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Despite the charm of the name, behind it lies a terrible disease that affects the olive tree in all areas where it is grown. This is a rather serious problem that must be treated with equal seriousness and stubbornness because the damage is by no means insignificant.
We can well say that thepeacock eye is the main cryptogamic disease of the olive tree and its development is closely linked to the whims of the sky, al weather. Unfortunately it has a very long incubation period so it is not easy to act to counter it with the readiness that would instead be needed to win it without recording too much damage. However, efforts were made and, as we shall see, in order not to succumb to this disease, a two-phase defense strategy was invented, autumn and spring, especially useful in areas that are most affected by the peacock's eye. Let's go and find out
Peacock eye or Cycloconio: what it is
This disease mainly affects the leaves and is so called because it creates spots on their surface that have the shape of a peacock eye. What happens next? The older leaves tend to fall and as the rains, wind and rain vary, there is a certain spread of the disease throughout the tree canopy, especially in spring. If the fall is full-bodied and fast, you can get to lose the harvest of the vintage but it would be the least because in some cases it is the plant itself that can die.
We see immediately how the disease spreading mechanism works, understanding why the weather factor it is so important. It is precisely the wind and rain that facilitate its proliferation because they transport the conidia that reach the healthy parts of the plant. When the humidity level it is always high the conidia release the zoospores which develop a mycelium and this mycelium "sucks" the cellular substances of the plant, of its epidermal tissue, by osmosis, weakening it. It's not over, the mycelium emits some conidiospores which contain new conidia and thus diffusion proceeds at a rather high rate, especially if high percentages of relative humidity and temperatures between 10 and 20 ° C are recorded.
This happens both in spring and in autumn and the disease is diabolical to fight also because of its incubation period which can even reach 5 full months: spots seen in August, they may be the result of an infection that occurred in May, just to be clear. If you want to make a early diagnosis Samples of leaves are used to put in a 5% solution of sodium or potassium hydroxide for a few minutes at room temperature. If circular spots appear on the top page, the disease is ongoing.
Peacock eye: symptoms
The peacock eye attacks and manifests itself on the leaves but not only, also on the fruits and on the peduncle. At first we saw that it causes circular spots of color to appear brown, yellowish or greenish, up to one centimeter in diameter, spots that become blackish when spores appear and then whitish when an air chamber forms between the cuticle of the leaf and the underlying tissues. All this on the upper page while in the lower one in correspondence, there is a blackening of the central rib.
Also on the fruits this disease leaves its marks at the moment of ripening, when it drops them at the moment of harvesting, while already on peduncle dark spots appear but above all the passage of sap is blocked at the beginning of fruit formation or in the early stages of ripening, causing serious developmental damage to them.
Peacock eye: prevention
Given the really exaggerated incubation time, it is more important than ever to act in advance and try to prevent this disease in all ways. The most common preventive treatments are those that involve the use of copper-based products, to be applied before the germination of zoospore both in spring and autumn. More than Bordeaux mixture I am more effective are oxychlorides, among the cupric, and should be used twice during the year, towards the end of winter - early spring and after the first autumn rains.
It is important to know that cupric fungicides in this context can have a double value: they protect the healthy leaves and defoliate the infected ones because the copper is phytotoxic and penetrates the mesophyll of the leaves attacked by the peacock's eye. It is important that this happens because in this way the infected leaves, once fallen, do not constitute a danger to the healthy ones.
Broad spectrum fungicide against peacock eye
Among the many effective products that we can find online at our disposal, there is this broad spectrum of action containing copper in the form of tetraramic oxychloride precisely for the reasons we have explained. It is a fungicide in water-dispersible granules, convenient because it minimizes dusting phenomena during the preparation of the suspension to be sprayed and is therefore very easy to use.
Dodina versus Peacock Eye
Another type of product that we can use against the peacock's eye is dodine which therefore acts both curing old infections, both by preventing new ones from penetrating the leaf and eliminating the fungus just as it is developing and at the same time blocking new infections. There dodina leaves the cured leaves on the plant and allows them to feed the olives without interruption so as not to damage the crop. When choosing this product it is important to know that it also fights other diseases such as Olive mange and Anthracnose. Even with dodine, two treatments per year can be carried out, lasting at least 7 days.
Resistant olive tree against peacock eye
A complementary and not alternative way of preventing the peacock's eye may also be to choose more resistant varieties to this disease and avoid the most sensitive ones. This means to prefer Leccino, Coratina, Carolea, Santagatese, Tonda Iblea and Ogliarola Messina and at the same time forget the Pendolino, the Moraiolo, the Frantoio.