The application of copper is essential in cherry orchards in formation and production, with the aim of preventing certain diseases, one of the main ones being bacterial cancer. We spoke about this with the Co-founder and general manager of Diagnofruit Laboratories, Héctor García.
- When and why to apply copper in cherry orchards?
«We could talk about three periods: winter, autumn (leaf fall) and early spring. The idea is to keep Pseudomonas populations low, essentially, at critical times of infection. Critical times are determined by the phenology of the plant, which is closely related to the climate. In a simple way, during dry and hot periods, or on the contrary, very cold periods, populations remain at very low levels. Then, in spring, when temperatures are mild, there are occasional frosts, but then conditions recover and there are also sessile tissues such as flowers, it is the time of greatest risk due to significant population increases that could end up triggering an infectious process. In autumn, when humidity increases with mild temperatures and we have the presence of wounds from falling leaves, it is another critical time to take care of the plant.»
- What is the relevance of copper in the phytosanitary program?
«The fungicidal and bactericidal properties of copper are well known and recognised. Its use in modern agriculture was probably consolidated when grapes were “painted” with Bordeaux mixture in Europe so that they would not be consumed before the harvest. At that time, it was realised that it stopped important fungal diseases and its use began worldwide. Today, technologies have been generated that consider copper nanoparticles as a powerful source of pathogen control. In this way, it is a fundamental tool to maintain the phytosanitary status of crops such as stone fruit and walnuts, but it must obviously be used rationally.»
- Should copper be applied regardless of the geographical area where the orchard is located? That is, are the same applications indicated for Ovalle, the central area or Chile Chico?
«Without having extensive knowledge of the northern region of Chile in relation to cherry trees (I take this opportunity to be invited), I believe that it is a biocide that we cannot ignore in any region. Climate change and new varieties leave us with doubts and risks, so we must leave as few uncertainties as possible associated with crop protection, considering, in addition, that this type of product acts preventively, there is not much room for speculation. Depending on the area, the more southerly the greater the risk, we could shorten application windows or add other strategies due to this possibility of higher infections.»
- What are the main recommendations when applying copper?
«The ideal, for me, but I know that it is not easy for the producer, is to always apply copper only in the pond, because what we are looking for is a release of Cu+2, without interference. Some copper sulphates pentahydrate require the use of pH correctors, to increase the release of ionic copper, so when using this type of product always read recommendations for use. Personally, my preference, something that we are studying in the field as well, is to leave copper hydroxide or cuprous oxides for this time, winter, and flank this period, that is, leaf fall (autumn) and then the beginning of spring with formulations based on copper sulphate, with this we reduce the total amount of copper applied, maintaining constant protection of the orchard.
- Following the floods, should copper applications included in the phytosanitary programme be modified or increased?
«In damaged orchards we could increase the number of applications occasionally. If we manage to enter the orchard to apply, and we have cleaned the plants, an application of copper sulphate could hit the existing populations of Pseudomonas and some fungi, in some way the idea is to reduce the risk of infection in wounds caused by material washed away by overflowing rivers and canals. After that, I would continue with my usual winter copper plan. Now, according to the status of the orchard, we could add synthetic fungicides and/or biological control, if there is a threat of wood fungi or from heavy flooded soils the appearance of Phytophtora, but this analysis must be done case by case, for this we must examine plants, record the behavior of wounds, make a diagnosis and conclude the appropriate management.»
