Copper for olive groves has historically been used to prevent and cure some of the main diseases of this tree, such as repilo or verticillium wilt.
This mineral has historically been used for its ease of use, its effectiveness especially in the disease prevention caused by fungi and bacteria and their relative harmlessness compared to other more aggressive phytosanitary products.
Copper works very well against the different diseases of the olive grove, since it has an etoxic effect on fungiinhibiting spore germination.
In this article, we explain copper master keys for olive groves with the date of application, the dose and the main products used.
When to apply copper in olive groves
Initially, there is no established protocol for the use of copper for olive groves, as it can be used throughout the year. However, there are 2 clearly advanced seasons when copper is used in this crop (autumn and spring).
It must be taken into account that, according to the legislation, the the maximum dose of inorganic copper per year is 2.1 kg/ha. That is, pure copper. Thus, if we use a base of copper oxychloride (Cu 70% w/w), the maximum quantity of product per year is 3 kg/ha.
Some of the main types of copper suitable for olive groves are:
Modern forms of copper complexation are not registered as phytosanitary products but as nutritional products. They use organic agents to complex and protect copper, increasing its assimilation by the plant.
In the case of copper gluconate, the gluconic acid to complex it. Different studies have verified that, although the percentage of copper in the composition is much lower than with other products, the ability to enter the plant can even be higher.
At the beginning of bud break and before flowering, we have a margin of 1 to 2 months to carry out a stimulating treatment (usually nitrogen, amino acids or seaweed extracts) and the supply of copper.
The main purpose of copper for olive groves in spring is to reduce the multiplication of repilo, a disease that affects the leaves and that develops mainly with temperatures of 20 ºC and a little humidity, usual with spring rains.
The copper treatment prevents the installation of the repilo and can also considerably reduce the infection if it is already in the leaves of the olive grove, something that can be checked with the famous soda test or “repilo test”.
In the case where a large volume of infection has been detected in the soda test, it is interesting to combine copper with active phytosanitary materials. Here you can see those authorized with today’s date.
In the spring copper for the olive grove we generally recommend complexed or chelated coppers, since we are looking for greater penetration at the level of the leaf cuticle and less persistence in the leaf. Furthermore, it is important that the the olive grove does not stop growingespecially with the budding of its branches.
Copper in autumn and winter
The most recommended copper treatments for olive groves are those of autumn and winter, a period that coincides with the greatest ease of propagation of Spilocaea oleagina (I repeat).
In humid areas, this treatment with the fruits still on the tree prevents the advance of olive grove anthracnose (Colletotrichum). If the weather is very rainy and the ambient humidity is high, it is recommended to carry out more than one treatment.
At this time of year, a copper formulation that persists in sheet metal and resists washout (winter rains) is recommended. Higher concentration copper formulations are usually applied, such as copper hydroxide or copper oxychloride.
It is also advisable to apply a copper formulation with good penetration into the plant during pruning or just after harvest (especially when mechanized), because small wounds are generated in stems and branches which is necessary to heal to prevent the entry of any pathogen in wet weather
Copper dose for the olive tree
Foliar applications of copper for olive trees vary between 2 and 3 kg/ha, using a foliar mixture of approximately 1000 L.
Search for the direct contact of metallic copper with leaves and wood, a source of the development of diseases such as repilo or verticillium wilt, applications are generally made by by foliar application.
- Complexed copper (5-8% Cu w/w): 150-300 cc/hl in foliar application.
- Copper oxychloride 70% Cu: 200 g/hl in foliar application.
- Copper hydroxide 40% Cu: 2-2.5 kg/ha
Excess copper in the olive tree
The Cu2+ ion can be toxic for the olive grove under high dose conditions. Depending on whether or not the crop has enough openings in the leaves caused by the repilo fungus, the supply of copper may be greater and promote the selective drop of injured leaves.
However, under the doses recommended by the manufacturers and controlling the products with which they are mixed, it is quite difficult for an olive tree to suffer from toxicity by copperbecause it is quite tolerant to this metal.