Treatment and fight against repilo in olive grove

If we had to ask a farmer about a disease in the olive grove , the first thing that would cross his mind is the repilo . A fungus spread almost throughout the whole of Spain and that affects many hectares of olive groves. We are going to learn a little more about this well-known problem in olive trees. 

The repilo, as it is known normally, is a typical disease of the olive tree caused by the fungus  There is no problem that can match it in terms of presence (yes in terms of difficulty of treatment).

For this reason, the most typical measures for its treatment consist of preventive treatments based on copper , as we will see later.

One of the problems that it creates in the tree, whose fungus is installed in the olive leaves, is that, in the long run, it produces an intense defoliation and loss of vegetative mass. With that, he manages to greatly weaken the tree and decrease its productivity.

SYMPTOMS AND DAMAGE OF THE OLIVE LEAF SPOT

Although it can appear in different ways, the most characteristic symptom of the repilo is the appearance, in the upper part of the leaf, of a very characteristic circular spot.

It has a very striking color and a dark colored circle. Later, as the disease progresses, a yellow halo forms and the central area also turns yellow.

Once the conidia are formed, again that halo or spot turns dark in color.

Although it is not very frequent, the repilo can also be seen in the petiole of the leaves , the part that joins the branch and the fruit. They are spots with a dark hue and an elongated shape. The petiole weakens and the leaf abcisions, which falls to the ground.

HOW AND WHEN DOES THE REPILO APPEAR IN THE OLIVE GROVE?

We have to know that the repilo is a fungus that survives in difficult conditions and has a great propagation capacity.

It survives on fallen leaves found on the ground and even on olive tree leaves that have not yet fallen. Its spread occurs practically throughout the year, although there are more common periods of infection.

These periods of greatest spread of the repilo occur in the months of September to November and from February to April. For this reason, in many areas two treatments are usually carried out to eliminate the disease in the olive grove.

For its germination, the repilo needs availability of water (environmental humidity that captures the leaves). It survives in a wide range of temperatures, these being between 8ºC and 24ºC. The optimum temperature for its maximum development and propagation is 20 ºC.

Being the repilo in the leaf and with good climatic conditions, the mycelium of the fungus begins to penetrate inside the epidermis, growing inter and intracellularly. This also usually happens in the rainy season (due to the availability of water or humidity that we have said needed the disease).

Once the mycelium is already inside the leaves, the conidia or fruiting bodies begin to be seen physically in the upper part of the leaves, forming those circular spots or chlorotic rings that we have mentioned previously.

If the rainy period continues, the conidia of the repilo spread rapidly . That is why, initially, this disease is expressed in the lower part of the olive tree, which is the area that is normally most affected.

TREATMENT OF THE REPILO IN THE OLIVE TREE

Let’s see the active materials authorized for the control of the repilo in the olive grove.

  • ENTIAVALICARB ISOPROPIL 1,75% + MANCOZEB 70%
  • DIFENOCONAZOL 1,67% y 25%
  • DODINA 40% [SC] P/V
  • CUPRIC HYDROXIDES
  • KRESOXIM-METIL 50% [WG] P/P
  • MANCOZEB
  • COPPER OXYCHLORIDE
  • CUPROSE OXIDE
  • CUPROCALLIC SULFATE
  • COPPER SULPHATE
  • TEBUCONAZOL 20%
  • TRIFLOXISTROBIN 50% [WG] P/P

date: 03/28/2016

It is also important to know when to perform the treatment. The application of these compounds is usually done after the harvest (for many in October, for others after December, depending on the area), and at the end of winter, before the olive season begins again.

If we are in an area that is very sensitive to repilo infection, we must be more vigilant and carry out treatments every time there is rain in autumn or winter. 

It is also interesting to carry out a copper-based treatment after pruning. With this we avoid the entry of fungi in the felling cuts.

Let’s not forget that many of these treatments are preventive and not curative, so the application of the products must be as effective as possible. Emphasis must be placed on the lower part of the tree (low and interior areas), where the repilo is installed more easily.

Normally, it is preferable to do preventive treatments against the repilo after the harvest and before the emergence of new buds. The use of copper is more than standardized in the olive grove.

 

SOME TIPS IN THE APPLICATION OF COPPERS AND PHYTOSANITARY PRODUCTS

  • Take into account the safety period of the products we use and, above all, their mixtures. Not all phytosanitary products mix well, depending on their dose, with coppers or other nutritional products.
  • The working pressure in foliar application is recommended not to exceed 40 atm.
  • Summer is the time of least activity of the fungus, due to the low humidity and the temperature.
  • The pruning operation is very important, since it improves the ventilation of the internal parts of the tree and reduces the proliferation of the repilo.
  • Excess nitrogen fertilizers, whatever their type, increase the probability of disease development, as occurs with other fungi and insects.

ECOLOGICAL TREATMENT OF THE OLIVE LEAF

Within the ecological techniques, there are cultural tasks that reduce the propagation capacity of the repilo.

Good ventilation of the crop is a very important task to reduce the accumulation of moisture on the leaves and branches that the repilo likes so much. Hence, pruning is very important in the olive grove.

Guide to pruning the olive grove

In addition, if we are in an area that is very prone to the development of the repilo (due to the environmental conditions of the environment) it is a good idea to select seedlings with greater resistance to the repilo, such as:

  • Picual variety
  • Hojiblanca
  • Manzanilla
  • Zorzaleña
  • Acebuche
  • Surcharge
  • Cornicabra
  • Lechin

Apart from the correct selection of plant material, the pruning carried out at the time to improve the collection and control of nitrogen fertilization, in  organic farming there are also preventive treatments for the olive grove, based on copper.

We go to REGULATION (CE) nº 889/2008, on production and labeling of organic products.

In the section on substances traditionally used in organic farming, table A:

Copper in the form of copper hydroxide, copper oxychloride, tribasic copper sulfate, cuprous oxide, or copper octanate. 

You just have to keep in mind that the description says the following:

Use as a fungicide.

Up to 6 kg of copper per hectare and year.

ONE MORE COMPLICATION, THE LEADEN REPILO

The leaden repilo is caused by Cercospora cladosporioides , and it presents many differences with the repilo and also with anthracnose.

It is also known as cercosporiosis and practically all olive growing areas in Spain and the world suffer.

The damage caused by the leaden horn is often quite confused (often due to ignorance of the disease) and a symptom of chlorosis that is attempted to be corrected with the application of correctors (iron chelates, for example).

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