The peacock eye of the olive tree

Peacock eye or cycloconium is one of the most common fungal diseases that attack olive trees, especially in areas with a Mediterranean climate. It is characterized by characteristic circular spots on the leaves, called eyes.

The damage caused can be more or less serious depending on the soil conditions and the climate of the area where the olive trees are located.

The greatest infections are found mainly in flat areas, where there is stagnation of moisture. The variety of olive chosen also influences, since there are varieties that are less sensitive than others.

Contents [Ocultar]

  • How to recognize the disease

  • Peacock Eye Diseases

  • Cycloconium Damage

  • diagnostic techniques

  • The fight against cycloconium by biological methods

    • prevent disease

    • Organic Peacock Eye Care


How to recognize the disease

The most obvious symptoms of peacock eye (Spilacea oleaginea) are found on the leaves, where circular gray spots tending to dark green appear, surrounded by a yellow halo, called “eyes”. The spots will be more or less extensive depending on the vegetative stage of the fungus.

Compared to the surface occupied by the spot, the sheet gradually tends to yellow and fall off. The olive tree is weakened by this defoliation which eliminates photosynthesis on the surface of the plant.

Conditions Under Which Peacock Eye Occurs

Cycloconium is spread by conidia, which are the asexually reproducing form of the disease-causing fungus. Conidia are transported through the environment by insects and rainwater. For this reason, the presence of water in the olive leaves is the main infection factor, as it favors the germination and penetration of the cones inside the leaves.

For infection to occur, there must be a veil of water on the surface of the leaf, after heavy rainfall or persistent fog, with a humidity percentage close to saturation. The optimal infection temperature is between 18 and 20°C. These climatic conditions are typical of southern regions, especially in the autumn and spring periods, but also in the milder winter periods.

Another interesting aspect to consider in the control of the disease is the lack of possibility of determining cone infections present on fallen leaves.

cycloconium damage

It has been mentioned that mouse damage mainly affects leaves. In reality, for there to be a significant drop in production, the peacock eye attack must affect at least 30% of the leaves of the olive tree. Significant leaf drop can lead to serious hormonal imbalances that interfere with flower formation and thus lead to a significant drop in olive production.

diagnostic techniques

In organic farming, it is important to be aware of problems early on, so that you can act quickly to counter them. Here are two methods that can be useful for early diagnosis. These techniques should be applied when temperatures and humidity levels are favorable for the disease.

  • Immerse a leaf sample in a 5% sodium or potassium hydroxide solution or at 50-60°C for 3-4 minutes. If the leaves have been infected under these conditions, the characteristic peacock eye notches will appear.

  • Latent infections can also be visualized by exposing olive leaves to UV light. which makes it possible to highlight the fluorescence produced by the infected zones.

The fight against cycloconium by biological methods

disease prevention

For the organic cultivation of the olive tree, it is essential to prevent the disease, which is carried out with various means.

  • Use of resistant varieties . There are cultivars less susceptible to peacock eye, studies in Italy have revealed some interesting indications. It seems that cultivars such as ‘Cassanese’, ‘Gentile di Chieti’, ‘Kalinjot’, ‘Kokermadh i Berat’, ‘Leccino’ and ‘Cipressino’ are less susceptible to this disease. The small susceptibility also shows ‘Ottobratica’, ‘Zaituna’, ‘Pisciottana’, ‘Cellina di Nardò’, ‘Dolce Agogia’.
  • Distance between floors . In the case of new olive plantations in areas where the disease is present, it is advisable to adopt wide sixths, especially 6×6 or even 7×7. In fact, the sixth wide does not favor the stagnation of moisture.
  • Cut. Another method of preventing the disease is to carry out a pruning that favors aeration and the penetration of the sun’s rays inside the crown of the tree and that avoids having shaded areas, always with the aim discourage stagnation of water and moisture. In any case, it is advisable to carry out a balanced pruning, which minimizes the phenomenon of alternate production and extensive wounds.
  • Irrigation . In the case of irrigated olive groves, attention should also be paid to the choice of irrigation method. A method that avoids wetting the crown, such as drip irrigation, would be preferable.

biological treatments for peacock eye

The eye of the peacock is also contrasted by carrying out treatments, in organic farming we generally intervene with copper-based products, in particular with the use of oxychlorides, which are more effective and associated with insecticides. They promote phyliptosis, therefore the elimination of the inoculum. However, copper-based treatments stay in the ground for a long time and are therefore not without consequences, so they should only be carried out when really needed. A more natural alternative is the use of horsetail decoctions, which can serve as a preventive measure to strengthen the plant’s defences, even if it is a mild precaution, which does not have the effectiveness of a treatment.

To plan when to carry out the treatments on the olive tree, it must be taken into account that spring infections have a longer incubation period (2-3 months) than autumn ones. In the summer period, it is possible to diagnose the presence of infections before their obvious manifestation on the leaves thanks to the method of “early diagnosis”, illustrated above.

Autumn infections, on the other hand, appear in a short time, usually 15 to 20 days, and are characterized by smaller spots, which also affect young leaves.

Disease control should be carried out according to the degree of infection found in the olive grove at the end of winter. If the olive grove has a high percentage of infected leaves, an intervention must be carried out before vegetative regrowth occurs. Subsequently, before flowering, when the first 3-4 leaf nodes are formed, a second intervention must be carried out to protect the newly formed vegetation and devitalize the cones present on the leaves.

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