It is recommended to stop treatments with mineral oils when temperatures are high – above 30 °C –; however, this condition is difficult to achieve at times of application in summer months. Mineral oils create a fatty film on the surface of the plant, thus preventing it from transpiring. This action, in combination with high temperatures, leads to an increase in vapour pressure, which originates the production of highly reactive free radicals, causing irreversible damage at cell level (ostioles of the stomata) and thus resulting in burns, desiccation, defoliation, etc.
Free radicals are highly reactive species, and therefore interact rapidly with the substances that are around them, leading to the degradation of these latter. This degradation results in visible tissue burns (cell necrosis).
Antioxidants are substances able to neutralise the action of free radicals. That is why it is highly recommended to apply stressoil in combination with mineral oils, so as to avoid the oxidative and destructive action of these free radicals from the beginning.
Because of its special formulation, stressoil protects the fatty acids of oil against oxidation by atmospheric oxygen and high temperatures.
It is well-known that the application of mineral oils has a negative action on fruit growth, as it may temporarily paralyse fruit development and even cause stress (accumulation of sodium ions Na+).
Applications of stressoil help the fruit not to stop growing, through the action of both the anti-stress agents it contains and that of potassium. This latter optimises the functioning of the Na+/K+ pump, which plays an important role in maintaining cell volume and turgency, thus attenuating fruit stress.
