no longer com­ing.”

Olive oil acid­ity — the level of free fatty acids present in the oil — is a key indi­ca­tor of qual­ity. Oils with acid­ity up to 0.8 per­cent may be clas­si­fied as extra vir­gin, the high­est qual­ity grade, pro­vided they also meet the required sen­sory stan­dards.

Producers said their biggest con­cern this year is gloeospo­rium, a fun­gal dis­ease that causes olives to rot and become unsuit­able for pro­cess­ing.

The fun­gus pro­lif­er­ates rapidly under mild tem­per­a­tures and high humid­ity, caus­ing olive anthrac­nose, which leads to fruit rot­ting and mum­mi­fi­ca­tion and can severely com­pro­mise olive oil qual­ity.

However, pest dam­age has not been uni­form across Messenia, with some areas largely spared.

Our fresh oils have an acid­ity of 0.3, which shows that qual­ity remains high this sea­son,” said olive farmer Ilias Koroneos from the vil­lage of Lambena.

In neigh­bor­ing Ilia, in the west­ern Peloponnese, har­vest­ing also began ear­lier than usual to min­i­mize pest-related losses.

Local agron­o­mist Panagiotis Gourdoumpas said gloeospo­rium has spread to olive groves at higher alti­tudes, threat­en­ing oil qual­ity and forc­ing pro­duc­ers to rush their olives to the mills.

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He added that olive oil pro­duc­tion in Ilia is expected to fall by 30 to 35 per­cent com­pared to last year, due to pest pres­sure and the nat­ural pro­duc­tion cycle fol­low­ing a strong 2024/25 sea­son.

Olive pests have also inten­si­fied pres­sure on grow­ers in Aetolia-Acarnania in west­ern-cen­tral Greece, where gloeospo­rium infes­ta­tions have caused exten­sive fruit drop.

Aetolia-Acarnania is among Greece’s most impor­tant olive-pro­duc­ing regions, cul­ti­vat­ing mainly Koroneiki olives as well as Kalamon (Kalamata) table olives, which are also widely used for olive oil pro­duc­tion.

Producers in other regions were hop­ing for rain, but for us the heavy rain­fall had the oppo­site effect,” said miller Dimitris Gantzoudis, who oper­ates an olive mill in Stamna, north of Mesolonghi.

October rains com­bined with mild tem­per­a­tures favored the spread of gloeospo­rium, with dev­as­tat­ing con­se­quences for both qual­ity and quan­tity,” Gantzoudis added.

He said many pro­duc­ers are har­vest­ing as early as pos­si­ble to limit fur­ther dam­age and shorten the sea­son, while some have aban­doned har­vest­ing alto­gether.

Gantzoudis also said labor short­ages have forced him to adopt milling prac­tices more com­monly used in Italy and Spain.

Due to the lack of work­ers, we can­not process each producer’s olives sep­a­rately,” he said. Instead, we pur­chase the olives and process them together based on qual­ity.”

Joint milling remains rare in Greece, where olives are tra­di­tion­ally processed sep­a­rately due to the frag­men­ta­tion of olive groves, with millers retain­ing a per­cent­age of oil as pay­ment.

The chal­lenges we face require adap­ta­tion,” Gantzoudis said. Labor short­ages and abnor­mal weather con­di­tions are our biggest prob­lems, and they are unlikely to dis­ap­pear any­time soon.”

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