By the end of November 2025, sudden and marked drops in temperature had occurred. Although the temperature drops did not reach immediately lethal freezing levels, a drop below 3 – 5°C puts the olive tree in a state of physiological alarm.
At this threshold, in fact, the cold acclimatization process (Cold Hardening), a phase that requires a slow and gradual drop in temperature to fully develop winter tolerance. A sudden drop in temperature in November abruptly interrupts this acclimatization, leaving the tissues vulnerable and less protected in the event of subsequent frosts below freezing.
Il Frost damage in olive trees is one of the main critical issues. It is triggered by the transformation of free water into ice, a process that occurs mainly in the extracellular space, i.e., theor microscopic space between cells, Called apoplast.
When water freezes in the apoplast, the ice crystals that form attract and withdraw liquid water from the interior of the cell (the cytoplasm). This phenomenon causes a prolonged dehydration of the cell which, rapidly losing its water content, can cause it to collapse and lead to lethal damage.
The greatest sensitivity is found in young tissues, such as shoots and growing branches. The high percentage of free water and the lower rigidity of the cell walls of these tissues make them particularly vulnerable. The rapidity with which ice forms and grows can cause physical tearing of plasma membranes and irreversible disorganization of cytoplasmic structures.
It is proven that a sudden cooling is more harmful, as it inhibits the effective activation of acclimatization mechanisms. A gradual reduction, on the other hand, favors the accumulation of cryoprotective solutes and promotes partial, controlled cellular dehydration.
Functional nutrition in the olive grove
In this scenario, functional nutrition is proposed as a preventive strategyPhosphorus and potassium, along with trace elements such as calcium, boron, zinc, and silicon, play an important role in reducing the risk of frost damage.
Il Phosphorus It is essential for the synthesis of membrane phospholipids and for cellular energy, helping to lower the intracellular freezing point. Potassium regulates osmotic potential and stomatal response, limiting dehydration. Calcium stabilizes membranes and the middle lamella, while boron strengthens the wall and sugar transport. Zinc and silicon complete the picture, supporting antioxidant enzymes and strengthening cellular structures.
Between North and South Italy
However, a crucial geographical difference must be underlined, Northern Italy, where low temperatures already at the end of November significantly reduce root activity, the absorption capacity from the soil is limited. Under these conditions, phosphorus, potassium, and microelement inputs must be scheduled before the temperature drops or managed with targeted foliar treatments, which become the only operational channel for increasing cellular solutes and strengthening membranes. South and IslandsOn the other hand, the milder climate allows the roots to maintain a certain level of absorption. Under these conditions, it's possible to intervene not only with soil fertilizers based on potassium sulfate or magnesium sulfate, but also with phosphorus supplements, for example through formulations such as monoammonium phosphate.
In practical terms, we are talking about orientative contributions equal to 30–60 kilograms of P2O5 per hectare and 60–120 kilograms of K2O per hectare, distributed in the post-harvest period and until December.
Phosphorus, in addition to supporting cellular energy, contributes to membrane stability and lowers the intracellular freezing point, while potassium regulates osmotic balance and reduces dehydration. The application window extends until December and allows for a combined approach, in which root nutrition can be combined with targeted foliar treatments, further strengthening the olive tree's ability to withstand temperature changes.
Foliar products
In addition to internal nutrition, which supports the biochemical mechanisms of resistance, there is the possibility of combine foliar products with "thermoprotective" and "osmoregulating" functions, composed of short-chain polyols such as glycerol or sorbitol (for example the product “Cerere” by FCP Cerea), indicated to help the plant limit damage from cold stress.
An additional protection tool is represented by the use of glycol-based formulations, such as ethylene or propylene glycol.
These compounds, applied via foliar application, create a protective film on the plant surface that reduces heat dispersion and minimizes heat loss through radiation, helping to maintain a slightly warmer tissue microclimate.
In conclusion, managing frost resistance in olive trees involves several fronts: on the one hand, optimizing internal biochemical mechanisms through targeted nutrition that varies according to geographic and climatic conditions; on the other, applying thermal protectors and external physical barriers, such as polyols and glycols, which help modulate freezing kinetics and limit thermal energy loss. It is precisely this integration—calibrated between North and South—that can offer olive trees greater resilience to the challenges of winter cold.
Director Aipo
Interregional Association
Olive producers
