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Pistachio flowering: the biological clock that determines harvest success
Olive leaf spot disease (Spilocaea oleagina) is undoubtedly one of the most widespread and concerning diseases for olive growers worldwide. This fungus mainly affects the leaves, but can also affect the fruit or stalk. If it is not managed accurately, it can cause significant production losses and jeopardise the profitability of the farm.
Not only does its presence reduce the tree’s photosynthetic capacity, it also causes premature defoliation, which weakens the olive grove and drastically reduces the current and future harvests.
The occurrence of olive leaf spot is closely linked to specific weather conditions. The fungus requires very high relative humidity and the presence of rainwater or persistent dew on the leaf surface in order for its conidia to germinate.
In terms of temperature, this olive disease develops optimally at temperatures between 14°C and 20°C, making spring and autumn the periods of maximum risk. It is important to take into account the fungus’s ability to survive in a dormant state, as infection may occur in one season and not manifest until the next.
The most characteristic symptoms of olive leaf spot, popularly known as ‘turkey eye’ or ‘rooster eye’ due to their resemblance to the organs of these birds, appear on the upper side of the leaf as dark circular spots surrounded by a yellowish halo. This is an unmistakable sign that the infection has colonised the tissue.
Historically, control of this disease has relied almost exclusively on preventive treatments based on copper salts. However, the current regulatory framework increasingly limits the use of heavy metals, and the growing demand for sustainable, rational agriculture pushes us to look for alternatives that reduce the copper load in the soil without compromising crop protection.
It is in this context that biocontrol solutions become vitally important. These products act as an effective tool against the pathogen and allow more balanced and sustainable management of olive groves, in line with integrated strategies and residue-free farming. Understanding how to integrate these solutions into the phytosanitary strategy is essential for maintaining plant health efficiently.
To control olive leaf spot, the Spanish company Seipasa has just launched Basei Mg, a new foliar protection tool based on magnesium hydroxide, with a preventive and curative contact action. Basei Mg generates a stable alkaline coating that hinders the germination and development of surface fungi. The product works with a barrier effect whereby the alkaline pH film of microparticles on the plant surface hinders spore germination and fungal penetration. Basei Mg can also activate plant defence mechanisms.
Graph 1 shows the performance of Basei Mg for controlling olive leaf spot, comparing the product’s efficacy with a conventional treatment based on copper oxychloride. The trial was carried out in a manzanilla olive grove in the Valencian town of Anna, with one application and four repetitions per treatment.
Focusing on leaf incidence (the percentage of leaves displaying symptoms), we observe that Basei Mg demonstrates comparable or superior performance to the copper-based reference treatment, thereby slowing down the development of inoculum and disease.
One of the major advantages of Basei Mg is that it effectively treats the disease, reducing the need for copper-based treatments and dependence on conventional, chemically synthesised fungicides.
EU regulations limit the amount of copper per hectare due to its accumulation in the soil, so Basei Mg is an optimal alternative for use in integrated strategies that reduce the use of this heavy metal and replace it with more sustainable, effective solutions.
