Olive rot

Olive rot, rotten olives PhotosVarious fungi cause olive rot, the best known for their incidence are the soapy olive (Colletotrichum), Leprosy (Phlyctema wanderer) and the olive fruit root  (Dalmatian Sphaeropsis).

Other fungi that are considered secondary pathogens and even fungi saprophytes penetrate the olives that have been damaged. Spreading fungi reduces fatty performance and get worse the quality of the oil.

Symptoms according to the fungi causing the rot

There are various fungi that affect the olive causing rotting and reducing the quality of olive oil.

Fusarium moniliforme: in the position of the lenticels of the olive, orange or red dots appear.

Geotrichum candidum: wrinkles the olive and a whitish coloration occurs on the surface (mycelium of the fungus).

Alternaria alternata: dry and black rot.

Cladosporium herbarum: generates a mold of color greenish.

Phomopsis sp.: Mummifies the olive.

All these and other mushrooms reduce the quality of the oil by varying the following factors:

Acidity: increase the degree of acidity of the oil.

Peroxides: The peroxide index is increased.

Toxins: fungi such as Alternaria alternata produce toxins that can pass into the oil.

Development of the rot of the olive

Generally the rot affects the ripe olives and with wounds (from insects, weather causes (hail), during the collection…). Day laborers should be aware of this and step on the smallest number of olives possible during harvest.

The main cause of olive rot is cultural practices. Storing the olives in sacks for several days or in the mill itself progressively reduces the quality of the oil due to the effects of fungi and oxidation.

As a consequence of prolonged olives storage, the olive oil crushing occurs.

Therefore, it is essential to deliver the olives collected daily to the mill and a quick grind. Do not store the olive is the best way not to lose the quality of the oil from our harvested olives. It is important to note that the loss of quality has influence on the price of olive oil.

Recommended Reading

More information about olive diseases:

Acariosis of the olive tree


Olive Moth


Olive fly

Fumagina or Negrilla


We have translated the information on our website from Spanish to English. Note that some words may have seen their meaning altered during their translation.

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